Open circuit fault diagnosis method for NPC three-level photovoltaic inverter

Abstract

The invention discloses an open circuit fault diagnosis method for an NPC three-level photovoltaic inverter. The method comprises the following steps of (1) building an NPC three-level inverter simulation model for simulating a fault condition; (2) collecting phase voltage time domain signals of three phases; (3) performing wavelet packet transform on the phase voltage signals to obtain frequencyband energy after the transform, and taking the frequency band energy after the transform as signal eigenvectors; (4) performing dimension reduction processing on the extracted eigenvectors by using aprincipal component analysis method to obtain low-dimensional data matrix samples, and classifying the samples into two parts including training samples and test samples; (5) establishing a radial basis neural network, training the radial basis neural network by using the training samples, and storing the trained neural network; and (6) testing the trained radial basis neural network by using thetest samples, and analyzing a fault diagnosis result. The method is high in diagnosis speed and high in diagnosis accuracy.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation. Background technique [0002] In the photovoltaic power generation system, the inverter plays a very important role. Compared with traditional two-level inverters, NPC (Neutral Point Clamped) three-level photovoltaic inverters have many advantages, such as various control methods, low stress on switching devices, low electromagnetic interference, and low harmonics of output voltage waveforms , High inverter efficiency during work. However, the three-level inverter requires more power switching devices than the two-level inverter, and the circuit structure is more complicated, so the possibility of failure is higher and the reliability is worse. If the power switching device of the inverter fails, it will have an important impact on the normal operation of the entire inverter system, and even cause huge economic losses. Therefore, it is very necessary to perform fault diag...

AI Technical Summary

Problems solved by technology

However, the three-level inverter requires more power switching devices than the two-level inverter, and the circuit structure is more complicated, so the possibility of failure is higher and the reliability is worse.

If the power switching device of the inverter fails, it will have an important impact on the normal operation of the entire inverter system, and even cause huge economic losses

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