CN115207984B

CN115207984B - Power distribution method of micro-grid system and micro-grid system

Info

Publication number: CN115207984B
Application number: CN202110381686.3A
Authority: CN
Inventors: 王润涛; 李旸熙; 熊刚
Original assignee: Chint Group R & D Center Shanghai Co ltd
Current assignee: Chint Group R & D Center Shanghai Co ltd
Priority date: 2021-04-09
Filing date: 2021-04-09
Publication date: 2024-06-04
Anticipated expiration: 2041-04-09
Also published as: CN115207984A

Abstract

The invention relates to the technical field of energy, in particular to a power distribution method of a micro-grid system. The invention also relates to a micro-grid system applying the power distribution method, which can realize more reasonable and accurate power distribution.

Description

Power distribution method of micro-grid system and micro-grid system

Technical Field

The invention relates to the technical field of energy, in particular to a power distribution method of a micro-grid system, and especially relates to a power distribution method applied to the micro-grid system comprising an energy management system; the invention also relates to a micro-grid system applying the power distribution method.

Background

Micro grid systems include energy management systems (EMS systems) that involve a number of distributed power devices, such as photovoltaic power generation devices, fan power generation devices, etc., whose output power is subject to weather conditions; the reasonable power distribution method is beneficial to maximally utilizing the electric energy generated by the distributed power supply equipment. In addition, for the micro-grid system, in order to keep the electric quantity balance of each PCS (energy storage converter, power Conversion System) subsystem, the target power scheduling value of the micro-grid system is related to the available electric quantity (capacity) and rated power of the system, in general, the higher the available electric quantity of the system is, the higher the discharge power is, and the higher the available capacity is, the higher the charging power is; however, if the micro-grid system includes a plurality of PCS subsystems, brands, rated capacities and rated powers of the PCS subsystems are different, there is often a case that the target power scheduling value of the PCS subsystem is not matched with the rated power of the PCS subsystem, for example, the target power calculated according to the available electric quantity may be far greater than the rated power of the system.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a power distribution method of a micro-grid system, which is more reasonable and accurate in power distribution; the micro-grid system applying the power distribution method can realize reasonable and accurate power distribution.

In order to achieve the above purpose, the invention adopts the following technical scheme:

A power distribution method of a micro-grid system comprises an energy management system, a photovoltaic system and an energy storage system, wherein the power distribution method comprises the following steps:

step 1, the energy management system judges whether third party scheduling exists or not, and determines the total power P of the system according to a judging result;

step 2, comprising step 2a and step 2b:

Step 2a, if the total system power P is greater than a power threshold value P10, and the power threshold value P10 is greater than 0, the energy management system sequentially distributes the total system power P to the photovoltaic system and the energy storage system; if the total power P of the system is smaller than or equal to a power threshold value P10, executing the step 2b;

Step 2b, the energy management system judges whether the photovoltaic system and the energy storage system are available; if the photovoltaic system and the energy storage system are available, the energy management system sequentially distributes the total power P of the system to the photovoltaic system and the energy storage system; and if any one of the photovoltaic system and the energy storage system is unavailable, keeping the power of the photovoltaic system and the energy storage system unchanged.

Preferably, the power threshold value p10=rated power of the photovoltaic system x adjustment error of the photovoltaic system, wherein the adjustment error of the photovoltaic system is more than 0 and less than or equal to 5%.

Preferably, in step 1, when there is third party scheduling, the third party scheduling requires that the gateway table power is constant to be P0, then p= (p0—p01+p11); when the third party scheduling does not exist, the value range of the total power P of the system is [ max (ratio (P01-P03), P01-P03+P 04) +P11, min (ratio (P01-P02), P01-P02-P04) +P11];

Wherein, P0 is a system power scheduling value, and P01 is the gateway table power of the micro-grid system; p02 is the inverse power value of the micro-grid system; p03 is the current month demand of the micro grid system; p04 is an adjustment error of a photovoltaic device of the photovoltaic system or an energy storage device of the energy storage system; ratio is an adjustable coefficient; p11 is the current total power of the photovoltaic system and the energy storage system.

Preferably, 0 < ratio is less than or equal to 1.0.

Preferably, if the system power scheduling value P0 is smaller than max (ratio (P01-P03), P01-p03+p04) +p11, triggering a power adjustment process of the energy management system;

If the system power scheduling value is greater than min (ratio (P01-P02), P01-P02-P04) +P11, triggering the anti-reflux control of the energy management system;

If the photovoltaic system generates electricity with maximum power, the total power of the system p=min (ratio (P01-P02), P01-P02-P04) +p11.

Preferably, in step 2, the energy management system allocates the total system power P to the photovoltaic system and the energy storage system according to the following method: and after the power distribution of all the photovoltaic inverters of the photovoltaic system is completed, the sum of the power of all the photovoltaic inverters is P12, and the power to be distributed to the energy storage system is the energy storage system power target P1=P-P12.

Preferably, the available power of the photovoltaic system is greater than 0, which indicates that the photovoltaic system is available; and if the operation of the energy storage system is fault-free and the real-time power is larger than the rated charging power, the energy storage system is usable.

Preferably, in step 2, power distribution is performed on the energy storage system according to a current state of the energy storage system, where the current state of the energy storage system includes a discharging state and a charging state.

Preferably, the energy storage system is in a discharge state, and the power distribution is performed on the energy storage system according to the following rule:

If the remaining value of the power target P1 of the energy storage system is less than or equal to 0, the power distribution of the energy storage system is finished; if the remaining value of the power target P1 of the energy storage system is more than 0, continuing to distribute the power of each energy storage device of the energy storage system until the remaining value of the power target P1 of the energy storage system is less than or equal to 0;

Subtracting the power distributed to the energy storage equipment from the remaining value of the power target P1 of the energy storage system after finishing the power distribution of one energy storage equipment;

Any one of the energy storage devices sets the set power value of the energy storage device equal to the rated power of the energy storage device if the power to be distributed to the energy storage device is larger than the rated power of the energy storage device, and continues to distribute the power of other energy storage devices of the energy storage system; any energy storage equipment, if the power to be allocated to the energy storage equipment is less than or equal to the rated power of the energy storage equipment, setting the set power value of the energy storage equipment to be equal to the power to be allocated to the energy storage equipment;

Any of the energy storage devices, the power to be allocated to the energy storage device=the power target p1 of the energy storage system×the rated power of the energy storage device×the total remaining power of the SOC/energy storage system of the energy storage device.

Preferably, when the energy storage system is in a discharging state, the power distribution is performed on the energy storage system through the following steps:

Step S01: initializing, setting flag [ i ] =0, ps [ i ] =0; step S02 is performed.

Step S02: if P1 is less than or equal to 0, ending; if P1 > 0, setting i=0, count=0 and turning to step S03;

Step S03: if i < M, turning to step S04; if i is more than or equal to M, turning to step S05;

step S04: if flag [ i ] =1 then i=i+1 and go to step S03; if flag [ i ] =0, go to S06;

Step S05: if count >0, go to step S02; ending if count is less than or equal to 0;

step S06: if PR [ i ] =1, then fTemp =0, flag [ i ] =1 and go to step S07; if PR [ i ] =0, go to step S09;

Step S07: if fTemp > PE [ i ] then PS [ i ] =PE [ i ], P1=P1-PE [ i ], flag [ i ] =1, count=1, i=i+1 then go to step S03; if fTemp is less than or equal to PE [ i ], turning to step S08;

step S08: PS [ i ] = fTemp; i=i+1, turning to S03;

Step S09: if sum (E (i) SOC (i)) >0, then fTemp =p1×e (i) SOC (i)/sum (E (i) SOC (i)); fTemp =0.0 if sum (E (i) ×soc (i)) +.0 and step S07;

The energy storage system comprises M energy storage devices, M is an integer greater than 0, and the ith energy storage device is an energy storage device i; flag [ i ] =0 indicates that the energy storage device i is unoccupied, and flag [ i ] =1 indicates that the energy storage device i is occupied; PS [ i ] is the set power value of the energy storage device i; PE [ i ] represents the rated power value of the energy storage device i, when the energy storage device i discharges, the PE [ i ] is positive, and when the energy storage device i charges, the PE [ i ] is negative; SOC [ i ] is the real-time SOC of the energy storage device i, and Ei ] is the rated power of the energy storage device i; PR [ i ] represents the working condition of the energy storage device i, PR [ i ] =0 represents the normal communication state and operation state of the energy storage device i, and PR [ i ] =1 represents the abnormal communication state and/or operation state of the energy storage device i; the count is a variable representing the flag bit, if the count is more than 0, the power distribution is continued, and if the count is less than or equal to 0, the power distribution is completed; fTemp is a temporary variable representing the power to be allocated to the energy storage device i; p1 is the energy storage system power target.

Preferably, the energy storage system is in a charging state, and the following rules are followed for power distribution of the energy storage system:

If the remaining value of the power target P1 of the energy storage system is more than or equal to 0, the power distribution of the energy storage system is finished; if the remaining value P1 of the power target of the energy storage system is smaller than 0, continuing to distribute power to each energy storage device of the energy storage system until the remaining value P1 of the power target of the energy storage system is larger than or equal to 0;

Any of the energy storage devices, the power to be distributed to the energy storage device=the power target P1 of the energy storage system is multiplied by the rated power of the energy storage device (100-the SOC of the energy storage device)/the total residual power of the energy storage system.

Preferably, when the energy storage system is in a charging state, power is distributed to the energy storage system through the following steps:

Step S11: initializing, setting flag [ i ] =0, ps [ i ] =0; step S12 is performed.

Step S12: ending if P1 is more than or equal to 0; if P1 < 0, setting i=0, count=0 and turning to step S13;

Step S13: if i < M, go to step S14; if i is not less than M, turning to step S15;

step S14: if flag [ i ] =1, i=i+1 and go to step S13; if flag [ i ] =0, go to step S16;

Step S15: if count >0, go to step S12; ending if count is less than or equal to 0;

Step S16: if PR [ i ] is not equal to 0, fTemp =0 and flag [ i ] =1 are set, and step S17 is repeated; if PR [ i ] =0, go to step S19;

Step S17: if fTemp < PE [ i ], PS [ i ] =pe [ i ], p1=p1-PE [ i ], flag [ i ] =1, count=1, i=i+1, and go to step S13; if fTemp is more than or equal to PE [ i ], turning to step S18;

Step S18: if PS [ i ] = fTemp, i=i+1 and go to step S13;

Step S19: setting fTemp =p1×e (i) (100-SOC (i))/sum (E (i) (100-SOC (i))) if sum (E (i))) > 0; fTemp =0.0 if sum (E (i) ×100-SOC (i))) is less than or equal to 0 and step S17 is repeated;

The energy storage system comprises M energy storage devices, wherein M is an integer greater than or equal to 0, and the ith energy storage device is an energy storage device i; flag [ i ] =0 indicates that the energy storage device i is unoccupied, and flag [ i ] =1 indicates that the energy storage device i is occupied; PS [ i ] is the set power value of the energy storage device i; PE [ i ] represents the rated power value of the energy storage device i, when the energy storage device i discharges, the PE [ i ] is positive, and when the energy storage device i charges, the PE [ i ] is negative; SOC [ i ] is the real-time SOC of the energy storage device i; e i is the rated power of the energy storage device i; PR [ i ] represents the working condition of the energy storage device i, PR [ i ] =0 represents the normal communication state and operation state of the energy storage device i, and PR [ i ] =1 represents the abnormal communication state and/or operation state of the energy storage device i; the count is a variable representing the flag bit, if the count is more than 0, the power distribution is continued, and if the count is less than or equal to 0, the power distribution is completed; fTemp is a temporary variable representing the power to be allocated to the energy storage device i; p1 is the energy storage system power target.

Preferably, the photovoltaic system is allocated power according to the following rules:

If the remaining value of the power target P2 of the photovoltaic system is less than or equal to 0, the power distribution of the photovoltaic system is finished; if the remaining value of the photovoltaic system power target P2 is more than 0, continuing to distribute power to all photovoltaic devices of the photovoltaic system until the remaining value of the photovoltaic system power target P2 is less than or equal to 0;

Subtracting the power distributed to the photovoltaic equipment from the remaining value of the photovoltaic system power target P2 after the power distribution of one photovoltaic equipment is completed;

Any one of the photovoltaic devices sets the set power value of the photovoltaic device equal to the rated power of the photovoltaic device if the power to be distributed to the photovoltaic device is larger than the rated power of the photovoltaic device, and continuously distributes power to other photovoltaic devices of the photovoltaic system; any one of the photovoltaic devices sets a set power value of the photovoltaic device equal to the power to be distributed if the power to be distributed to the photovoltaic device is less than or equal to the rated power of the photovoltaic device;

Any of the photovoltaic devices to which power is to be allocated is equal to the photovoltaic system power target x the available power value of the photovoltaic device/the total available power value of the photovoltaic system.

Preferably, the photovoltaic system is allocated power by:

step S21: initializing, setting flag [ j ] =0, ps [ j ] =0; turning to step S22;

step S22: ending if P2 is less than or equal to 0; if P2 > 0, setting j=0, count=0, and turning to step S23;

Step S23: if j < N, go to step S24; if j is less than or equal to N, turning to step S25;

Step S24: if flag [ j ] =1 then j=j+1 and go to step S23; if flag [ j ] =0, go to step S26;

Step S25: if count >0, go to step S22; ending if count is less than or equal to 0;

step S26: if PR [ j ] is not equal to 0, fTemp =0 and flag [ j ] =1 are set, and step S27 is repeated; if PR [ j ] =0, go to step S29;

Step S27: if fTemp > PE [ j ] then PS [ j ] = PE [ j ], P2= P2-PS [ j ], flag [ j ] = 1, count = 1, j = j +1 and go to step S23; if fTemp is less than or equal to PE [ j ], turning to step S28;

Step S28: setting PS [ j ] = fTemp, j = j+1, and turning to step S23;

Step S29: if sum (PU [ j ]) >0, fTemp =P2 is set to be PU [ j ]/sum (PU [ j ]); if sum (PU [ j ]) is less than or equal to 0, fTemp =0.0 is set, and step S27 is carried out;

The photovoltaic system comprises N photovoltaic devices, wherein N is an integer larger than 0, and the j-th photovoltaic device is photovoltaic device j; flag [ j ] =0 indicates that the photovoltaic device j is unoccupied, and flag [ j ] =1 indicates that the photovoltaic device is occupied; PS [ j ] represents the set power value of the photovoltaic equipment j; PE [ j ] represents the rated power value of the photovoltaic equipment j; PC [ j ] represents the real-time power value of the photovoltaic equipment j; PU [ j ] represents an available power value of the photovoltaic equipment j; PR [ j ] represents the working condition of the photovoltaic equipment j, PR [ j ] =0 represents the normal communication state and operation state of the photovoltaic equipment j, and PR [ j ] =1 represents the abnormal communication state and/or operation state of the photovoltaic equipment j; the count is a variable representing the flag bit, if the count is more than 0, the power distribution is continued, and if the count is less than or equal to 0, the power distribution is completed; fTemp is a temporary variable representing the power to be distributed to the photovoltaic device j; p2 is a photovoltaic system power target; if PS [ j ] > PC [ j ], then PU [ j ] =PC [ j ], if PS [ j ]. Ltoreq.PC [ j ], then PU [ j ] =PE [ j ].

A micro grid system to which the power distribution method is applied; the micro-grid system comprises an energy management system, an auxiliary control system, a photovoltaic system and an energy storage system; the photovoltaic system comprises photovoltaic equipment and an inverter which are matched for use, and is connected into the micro-grid system through a switch K2; the energy storage system comprises a transformer T1, an energy storage battery and PCS which are matched for use, wherein each PCS is connected with one side of the transformer T1, and the other side of the transformer T1 is connected into the micro-grid system through a switch K1; the micro-grid system is connected with a public power supply through a switch K0 and connected with a load through a switch K3; the auxiliary control system comprises electric meters KMH1, KMH2 and KMH3 which are respectively in communication connection with the energy management system, the electric meters KMH2 are configured between the switch K1 and the transformer T1, the electric meters KMH1 are configured between the switch K0 and the photovoltaic system and the energy storage system, and the electric meters KMH3 are configured between the switch K0 and the switch K2.

According to the power distribution method of the micro-grid system, the total power P of the system is determined according to the judging result of whether the third party scheduling exists, so that the obtained total power P of the system is more accurate; and distributing the total system power P according to the comparison result of the total system power P and the power threshold value P10, so that the power distribution is more reasonable. In addition, the power distribution method defines the available power value of the photovoltaic equipment when the power distribution is carried out on the photovoltaic equipment, and avoids the conditions of excessive demand and countercurrent caused by excessive power fluctuation of the photovoltaic equipment in the adjusting process.

The micro-grid system can realize reasonable and accurate power distribution by applying the power distribution method.

Drawings

FIG. 1 is a schematic flow chart of an energy management system distributing power to an energy storage system when the energy storage system is in a discharging state;

FIG. 2 is a schematic flow chart of the energy management system distributing power to the energy storage system when the energy storage system is in a charged state;

FIG. 3 is a schematic flow chart of the power distribution of the photovoltaic system by the energy management system of the present invention;

FIG. 4 is a graph of theoretical operation of the photovoltaic system and energy storage system of the present invention;

FIG. 5 is a graph of actual operation of the photovoltaic system and energy storage system of the present invention;

fig. 6 is a schematic structural diagram of the micro grid system of the present invention.

Detailed Description

Specific embodiments of the power distribution method of the micro grid system of the present invention are further described below with reference to the embodiments shown in fig. 1-6. The power distribution method of the micro grid system of the present invention is not limited to the description of the following embodiments.

The invention relates to a power distribution method of a micro-grid system, which comprises an Energy Management System (EMS), a photovoltaic system and an energy storage system, and comprises the following steps:

step 2, comprising step 2a and step 2b:

Step 2a, if the total system power P is greater than a power threshold value P10, and the power threshold value P10 is greater than 0, the energy management system sequentially distributes the total system power P to the photovoltaic system and the energy storage system of the micro-grid system; if the total power P of the system is smaller than or equal to a power threshold value P10, executing the step 2b;

According to the power distribution method of the micro-grid system, the total power P of the system is determined according to the judging result of whether the third party scheduling exists, so that the obtained total power P of the system is more accurate; and distributing the total system power P according to the comparison result of the total system power P and the power threshold value P10, so that the power distribution is more reasonable.

It should be noted that the user sends a third party scheduling instruction to the energy management system through the upper computer.

Preferably, the power threshold value p10=rated power of the photovoltaic system x adjustment error of the photovoltaic system, wherein the adjustment error of the photovoltaic system is more than 0 and less than or equal to 5%. Further, the photovoltaic system adjustment error is 2%.

Preferably, in step 1, when there is third party scheduling, the third party scheduling requires that the gateway table power is constant to be P0, then p= (p0—p01+p11); when the third party scheduling does not exist, the value range of the total power P of the system is [ max (ratio (P01-P03), P01-P03+P 04) +P11, min (ratio (P01-P02), P01-P02-P04) +P11]; wherein, P0 is a system power scheduling value, and P01 is the gateway table power of the micro-grid system; p02 is the inverse power value of the micro-grid system; p03 is the current month demand of the micro grid system; p04 is an adjustment error of a photovoltaic device of the photovoltaic system or an energy storage device of the energy storage system; ratio is an adjustable coefficient; p11 is the current total power of the photovoltaic system and the energy storage system. Further, 0 < ratio is less than or equal to 1.0.

Preferably, if the system power scheduling value P0 is smaller than max (ratio (P01-P03), P01-p03+p04) +p11, triggering a power adjustment process of the energy management system; if the system power scheduling value is greater than min (ratio (P01-P02), P01-P02-P04) +P11, triggering the anti-reflux control of the energy management system; if the photovoltaic system generates power with maximum power, the total power of the system p=min (ratio (P01-P02), P01-P02-P04) +p11; otherwise, the total system power P is any value in the range of values, namely min (ratio (P01-P02), P01-P02-P04) +p11 < total system power P less than or equal to max (ratio (P01-P03), and P01-p03+p04) +p11.

Preferably, in step 2, power is distributed to the energy storage system according to the current state of the energy storage system, where the current state of the energy storage system includes a discharging state and a charging state.

As shown in fig. 6, an embodiment of the micro grid system is shown: the micro-grid system applies the power distribution method and comprises an Energy Management System (EMS), an auxiliary control system, a photovoltaic system and an energy storage system; the photovoltaic system comprises distributed photovoltaic equipment and an inverter which are matched for use, and is connected into the micro-grid system through a switch K2; the energy storage system comprises a transformer T1, an energy storage battery and PCS which are matched for use, wherein each PCS is connected with one side of the transformer T1, and the other side of the transformer T1 is connected into the micro-grid system through a switch K1; the micro-grid system is connected with a public power supply through a switch K0 and connected with a load through a switch K3; the auxiliary control system comprises electric meters KMH1, KMH2 and KMH3 which are respectively in communication connection with an Energy Management System (EMS), wherein the electric meters KMH2 are configured between a switch K1 and a transformer T1, the electric meters KMH1 are configured between a switch K0 and a photovoltaic system and an energy storage system, and the electric meters KMH3 are configured between the switch K0 and the switch K2.

Preferably, as shown in fig. 6, the auxiliary control system further includes a DI/DO device, and the DI/DO device is disposed between the switch K2 and the switch K1.

Preferably, as shown in fig. 2, the auxiliary control system further includes an RS485 bus and an ethernet, and the electric meters KMH1, KMH2, KMH3 and DI/DO devices are communicatively connected to an Energy Management System (EMS) through the RS485 bus, and the PCS of the energy storage system is communicatively connected to the Energy Management System (EMS) through the ethernet.

Specifically, as shown in fig. 6, the micro-grid system includes an Energy Management System (EMS), a DI/DO module, an energy storage system, a photovoltaic system, a load, and a transformer T1, where the energy storage system includes a plurality of PCS and a plurality of energy storage batteries, the PCS and the energy storage batteries are matched one to one (the PCS and the energy storage batteries may not be matched one to one, for example, one PCS is connected to more than two energy storage batteries at the same time), each PCS is respectively connected to the EMS by communication, each PCS is respectively connected to the load, the photovoltaic system, and a public power supply through the transformer T1 and the electric meter KMH2 which are sequentially connected in series, a switch K3 is serially connected between the load and the electric meter KMH2, a switch K3 and a switch K1 are sequentially serially connected between the photovoltaic system, the DI/DO module, the electric meter KMH1, the electric meter KMH2, and the electric meter KMH3 are respectively connected to the Energy Management System (EMS). Further, the PCS is communicatively connected to an Energy Management System (EMS) via an Ethernet network (i.e. "Ethernet"); the photovoltaic system, the DI/DO module, the ammeter KMH1, the ammeter KMH2 and the ammeter KMH3 are respectively connected with the EMS through an RS485 bus in a communication mode.

The electricity meter KMH1 is used for metering electricity information of the whole micro-grid system, and KMH2 and KMH3 are used for metering electricity information of the energy storage system and the photovoltaic system respectively.

Preferably, the energy storage battery can be a storage battery or a lithium ion battery.

The following is an embodiment of a power distribution method of the micro grid system of the present invention, which is performed by an energy management system.

The power distribution method of the micro-grid system comprises the following steps:

and step 1, the energy management system judges whether third party scheduling exists or not, and determines the total power P of the system according to a judging result.

Preferably, in step 1, when there is third party scheduling, the third party scheduling requires that the gateway table power is constant to be P0, then p= (p0—p01+p11); when the third party scheduling does not exist, the value range of the total power P of the system is [ max (ratio (P01-P03), P01-P03+P 04) +P11, min (ratio (P01-P02), P01-P02-P04) +P11]; wherein, P0 is a system power scheduling value, and P01 is the gateway table power of the micro-grid system; p02 is the inverse power value of the micro-grid system; p03 is the current month demand of the micro grid system; p04 is an adjustment error of a photovoltaic device of the photovoltaic system or an energy storage device of the energy storage system; ratio is an adjustable coefficient; p11 is the total power of the current photovoltaic system and the energy storage system. Further, 0 < ratio is less than or equal to 1.0.

It should be noted that when there is a third party scheduling (the user sends a third party scheduling instruction to the energy management system through the upper computer), the third party scheduling will issue a system power scheduling value P0, where the value of P0 is set according to the need, and since the gateway table power value is determined by the photovoltaic system, the energy storage system and the load together, the power value is often changed, and since the third party scheduling gives a certain power value P10, the EMS is required to continuously adjust the power of the photovoltaic system and the energy storage system so as to keep the gateway table power value to be P0.

It should be noted that, when the demand is adjusted (the demand is adjusted according to the power distribution method of the present invention) and the reverse flow is prevented, the higher the ratio value is, the faster the adjustment speed is, whereas the lower the ratio value is, the slower the adjustment speed is, but with the change of the adjustment speed, the stability of the system is also deteriorated, so that the value is required to be taken according to the actual demand, and meanwhile, the sufficient adjustment speed and the system stability are ensured.

It should be noted that, the micro-grid system may or may not set a gateway table (i.e. a grid ammeter, such as ammeter KMH1 shown in fig. 6); when the micro-grid system sets a gateway table, the power P0 of the gateway table is obtained by reading data of the gateway table; and when the micro-grid system is not provided with the gateway table, the gateway table power P0=total power generation power in the system+total discharge power in the system-total load power in the system.

Preferably, if the system power scheduling value is less than max (ratio is P01-P03), P01-p03+p04) +p11, triggering a power adjustment process of the energy management system; if the system power scheduling value is greater than min (ratio (P01-P02), P01-P02-P04) +P11, triggering the anti-reflux control of the energy management system; if the photovoltaic system generates power with maximum power, the total power of the system p=min (ratio (P01-P02), P01-P02-P04) +p11; otherwise, the total system power P is any value in the range of values, namely min (ratio (P01-P02), P01-P02-P04) +p11 < total system power P less than or equal to max (ratio (P01-P03), and P01-p03+p04) +p11.

It should be noted that, for example, when the load power in the micro-grid system becomes large, the system needs to draw electricity from the grid, if the power value (i.e., P01) of the electricity drawn from the grid exceeds the power threshold value P10, a power adjustment process (the power adjustment process may be implemented by the prior art) is triggered, and the specific adjustment process is that the system increases the power generated by the photovoltaic system and increases the discharge power of the energy storage system, so that the power P01 of the gateway table falls back into the set range, so that the power of the gateway table is stabilized within a certain value interval, and the value interval is a preconfigured parameter.

Preferably, the anti-reflux control of the energy management system can be realized by the prior art; or the anti-reflux control of the energy management system can be realized by the following method, which specifically comprises the following steps:

Step S1, acquiring a gateway table power value P01 of the micro-grid system, and calculating the change rate of the gateway table power value P01 to be a first change rate dP01; further, the first change rate dP01= (P012-P011)/dT 01; wherein dT01 is the acquisition period of the gateway table power value P01, P011 is the gateway table power value of the previous sampling period of the current sampling period, P012 is the gateway table power value of the next sampling period of the current acquisition period, and the calculation period of the first change rate dP01 is the same as dT 01.

Step S2, including step S2a and step S2b:

Step S2a, if the gateway table power value P01 is smaller than or equal to the anti-backflow threshold value P110, an Energy Management System (EMS) judges that the current state of the micro-grid system is an emergency anti-backflow state and performs an emergency anti-backflow measure; if the gateway power value P01 is greater than the anti-backflow threshold value P110, step S2b is executed. Further, in step S2a, the reverse flow occurrence time t0= (P01-P110)/dP 01; if T0+Tmax is more than 0.0, the Energy Management System (EMS) judges that the current state of the micro-grid system is an emergency countercurrent state and performs emergency countercurrent prevention measures; if T0+Tmax is less than or equal to 0.0, an Energy Management System (EMS) judges that the current state of the micro-grid system is a general anti-backflow state and implements general anti-backflow measures; where Tmax is the response time of the longest responding device of the photovoltaic devices and the energy storage devices of the micro grid system.

Step S2b, if the gateway table power value P01 is greater than the backflow prevention threshold value P110 and less than the backflow prevention threshold value P120, the backflow prevention threshold value P110 (the backflow prevention threshold value P110 is preferably 0.0kW or any value between 0.0 and 0.5 kW) < the backflow prevention threshold value P120 (the backflow prevention threshold value P120 is preferably 1.0kW or any value between 0.0 and 5.0kW, and P120 is always greater than P110), predicting the backflow occurrence time T0 according to the first change rate dP01 and the backflow prevention threshold value P110, determining that the current state of the micro-grid system is an emergency backflow prevention state or a general backflow prevention state according to the backflow occurrence time T0, and implementing an emergency backflow prevention measure or a general backflow prevention measure; if the gateway power value P01 is greater than or equal to the anti-backflow threshold value P120, step S1 is executed.

In theory, in the anti-backflow control method of the invention, as long as P110 is less than P120, the values of the two are not absolutely limited; however, in practical operation, the preferable value range of P11 is 0.0 kW.ltoreq.P110 < 1.0kW, and the preferable value range of P120 is P120.gtoreq.1.0 kW. In addition, the value of P120 is related to the speed of the device response reverse flow, if the device response is slow, the reverse flow prevention treatment needs to be performed as early as possible, the value of P120 is relatively large, but if the value of P120 is too large, the utilization rate of the distributed photovoltaic device is inhibited.

Preferably, the micro-grid system executes emergency anti-reflux measures or general anti-reflux measures to ensure that Ps is more than or equal to 0.0, ps=P01×a, and 1.0 < a < 2.0; where Ps is the weighted gateway table power value. Further, a=1.3. It should be noted that Ps aims to leave an adjustment margin, ensure that one adjustment can complete the anti-reflux control, and prevent multiple adjustments; the initial value of Ps is generally negative, and each time the adjustment is performed, the adjusted value is subtracted from Ps until Ps becomes positive, i.e. the Ps is adjusted in place, and the countercurrent adjustment is stopped; the coefficient a can be adjusted so that when the countercurrent is adjusted for the first time, some more adjustment can be performed instead of adjustment to the right value, because the power change of some equipment is a curve, when the countercurrent is found, the countercurrent adjustment is performed according to the value at the moment, and the countercurrent occurs again after the adjustment is completed, so that the value of a is larger than 1.0, but the value of a is not set too large, and is generally smaller than 2.0 in consideration of the stability of the power grid.

Preferably, the emergency countercurrent prevention measures comprise an energy storage device emergency countercurrent prevention measure and a photovoltaic device emergency countercurrent prevention measure, and the priority of the energy storage device emergency countercurrent prevention measure is higher than that of the photovoltaic device emergency countercurrent prevention measure. It should be noted that, the meaning of the "priority of the emergency anti-backflow measure of the energy storage device is higher than that of the photovoltaic device" is that when the micro-grid system executes the emergency anti-backflow measure, the emergency anti-backflow measure of the energy storage device is executed first, the anti-backflow control is performed on the energy storage device first, if Ps can be adjusted to be more than or equal to 0.0, the emergency anti-backflow measure of the photovoltaic device is not executed any more, that is, the anti-backflow control is not performed on the distributed photovoltaic device any more; if Ps is still less than 0.0 after the emergency anti-reflux measures of the energy storage system are executed, the micro-grid system continues to execute the emergency anti-reflux measures of the photovoltaic system until Ps is more than or equal to 0.

The emergency anti-reflux measure of the energy storage device comprises the following operations: all the energy storage devices are ranked from large to small according to real-time power, the energy storage device with the foremost ranking is the energy storage device i _max, the energy storage device i _max is classified according to the response time T3i _max and the response time index T11 of the energy storage device i _max, if the response time T3i _max is less than or equal to T11, the energy storage device i _max is of a type of quick response energy storage device and is subjected to power control, if the response time T3i _max is more than T11, the type of the energy storage device i _max is slow response energy storage device and performs shutdown control on the slow response energy storage device; t11 is more than 0s and less than or equal to 5s. Further, in the emergency backflow prevention measure of the energy storage device, when the power of the energy storage device i _max is controlled, the SOC of the energy storage device i _max is SOC _max, and if the SOC _max is more than or equal to 100.0 and the energy storage device i _max is in a discharge state, the discharge power P3i _max of the energy storage device i _max is reduced; if SOC _max is less than 100.0, the charging power of energy storage device i _max is increased. Further, in the emergency anti-backflow measure of the energy storage device, if the SOC _max is smaller than 100.0 and the power difference dP3i _max of two adjacent power settings before and after the energy storage device i _max is larger than or equal to the power setting return difference dP3 of the energy storage device i _max or the time interval dP3iT _max of two power settings before and after the energy storage device i _max is larger than or equal to the time return difference dP3T of the energy storage device i _max when the power control is performed on the energy storage device i _max, the energy management system issues a power scheduling command to the energy storage device i _max to increase the charging power of the energy storage device i _max.

The emergency anti-reflux measure of the photovoltaic equipment comprises the following operations: all the distributed photovoltaic devices are ordered from big to small according to real-time power, the distributed photovoltaic device with the forefront ordering is the photovoltaic device i _max, the photovoltaic device i _max is classified according to the response time T2i _max and the response time index T11 of the photovoltaic device i _max, if the response time T2i _max is less than or equal to the response time index T11, the type of the photovoltaic device i _max is the fast response photovoltaic device and the power control is carried out on the fast response photovoltaic device, if the response time T2i _max is more than the response time index T11, the photovoltaic device i _max is a slow response photovoltaic device and is subject to shutdown control. Further, in the emergency backflow prevention measure of the photovoltaic device, when the power of the photovoltaic device i _max is controlled, if the real-time power P2i _max of the photovoltaic device i _max is smaller than the rated power P2Ei _max of the photovoltaic device i _max, a power setting command is sent to the photovoltaic device i _max, so that the generated power of the photovoltaic device i _max is reduced; if the real-time power P2i _max is larger than or equal to the rated power P2Ei _max, the shutdown control of the photovoltaic equipment i _max is carried out. Further, in the emergency backflow prevention measure of the photovoltaic equipment, when the power control is carried out on the photovoltaic equipment i _max, if the real-time power P2i _max is smaller than the rated power P2Ei _max, and the power difference value dP2i _max of two adjacent power settings before and after the photovoltaic equipment i _max is larger than or equal to the power setting return difference value dP2 of the photovoltaic equipment i _max or the time interval dP2iT _max of two power settings before and after the photovoltaic equipment i _max is larger than or equal to the time return difference value dP2T of the photovoltaic equipment i _max, the energy management system issues a power scheduling command to the photovoltaic device i _max to cause the photovoltaic device i _max to reduce the generated power.

It should be noted that, setting T11 as a time response index for preventing reverse flow, in seconds, in a specific network, the communication delay is generally smaller, and is also relatively fixed, and this value can be adjusted by T11, so that t11=2.0 s.

The general anti-reflux measures comprise an energy storage device general anti-reflux measure and a photovoltaic device general anti-reflux measure, and the priority of the energy storage device general anti-reflux measure is higher than that of the photovoltaic device general anti-reflux measure. It should be noted that, the meaning of the "priority of the general anti-backflow measure of the energy storage device is higher than that of the photovoltaic device" is that when the micro-grid system executes the general anti-backflow measure, the general anti-backflow measure of the energy storage device is executed first, the anti-backflow control is performed on the energy storage device first, if Ps can be adjusted to be more than or equal to 0.0, the general anti-backflow measure of the photovoltaic device is not executed any more, that is, the anti-backflow control is not performed on the distributed photovoltaic device any more; if Ps is still less than 0.0 after the general anti-reflux measures of the energy storage system are executed, the micro-grid system continues to execute the general anti-reflux measures of the photovoltaic system until Ps is more than or equal to 0.

The energy storage device generally prevents counter current measures including the following: the energy storage devices of the micro-grid system are ranked from large to small according to real-time power, the energy storage device with the forefront ranking is the energy storage device i _max, the SOC of the energy storage device i _max is the SOC _max, and if the SOC _max is less than 100.0, the energy management system sends a power setting command to the energy storage device i _max to enable the energy storage device i _max to increase charging power; if SOC _max is greater than or equal to 100.0, the energy management system sends a power setting command to energy storage device i _max, so that energy storage device i _max reduces discharge power to 0. Further, in the general anti-backflow measure of the energy storage device, if the SOC _max is less than 100.0 and the power difference dP3i _max between two adjacent power settings before and after the energy storage device i _max is greater than or equal to the power setting return difference dP3 of the energy storage device i _max or the time interval dP3iT _max between two power settings before and after the energy storage device i _max is greater than or equal to the time return difference dP3T of the energy storage device i _max, the energy management system issues a power scheduling command to the energy storage device i _max, causing the energy storage device i _max to increase the charging power.

The general anti-reflux measures of the photovoltaic device include the following operations: the distributed photovoltaic devices of the micro-grid system are ranked from large to small according to real-time power, the distributed photovoltaic device with the forefront ranking is photovoltaic device i _max, and the energy management system sends a power setting command to photovoltaic device i _max to enable photovoltaic device i _max to reduce power generation power. Further, in the general anti-backflow measures of the photovoltaic device, if the power difference dP2i _max of the two adjacent power settings before and after the photovoltaic device i _max is greater than or equal to the power setting back difference dP2 of the photovoltaic device i _max or the time back difference dP2T of the two power settings before and after the photovoltaic device i _max is greater than or equal to the time back difference dP2T of the photovoltaic device i _max, the energy management system issues a power scheduling command to the photovoltaic device i _max, so that the power generation power of the photovoltaic device i _max is reduced.

Preferably, the emergency and general anti-reflux measures are constrained by the following rules:

and according to a rule I, sorting the devices of the micro-grid system according to the real-time power, and preferentially controlling the devices which are ranked at the front. Further, in the micro-grid system, the devices of the same type are arranged in a group according to the real-time power.

Specifically, in the micro-grid system, all the distributed energy storage devices are in a group and are ranked according to the real-time power, and all the energy storage devices are in a group and are ranked according to the real-time power. It should be noted that if the real-time power of more than two energy storage devices is the same and the real-time power is the maximum, the energy storage device with the maximum real-time power which appears first is arranged in the first position according to the principle of last coming; the appearance sequence of the energy storage devices is arranged according to the sequence from the big to the small of the device number IDs of the energy storage devices.

It should be noted that in rule one, all devices of the micro grid system may be ordered by real-time power level.

And a second rule, classifying the devices according to the response time of the devices of the micro-grid system, and performing power reduction or shutdown control on the corresponding devices according to the types of the devices. Further, in the micro grid system: if the response time of the equipment is larger than the response time threshold value, judging that the equipment is slow response equipment and performing shutdown control on the equipment; if the response time of the equipment is less than or equal to the response time threshold value, judging the equipment to be quick response equipment and performing power reduction control on the equipment; the response time threshold is 400ms or less or 600ms or less. Further, the response time threshold is 500ms.

And in the third rule, the micro-grid system comprises distributed photovoltaic equipment and energy storage equipment, and the energy storage equipment is controlled preferentially.

The priority order of the three rules is as follows: rule three > rule one > rule two.

Specifically, when the emergency anti-backflow measure or the general anti-backflow measure is executed, the energy storage devices are first controlled by the third constraint of the rule, namely in the distributed photovoltaic devices and the energy storage devices of the micro-grid system, then the energy storage devices are first controlled by the first constraint of the rule, namely when the energy storage devices are controlled, the energy storage devices which are first ordered according to the real-time power, namely the energy storage devices with the largest real-time power, are first controlled by the first constraint of the rule, then the type of the energy storage devices (belonging to slow response devices or fast response devices) is determined according to the response time of the energy storage devices, and the power reduction or shutdown control is carried out on the energy storage devices according to the type of the energy storage devices.

Preferably, the response time is a time between a moment when the device receives the power scheduling instruction and a moment when the device actually outputs power to be stable. Further, the response time of the device is obtained by setting the initial power of the device to 0, writing a power value into the device (i.e., transmitting a power scheduling command to the device), and then reading the actual power value of the device, wherein the read actual power value is the same as the written power value, i.e., the response time.

Preferably, the power difference value of two adjacent power settings before and after any one device in the micro-grid system is dPi, the power setting return difference value is dP, the time interval of two adjacent power settings before and after is dPiT, and the time setting return difference value is dPT; if dPi is more than or equal to dP or dPiT is more than or equal to dPT, an Energy Management System (EMS) of the micro-grid system issues a command to the device.

Step 2, comprising step 2a and step 2b:

Step 2a, if the total system power P is greater than a power threshold value P10, and the power threshold value P10 is greater than 0, the energy management system sequentially distributes the total system power P to the photovoltaic system and the energy storage system of the micro-grid system; if the total power P of the system is less than or equal to the power threshold value P10, step 2b is executed.

Preferably, the power threshold value p10=rated power of the photovoltaic system x adjustment error of the photovoltaic system, wherein the adjustment error of the photovoltaic system is more than 0 and less than or equal to 5%. Further, the photovoltaic system adjustment error is 2%. It should be noted that, the rated power of the photovoltaic system is a determined value, the adjustment error of the photovoltaic system is different according to the specific brands of the photovoltaic equipment of the photovoltaic system, and the adjustment error of the photovoltaic system is generally set to be 2%.

Step 2b, the Energy Management System (EMS) judges whether the photovoltaic system and the energy storage system are available; if the photovoltaic system and the energy storage system are available, sequentially distributing the total power P of the system to the photovoltaic system and the energy storage system; if either of the photovoltaic system and the energy storage system is unavailable, the power of the photovoltaic system and the energy storage system is kept unchanged (i.e., no power distribution or power adjustment is performed on the micro-grid system).

Preferably, in step 2b, if the available power of the photovoltaic system is greater than 0, it indicates that the photovoltaic system is available; and if the operation of the energy storage system is fault-free and the real-time power is larger than the rated charging power, the energy storage system is usable. Further, the available power of the photovoltaic system is the sum of the available power of each photovoltaic device of the photovoltaic system.

It should be noted that when the energy storage system is in operation, charging is represented by a negative value, discharging is represented by a positive value, and rated charging power is the minimum power value of the energy storage system.

Preferably, when the energy storage system is in a discharge state, the power distribution is performed on the energy storage system according to the following rule: if the remaining value of the power target P1 of the energy storage system is less than or equal to 0, the power distribution of the energy storage system is finished; if the remaining value of the power target P1 of the energy storage system is more than 0, continuing to distribute the power of each energy storage device of the energy storage system until the remaining value of the power target P1 of the energy storage system is less than or equal to 0; subtracting the power distributed to the energy storage equipment from the remaining value of the power target P1 of the energy storage system after finishing the power distribution of one energy storage equipment; any energy storage device sets a set power value of the energy storage device (i.e. a power target of the energy storage device, that is, a power value to be finally reached by the energy storage device) equal to the rated power if the power to be allocated to the energy storage device is greater than the rated power of the energy storage device, and continues to allocate power to other energy storage devices of the energy storage system; any energy storage equipment, if the power to be allocated to the energy storage equipment is less than or equal to the rated power of the energy storage equipment, setting the set power value of the energy storage equipment to be equal to the power to be allocated to the energy storage equipment; any of the energy storage devices, the power to be allocated to the energy storage device=the power target p1 of the energy storage system×the rated power of the energy storage device×the total remaining power of the SOC/energy storage system of the energy storage device.

Specifically, as shown in fig. 1, when the energy storage system is in a discharging state, power is distributed to the energy storage system through the following steps:

step S08: PS [ i ] = fTemp; i=i+1, turning to S03;

Step S09: if sum (E (i) SOC (i)) >0, then fTemp =p1×e (i) SOC (i)/sum (E (i) SOC (i)); if sum (E (i) ×soc (i)) +.0 then fTemp =0.0 and step S07 is repeated.

The energy storage system comprises M energy storage devices, wherein M is an integer greater than or equal to 0, and the ith energy storage device is an energy storage device i; flag [ i ] =0 indicates that the energy storage device i is unoccupied, and flag [ i ] =1 indicates that the energy storage device i is occupied; PS [ i ] is the set power value of the energy storage device i; PE [ i ] represents the rated power value of the energy storage device i, when the energy storage device i discharges, the PE [ i ] is positive, and when the energy storage device i charges, the PE [ i ] is negative; SOC [ i ] is the real-time SOC of the energy storage device i; e i is the rated power of the energy storage device i; PR [ i ] represents the working condition of the energy storage device i, PR [ i ] =0 represents the normal communication state and operation state of the energy storage device i, and PR [ i ] =1 represents the abnormal communication state and/or operation state of the energy storage device i; the count is a variable representing the flag bit, if the count > 0, the power distributed to the energy storage device i is larger than the rated power thereof and the power distribution needs to be continued, and if the count is less than or equal to 0, the power distribution is completed; fTemp is a temporary variable representing the power to be allocated to the energy storage device i; p1 is the energy storage system power target. Further, in the operation process, if the count is set to 1, the power distribution is continued, otherwise, the power distribution is ended.

The following is a calculation example of the power to be allocated to any energy storage device in the energy storage system when the energy storage system is in a discharge state: it is assumed that the number of the sub-blocks,

The energy storage system comprises two sets of energy storage devices, namely an energy storage device PCS1 and an energy storage device PCS2, wherein the power target of the energy storage system is 50kW (positive number represents discharging and negative number represents charging);

the rated electric quantity of the energy storage device PCS1 is 100kWh, and the SOC is 90 (100 times of SOC amplification);

the rated power of the energy storage device PCS2 is 100kWh, and the SOC is 10 (the SOC is amplified 100 times).

The calculation process is as follows,

The total residual capacity of the energy storage system is 100×90+100×10=10000 (since the SOC is amplified by 100 times, the total residual capacity of the energy storage system is also amplified by 100 times, and the actual total residual capacity is 100); the power to be allocated to the energy storage device PCS1 is 50×100×90/10000=45 kW, and the power to be allocated to the energy storage device PCS2 is 50×100×10/10000=5 kW.

Preferably, when the energy storage system is in a charging state, the power distribution is performed on the energy storage system according to the following rule: if the remaining value of the power target P1 of the energy storage system is more than or equal to 0, the power distribution of the energy storage system is finished; if the remaining value P1 of the power target of the energy storage system is smaller than 0, continuing to distribute power to each energy storage device of the energy storage system until the remaining value P1 of the power target of the energy storage system is larger than or equal to 0; subtracting the power distributed to the energy storage equipment from the remaining value of the power target P1 of the energy storage system after finishing the power distribution of one energy storage equipment; any one of the energy storage devices sets the set power value of the energy storage device equal to the rated power of the energy storage device if the power to be distributed to the energy storage device is larger than the rated power of the energy storage device, and continues to distribute the power of other energy storage devices of the energy storage system; any energy storage equipment, if the power to be allocated to the energy storage equipment is less than or equal to the rated power of the energy storage equipment, setting the set power value of the energy storage equipment to be equal to the power to be allocated to the energy storage equipment; any of the energy storage devices, the power to be distributed to the energy storage device=the power target P1 of the energy storage system is multiplied by the rated power of the energy storage device (100-the SOC of the energy storage device)/the total residual power of the energy storage system.

Specifically, as shown in fig. 2, when the energy storage system is in a charging state, power is distributed to the energy storage system through the following steps:

Step S18: if PS [ i ] = fTemp, i=i+1 and go to step S13;

Step S19: setting fTemp =p1×e (i) (100-SOC (i))/sum (E (i) (100-SOC (i))) if sum (E (i))) > 0; if sum (E (i)) +.0 then fTemp =0.0 and go to step S17.

The following is a calculation example of the power to be allocated to any energy storage device in the energy storage system when the energy storage system is in a charged state: it is assumed that the number of the sub-blocks,

The energy storage system comprises two sets of energy storage equipment, namely an energy storage equipment PCS1 and an energy storage equipment PCS2, wherein the power target of the energy storage system is-50 kW (positive number represents discharging and negative number represents charging);

The calculation process is as follows,

The total residual capacity of the energy storage system is 100×90+100×10=10000 (since the SOC is amplified by 100 times, the total residual capacity of the energy storage system is also amplified by 100 times, and the actual total residual capacity is 100); the power to be allocated to the energy storage device PCS1 is-50 multiplied by 100 multiplied by 90/10000= -45kW, and the power to be allocated to the energy storage device PCS2 is-50 multiplied by 100 multiplied by 10/10000= -5kW.

Preferably, the power distribution to the photovoltaic system is performed according to the following rules:

If the remaining value of the power target P2 of the photovoltaic system is less than or equal to 0, the power distribution of the photovoltaic system is finished; if the remaining value of the photovoltaic system power target P2 is more than 0, continuing to distribute power to all photovoltaic devices of the photovoltaic system until the remaining value of the photovoltaic system power target P2 is less than or equal to 0; subtracting the power distributed to the photovoltaic equipment from the remaining value of the photovoltaic system power target P2 after the power distribution of one photovoltaic equipment is completed; any one of the photovoltaic devices sets the set power value of the photovoltaic device equal to the rated power of the photovoltaic device if the power to be distributed to the photovoltaic device is larger than the rated power of the photovoltaic device, and continuously distributes power to other photovoltaic devices of the photovoltaic system; any one of the photovoltaic devices sets a set power value of the photovoltaic device equal to the power to be distributed if the power to be distributed to the photovoltaic device is less than or equal to the rated power of the photovoltaic device; any of the photovoltaic devices to which power is to be allocated is equal to the photovoltaic system power target x the available power value of the photovoltaic device/the total available power value of the photovoltaic system.

Specifically, as shown in fig. 3, the power distribution of the photovoltaic system is performed by:

Step S28: setting PS [ j ] = fTemp, j = j+1, and turning to step S23;

Step S29: if sum (PU [ j ]) >0, fTemp =P2 is set to be PU [ j ]/sum (PU [ j ]); if sum (PU [ j ]) is less than or equal to 0, fTemp =0.0 is set, and step S27 is performed.

The photovoltaic system comprises N photovoltaic devices, N is an integer greater than or equal to 0, and the j-th photovoltaic device is photovoltaic device j; flag [ j ] =0 indicates that the photovoltaic device j is unoccupied, and flag [ j ] =1 indicates that the photovoltaic device j is occupied; PS [ j ] represents the set power value of the photovoltaic equipment j; PE [ j ] represents the rated power value of the photovoltaic equipment j; PC [ j ] represents the real-time power value of the photovoltaic equipment j; PU [ j ] represents an available power value of the photovoltaic equipment j; PR [ j ] represents the working condition of the photovoltaic equipment j, PR [ j ] =0 represents the normal communication state and operation state of the photovoltaic equipment j, and PR [ j ] =1 represents the abnormal communication state and/or operation state of the photovoltaic equipment j; the count is a variable representing the flag bit, if the count is more than 0, the power to be distributed to the photovoltaic equipment j is more than the rated power thereof, the power distribution needs to be continued, and if the count is less than or equal to 0, the power distribution is completed; fTemp is a temporary variable representing the power to be distributed to the photovoltaic device j; p2 is a photovoltaic system power target; if PS [ j ] > PC [ j ], PU [ j ] =PC [ j ], if PS [ j ]. Ltoreq PC [ j ], PU [ j ] =PE [ j ], the available power value PU [ j ] is introduced, thereby realizing the maximum utilization of photovoltaic power generation, realizing the precise control of photovoltaic power generation power and avoiding the occurrence of over-demand and countercurrent conditions caused by overlarge stirring of the photovoltaic power in the adjusting process.

The following is a calculation example of the power to be distributed to any one of the photovoltaic systems:

It is assumed that the number of the sub-blocks,

The photovoltaic system comprises two sets of photovoltaic equipment, namely photovoltaic equipment PV1 and photovoltaic equipment PV2, and the power target of the photovoltaic system is 50kW; the available power value of the photovoltaic equipment PV1 is 10kW, the available power value of the photovoltaic equipment PV2 is 90kW, and the total available power value of the photovoltaic system is 10+90=100 kW.

In the course of the calculation process,

The power to be distributed to the photovoltaic device PV1 is 50×10/100=5 kW, and the power to be distributed to the photovoltaic device PV2 is 50×90/100=45 kW.

As shown in fig. 4 and 5, experiments prove that the theoretical operation curves of the photovoltaic system and the energy storage system are basically consistent with the actual operation curves of the photovoltaic system and the energy storage system; wherein 9:00 is the time when the power of the photovoltaic system is increased to 20kW and the load is increased to 5kW, from 9:00 to 9:12, the EMS slowly increases the photovoltaic output until the photovoltaic system reaches the maximum output power, and simultaneously, because the photovoltaic power is increased, the power grid power and the PCS power are reduced to absorb the output power of the photovoltaic system.

The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.

Claims

1. The power distribution method of the micro-grid system comprises an energy management system, a photovoltaic system and an energy storage system, and is characterized by comprising the following steps of:

Step 1, the energy management system judges whether third party scheduling exists or not, and determines the total power P of the system according to a judging result; when the third party scheduling exists, the third party scheduling requires that the gateway table power is constant to be P0, and then P= (P0-P01+P11); when the third party scheduling does not exist, the value range of the total power P of the system is [ max (ratio (P01-P03), P01-P03+P 04) +P11, min (ratio (P01-P02), P01-P02-P04) +P11];

Wherein, P0 is a system power scheduling value, and P01 is the gateway table power of the micro-grid system; p02 is the inverse power value of the micro-grid system; p03 is the current month demand of the micro grid system; p04 is an adjustment error of a photovoltaic device of the photovoltaic system or an energy storage device of the energy storage system; ratio is an adjustable coefficient; p11 is the current total power of the photovoltaic system and the energy storage system;

step 2, comprising step 2a and step 2b:

2. The power distribution method of a micro grid system according to claim 1, wherein: the power threshold value P10=rated power of the photovoltaic system multiplied by the regulating error of the photovoltaic system, and the regulating error of the photovoltaic system is more than 0 and less than or equal to 5 percent.

3. The power distribution method of a micro grid system according to claim 1, wherein: ratio is more than 0 and less than or equal to 1.0.

4. The power distribution method of a micro grid system according to claim 1, wherein:

If the system power scheduling value P0 is smaller than max (ratio is P01-P03), P01-P03+P04) +P11, triggering the power adjustment process of the energy management system;

5. The power distribution method of a micro grid system according to claim 1, wherein: in step 2, the energy management system distributes the total power P of the system to the photovoltaic system and the energy storage system according to the following method: and after the power distribution of all the photovoltaic inverters of the photovoltaic system is completed, the sum of the power of all the photovoltaic inverters is P12, and the power to be distributed to the energy storage system is the energy storage system power target P1=P-P12.

6. The power distribution method of a micro grid system according to claim 1, wherein: the available power of the photovoltaic system is larger than 0, and the photovoltaic system is available; and if the operation of the energy storage system is fault-free and the real-time power is larger than the rated charging power, the energy storage system is usable.

7. The power distribution method of a micro grid system according to claim 1, wherein: in step 2, power distribution is performed on the energy storage system according to the current state of the energy storage system, wherein the current state of the energy storage system comprises a discharging state and a charging state.

8. The method of power distribution for a microgrid system according to claim 7, characterized in that:

The energy storage system is in a discharge state, and power distribution is carried out on the energy storage system according to the following rules:

9. The method of power distribution for a microgrid system according to claim 8, characterized in that: when the energy storage system is in a discharging state, the power distribution is carried out on the energy storage system through the following steps:

step S01: initializing, setting flag [ i ] =0, ps [ i ] =0; turning to step S02;

step S08: PS [ i ] = fTemp; i=i+1, turning to S03;

10. The method of power distribution for a microgrid system according to claim 7, characterized in that:

The energy storage system is in a charging state, and the following rules are followed for power distribution of the energy storage system:

11. The method of power distribution for a microgrid system according to claim 10, characterized in that: when the energy storage system is in a charging state, power is distributed to the energy storage system through the following steps:

Step S11: initializing, setting flag [ i ] =0, ps [ i ] =0; turning to step S12;

Step S18: if PS [ i ] = fTemp, i=i+1 and go to step S13;

12. The power distribution method of a micro grid system according to claim 1, wherein: distributing power to the photovoltaic system according to the following rules:

13. The method of power distribution for a microgrid system according to claim 12, characterized in that: distributing power to the photovoltaic system by:

Step S28: setting PS [ j ] = fTemp, j = j+1, and turning to step S23;

14. A micro-grid system, characterized in that it applies the power distribution method according to any one of claims 1-13; the micro-grid system comprises an energy management system, an auxiliary control system, a photovoltaic system and an energy storage system; the photovoltaic system comprises photovoltaic equipment and an inverter which are matched for use, and is connected into the micro-grid system through a switch K2; the energy storage system comprises a transformer T1, an energy storage battery and PCS which are matched for use, wherein each PCS is connected with one side of the transformer T1, and the other side of the transformer T1 is connected into the micro-grid system through a switch K1; the micro-grid system is connected with a public power supply through a switch K0 and connected with a load through a switch K3; the auxiliary control system comprises electric meters KMH1, KMH2 and KMH3 which are respectively in communication connection with the energy management system, the electric meters KMH2 are configured between the switch K1 and the transformer T1, the electric meters KMH1 are configured between the switch K0 and the photovoltaic system and the energy storage system, and the electric meters KMH3 are configured between the switch K0 and the switch K2.