Electrical fault diagnosis of grid connected photovoltaic inverters

introduction:

Solar photovoltaic power generation, as a form of clean energy, has been widely applied and developed in recent years. Grid connected photovoltaic inverters are key equipment in solar power generation systems, used to convert direct current into alternating current and inject it into the grid. However, in practical applications, electrical failures are inevitable due to the harsh working environment of photovoltaic inverters and potential defects in the equipment itself. Therefore, carrying out the diagnosis of electrical faults in photovoltaic inverters is of great significance for ensuring the normal operation and safety reliability of photovoltaic power generation systems.

1、 Types of electrical faults in photovoltaic inverters

The electrical faults of photovoltaic inverters can be divided into two categories: software faults and hardware faults. Software failures include logic failures and program failures; Hardware failures include circuit component failures and circuit failures.

1. Logic failure: Logic failure refers to a malfunction caused by programming errors or control logic problems. For example, the inverter cannot start and the protection function cannot work properly.

2. Program failure: Program failure refers to errors or abnormalities in the inverter control program, which prevent the inverter from working properly. For example, frequency calculation errors, abnormal voltage regulation, etc.

3. Circuit component failure: Circuit component failure includes damage or deterioration of resistors, capacitors, inductors, diodes, transistors, and other components. For example, capacitor leakage, diode open circuit, etc.

4. Circuit failure: Circuit failure refers to faults caused by factors such as circuit connection and insulation damage. For example, short circuit in the circuit, poor contact, etc.

2、 Diagnostic methods for electrical faults in photovoltaic inverters

The diagnostic methods for electrical faults in photovoltaic inverters mainly include signal analysis, characteristic parameter method, fault pattern recognition method, and empirical method.

1. Signal analysis method: Signal analysis method is to collect and analyze the internal signals of the inverter to determine whether there are abnormalities or faults in the inverter. The commonly used signal analysis methods include spectrum analysis, time-domain analysis, and correlation analysis.

2. Characteristic parameter method: The characteristic parameter method extracts characteristic parameters such as inverter output current and voltage, establishes a fault characteristic parameter database, and compares the real-time data of the inverter with the characteristic parameters in the database to diagnose whether the inverter has a fault.

3. Fault pattern recognition method: Fault pattern recognition method is to analyze and process the fault data during the operation of the inverter, establish a fault pattern recognition model, and thus realize the identification and judgment of faults.

4. Empirical method: Empirical method is to classify similar faults based on past photovoltaic inverter fault cases and summarize corresponding diagnostic methods. This method requires engineers to be very familiar with the working mode and fault characteristics of photovoltaic inverters, and have high professional knowledge requirements.

3、 Example of Electrical Fault Diagnosis for Photovoltaic Inverters

Taking the abnormal frequency fault of a certain photovoltaic inverter as an example, this article introduces the diagnostic steps for electrical faults of photovoltaic inverters.

1. Signal acquisition: Collect frequency signals and other related signals of the inverter through sensors inside the inverter.

2. Signal analysis: Perform spectral analysis, time-domain analysis, and correlation analysis on the collected frequency signals to obtain characteristic signals of frequency anomalies.

3. Feature parameter extraction: Based on the feature signal, extract frequency abnormal feature parameters, such as frequency deviation, frequency fluctuation, etc.

4. Feature parameter comparison: Compare with the established fault feature parameter database to find feature parameters that match the real-time data.

5. Fault diagnosis: Based on the matched feature parameters, search for the corresponding fault mode in the database and determine the fault type.

6. Fault handling: Based on the diagnosis results, take corresponding fault handling measures, repair or replace the faulty components.

Conclusion:

The diagnosis of electrical faults in photovoltaic inverters is a crucial step in ensuring the normal operation of photovoltaic power generation systems. Signal analysis method, characteristic parameter method, fault mode recognition method, and empirical method are commonly used diagnostic methods, and appropriate methods can be selected for diagnosis according to specific situations. In practical applications, engineers need to possess profound professional knowledge and experience in order to quickly and accurately diagnose and handle electrical faults, and improve the reliability and safety of photovoltaic power generation systems

The diagnosis of electrical faults in photovoltaic inverters is an important step in ensuring the normal operation of photovoltaic power generation systems. By collecting and analyzing signals, it is possible to obtain characteristic signals of frequency anomalies and extract corresponding feature parameters. By comparing with the established fault characteristic parameter database, the fault type can be determined. According to the diagnosis results, corresponding fault handling measures can be taken to repair or replace the faulty components. The diagnostic methods for electrical faults in photovoltaic inverters mainly include signal analysis, characteristic parameter method, fault pattern recognition method, and empirical method. Engineers need to possess profound professional knowledge and experience in order to quickly and accurately diagnose and handle electrical faults, and improve the reliability and safety of photovoltaic power generation systems