CN110165786A - A kind of intelligent low-pressure photovoltaic counnter attack power transmission monitor control system - Google Patents

Abstract

An intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system relates to the technical field of electric equipment. When the public network is powered off for maintenance, the voltage monitoring unit collects the voltage fluctuation signal of the public network and uploads it to the control unit. The collected voltage is compared with the preset threshold value. The network is connected to the photovoltaic user, and the communication unit communicates with the operation and maintenance personnel in time to inform the switch status; when the power supply on the public network side is restored, the operation unit controls the switch to close and restores the connection between the public network and the photovoltaic user. In the intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system of the present invention, its voltage monitoring unit can realize real-time monitoring of public network voltage. The electric operating mechanism can make the switch open and close reliably. The control unit accurately analyzes the voltage collected by the voltage monitoring unit, controls the action of the operating mechanism, and finally collects the switch action signal and transmits it to the communication module. The communication module immediately sends the switch status to the mobile phone of the operation and maintenance personnel after the switch action.

Description

An intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system

technical field

The invention relates to the technical field of electric power equipment, in particular to an intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system.

Background technique

As a kind of green energy, solar energy is an inexhaustible and reliable energy source for human beings. Vigorously developing and utilizing solar energy is the only way to establish a clean and sustainable energy system. Solar photovoltaic power generation is the most flexible and convenient way to utilize solar energy. In recent years, it has received extensive attention internationally and has made great progress. Therefore, in-depth research on photovoltaic grid-connected power generation systems has extremely important practical and far-reaching historical significance for saving conventional energy, protecting the environment, and promoting economic development.

A large number of distributed power sources are connected to the grid, so that the distribution network changes from a traditional radial single-ended network to a multi-terminal network interconnected between power sources and users. The power flow no longer flows unidirectionally from the busbar of the substation to each load. There may be distributed power sources operating in "isolated islands" in the region, causing "reverse power transmission" and becoming a new risk that threatens the safety of maintenance personnel. Inverter-type distributed power access systems, due to the mismatch between the power supply and the load, the load is highly dependent on the power supply of the public grid. After the public grid is powered off, the inverter prevents "island" operation. However, in actual operation, there are some hidden dangers in the user's grid-connected inverter, and it cannot be used as the only reliable device for preventing "reverse power transmission". Distributed power grid-connected inverters are user assets, and they can independently choose equipment manufacturers. It is difficult for public grid maintenance units to grasp and control the quality of equipment, and users of distributed power generally lack professional knowledge. Basic security measures such as installing fences and signage are difficult. At the same time, because the inverter and the low-voltage grid-connected point breaking equipment have no obvious breaking points, the grid maintenance workers cannot directly confirm their status. In the low-voltage distribution network connected to the distributed power supply, there is a risk of "reverse power transmission" of the distributed power supply connected to the grid through the 220V/380V voltage level, especially when the user is equipped with energy storage components. The probability of forming a microgrid "island" operation is high, and the pressure to prevent "reverse power transmission" is high.

After preliminary research and investigation, it was found that "Design Principle and Parameter Calculation of Low-Voltage Anti-islanding Device for Distribution Network" is aimed at the islanding operation mechanism and anti-islanding protection strategy in the inverter of the distributed photovoltaic power generation system in the 220V/380V distribution network. "Realization of Photovoltaic Monitoring System Based on Wireless Communication and Android Phone" is a photovoltaic monitoring system based on WiFi communication and Android smart phone client display, which mainly monitors various parameters of photovoltaic power generation and realizes real-time monitoring of photovoltaic power generation system. However, none of the above-mentioned similar technologies can automatically cut off the connection between photovoltaic users and the public network when the public network is scheduled to be shut down for maintenance; the connection between. Therefore, it is imperative to design an intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system.

Contents of the invention

The purpose of the present invention is to provide an intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system for the deficiencies of the prior art.

In order to achieve the above purpose, the technical solution adopted in the present invention is: an intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system, the public network enters the indoor distribution box of the user through the metering cabinet of the power supply company, and the indoor distribution box and the user The internal loads are connected; the photovoltaic power station and the inverter are connected to the user-side power generation metering box through the AC grid-connected switch, and the photovoltaic power generation is connected to the indoor distribution box through the power generation metering electric energy meter to directly supply power to the user's internal load or to the public network The system is mainly composed of an operating mechanism and a control mechanism; the operating mechanism is placed in the metering cabinet of the power supply company to cut off and close the connection between the public network and the user side, which consists of an operating unit, a motor and a switch , the operation unit receives the opening and closing signal and controls the motor action, and the motor controls the opening and closing of the switch to realize cutting and closing the connection between the public network and the user side; the control mechanism is composed of a voltage monitoring unit, a control unit and a communication module. Placed on the public network side; the voltage monitoring unit of the control mechanism and the operating unit of the operating mechanism are connected to each other to realize the opening and closing signal transmission; the voltage monitoring unit monitors the voltage of the public network in real time and outputs signals to the control unit, and the control unit analyzes the data collected by the voltage monitoring unit The voltage and send a control signal to the operation unit to realize the switch opening or closing; the control unit collects the switch action signal and transmits it to the communication module, and the communication module immediately sends the switch status information to the operation and maintenance personnel.

As the preferred technical solution of the intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system of the present invention, the control unit is composed of a three-phase voltage monitoring circuit and a microprocessor, and the three-phase voltage monitoring circuit mainly completes the conversion of the three-phase voltage into a low voltage The voltage signal is input to the controller for AD sampling, and the controller judges whether the three-phase voltage is undervoltage, undervoltage, or normal according to the sampling results; the microprocessor chooses the Pic16f616 single-chip microcomputer produced by Huzhou Tailun, which can reliably send control signals to Operating unit and communication unit.

As a preferred technical solution of the intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system of the present invention, when the voltage of the operating unit is 7% higher than the rated voltage or 10% lower than the rated voltage, the delay time is ten seconds. If it is still abnormal, an opening command is issued, the voltage returns to the selected range, and a closing command is issued after a delay of 30 seconds.

In the present invention, an operation unit and a control switch are installed at the boundary point between the user and the public network, and a voltage monitoring and control unit is set on the public network at the same time. When the public network is powered off for maintenance, the voltage monitoring unit collects the public network voltage fluctuation signal and Upload to the control unit, compare the collected voltage with the preset threshold value, when the threshold value is exceeded, the operation unit controls the switch to open, disconnect the public network and the photovoltaic user connection, and the communication unit communicates with the operation and maintenance personnel in time to inform the switch status ; When the power supply on the public network side is restored, the operating unit controls the switch to close, and the connection between the public network and the photovoltaic user is restored.

Compared with the prior art, the beneficial effects of the present invention are as follows:

(1) Compared with "Design Principle and Parameter Calculation of Low-Voltage Anti-Islanding Device for Distribution Network", the present invention installs the device and collects data within the scope of the public network side. Compared with "Realization of Photovoltaic Monitoring System Based on Wireless Communication and Android Mobile Phone", the present invention monitors the switch action and then feeds back to the on-site staff through a certain communication method. When the public network line side is powered off for maintenance, the connection between the photovoltaic grid-connected users and the public network can be cut off in time, the action accuracy can reach 100%, and the operation and maintenance personnel can timely and accurately know the connection between the photovoltaic grid-connected users and the public network In the connection state, the delay can be controlled within 1 minute.

(2) The voltage monitoring unit of the intelligent low-voltage photovoltaic anti-reverse power transmission monitoring control system of the present invention can realize real-time monitoring of the public network voltage, and the deviation is less than 2% within the range of 85% Un to 115% Un. The electric operating mechanism can make the switch open and close reliably, and the action accuracy rate reaches 100%. The control unit design is based on the automatic control unit of the single-chip microcomputer platform, which accurately analyzes the voltage collected by the voltage monitoring unit, controls the action of the operating mechanism, and finally collects the switch action signal and transmits it to the communication module. The process reliability reaches 100%. The communication module immediately sends the switch status to the mobile phone of the operation and maintenance personnel after the switch action, and the delay is within 1 minute.

Description of drawings

The intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Figure 1 is a schematic structural diagram of an intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system.

Figure 2 is a schematic diagram of the local structure of the intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system.

Figure 3 is the test curve of the voltage acquisition original.

Figure 4 is a hardware block diagram of the communication module.

Figure 5 is a histogram of action accuracy (a) and switch action test (b).

Detailed ways

Referring to the "Typical Design Scheme of Distributed Photovoltaic Power Generation Access System of State Grid Corporation" XGF380-Z-1, the common low-voltage photovoltaic power generation grid-connected wiring diagram is shown in Figure 1:

The public network enters the indoor distribution box 13 of the user through the metering cabinet 15 of the power supply company, and the indoor distribution box 13 is connected with the user's internal load 14 to provide power when there is no photovoltaic power generation. When installing a photovoltaic power station at the user end, the photovoltaic power station and the inverter 10 are connected to the power generation metering box 12 on the user side through the AC grid-connected switch 11 , and the power generation meter 121 records the count of photovoltaic power generation power. The photovoltaic power generation is connected to the indoor distribution box 13 through the power generation metering electric energy meter 121 to directly supply power to the user's internal load 14 or transmit electric energy to the public network side. When electric energy is transmitted to the public network side, the electric energy meter in the power supply company's metering cabinet 151 records the counting of electric energy imported into the public network.

The intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system of the present invention is designed based on the above-mentioned access design scheme. Please refer to FIG. 2 together. The system is mainly composed of an operating mechanism 17 and a control mechanism 16 . The operating mechanism 17 is placed in the metering cabinet 15 of the power supply company and is used to cut off and close the connection between the public network and the user side. It is composed of an operating unit 171, a motor 172 and a switch 173. The operating unit 171 receives the opening and closing signals and The motor 172 is controlled to operate, and the motor 172 controls the opening and closing of the switch 173 to realize cutting off and closing the connection between the public network and the user side. The control mechanism 16 is composed of a voltage monitoring unit 162, a control unit 163 and a communication module 161, and is placed on the public network side. The voltage monitoring unit 162 of the control mechanism 16 is connected to the operating unit 171 of the operating mechanism 17 to realize the transmission of opening and closing signals. The voltage monitoring unit 162 monitors the public network voltage in real time and outputs a signal to the control unit 163. The control unit 163 analyzes the voltage collected by the voltage monitoring unit and sends a control signal to the operation unit 171 to open or close the switch 173. The control unit 163 collects the switch action signal and transmits it to the communication module 161, and the communication module 161 immediately sends the switch status information to the operation and maintenance personnel.

Among them, the composition and working principle of the above-mentioned components are as follows:

1. Voltage monitoring unit

The voltage monitoring unit adopts the voltage sensor of Qingzhou VIA, and the method of collecting voltage is inductive. It can be installed or disassembled directly without power failure during installation. The collection accuracy is high, and it can ensure that the system does not malfunction or refuse to operate. The test data of the voltage acquisition original is shown in Table 1 and Figure 3.

Table 1 Voltage acquisition original test data

serial number Voltage target parameter actual parameters error 1 85% Un 187V 190V +1.6% 2 87% Un 191.4V 194.3V +1.5% 3 90% Un 198V 200.2V +1.0% 4 93% Un 204.6V 202V -1.2% 5 95% Un 209V 210.8 +0.9% 6 97% Un 213.4V 211.8V -0.7% 7 100%Un 220V 219V -0.5% 8 103% Un 226.6V 228.3V +0.8% 9 105% Un 231V 229.4V +0.7% 10 107% Un 235.4V 233.6V -0.8% 11 110% Un 242V 239.8V -0.9% 12 115% Un 253V 255.3 +0.9%

It can be seen from Table 1 and Figure 3 that the voltage monitoring unit can realize real-time monitoring of the public network voltage, and the deviation is less than 2% within the range of 85% Un to 115% Un.

2. Control unit

The control unit is composed of a three-phase voltage monitoring circuit and a microprocessor. The three-phase voltage monitoring circuit mainly completes the conversion of the three-phase voltage into a low-voltage voltage signal, which is input to the controller for AD sampling. The controller judges whether the three-phase voltage is undervoltage, undervoltage or normal according to the sampling result. The measuring circuit of the three-phase voltage is shown in Fig. 2 . Among them, Ua is the 220VAC voltage of phase A, and SignUA is the low-voltage measurement signal obtained after conversion relative to the voltage of phase A. This signal is directly input to the AD sampling terminal AN0 of the controller, and the voltage information can be collected reliably during the test.

The microprocessor chooses the Pic16f616 single-chip microcomputer produced by Huzhou Tailun, which has the characteristics of 8-bit microcomputer, the stability is the best among all single-chip microcomputers, the power consumption is very small, only 2mA current, the speed is fast, the anti-interference is good, and the control signal can be sent out reliably For operating unit and communication unit. The microprocessor is mainly responsible for the sampling calculation of the three-phase voltage, the reading of the delay time and the control of the relay. After the three-phase phase voltage is transformed, the signals SignUa, SignUb and SignUc are respectively input to the AD sampling terminals AN0, AN1 and AN2 of the microcontroller for sampling.

3. Communication module

The communication module is shown in Figure 4, which uses the SIM800C module, and requires an additional SIM card and GSM antenna. This invention uses the GSM text message function to send text messages to the mobile phone of the operation and maintenance personnel to inform the operation and maintenance personnel of the status of the photovoltaic grid-connected switch for emergency repairs Personnel check.

Through comparative tests, it is found that compared with optical fiber communication, WIFI communication and other modes, GSM communication is more convenient, and can achieve the goal well, and the research and development cost is low.

4. Operating unit

The operating unit uses an electric operating mechanism to realize the function of automatic tripping under voltage loss and automatic closing when the voltage returns to normal.

The operating unit adopts Delixi's electric operating mechanism, which has low cost, good stability, low power consumption, and over-current protection. After the test receives the signal, it can operate reliably and meet the set goals.

The operating unit of the present invention has a time-delay function and can issue an opening and closing command; when the voltage is 7% higher than the rated voltage or 10% lower than the rated voltage, the delay time is ten seconds, and if the voltage is still abnormal after ten seconds, an The opening command, the voltage returns to the selected range (selected according to the regulations of the State Grid), and the closing command is issued with a delay of 30 seconds; the control unit monitors the switch status in real time, and sets the delay to avoid too frequent switching and protect the equipment.

The invention mainly installs an operation unit and a control switch at the boundary point between the user and the public network, and at the same time sets a voltage monitoring and control unit on the public network. When the public network is powered off for maintenance, the voltage monitoring unit collects the voltage fluctuation signal of the public network , and uploaded to the control unit, the collected voltage is compared with the preset threshold value, when the threshold value is exceeded, the operation unit controls the switch to open, disconnects the connection between the public network and the photovoltaic user, and the communication unit communicates with the operation and maintenance personnel in time to inform Switch state: when the power supply on the public network side is restored, the operating unit controls the switch to close, and the connection between the public network and the photovoltaic user is resumed.

Assemble the above-mentioned components according to the set connection relationship and then debug. The working voltage is directly powered from the ammeter. The test results of the whole machine are shown in Table 2, the bar graph of the action accuracy (a) and switch action test (b) As shown in Figure 5.

Table 2 Test results of the whole machine

The intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system of the present invention has been tested in multiple low-voltage photovoltaic grid-connected projects, and the effect is as follows:

Table 3 system trial situation

Goal 1 is achieved: when the voltage is 7% higher than the rated voltage or 10% lower than the rated voltage, the connection between the photovoltaic user and the public network will be automatically cut off; when the voltage is normal, the connection between the photovoltaic user and the public network will be automatically restored.

Goal 2 is achieved: the time to determine the status of the grid-connected point after the power outage on the public network side is shortened from 70 minutes before the event to 1 minute to receive a text message notification, and the judgment accuracy reaches 100%.

Table 4 Target Achievement

Combining the above application data table, it can be seen that after nearly 3 months of actual use, the intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system of the present invention has achieved the expected goals in terms of intelligent control of the connection status of the grid connection point and SMS notification to operators.

In the case of the explosive development of the photovoltaic industry, the traditional supporting distributed photovoltaic equipment is relatively lagging behind, and the equipment cannot reliably meet the specification requirements. The invention's professional knowledge and practical work experience have successfully produced an intelligent low-voltage photovoltaic anti-reverse power transmission monitoring and control system, enabling operators to effectively grasp the connection status of low-voltage photovoltaic grid-connected points, and playing a positive role in the development of society. Its advantages are also as follows:

1) Save social resources

This event can intelligently control the connection status of low-voltage photovoltaic grid-connected points, which greatly saves human resources, avoids a lot of time loss, and reduces the power loss caused by photovoltaic users due to power outages on the public grid side.

2) Promote social development

Through this device system, the service level and service skills of the power company have reached a new level, which better ensures the safe and stable power consumption of users, reduces the time-consuming maintenance of power outages on the public network side, and greatly improves the user's photovoltaic power consumption. The power generation is lost in vain without being connected to the grid, which promotes the construction of new energy in cities

3) This set of devices can ensure the safety of the staff and avoid hurting people due to photovoltaic reverse power transmission; at the same time, it greatly reduces the time for users to leave the main power grid.

The above content is only an example and description of the concept of the present invention. Those skilled in the art make various modifications or supplements to the described specific embodiments or replace them in similar ways, as long as they do not deviate from the concept of the invention Or beyond the scope defined in the claims, all should belong to the protection scope of the present invention.

Claims (6)

1. a kind of intelligent low-pressure photovoltaic counnter attack power transmission monitor control system, public network enters user by power supply company's metering cabinet (15) The indoor distribution box (13) at end, indoor distribution box (13) are connected with user's internal load (14)；Photovoltaic plant and inverter (10) it is connected by exchanging grid-connected switch (11) with user side power generation batch meter (12), photovoltaic power generation is through the metering electric energy meter that generates electricity (121) it accesses and directly powers to user's internal load (14) in indoor distribution box (13) or convey electric energy to public network side, it is special Sign is that the system is mainly made of operating mechanism (17) and control mechanism (16)；

Operating mechanism (17) is placed in power supply company's metering cabinet (15), for cutting off, being closed the company between public network and user side It connects, is made of operating unit (171), motor (172) and switch (173), operating unit (171) receives divide-shut brake signal and controls Motor (172) movement processed, the opening and closing of motor (172) control switch (173) are to realize cutting, closure public network and user side Between connection；

Control mechanism (16) is made of voltage monitoring unit (162), control unit (163) and communication module (161), is placed in public affairs Net side；The voltage monitoring unit (162) of control mechanism (16) and the operating unit (171) of operating mechanism (17) are connected to each other realization The transmission of divide-shut brake signal；Voltage monitoring unit (162) to public network voltage real-time monitoring and to control unit (163) output signal, Control unit (163) analyzes the voltage of voltage monitoring unit acquisition, and issues control signal to operating unit (171), to realize Switch (173) open or close；Control unit (163) acquisition switch actuating signals simultaneously pass to communication module (161), communicate mould Block (161) sends switching-state information to operation maintenance personnel immediately.

2. intelligent low-pressure photovoltaic counnter attack power transmission monitor control system as described in claim 1, which is characterized in that the control is single Member is made of three-phase-voltage monitoring circuit and microprocessor, and three-phase-voltage monitoring circuit mainly completes three-phase phase voltage to be converted into The voltage signal of low pressure, makes its input controller carry out AD sampling, and whether controller judges three-phase voltage according to the result of sampling It is decompression, under-voltage, normal；The Pic16f616 single-chip microcontroller that microprocessor selects the human relations of Huzhou Thailand to produce, can reliably issue control signal To operating unit and communication unit.

3. intelligent low-pressure photovoltaic counnter attack power transmission monitor control system as described in claim 1, which is characterized in that the operation is single Member is delayed ten seconds when voltage is higher than voltage rating 7% or is lower than voltage rating 10%, if voltage is still abnormal after ten seconds, Separating brake instruction is issued, voltage restores to selected range, and be delayed 30 seconds sending reclosing commands.

4. intelligent low-pressure photovoltaic counnter attack power transmission monitor control system as described in claim 1, which is characterized in that when public network has a power failure When maintenance, voltage monitoring unit acquires public network voltage fluctuation signal, and is uploaded to control unit, the voltage of acquisition with preset Threshold values comparison, exceed threshold values when, operating unit control switch separating brake, disconnect public network connect with photovoltaic user, communication unit and When with operation maintenance personnel communicate, telling switch state；After public network side restores electricity, operating unit control switch is closed a floodgate, and restores public Net is connect with photovoltaic user.

5. intelligent low-pressure photovoltaic counnter attack power transmission monitor control system as described in claim 1, which is characterized in that when public network route When the interruption maintenance of side, the connection between grid-connected user and public network can be cut off in time, and operation maintenance personnel in time, can be obtained accurately Know the connection status between grid-connected user and public network.

6. intelligent low-pressure photovoltaic counnter attack power transmission monitor control system as described in any one in claim 1-5, which is characterized in that logical Cross at the separation of user and public network installation one operating unit and control switch, at the same be arranged on public network voltage monitoring and Control unit, when public network interruption maintenance, voltage monitoring unit acquires public network voltage fluctuation signal, and is uploaded to control unit, The voltage of acquisition and preset threshold values compare, and when exceeding threshold values, operating unit control switch separating brake disconnects public network and photovoltaic User's connection, communication unit are communicated with operation maintenance personnel in time, telling switch state；After public network side restores electricity, operating unit Control switch is closed a floodgate, and is restored public network and is connect with photovoltaic user.