CN-115955192-B - Photovoltaic power generation system diagnosis method, device, diagnosis system and storage medium

CN115955192BCN 115955192 BCN115955192 BCN 115955192BCN-115955192-B

Abstract

The invention provides a photovoltaic power generation system diagnosis method, a device, control equipment and a diagnosis system. The method is based on differential power processing equipment in a photovoltaic power generation system, and comprises the steps of acquiring a terminal voltage signal of a tested photovoltaic panel and a current signal which is output in response to a preset excitation voltage signal based on a fault diagnosis trigger signal, wherein the terminal voltage signal is a voltage signal which is output by the tested photovoltaic panel based on the preset excitation voltage signal sent by the differential power processing equipment, matching the terminal voltage signal and the current signal with diode models of preset solar cells, determining various modeling circuit parameter values corresponding to the terminal voltage signal and the current signal in the diode models of the preset solar cells, and carrying out fault diagnosis on the tested photovoltaic panel according to the modeling circuit parameter values. The invention can avoid the reduction of the power generation efficiency of the photovoltaic power station caused by the fault points which are not easy to be found in a local long-term way, and meanwhile, the cost of devices is not required to be increased additionally.

Inventors

ZHANG CHAO
SHEN HONGTAO
TAO PENG
ZHU YAKUI
ZHANG BINGYU
LIU XIAOYU

Assignees

国网河北省电力有限公司营销服务中心
国家电网有限公司

Dates

Publication Date: 20260505
Application Date: 20221230

Claims (9)

1. A photovoltaic power generation system diagnosis system is characterized by comprising a differential power processing device and a control device; The differential power processing equipment is connected across at least two photovoltaic plates connected in series and is used for sending a preset excitation voltage signal to at least one tested photovoltaic plate in the at least two photovoltaic plates connected in series based on different non-zero disturbance frequencies when a fault diagnosis trigger signal is received, and detecting a terminal voltage signal of the tested photovoltaic plate and a current signal output in response to the preset excitation voltage signal; under the normal mode without receiving the fault diagnosis trigger signal, carrying out maximum power point tracking on at least two photovoltaic panels connected in series; The control equipment is used for acquiring a terminal voltage signal of the tested photovoltaic panel and a current signal which is output in response to a preset excitation voltage signal based on a fault diagnosis trigger signal, wherein the terminal voltage signal is a voltage signal output by the tested photovoltaic panel based on the preset excitation voltage signal sent by the differential power processing equipment; Matching the terminal voltage signal and the current signal with diode models of preset solar cells, and determining various modeling circuit parameter values corresponding to the terminal voltage signal and the current signal in the diode models of the preset solar cells; Performing fault diagnosis on the tested photovoltaic panel according to the parameter values of the modeling circuits; the differential power processing device comprises a communication module, a driving circuit, a power converter, a sampling module and a controller; the power converter comprises a first capacitor, a second capacitor, an inductor, a first switching tube and a second switching tube; the first end of the first capacitor is respectively connected with the first end of a first photovoltaic panel and the source electrode of the first switch tube of at least two photovoltaic panels connected in series, and the second end of the first capacitor is respectively connected with the second end of the first photovoltaic panel and the first end of the second capacitor; The first end of the second capacitor is also connected with the first end of a second photovoltaic panel in the at least two photovoltaic panels connected in series, and the second end of the second capacitor is respectively connected with the second end of the second photovoltaic panel and the drain electrode of the second switch tube; The first end of the inductor is connected between the first capacitor and the second capacitor, and the second end of the inductor is connected between the drain electrode of the first switching tube and the source electrode of the second switching tube; the grid electrode of the first switching tube and the grid electrode of the second switching tube are connected with the driving circuit.
2. The photovoltaic power generation system diagnosis system according to claim 1, wherein the communication module is connected with the driving circuit and the sampling module, respectively, and is configured to receive a fault diagnosis trigger signal, send the fault diagnosis trigger signal to the driving circuit, acquire a terminal voltage signal of the tested photovoltaic panel detected by the sampling module, and send a current signal output in response to a preset excitation voltage signal to the control device; The driving circuit is respectively connected with the power converter and the controller and is used for providing a gating signal to control a switching tube in the power converter according to the fault diagnosis trigger signal and a control signal output by the controller; the power converter is connected across at least two photovoltaic panels connected in series and is used for sending a preset excitation voltage signal to at least one tested photovoltaic panel in the at least two photovoltaic panels connected in series based on different non-zero disturbance frequencies under the control of the gating signal; the sampling module is connected to the tested photovoltaic panel and is also connected with the controller, and is used for detecting a terminal voltage signal of the tested photovoltaic panel and a current signal which is output in response to a preset excitation voltage signal and is sent to the controller, so that the controller outputs a control signal based on the detected difference between the terminal voltage signal and a reference voltage signal with a non-zero disturbance frequency, and the control signal is used for controlling the terminal voltage signal of the tested photovoltaic panel to follow the reference voltage signal.
3. A photovoltaic power generation system diagnostic method applied to the photovoltaic power generation system diagnostic system according to claim 1 or 2, the method comprising: acquiring a terminal voltage signal of a tested photovoltaic panel and a current signal which is output in response to a preset excitation voltage signal based on a fault diagnosis trigger signal, wherein the terminal voltage signal is a voltage signal output by the tested photovoltaic panel based on the preset excitation voltage signal sent by the differential power processing equipment; Matching the terminal voltage signal and the current signal with diode models of preset solar cells, and determining various modeling circuit parameter values corresponding to the terminal voltage signal and the current signal in the diode models of the preset solar cells; and carrying out fault diagnosis on the tested photovoltaic panel according to the parameter values of the modeling circuits.
4. The method of claim 3, wherein the predetermined excitation voltage signal is used to drive the terminal voltage signal of the photovoltaic panel under test from a minimum voltage level to a maximum voltage level, the maximum voltage level being determined based on a current level of degradation or radiation of the photovoltaic panel under test and an operating point of a grid-tie inverter operatively connected to the photovoltaic panel under test.
5. The method according to claim 3, wherein the diode model of the preset solar cell is a dynamic single diode model of the solar cell.
6. The method according to any one of claims 3 to 5, wherein the performing fault diagnosis on the photovoltaic panel under test based on each of the modeled circuit parameter values includes: predicting a predicted terminal current signal generated in a diode model of a preset solar cell according to the terminal voltage signal and each of the modeled circuit parameter values; And carrying out fault diagnosis on the tested photovoltaic panel according to the current signal of the prediction end and the current signal.
7. A photovoltaic power generation system diagnostic apparatus, characterized by being applied to the photovoltaic power generation system diagnostic system according to claim 1 or 2, comprising: The acquisition module is used for acquiring a terminal voltage signal of the tested photovoltaic panel and a current signal which is output in response to a preset excitation voltage signal based on a fault diagnosis trigger signal, wherein the terminal voltage signal is a voltage signal output by the tested photovoltaic panel based on the preset excitation voltage signal sent by the differential power processing equipment; The matching module is used for matching the terminal voltage signal and the current signal with diode models of preset solar cells and determining parameter values of each modeling circuit corresponding to the terminal voltage signal and the current signal in the diode models of the preset solar cells; and the diagnosis module is used for carrying out fault diagnosis on the tested photovoltaic panel according to the parameter values of the modeling circuit.
8. A control device comprising a memory for storing a computer program and a processor for calling and running the computer program stored in the memory for performing the method according to any of claims 3 to 6.
9. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the method according to any of the preceding claims 3 to 6.

Description

Photovoltaic power generation system diagnosis method, device, diagnosis system and storage medium Technical Field The invention relates to the technical field of photovoltaic power generation, in particular to a photovoltaic power generation system diagnosis method, a device, control equipment and a diagnosis system. Background With the increasing approach of energy crisis, new energy has become one of the main energy sources in the world in the future, and photovoltaic power generation is an emerging green energy industry, and is gradually gaining importance and support from the country. However, due to the large number of photovoltaic power generation plates in the photovoltaic power station, the failure rate of the photovoltaic power generation plates caused by internal and external factors is high, and the reason that the current collection circuit between the photovoltaic plates and the junction box is not easy to detect when the circuit is broken is that the photovoltaic power generation plates are subjected to the failure, the photoelectric conversion rate of the photovoltaic power generation is gradually reduced, and the increase of operation and maintenance cost and the waste of power resources are caused. If a professional fault diagnosis device is added to the photovoltaic power station, the investment cost of the photovoltaic power station is greatly increased. Disclosure of Invention The embodiment of the invention provides a diagnosis method, a device, control equipment and a diagnosis system of a photovoltaic power generation system, which are used for solving the problems that the photoelectric conversion rate of photovoltaic power generation is reduced due to the failure of a photovoltaic panel, and the cost of devices is greatly increased due to the failure diagnosis device of a newly added photovoltaic panel. In a first aspect, an embodiment of the present invention provides a diagnostic method for a photovoltaic power generation system, based on a differential power processing device in the photovoltaic power generation system, including: acquiring a terminal voltage signal of a tested photovoltaic panel and a current signal which is output in response to a preset excitation voltage signal based on a fault diagnosis trigger signal, wherein the terminal voltage signal is a voltage signal output by the tested photovoltaic panel based on the preset excitation voltage signal sent by the differential power processing equipment; Matching the terminal voltage signal and the current signal with diode models of preset solar cells, and determining various modeling circuit parameter values corresponding to the terminal voltage signal and the current signal in the diode models of the preset solar cells; and carrying out fault diagnosis on the tested photovoltaic panel according to the parameter values of the modeling circuits. In one possible implementation, the preset excitation voltage signal is used to drive the terminal voltage signal of the photovoltaic panel under test from a minimum voltage level to a maximum voltage level, the maximum voltage level being determined based on the current level of degradation or radiation of the photovoltaic panel under test and the operating point of the grid-tie inverter operatively connected to the photovoltaic panel under test. In one possible implementation, the preset diode model of the solar cell is a dynamic single diode model of the solar cell. In one possible implementation manner, the performing fault diagnosis on the tested photovoltaic panel according to each modeling circuit parameter value includes: predicting a predicted terminal current signal generated in a diode model of a preset solar cell according to the terminal voltage signal and each of the modeled circuit parameter values; And carrying out fault diagnosis on the tested photovoltaic panel according to the current signal of the prediction end and the current signal. In a second aspect, an embodiment of the present invention provides a diagnostic apparatus for a photovoltaic power generation system, including: The acquisition module is used for acquiring a terminal voltage signal of the tested photovoltaic panel and a current signal which is output in response to a preset excitation voltage signal based on a fault diagnosis trigger signal, wherein the terminal voltage signal is a voltage signal output by the tested photovoltaic panel based on the preset excitation voltage signal sent by the differential power processing equipment; The matching module is used for matching the terminal voltage signal and the current signal with diode models of preset solar cells and determining parameter values of each modeling circuit corresponding to the terminal voltage signal and the current signal in the diode models of the preset solar cells; and the diagnosis module is used for carrying out fault diagnosis on the tested photovoltaic panel according to the parameter values of the modeling circuit. In