Chain type STATCOM interphase direct current voltage balance control method

Abstract

The invention discloses a chain type STATCOM interphase direct current voltage balance control method. The method comprises: acquiring active power caused by chain type STATCOM three-phase unit difference; calculating active power generated by the negative sequence voltage in real time when an asymmetric fault occurs in the power grid; superposing the active power generated by the negative sequence voltage and the active power caused by the difference of the chain-type STATCOM three-phase units to obtain the active power required to be adjusted by the whole system; and calculating a zero-sequence voltage value required to be injected according to the active power required to be adjusted by the whole system and the zero-sequence voltage calculation formula. Based on a zero-sequence voltageinjection method, a simple zero-sequence voltage calculation method and a power feed-forward control method are provided for inter-phase direct-current voltage imbalance caused by H-bridge unit difference and negative-sequence components in power grid voltage, and inter-phase direct-current voltage imbalance fluctuation of a power grid under different working conditions can be effectively suppressed.

Description

technical field [0001] This application relates to the field of power electronics technology research, in particular to a chained STATCOM phase-to-phase DC voltage balance control method. Background technique [0002] Static Synchronous Compensator (STATCOM) has the functions of enhancing system stability, improving power flow and voltage distribution, and has been widely used in recent years. Among them, the STATCOM with chain structure has attracted a lot of attention because of its advantages of easy modularization, high reliability, low switching loss and small harmonic distortion. However, the capacitors on the DC side of the chained STATCOM are independent of each other. Due to the differences in the parallel loss, switching loss, modulation ratio, and pulse delay of each H-bridge unit, the DC voltage of each H-bridge unit is unbalanced. [0003] Existing research uses the method of zero-sequence voltage injection to realize the balance control of DC voltage between p...

AI Technical Summary

Problems solved by technology

However, the capacitors on the DC side of the chained STATCOM are independent of each other. Due to the differences in the parallel loss, switching loss, modulation ratio, and pulse delay of each H-bridge unit, the DC voltage of each H-bridge unit is unbalanced.

[0003] Existing research uses the method of zero-sequence voltage injection to realize the balance control of DC voltage between phases, but the calculation is too complicated

At the same time, when the grid voltage is asymmetrical, the negative sequence component in the grid voltage will affect the voltage equalization control of the DC voltage between phases, resulting in large fluctuations in the DC voltage and affecting the output of the chained STATCOM

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