CN104410165A - Micro-network interconnection method and system - Google Patents

Abstract

The invention discloses a method and system for interconnection between microgrids, relates to the field of distributed energy technology, and is invented to effectively overcome the problem of large current impact when interconnecting microgrids. Including: when it is determined that the two micro-grids meet the interconnection conditions, the network dispatching system sends a closing operation command to the demand-side micro-grid; after sending the closing operation command to the demand-side micro-grid, after a preset period of time Sending a switch-on command to the supply-side microgrid; then, the network dispatching system receives information that the connection is successful fed back by the supply-side microgrid. The invention is suitable for distributed energy technology.

Description

A method and system for interconnecting microgrids

technical field

The present invention relates to the field of distributed energy technology, in particular to a method and system for interconnecting microgrids.

Background technique

Distributed energy technology refers to the small-scale, small-capacity, modularized, and decentralized installation of cooling/heating power systems directly at the user end, which can independently output cold, heat, and electricity. As an important utilization method of distributed energy technology, microgrid (also known as distributed energy island system) refers to multiple loads and multiple distributed power sources according to a certain topology to form a micro network, and through static switches to connect to conventional grid.

In the existing technology, the microgrid has a certain degree of spatial independence, can provide a dispatchable load for the local power system, can respond within a few seconds to meet the needs of the system, and provide strong support to the large power grid in a timely manner; and can maintain the system At the same time does not affect the customer's load. For users, the microgrid can also be used as a customizable power supply to meet the diverse needs of users.

However, the inventors found at least the following problems in the prior art: at the beginning of designing the above-mentioned distributed energy system, the energy consumption scale and energy consumption law of each microgrid can basically match, but as time goes by, the energy consumption scale and energy consumption law of each microgrid can be basically matched. The lawful supply and demand may well no longer match. One way this is possible is to interconnect microgrids to redistribute energy. But in fact, various obstacles need to be overcome when the microgrid is interconnected, for example, the current impact is large when interconnecting or disconnecting. Therefore, how to overcome the large current impact when interconnecting or disconnecting has become a problem that needs to be solved at present.

Contents of the invention

Embodiments of the present invention provide a method and system for interconnection between microgrids, which can overcome the problem of large current impact during interconnection between microgrids.

The embodiment of the present invention adopts following technical scheme:

A method for interconnection between microgrids, applied to a network dispatching system, comprising:

When it is determined that the two micro-grids meet the interconnection conditions, a command to close the switch is sent to the demand-side micro-grid;

After sending the closing operation command to the demand-side microgrid, send the closing operation command to the supply-side microgrid after a preset period of time;

Receive the connection success information fed back by the supplier microgrid.

A method for interconnection between microgrids, which is applied to demand-side microgrids, where a connection line is set between the demand-side microgrid and the supply-side microgrid, and the connection line is located close to the side of the demand-side microgrid on which is provided a first switch circuit breaker comprising:

receiving an order to connect the tie line sent by the network dispatching system;

Detecting whether the line on the connection line close to the side of the demand-side microgrid has no pressure;

If it is detected that the line has no voltage, the first switch circuit breaker is turned on, and the information of no-voltage closing is sent to the network dispatching system.

A method for interconnection between microgrids, applied to supply-side microgrids, characterized in that a tie line is set between the supply-side microgrid and the demand-side microgrid, and the tie line is close to the supply-side microgrid The position is provided with a second switch circuit breaker, including:

receiving an order to connect the tie line sent by the network dispatching system;

Issue an instruction to increase the power generation to the distributed energy equipment, so that the power difference between the total load and the total power generation reaches the second preset power threshold;

If the power difference between the total load and the total power generation reaches a second preset power threshold, detecting whether the same-frequency grid connection condition is satisfied between the supply-side microgrid and the demand-side microgrid;

If the same-frequency grid-connection condition is met between the supply-side microgrid and the demand-side microgrid, the second switch circuit breaker is turned on, and information about switching on and off is sent to the network dispatching system.

A microgrid interconnection system, characterized in that the system includes at least two microgrids, a network scheduling system and a tie line, the tie line is used to connect the demand side microgrid and the supply side microgrid, and the tie line A first switch circuit breaker is provided at a position close to the side of the demand-side microgrid, and a second switch circuit breaker is provided at a position close to the side of the supply-side microgrid on the tie line, wherein,

The demand-side microgrid is used for:

receiving an order to connect the tie line sent by the network dispatching system;

Detecting whether the line on the connection line close to the side of the demand-side microgrid has no pressure;

If it is detected that the line has no voltage, turn on the first switch circuit breaker, and send the information of no-voltage closing to the network dispatching system;

The supply-side microgrid is used to:

receiving an order to connect the tie line sent by the network dispatching system;

Issue an instruction to increase the power generation to the distributed energy equipment, so that the power difference between the total load and the total power generation reaches the second preset power threshold;

If the power difference between the total load and the total power generation reaches a second preset power threshold, detecting whether the supply-side microgrid satisfies the same-frequency grid-connection condition;

If the supply-side microgrid satisfies the same-frequency grid-connection condition, turn on the second switch circuit breaker, and send the information of pressing and closing the switch to the network dispatching system;

The network scheduling system is used for:

When it is determined that the two micro-grids meet the interconnection conditions, a command to close the switch is sent to the demand-side micro-grid;

After sending the closing operation command to the demand-side microgrid, send the closing operation command to the supply-side microgrid after a preset period of time;

Receive the information that the contact line connection is successful fed back by the supplier microgrid.

In the method and system for interconnection between microgrids provided by the embodiments of the present invention, when it is determined that the two microgrids meet the interconnection conditions, the network dispatching system sends a closing operation command to the demander microgrid; After the switch-on operation command, the switch-on operation command is sent to the supplier microgrid after a preset period of time; then, the network dispatching system receives the connection success information fed back by the supplier microgrid. This process of closing the microgrid on the demand side first without voltage and then closing the microgrid on the supply side enables the interconnection between microgrids to be carried out without power failure, and can overcome the problem of large current impact when interconnecting between microgrids , so as to ensure the quality of power supply when the microgrid is connected.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that are used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic flowchart of a method for interconnecting microgrids provided in Embodiment 1 of the present invention;

Fig. 2 is an exemplary schematic diagram of an electrical connection between microgrids in the system;

FIG. 3 is a schematic flowchart of a method for interconnecting microgrids provided in Embodiment 2 of the present invention;

FIG. 4 is a schematic flowchart of a method for interconnection between microgrids provided in Embodiment 3 of the present invention;

FIG. 5 is a schematic diagram of a system architecture of a microgrid interconnection system provided by Embodiment 4 of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiment one

Embodiment 1 of the present invention provides a method for interconnection between microgrids, which is applied to a network scheduling system. As shown in FIG. 1, the method includes the following steps:

S11. When the network dispatching system determines that the two microgrids meet the interconnection conditions, it sends a closing operation command to the microgrid on the demand side.

In this step, firstly, the network dispatching system analyzes and judges the complementary supply and demand situation of the two microgrids in each microgrid within a certain period of time in the future, so as to determine whether the two microgrids have interconnection requirements. Determining that the two microgrids have interconnection requirements means determining that the two microgrids can be interconnected. Then, the network dispatching system sends a closing operation command to the demand-side microgrid, so that the demand-side microgrid first completes the closing operation.

Optionally, in a specific embodiment of the present invention, determining that the two microgrids meet the interconnection conditions may specifically be determining that there is an interconnection requirement between the two microgrids and that the two microgrids meet the requirement of co-frequency closing.

The above steps determine that there is an interconnection requirement between the two micro-grids and that the two micro-grids meet the same-frequency closing requirements and may specifically include the following steps:

111. According to the real-time operation data of each microgrid, analyze and judge the complementary supply and demand situation of the two microgrids in the respective microgrids within a period of time in the future, so as to determine whether the two microgrids have interconnection requirements;

112. When it is determined that the two microgrids have an interconnection requirement, determine whether the two microgrids meet the requirement for co-frequency closing;

113. If the two microgrids meet the same-frequency closing requirement, send a control instruction to the two microgrids to instruct the two microgrids to perform interconnection.

Specifically, analyzing and judging the complementary supply and demand situation of the two microgrids in each of the microgrids in the future may specifically be that the network dispatching system calculates each microgrid according to the real-time operation information sent by each microgrid Carry out power prediction at intervals, and analyze and judge the power generation capacity and power consumption of each of the two microgrids in the future according to the power prediction results, thereby determining the supply-side microgrid and the demand-side microgrid. Specifically, the network scheduling system predicts the power of systems such as microgrids at intervals based on conditions such as weather and historical data. Among them, every period of time can be set as 15-minute level, 2-hour level, 24-hour level, and 48-hour level four time interval predictions. Then, according to the power prediction results, the network dispatching system can judge the power generation capacity and power consumption of each microgrid in the future. The power generation capacity of the microgrid is greater than a set threshold of electric power, and it is determined that the microgrid is a supplier microgrid. Preferably, the threshold should be set to be more than 50% of the rated power. At the same time, if the power generation capacity of the microgrid is less than a certain set threshold of electric power, it can be determined that the microgrid is a demand-side microgrid. Preferably, the threshold should be designed to be less than 20% of the rated power. In addition, the power generation capacity and power consumption are forecasted average values for a period of time in the future. The period of time in the future can be specifically set by those skilled in the art according to the actual situation, for example, it is set to 4 hours in the future.

Then, determining whether the two microgrids meet the same-frequency closing requirement in the network dispatching system may specifically be to determine whether the voltage frequencies on the sides of the two microgrids are the same. When the voltage frequencies of the two microgrids are the same, the network scheduling system sends a control instruction to the two microgrids to instruct the two microgrids to perform interconnection. If the voltage frequencies of the two microgrids are different, the network dispatching system will not instruct the two microgrids to perform interconnection.

S12. After the network dispatching system sends the switch-on operation command to the demand-side microgrid, it sends the switch-on operation command to the supply-side microgrid after a preset period of time.

In this step, after the network dispatching system sends the closing operation command to the demand-side microgrid, if the demand-side microgrid completes the closing operation within the preset time, the demand-side microgrid directly sends the closing operation command to the network dispatching system For successful feedback information, after the network dispatching system receives the feedback information, it will immediately send a closing operation command to the supplier microgrid. Therefore, it can be understood that the preset period of time in this step mainly refers to the time required for the microgrid on the demand side to complete the closing operation, and the time can be set to 5s, 7s, 10s, etc., which is not limited in the present invention.

S13. The network dispatching system receives the information that the connection is successful fed back by the supplier microgrid.

In this step, after the network dispatching system sends the closing operation command to the supply-side microgrid, the supply-side microgrid will perform the closing operation corresponding to the demand-side microgrid. If the closing and interconnection is successful, the supply-side microgrid will send The network dispatching system feeds back the information that the supply-side microgrid and the demand-side microgrid are successfully connected, and then the network dispatching system sends energy transaction instructions to the supply-side microgrid and the demand-side microgrid. If the closing interconnection fails, the supply-side microgrid will feed back the connection failure information to the network dispatching system to inform the network dispatching system that the supply-side microgrid cannot be interconnected with the demand-side microgrid.

Optionally, in a specific embodiment of the present invention, after receiving the information that the connection is successful fed back by the supplier microgrid, the method further includes the following steps:

The network dispatching system sends the upper and lower limit parameters of active power to the supply-side microgrid, so that the supply-side microgrid can supply energy to the demand-side microgrid according to the upper and lower limit parameters of active power.

The method for interconnection between microgrids provided by Embodiment 1 of the present invention is applied to a network scheduling system, including: when it is determined that two microgrids meet the interconnection conditions, the network scheduling system sends a closing operation command to the demand side microgrid; After the demand-side microgrid sends the closing operation command, it sends a closing operation command to the supply-side microgrid after a preset period of time; then, the network dispatching system receives the information that the connection is successful fed back by the supply-side microgrid . This process of closing the microgrid on the demand side first without voltage and then closing the microgrid on the supply side enables the interconnection between microgrids to be carried out without power failure, and can overcome the problem of large current impact when interconnecting between microgrids , so as to ensure the quality of power supply when the microgrid is connected.

Optionally, in a specific embodiment of the present invention, after the network scheduling system receives the information that the connection is successful fed back by the supplier microgrid, the method further includes the following steps:

141. When the network dispatching system determines that the two micro-grids no longer meet the interconnection conditions, it sends a command to the supplier's micro-grid to open the gate;

142. After sending the opening operation command to the supply-side microgrid, after a preset period of time, the network dispatching system sends the opening operation command to the demand-side microgrid;

143. The network dispatching system receives feedback from the microgrid on the demand side that the gate opening and disconnection are successful.

Wherein, the preset period of time mainly refers to the time taken for the supplier microgrid to complete the opening operation, and the time can be set to 5s, 7s, 10s, etc., which is not limited in the present invention.

Embodiment two

Embodiment 2 of the present invention provides a method for interconnection between microgrids, which is applied to the microgrid on the demand side. As shown in Figure 2, a connection line is set between the microgrid on the demand side and the microgrid on the supply side, and the connection line A first switch circuit breaker, such as a K1 switch circuit breaker, is provided at a position close to the side of the microgrid on the demand side. As shown in Figure 3, the method includes the following steps:

S21. The microgrid on the demand side receives the command to connect the connection line sent by the network dispatching system.

Specifically, when the network dispatching system determines that two microgrids are interconnected, the network dispatching system sends a closing operation command to the demand-side microgrid. That is, the microgrid on the demand side receives the command to connect the tie line sent by the network dispatching system.

S22. The microgrid on the demand side detects whether there is no pressure on the line on the side of the contact line close to the microgrid on the demand side.

Optionally, in a specific embodiment of the present invention, when the first line voltage transformer is set at the position of the first switch circuit breaker, step S22 detects that the connection line is close to the demand-side microgrid- Whether the line on the side is pressure-free can specifically include the following steps:

The voltage is collected by the first line voltage transformer, and it is determined whether the effective value of the three-phase average voltage on the side of the microgrid on the demand side is less than a preset ratio of the rated voltage on the side of the microgrid on the demand side. The preset ratio can be set within a range of 10% to 50%, for example, 10%, 45%, 50% and so on.

Wherein, the rated voltage at the microgrid side of the demand side is the rated voltage at the first switch circuit breaker. For example, the rated voltage is 10 kV, 35 kV, or the like.

S23. If the micro-grid on the demand side detects that there is no voltage on the line, turn on the first switch circuit breaker, and send the information of no-voltage closing to the network dispatching system.

Among them, the no-voltage closing operation at the microgrid on the demand side can reduce the impact of current when the two microgrids are connected under normal power supply conditions, thereby ensuring the quality of power supply when the microgrids are connected.

The method for interconnection between microgrids provided by Embodiment 2 of the present invention is applied to the demand-side microgrid. There is a connection line between the demand-side microgrid and the supply-side microgrid, and the connection line is close to the side of the demand-side microgrid. The position is provided with a first switch circuit breaker, including: the micro-grid on the demand side receives the command to connect the connection line sent by the network dispatching system; No voltage; if it is detected that the line has no voltage, turn on the first switch circuit breaker, and send the information of no-voltage closing to the network dispatching system. Therefore, this method of detecting whether there is no voltage on the line close to the demand-side micro-grid through the demand-side micro-grid before closing can overcome the problem of large current impact when interconnecting between micro-grids, thereby ensuring that the micro-grid The quality of power supply when connected to the network.

Optionally, in the embodiment of the present invention, a first line current transformer may be further provided at the position of the first switch circuit breaker, and the first line current transformer is used for collecting current. Then, after step S23 sends the information of no-voltage closing to the network dispatching system, the following steps are also included:

241. The demand-side microgrid receives the command to disconnect the connection line sent by the network dispatching system.

242. According to the current collected by the current transformer of the first line and the voltage collected by the voltage transformer of the first line, the microgrid on the demand side determines the power on the tie line;

243. The demand-side microgrid compares whether the determined power on the tie line is less than a first preset power threshold.

Wherein, the power on the tie line may specifically be the active power on the tie line. Specifically, the demand-side microgrid collects and preliminarily calculates the operating data on the contact line close to the demand-side microgrid, and then the demand-side microgrid can send these operating data to the network dispatching system for analysis based on the operating data. Determine the active power on the tie-line on the demand-side microgrid side. Then, the network dispatching system sends the analysis result to the demand-side microgrid, and the demand-side microgrid determines whether the value of the active power is less than the first preset power threshold. Wherein the first preset power threshold can be set to any value between 0-20kW, such as 20kW.

244. If the power on the tie line is less than the first preset power threshold, the micro-gateway on the demand side shuts off the first switch circuit breaker, and sends opening information to the network dispatching system.

Embodiment Three

Embodiment 3 of the present invention provides a method for interconnection between microgrids, which is applied to the supply side microgrid. As shown in Figure 2, there is a connection line between the demand side microgrid and the supply side microgrid, and the connection line A second switch circuit breaker, such as a K2 switch circuit breaker, is arranged at a position close to the supply-side microgrid. As shown in Figure 4, the method includes the following steps:

S31. The supply-side microgrid receives a command to connect the tie line sent by the network dispatching system.

After the microgrid on the demand side is closed, the network dispatching system sends an order to connect the connection line on the side of the microgrid on the supply side to the microgrid on the supply side.

S32. The supply-side microgrid issues an instruction to increase power generation to the distributed energy equipment, so that the power difference between the total load and the total power generation reaches a second preset power threshold.

Wherein, the second preset power threshold may be set to 50kW.

Optionally, in a specific embodiment of the present invention, after step S32 sends an instruction to increase the power generation to the distributed energy equipment, so that the power difference between the total load and the total power generation reaches the second preset power threshold, Also includes the following steps:

Step 32', when the power difference between the total load and the total power generation reaches the second preset power threshold, detect whether there is pressure on the line on the side of the tie line close to the supplier microgrid.

Through the above step 32', that is, the supply-side micro-grid can judge that the demand-side micro-grid has been closed by detecting the voltage of the tie line, so that it can be determined again that the supply-side micro-grid has been closed, thereby improving the micro-grid close. gate security.

Further, in a specific embodiment of the present invention, a second line voltage transformer is provided at the position of the second switch circuit breaker, and the supply side microgrid detects whether there is a line near the side of the supply side microgrid on the tie line Pressure specifically includes:

The voltage is collected by the second line voltage transformer, and it is determined whether the three-phase voltage on the side of the microgrid on the demand side is greater than a preset ratio of the rated voltage on the side of the microgrid on the demand side. Wherein, the preset ratio can be set to 70%, 90%, 95% and so on.

S33. If the supply-side microgrid detects that the line on the side of the supply-side microgrid is under pressure, it is detected whether the same-frequency grid connection condition is satisfied between the supply-side microgrid and the demand-side microgrid.

Optionally, in a specific embodiment of the present invention, detecting whether the same-frequency grid connection condition is satisfied between the supply-side microgrid and the demand-side microgrid specifically includes the following content:

1) Detect whether the three-phase voltage on the side of the tie-line close to the microgrid of the supplier is greater than the preset ratio of the rated voltage on the side of the microgrid of the supplier; the preset ratio can be set to 90%.

2) The absolute value of the active power at the common connection point between the grid and the microgrid is less than a third preset power threshold; wherein the third preset power threshold can be set to 50kW.

3) Whether the frequency difference between the demand-side microgrid side and the supply-side microgrid side is less than the preset frequency threshold; the preset frequency threshold can be set to 0.02Hz. as well as,

4) Whether the voltage phase difference between the demand side microgrid side and the supply side microgrid side is less than the preset voltage phase threshold, and whether the change value of the voltage phase difference is less than or equal to the preset voltage phase change threshold. Wherein, the preset voltage phase threshold can be set to 30°, and the preset voltage phase change threshold can be set to 5°/s.

Optionally, on the basis of step 32', step S33 is specifically:

If it is detected that the line on the side of the supply-side microgrid is under pressure, it is detected whether the same-frequency grid connection condition is met between the supply-side microgrid and the demand-side microgrid.

S34. If the same-frequency grid-connection condition is satisfied between the supply-side microgrid and the demand-side microgrid, the supply-side microgrid connects the second switch circuit breaker, and sends a press-closed message to the network dispatching system.

The method for interconnection between microgrids provided by Embodiment 3 of the present invention is applied to the supply-side microgrid. A connection line is set between the supply-side microgrid and the demand-side microgrid, and the connection line is located close to the supply-side microgrid. A second switch circuit breaker is provided, including: the supply-side microgrid receives the command to connect the connection line sent by the network dispatching system; and sends an instruction to increase the power generation to the distributed energy equipment, so that the total load and the total power generation The power difference between the total load and the total power generation reaches the second preset power threshold; if the power difference between the total load and the total power generation reaches the second preset power threshold, it is detected whether the same frequency is satisfied between the supply-side microgrid and the demand-side microgrid. Grid-connection conditions: if the same-frequency grid-connection condition is met between the supply-side microgrid and the demand-side microgrid, the second switch circuit breaker is turned on, and a press-closed message is sent to the network dispatching system. Therefore, by increasing the power generation and confirming that the supply-side microgrid and the demand-side microgrid meet the same-frequency grid-connection conditions, the problem of large current impact when the microgrids are interconnected can be overcome, thereby ensuring that the microgrid The quality of the power supply when connected.

In addition, optionally, in a specific embodiment of the present invention, a second line current transformer is also provided at the position of the second switch circuit breaker, and the second line current transformer is used for collecting current; After sending the information of pressing and closing the gate to the network dispatching system, the method further includes:

351. Receive a command to disconnect the tie line sent by the network dispatching system;

352. Issue an instruction to reduce power generation to the distributed energy equipment, so that the power on the connection line is less than the fourth preset power threshold; wherein, the fourth preset power threshold can be set to any value between 0 and 20kW , the present invention is not specifically limited.

353. Determine the power on the tie line according to the current collected by the second line current transformer and the voltage collected by the second line voltage transformer;

354. If the power on the tie line is less than a fourth preset power threshold, turn off the second switch breaker, and send opening information to the network dispatching system.

Embodiment Four

Embodiment 4 of the present invention provides a microgrid interconnection system 40. As shown in FIG. 5, the system 40 includes at least two microgrids 401, a network scheduling system 402, and a connection line 403. The connection line 403 is used to connect the demand side microgrid 401a and the supply side microgrid 401b, a first switch circuit breaker K1 is set on the side of the tie line 403 close to the demand side microgrid 401a, and a second switch breaker K1 is set on the tie line 403 close to the side of the supply side microgrid 401b. switch circuit breaker K2, where,

Demand side microgrid 401a is used for:

Receive an order to connect the tie line 403 sent by the network dispatching system 402;

Detecting whether there is no pressure on the line on the side of the contact line 403 close to the demand-side microgrid;

If it is detected that the line has no voltage, turn on the first switch circuit breaker K1, and send the information of no-voltage closing to the network dispatching system 402;

The supply side microgrid 401b is used to:

Receive an order to connect the tie line 403 sent by the network dispatching system 402;

Issue an instruction to increase the power generation to the distributed energy equipment 404, so that the power difference between the total load and the total power generation reaches the second preset power threshold, for example, 50KW;

If the power difference between the total load and the total power generation reaches the second preset power threshold, detect whether the supply-side microgrid 401b satisfies the same-frequency grid-connection condition;

If the supply-side micro-grid 401b satisfies the same-frequency grid-connection condition, turn on the second switch circuit breaker K2, and send the information of pressing and closing the switch to the network dispatching system 402;

The network scheduling system 402 is used for:

When it is determined that the two microgrids meet the interconnection conditions, a command to close the switch is sent to the demand side microgrid 401a;

After sending the closing operation command to the demand-side microgrid 401a, send the closing operation command to the supply-side microgrid 401b after a preset period of time;

Receive the information that the contact line connection is successful fed back by the supplier microgrid 401b.

The microgrid interconnection system 40 provided in Embodiment 4 of the present invention includes at least two microgrids 401, a network scheduling system 402, and a connection line 403. First, when the network scheduling system 402 determines that the two microgrids meet the interconnection conditions , and send a switch-on command to the demand-side microgrid 401a. The demand-side micro-grid 401a receives the command to connect the connection line 403 sent by the network dispatching system 402; and detects whether the line on the connection line 403 near the side of the demand-side micro-grid is without pressure; if it is detected that the line is without pressure , turn on the first switch circuit breaker K1 , and send the information of no-voltage closing to the network dispatching system 402 . Next, the network dispatching system 402 sends a switch-on command to the supplier microgrid 401b. The supply-side microgrid 401b receives the command to connect the connection line 403 sent by the network dispatching system 402; and sends an instruction to increase the power generation to the distributed energy equipment 404, so that the power difference between the total load and the total power generation reaches the second predetermined value. Set the power threshold; if the power difference between the total load and the total power generation reaches the second preset power threshold, check whether the supply-side microgrid 401b satisfies the same-frequency grid-connection condition; if the supply-side microgrid 401b meets the same-frequency grid-connection condition, connect Pass through the second switch circuit breaker K2, and send the information of pressing and closing to the network dispatching system 402. It can be seen from this that the demand-side microgrid first has no voltage closing, and the supply-side microgrid is followed by a pressure-closing process, and the supply-side microgrid and demand-side microgrid are determined to meet the same frequency grid connection conditions The method can overcome the problem of large current impact when the microgrids are interconnected, thereby ensuring the quality of power supply when the microgrids are connected.

Optionally, in a specific embodiment of the present invention, a transformer 4031 is also provided on the tie line 403, the low-voltage side of the transformer is connected to the low-voltage bus of the supply-side microgrid 401b, and the high-voltage side of the transformer 4031 is connected to the demand-side microgrid 401a HV bus connection; or

The low-voltage side of the transformer 4031 is connected to the low-voltage busbar of the demand-side microgrid 401a, and the high-voltage side of the transformer 4031 is connected to the high-voltage busbar of the supply-side microgrid 401b.

At this time, the second switch circuit breaker K2 can be a linkage circuit breaker, for example, on the tie line on the side of the supply side microgrid, there are two circuit breakers at both ends of the transformer 4031, which are controlled by the second switch circuit breaker K2 to turn off simultaneously , and connect at the same time.

Optionally, in a specific embodiment of the present invention, the capacity of the transformer 4031 is configured to have a ratio greater than 1:2 to the capacity of the main transformer of the demand-side microgrid 401a and the supply-side microgrid 401b.

Optionally, in a specific embodiment of the present invention, the two ends of the tie line 403 are also provided with current quick-break protection, so as to realize line relay protection.

Optionally, in a specific embodiment of the present invention, a first line voltage transformer and a first line current transformer are also provided at the position of the first switch circuit breaker K1, wherein the first line voltage transformer is used for collecting The voltage analog data on the side of the demand side microgrid 401a, the first line current transformer is used to collect the current analog data on the side of the demand side microgrid 401a; and, at the position of the second switch circuit breaker K2, there is also a The second line voltage transformer and the second line current transformer, wherein the second line voltage transformer is used to collect the voltage analog data on the side of the supply side microgrid 401b, and the second line current transformer is used to collect the supply side microgrid 401b Current analog data on one side.

By collecting the current analog data on the side of the demand-side microgrid 401a and the current analog data on the side of the supply-side microgrid 401b, the power at the side of the demand-side microgrid 401a and the side of the supply-side microgrid 401b is calculated.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (18)

1. a method for micro-internetworking, is applied to network scheduling system, it is characterized in that, comprising:

When determining that two microgrids meet interconnection condition, send the order of closing operation to party in request's microgrid;

After the order sending closing operation to described party in request microgrid, send the order of closing operation through default a period of time to supplier's microgrid;

Receive the successful information of connection of described supplier's microgrid feedback.

2. method according to claim 1, is characterized in that, after the successful information of connection receiving described supplier's microgrid feedback, described method also comprises:

Send active power upper and lower limit parameter to described supplier's microgrid, so as described supplier's microgrid according to described active power upper and lower limit parameter to described party in request microgrid supplying energy.

3. method according to claim 1, is characterized in that, describedly determines that two microgrids meet interconnection condition and are specially, and determines to have demand for interconnection between two microgrids and described two microgrids meet with requirement of frequently closing a floodgate.

4. method according to claim 3, is characterized in that, describedly determines to have demand for interconnection between two microgrids and described two microgrids meet and require specifically to comprise with frequently closing a floodgate:

According to the real-time running data of each microgrid, analyze the supply and demand complementary case of two microgrids within following a period of time judged in each microgrid described, to determine whether described two microgrids have demand for interconnection;

When determining that described two microgrids have demand for interconnection, then determine whether meet with requirement of frequently closing a floodgate between described two microgrids;

If meet with requirement of frequently closing a floodgate between described two microgrids, perform interconnected to described two microgrid sending controling instructions to indicate described two microgrids.

5. method according to claim 1, is characterized in that, after the successful information of connection of described reception described supplier microgrid feedback, described method also comprises:

When determining that two microgrids no longer meet interconnection condition, send the order of sub-switching operation to described supplier's microgrid;

After the order sending sub-switching operation to described supplier's microgrid, send the order of sub-switching operation through default a period of time to party in request's microgrid;

The separating brake receiving described party in request microgrid feedback disconnects and connects successful information.

6. the method for a micro-internetworking, be applied to party in request's microgrid, it is characterized in that, between described party in request microgrid and supplier's microgrid, be provided with interconnection, described interconnection is provided with the first switch disconnector on the position of described party in request's microgrid side, comprises:

Receive the order of the described interconnection of connection that network scheduling system sends;

Whether the circuit detected near described party in request's microgrid side on described interconnection is with no pressure;

If detect, described circuit is with no pressure, connects described first switch disconnector, and sends the information of combined floodgate with no pressure to described network scheduling system.

7. method according to claim 6, is characterized in that,

Described first switch disconnector position is provided with first line voltage transformer,

On the described interconnection of described detection, whether the circuit of close described party in request's microgrid side is with no pressure specifically comprises:

Gather voltage by described first line voltage transformer, determine whether the effective value of the three-phase average voltage of described party in request's microgrid side is less than the preset ratio of the rated voltage of described party in request's microgrid side.

8. method according to claim 7, is characterized in that,

Also be provided with first line current transformer in described first switch disconnector position, described first line current transformer is for gathering electric current;

Described send the information of combined floodgate with no pressure to described network scheduling system after, described method also comprises:

Receive the order of the described interconnection of disconnection that described network scheduling system sends;

The voltage that the electric current gathered according to described first line current transformer and described first line voltage transformer gather, determines the power on described interconnection;

Whether the power on the more described interconnection determined is less than the first predetermined power threshold value;

If the power on described interconnection is less than the first predetermined power threshold value, turn off described first switch disconnector, and send the information of separating brake to described network scheduling system.

9. a method for micro-internetworking, is applied to supplier's microgrid, it is characterized in that, is provided with interconnection between described supplier's microgrid and party in request's microgrid, described interconnection is provided with second switch circuit breaker on the position of described supplier's microgrid, comprises:

Receive the order of the described interconnection of connection that network scheduling system sends;

Issue the instruction increasing generated output to distributed energy equipment, make total load reach the second predetermined power threshold value with the power difference always generated electricity;

If total load reaches the second predetermined power threshold value with the power difference always generated electricity, detect between described supplier's microgrid and described party in request microgrid whether meet syn-collisional granite condition;

If meet syn-collisional granite condition between described supplier's microgrid and described party in request microgrid, connect described second switch circuit breaker, and send the information having pressing lock to described network scheduling system.

10. method according to claim 9, is characterized in that, increases the instruction of generated output described to issue to distributed energy equipment, and make after total load and the power difference always generated electricity reach the second predetermined power threshold value, described method also comprises:

When total load reaches the second predetermined power threshold value with the power difference always generated electricity, whether the circuit detected near described supplier's microgrid side on described interconnection has pressure;

If then described total load reaches the second predetermined power threshold value with the power difference always generated electricity, detect and whether meet syn-collisional granite condition between described supplier's microgrid and described party in request microgrid and be specially:

If when detecting that the circuit of described supplier's microgrid side has a pressure, detect between described supplier's microgrid and described party in request microgrid whether meet syn-collisional granite condition.

11. methods according to claim 10, is characterized in that,

Described second switch circuit breaker position place is provided with the second line voltage distribution instrument transformer,

Whether the circuit near described supplier's microgrid side on the described interconnection of described detection has pressing element body to comprise:

Gather voltage by described second line voltage distribution instrument transformer, determine whether the three-phase voltage of described party in request's microgrid side is greater than the preset ratio of the rated voltage of described party in request's microgrid side.

12. methods according to claim 9, is characterized in that, whether meet syn-collisional granite condition and specifically comprise between described detection described supplier microgrid and described party in request microgrid:

Detect the preset ratio whether described interconnection being greater than the rated voltage of described supplier's microgrid side near the three-phase voltage of described supplier's microgrid side;

The absolute value of the active power at the points of common connection place between electrical network and microgrid is less than the 3rd predetermined power threshold value;

Whether the difference on the frequency of described party in request's microgrid side and described supplier's microgrid side is less than predeterminated frequency threshold value; And,

Whether the voltage phase difference of described party in request's microgrid side and described supplier's microgrid side is less than predeterminated voltage phase threshold, and whether the changing value of described voltage phase difference is less than or equal to predeterminated voltage phase place change threshold.

13. methods according to claim 11, is characterized in that,

Also be provided with the second line current instrument transformer at described second switch circuit breaker position place, described second line current instrument transformer is for gathering electric current;

Described to send to described network scheduling system have the information of pressing lock after, described method also comprises:

Receive the order of the described interconnection of disconnection that described network scheduling system sends;

Issue the instruction reducing generated output to distributed energy equipment, make the power on described interconnection be less than the 4th predetermined power threshold value;

The voltage that the electric current gathered according to described second line current instrument transformer and described second line voltage distribution instrument transformer gather, determines the power on described interconnection;

If the power on described interconnection is less than the 4th predetermined power threshold value, turn off described second switch circuit breaker, and send the information of separating brake to described network scheduling system.

14. 1 kinds of microgrid interconnected systemss, it is characterized in that, described system comprises at least two microgrids, network scheduling system and interconnection, described interconnection is used for connection requirement side's microgrid and supplier's microgrid, described interconnection is provided with the first switch disconnector on the position of described party in request's microgrid side, described interconnection is provided with second switch circuit breaker on the position of described supplier's microgrid side, wherein

Described party in request microgrid is used for:

Receive the order of the described interconnection of connection that described network scheduling system sends;

Whether the circuit detected near described party in request's microgrid side on described interconnection is with no pressure;

If when detecting that described circuit is with no pressure, connect described first switch disconnector, and send the information of combined floodgate with no pressure to described network scheduling system;

Described supplier's microgrid is used for:

Receive the order of the described interconnection of connection that described network scheduling system sends;

Issue the instruction increasing generated output to distributed energy equipment, make total load reach the second predetermined power threshold value with the power difference always generated electricity;

If total load reaches the second predetermined power threshold value with the power difference always generated electricity, detect described supplier's microgrid and whether meet syn-collisional granite condition;

If described supplier's microgrid meets syn-collisional granite condition, connect described second switch circuit breaker, and send the information having pressing lock to described network scheduling system;

Described network scheduling system is used for:

When determining that two microgrids meet interconnection condition, send the order of closing operation to party in request's microgrid;

After the order sending closing operation to described party in request microgrid, send the order of closing operation through default a period of time to supplier's microgrid;

The interconnection receiving described supplier's microgrid feedback connects successful information.

15. systems according to claim 14, is characterized in that, described interconnection is also provided with transformer,

The low-pressure side of described transformer is connected with the low-voltage bus bar of described supplier's microgrid, and the high-pressure side of described transformer is connected with the high voltage bus of described party in request microgrid; Or

The low-pressure side of described transformer is connected with the low-voltage bus bar of described party in request microgrid, and the high-pressure side of described transformer is connected with the high voltage bus of described supplier's microgrid.

16. systems according to claim 15, is characterized in that, the capacity of described transformer is configured to be greater than 1:2 with the ratio of the main transformer capacity of described party in request microgrid, supplier's microgrid.

17. systems according to claim 14, is characterized in that, the two ends of described interconnection are also provided with current quick.

18. systems according to claim 14, is characterized in that,

First line voltage transformer and first line current transformer is also provided with in described first switch disconnector position, wherein, described first line voltage transformer is for gathering the voltage analog data of described party in request's microgrid side, and described first line current transformer is for gathering the current-mode analog quantity data of described party in request's microgrid side; And,

The second line voltage distribution instrument transformer and the second line current instrument transformer is also provided with at described second switch circuit breaker position place, wherein, described second line voltage distribution instrument transformer is for gathering the voltage analog data of described supplier's microgrid side, and described second line current instrument transformer is for gathering the current-mode analog quantity data of described supplier's microgrid side.