Expert fault analytical and diagnostic method of parallel mixed type power quality regulator

Abstract

The invention discloses an expert fault analytical and diagnostic method of a parallel mixed type power quality regulator. The method comprises the following steps that: a voltage signal is collected at a sampling point of a power quality regulator and is used as a fault sample signal; denoising processing is carried out on the collected fault sample signal; wavelet packet transform is utilized to carry out processing on the denoised fault sample signal so as to extract an energy characteristic vector; the extracted energy characteristic vector used as a target input vector, together with a set fault type output vector, is input into a BP neural network to carry out training, so that a fault classifier is established; and fault signals that are collected in real time are input into the fault classifier that compares the fault signals with various fault characteristics in the fault classifier, so that a fault disgnosis result is output. According to the invention, a fault state can be accurately diagnosed, so that losses caused by faults occur on a core component in the power quality regulator can be avoided or reduced.

Description

technical field [0001] The invention relates to a circuit fault diagnosis method, in particular to an expert fault analysis and diagnosis method for a parallel hybrid power quality conditioner. Background technique [0002] Power quality conditioners used in industrial production and daily life will generate a large number of harmonics, which will seriously pollute the power grid. Because the power quality conditioner can comprehensively compensate the power quality of the power grid comprehensively and centrally, and can solve the power quality problem of the power grid, it has become a research hotspot in recent years. Most of the studies focus on the topology of the main circuit of the power quality conditioner, the detection method and control method of the harmonic current, but there are few studies on the analysis and diagnosis of the fault of the power quality conditioner itself. However, once the power quality conditioner fails, the consequences caused by the failur...

AI Technical Summary

Problems solved by technology

When one IGBT on a certain bridge arm starts to turn on, but the other cannot be turned off in time due to a fault, or when one IGBT is turned on and the other is turned on due to a false trigger, then a straight-through occurs on the bridge arm short circuit phenomenon

[0006] (2) Drive circuit failure

Due to the interference of space electromagnetic and ground wires and the influence of environmental factors, the output pulse of the pulse generator may be disordered, endangering the normal operation of the IGBT

[0007] (3) Overvoltage fault

During the IGBT turn-on to turn-off process, due to the sharp change of the main circuit current, the main circuit wiring inductance induces a high voltage, and a small circuit inductance may cause a large Ldi / dt, which can easily cause a hazard to the safety of the IGBT. Overvoltage

[0008] (4) Overcurrent fault

[0009] (5) du / dt failure

This static du / dt pass creates a current flow to the gate drive circuit in the IGBT capacitor between the collector and the emitter, which in the worst case makes V GE increases (towards V GE (th)) and reaches the threshold voltage, causing the IGBT to be turned on and a direct short circuit fault occurs

[0010] (6) Short circuit fault

In the 35kv parallel hybrid power quality conditioner, when the inverter circuit composed of the main switching element IGBT has a load short circuit or a direct fault of the same bridge arm, the bus voltage is directly applied to the C and E terminals of the IGBT and flows through the collector of the IGBT The current will increase sharply. At this time, if the gate drive signal is not removed in time, the IGBT will burn out

[0011] (7) Overheating fault

Since the load of the reactive power compensation device is a power capacitor, if the current signal is wrong, the thyristor will not be fully wave-conducted

[0015] (3) The thyristor is turned on in open phase

Due to the large value of the discharge resistance connected in parallel with the capacitor, the voltage decay time is long, and it is possible that one of the three groups of thyristor valves will not conduct, that is, the thyristor will be turned on without phase.

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