CN105162409B - The embedded anti-electricity-theft device of the grid-connected modular electric power generation system of distributed photovoltaic - Google Patents

Abstract

The invention discloses an embedded anti-stealing device of a distributed photovoltaic grid-connected modular power generation system. At present, the anti-stealing technology based on the microprocessor has the defects of inconvenient use and poor reliability. The invention includes a DC module anti-stealing calculation communication unit and an AC module anti-stealing calculation communication unit, which are designed and installed according to the corresponding distributed photovoltaic grid-connected modular power generation system; the alarm circuit of the DC module anti-stealing calculation communication unit is in After receiving any electricity theft alarm signal from the RS485 communication interface, the indicator light and buzzer alarm will be issued immediately; when it is judged that electricity theft has occurred or any electricity theft alarm signal from the RS485 communication interface has been received, the AC module will prevent electricity theft The computing communication unit will immediately give an indicator light and a buzzer alarm. The invention can identify whether there is electricity stealing behavior in the distributed photovoltaic grid-connected modular power generation system, and at the same time, can accurately calculate the electricity stealing behavior and carry out alarm processing when the electricity stealing behavior occurs.

Description

Embedded anti-stealing device for distributed photovoltaic grid-connected modular power generation system

technical field

The invention belongs to the technical field of electricity-stealing prevention for distributed photovoltaic grid-connected power generation systems, in particular to an embedded anti-stealing device suitable for distributed photovoltaic grid-connected modularized power generation systems.

Background technique

Distributed photovoltaic grid-connected power generation is the main form of solar photovoltaic power generation at present. In order to promote the application of distributed photovoltaic grid-connected power generation systems, the country has introduced a policy of photovoltaic power generation grid-connected electricity price subsidies. However, under the temptation of the profit of the electricity price subsidy, criminals take measures such as reconnecting the distributed photovoltaic grid-connected power generation to falsely increase the display value of the photovoltaic power generation meter, and directly taking power from the grid through the DC/AC converter of the photovoltaic power generation system. Feedback to the power grid and other means to illegally obtain electricity price subsidies.

With the continuous expansion of the scale of distributed photovoltaic grid-connected power generation systems, the degree of dispersion of system components is getting higher and higher, and there are various methods of stealing electricity, which makes it more difficult for distributed photovoltaic grid-connected power generation systems to prevent electricity theft. The focus of anti-theft of distributed photovoltaic grid-connected power generation system is to monitor the consistency between the total power generation of photovoltaic modules and the output power of grid-connected DC/AC converters. The timeliness of manual investigation of electricity theft is poor, and it cannot provide accurate electricity theft information such as electricity theft time and electricity theft.

At present, some microprocessor-based anti-stealing technologies have emerged, such as calculating the actual photovoltaic power generation according to the real-time data of sunlight intensity and the number of installed photovoltaic modules, and comparing it with the measured value of grid-connected power generation to judge power theft. Historical meteorological data and photovoltaic power generation data in the same period and using intelligent algorithms to establish an anti-stealing model to judge the technology of stealing electricity, etc. These anti-stealing technologies have the disadvantages of inconvenient use and poor reliability.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned prior art, and provide an embedded anti-stealing device suitable for distributed photovoltaic grid-connected modular power generation systems, which can identify distributed photovoltaic grid-connected modular power generation Whether there is electricity stealing behavior in the system, and at the same time, it can accurately calculate the electricity stealing behavior and carry out alarm processing when electricity stealing behavior occurs.

For this reason, the present invention adopts the following technical scheme: the embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system includes an integer N identical DC module anti-stealing computing communication units and an integer M identical AC modules anti-stealing Stealing electricity calculation communication unit, the embedded anti-theft device is designed and installed according to the corresponding distributed photovoltaic grid-connected modular power generation system;

The distributed photovoltaic grid-connected modular power generation system includes an integer of N identical photovoltaic modules, an integer of N identical DC/DC converters, a DC bus, an integer of M identical DC/AC converters, an AC bus, and user The load, the electric energy meter and the low-voltage distribution network, each photovoltaic module of the string structure is connected to the DC bus through a corresponding DC/DC converter, and the DC input terminal of each DC/AC converter is connected to the DC bus. The AC output terminal of each DC/AC converter is connected to the AC bus, the user load is connected to the AC bus, the energy meter is connected between the AC bus and the low-voltage distribution network for bidirectional energy measurement, the voltage waveform of the AC bus and the low-voltage distribution network The voltage waveform is the same;

The DC module anti-stealing computing communication unit includes a current and voltage acquisition circuit, a microprocessor, an alarm circuit and an RS485 communication interface. It is designed simultaneously with the DC/DC converter of the distributed photovoltaic grid-connected modular power generation system. Each The DC module anti-theft calculation communication unit and the corresponding single DC/DC converter form a packaged DC module. The DC module anti-theft calculation communication unit calculates the photovoltaic module by measuring the corresponding DC output voltage and current of the photovoltaic module. The output power of the photovoltaic module, the output power of the photovoltaic module, and the serial number information of the DC module are output through the RS485 communication interface, and the alarm circuit immediately performs an indicator light and a buzzer alarm after receiving any electricity theft alarm signal from the RS485 communication interface;

The AC module anti-stealing calculation communication unit includes a current and voltage acquisition circuit, a microprocessor, an alarm circuit and an RS485 communication interface. It is designed simultaneously with the DC/AC converter of the distributed photovoltaic grid-connected modular power generation system. Each The AC module anti-stealing calculation communication unit and the corresponding single DC/AC converter form an AC module packaged together. The AC module anti-stealing calculation communication unit calculates the AC output voltage and current by measuring the corresponding DC/AC converter AC output voltage and current. The output power of the DC/AC converter, the serial number information of the AC module and the output power of the DC/AC converter of the AC module are output through the RS485 communication interface, and the anti-theft calculation communication unit of each AC module regularly collects all The serial number of the DC module and the corresponding output power information of the photovoltaic module, as well as the serial number information of all the AC modules and the corresponding output power information of the DC/AC converter, the total AC power is obtained by adding the output power of all DC/AC converters, and the The output power of all photovoltaic modules is added to obtain the total DC power. When the difference between the total AC power and the total DC power exceeds the specified range, it is judged that electricity stealing has occurred. Electricity alarm signal, electricity theft and AC module serial number information, when it is judged that electricity theft occurs or any electricity theft alarm signal is received from the RS485 communication interface, the AC module anti-theft calculation communication unit will immediately perform indicator lights and buzzers Call the police.

At present, most advanced photovoltaic grid-connected power generation systems adopt a modular structure. Each photovoltaic module with a string structure has a DC/DC converter for maximum power point tracking to improve efficiency. Multiple parallel DC/AC conversions are used. The converter can realize that only one of the DC/AC converters is in a non-full-load working state, while the other DC/AC converters are in a full-load or no-load working state, thus ensuring high efficiency of grid-connected power generation. The present invention is aimed at the advanced photovoltaic grid-connected modular power generation system. The DC/DC converter and DC/AC converter of the system usually need to detect state quantities such as current and voltage during control operation, so these internal detection quantities can be directly used for preventing The power calculation of the electricity stealing device, especially the calculation of the solar energy generated by the photovoltaic module, so while designing the photovoltaic grid-connected modular power generation system, the design of the embedded anti-theft electricity device can be carried out. The auxiliary equipment of the grid-connected modular power generation system will be installed and debugged together.

Further, in the DC module anti-theft computing communication unit, the DC output voltage and current of the photovoltaic module are measured through a DC voltage divider and a shunt respectively, or directly collected by a DC/DC converter.

Further, in the AC module anti-stealing computing communication unit, the AC output voltage and current of the DC/AC converter are measured through voltage transformers and current transformers respectively, or directly collected by DC/AC converters.

Further, when M is greater than 1, the distributed photovoltaic grid-connected modular power generation system is a multi-AC modular inverter power generation system; when M is 1, the distributed photovoltaic grid-connected modular power generation system is a centralized inverter In the generator power generation system, the AC busbar supplies power to user loads. When the power generated by M DC/AC converters exceeds the power required by user loads, the excess power is sent to the low-voltage distribution network. When the power generated by M DC/AC converters When the electric energy is less than the electric energy required by the user's load, the insufficient electric energy is input into the AC bus from the low-voltage distribution network, and M DC/AC converters provide all or part of the reactive power and harmonic current required by the user's load.

Further, the instantaneous output power of the photovoltaic module is P ₁ =u ₁ (t)i ₁ (t), where u ₁ (t) and i ₁ (t) are the DC output voltage and current instantaneous value of the photovoltaic module respectively , the output power of the photovoltaic module is the average value of multiple instantaneous output powers obtained at a certain time interval (usually one minute).

Furthermore, when the voltage waveform of the low-voltage distribution network is a non-sinusoidal wave, the output power of the DC/AC converter includes fundamental and harmonic active power, and the output power of the DC/AC converter is based on Calculate, where u ₂ (t) and i ₂ (t) are the instantaneous values of the AC output voltage and current of the DC/AC converter respectively, and T is the voltage cycle of the low-voltage distribution network. That is, the output power of the DC/AC converter is the average value of multiple output power calculation values.

The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system of the present invention can be used for up to 1MW, 7≤N≤168, 2≤M≤50, the highest voltage of the DC bus is 600V, and the voltage of the low-voltage distribution network is 220V/50Hz Distributed photovoltaic grid-connected modular power generation system, the maximum DC output power of photovoltaic modules that can be measured by the DC module anti-stealing calculation communication unit is 70KW, and the maximum AC output power of the DC/AC converter that can be measured by the AC module anti-stealing calculation communication unit 0.5MW, the allowable difference between the total AC power and the total DC power can be set, the DC module anti-theft calculation accuracy of the DC output voltage and current measurement of the photovoltaic module in the communication unit is not less than 1%, the AC module anti-theft The AC output voltage and current measurement accuracy of the DC/AC converter in the electrical computing communication unit is not less than 1%, and the minimum time interval between each electricity stealing judgment of the AC module anti-electricity theft computing communication unit is 1 minute.

The beneficial effects of the present invention are as follows: (1) most of the current advanced photovoltaic grid-connected power generation systems adopt a modular structure, because their DC/DC converters and DC/AC converters need to detect state quantities such as current and voltage during control operation, Therefore, these internal detection quantities of the advanced photovoltaic grid-connected power generation system can be directly used for the power calculation of the anti-theft device, especially the calculation of solar energy generated by photovoltaic modules, which avoids the use of sunlight radiation intensity for the anti-theft device of the ordinary photovoltaic grid-connected power generation system. The solar radiation sensor and other facilities that need to be used when calculating the converted solar energy with the time characteristic curve; The auxiliary device of the chemical power generation system is packaged together with the DC/DC converter and the DC/AC converter, and the DC module anti-stealing calculation communication unit of the anti-stealing device and the AC module anti-stealing calculation communication unit are designed in a modular manner, so It has the characteristics of good reliability, easy interchangeability, high degree of confidentiality and convenient installation; (3) communicates with each other through RS485, and each AC module anti-theft calculation communication unit can independently perform anti-theft calculation and judgment, so the anti-theft The anti-stealing technology of the power-stealing device has reliability and redundancy.

Description of drawings

Fig. 1 is a schematic diagram of the present invention, which shows a photovoltaic grid-connected modular power generation system, an anti-stealing device and a typical power-stealing circuit diagram of a photovoltaic grid-connected power generation system.

Among the figure: 101 is a total of N identical DC module anti-stealing calculation communication units (referred to as DC anti-stealing units in the figure), 102 is a total of M identical AC modules anti-stealing calculation communication units (abbreviated as AC anti-stealing units in the figure). power stealing unit), 103 is the RS485 communication line, 201 is a total of N photovoltaic modules, 202 is a total of N DC/DC converters (referred to as DC/DC in the figure), 203 is a DC bus, and 204 is a total of M 205 is the AC busbar, 206 is the user load, 207 is the electric energy meter, 208 is the low-voltage distribution network, and 301 is the typical electricity stealing line of the grid-connected photovoltaic power generation system. A rectifier that transmits power from the low-voltage distribution network to the DC bus.

detailed description

The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system of the present invention, as shown in Figure 1, includes an integer of N identical DC module anti-stealing calculation communication units 101, an integer of M identical AC modules for anti-stealing Stealing electricity calculation communication unit 102 and RS485 communication line 103, the embedded anti-theft electricity device is designed and installed according to the corresponding distributed photovoltaic grid-connected modular power generation system.

The distributed photovoltaic grid-connected modular power generation system includes N identical photovoltaic modules 201, N identical DC/DC converters 201, DC bus bars 203, M identical DC/AC converters 204, AC bus bars 205, and user loads 206. Electric energy meter 207 and low-voltage distribution network 208. Each photovoltaic module 201 of string structure is connected to DC bus 203 through a corresponding DC/DC converter 202. The DC input of each DC/AC converter 204 connected to the DC bus 203, the AC output of each DC/AC converter 204 is connected to the AC bus 205, the user load 206 is connected to the AC bus 205, and the electric energy meter 207 is connected between the AC bus 205 and the low-voltage distribution network 208 Perform bidirectional electric energy measurement, the voltage waveform of the AC bus 205 is the same as the voltage waveform of the low-voltage distribution network 208, when M is greater than 1, the distributed photovoltaic grid-connected power generation system is a multi-AC modular inverter power generation system, when M is 1 , the distributed photovoltaic grid-connected power generation system is a centralized inverter power generation system, and the AC bus 205 supplies power to the user load 206. When the power generated by M DC/AC converters 204 is more than the power required by the user load 206, the redundant The electric energy is sent to the low-voltage distribution network 208. When the electric energy generated by the M DC/AC converters 204 is less than the electric energy required by the user load 206, the insufficient electric energy is input to the AC bus 205 from the low-voltage distribution network 208, and the M DC/AC The converter 204 provides all or part of the reactive power and harmonic current required by the user load 206 .

The DC module anti-stealing calculation communication unit 101 of the embedded anti-stealing device mainly includes four parts: current and voltage acquisition circuit, microprocessor, alarm circuit and RS485 communication interface. The DC converter 202 is designed at the same time. Each DC module anti-theft calculation communication unit 101 and the corresponding single DC/DC converter 202 form a packaged DC module. The DC module anti-theft calculation communication unit 101 measures the corresponding The DC output voltage and current of the photovoltaic module 201 are used to calculate the output power of the photovoltaic module 201. The DC output voltage and current of the photovoltaic module 201 can be measured through a DC voltage divider and a shunt respectively, or directly using a DC/DC converter. The DC output voltage and current information of the photovoltaic module 201 collected by 202, the output power of the photovoltaic module 201 and the serial number information of the DC module are output through the RS485 communication interface, and the alarm circuit immediately receives any electricity theft alarm signal from the RS485 communication interface. Carry out indicator light and buzzer alarm.

The AC module anti-stealing calculation communication unit 102 of the embedded anti-stealing device mainly includes four parts: current and voltage acquisition circuit, microprocessor, alarm circuit and RS485 communication interface. The AC converter 204 is designed at the same time. Each AC module anti-theft computing communication unit 102 and the corresponding single DC/AC converter 204 form an AC module packaged together. The AC module anti-theft computing communication unit 102 measures the corresponding The AC output voltage and current of the DC/AC converter 204 are used to calculate the output power of the DC/AC converter 204, and the AC output voltage and current of the DC/AC converter 204 can be measured by a voltage transformer and a current transformer respectively, and also The output AC voltage and current information collected by the DC/AC converter 204, the serial number information of the AC module and the output power of the DC/AC converter 204 of the AC module can be directly output through the RS485 communication interface, and each AC module is anti-theft The calculation and communication unit 102 regularly collects all DC module serial numbers and corresponding output power information of photovoltaic modules 201, as well as all AC module serial numbers and corresponding DC/AC converter 204 output power information through the RS485 communication interface, The total AC power is obtained by adding the output power of the AC converter 204, and the total DC power is obtained by adding the output power of all photovoltaic modules 201. When the difference between the total AC power and the total DC power exceeds the specified range, it is judged that theft Electricity stealing behavior, the difference is electricity stealing, at this time, send electricity stealing alarm signal, electricity stealing and AC module serial number information through RS485, when it is judged that electricity stealing behavior occurs or receives any electricity stealing alarm from RS485 communication interface After the signal is received, the communication unit 102 of the AC module anti-stealing calculation and communication unit 102 immediately performs an indicator light and a buzzer alarm.

The specific design parameters of this embodiment are:

The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system of the present invention is used for distributed photovoltaic grid-connected with 1MW, N=168, M=2, the highest voltage of the DC bus is 600V, and the voltage of the low-voltage distribution network is 220V/50Hz Modular power generation system, embedded anti-stealing device The DC module anti-stealing calculation communication unit can measure the DC output power of photovoltaic modules as 6KW, and the AC module anti-stealing calculation communication unit can measure the AC output power of the DC/AC converter as 0.5MW, the allowable difference between the total AC power and the total DC power can be set, the DC module anti-stealing calculation The DC output voltage and current measurement accuracy of the photovoltaic module in the communication unit is not less than 1%, the AC module is anti-stealing The AC output voltage and current measurement accuracy of the DC/AC converter in the calculation communication unit is not less than 1%, and the time interval between each electricity stealing judgment of the AC module anti-stealing calculation communication unit is 10 minutes.

The content that is not described in detail in the description of the present invention belongs to the well-known technology of those skilled in the art.

It should be understood that: the above-mentioned embodiments are only descriptions of the present invention, rather than limitations of the present invention, and any inventions that do not exceed the spirit of the present invention fall within the protection scope of the present invention.

Claims (6)

1. The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system includes an integer number of N identical DC module anti-stealing calculation communication units and an integer M identical AC module anti-stealing calculation communication units. The anti-theft device is designed and installed according to the corresponding distributed photovoltaic grid-connected modular power generation system; The distributed photovoltaic grid-connected modular power generation system includes an integer of N identical photovoltaic modules, an integer of N identical DC/DC converters, a DC bus, an integer of M identical DC/AC converters, an AC bus, and user The load, the electric energy meter and the low-voltage distribution network, each photovoltaic module of the string structure is connected to the DC bus through a corresponding DC/DC converter, and the DC input terminal of each DC/AC converter is connected to the DC bus. The AC output terminal of each DC/AC converter is connected to the AC bus, the user load is connected to the AC bus, the energy meter is connected between the AC bus and the low-voltage distribution network for bidirectional energy measurement, the voltage waveform of the AC bus and the low-voltage distribution network The voltage waveform is the same; The DC module anti-stealing computing communication unit includes a current and voltage acquisition circuit, a microprocessor, an alarm circuit and an RS485 communication interface. It is designed simultaneously with the DC/DC converter of the distributed photovoltaic grid-connected modular power generation system. Each The DC module anti-theft calculation communication unit and the corresponding single DC/DC converter form a packaged DC module. The DC module anti-theft calculation communication unit calculates the photovoltaic module by measuring the corresponding DC output voltage and current of the photovoltaic module. The output power of the photovoltaic module, the output power of the photovoltaic module, and the serial number information of the DC module are output through the RS485 communication interface, and the alarm circuit immediately performs an indicator light and a buzzer alarm after receiving any electricity theft alarm signal from the RS485 communication interface; The AC module anti-stealing calculation communication unit includes a current and voltage acquisition circuit, a microprocessor, an alarm circuit and an RS485 communication interface. It is designed simultaneously with the DC/AC converter of the distributed photovoltaic grid-connected modular power generation system. Each The AC module anti-stealing calculation communication unit and the corresponding single DC/AC converter form an AC module packaged together. The AC module anti-stealing calculation communication unit calculates the AC output voltage and current by measuring the corresponding DC/AC converter AC output voltage and current. The output power of the DC/AC converter, the serial number information of the AC module and the output power of the DC/AC converter of the AC module are output through the RS485 communication interface, and the anti-theft calculation communication unit of each AC module regularly collects all The serial number of the DC module and the corresponding output power information of the photovoltaic module, as well as the serial number information of all the AC modules and the corresponding output power information of the DC/AC converter, the total AC power is obtained by adding the output power of all DC/AC converters, and the The output power of all photovoltaic modules is added to obtain the total DC power. When the difference between the total AC power and the total DC power exceeds the specified range, it is judged that electricity stealing has occurred. Electricity alarm signal, electricity theft and AC module serial number information, when it is judged that electricity theft occurs or any electricity theft alarm signal is received from the RS485 communication interface, the AC module anti-theft calculation communication unit will immediately perform indicator lights and buzzers Call the police. 2. The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system according to claim 1, characterized in that, In the DC module anti-stealing calculation communication unit, the DC output voltage and current of the photovoltaic module are respectively measured through a DC voltage divider and a shunt, or directly collected by a DC/DC converter. 3. The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system according to claim 1, characterized in that, In the AC module anti-stealing computing communication unit, the AC output voltage and current of the DC/AC converter are measured through voltage transformers and current transformers respectively, or directly collected by DC/AC converters. 4. The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system according to claim 1, characterized in that, When M is greater than 1, the distributed photovoltaic grid-connected modular power generation system is a multi-AC modular inverter power generation system; when M is 1, the distributed photovoltaic grid-connected modular power generation system is a centralized inverter power generation system In the system, the AC busbar supplies power to user loads. When the power generated by M DC/AC converters is more than the power required by user loads, the excess power is sent to the low-voltage distribution network. When the power generated by M DC/AC converters is less When the user load requires electric energy, the insufficient electric energy is input to the AC bus from the low-voltage distribution network, and M DC/AC converters provide all or part of the reactive power and harmonic current required by the user load. 5. The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system according to claim 1, characterized in that, The instantaneous output power of the photovoltaic module is P ₁ =u ₁ (t)i ₁ (t), where u ₁ (t) and i ₁ (t) are the DC output voltage and current instantaneous value of the photovoltaic module respectively, and the photovoltaic module The output power of the module is the average value of multiple instantaneous output power obtained at a certain time interval. 6. The embedded anti-stealing device of the distributed photovoltaic grid-connected modular power generation system according to claim 1, characterized in that, When the voltage waveform of the low-voltage distribution network is a non-sinusoidal wave, the output power of the DC/AC converter includes fundamental and harmonic active power, and the output power of the DC/AC converter is based on Calculate, where u ₂ (t) and i ₂ (t) are the instantaneous values of the AC output voltage and current of the DC/AC converter respectively, and T is the voltage cycle of the low-voltage distribution network.