Current Control Strategy of Harmonic Current Injection System for Power Capacitor

Abstract

In order to avoid excessive noise of power capacitors installed in HVDC converter station, it is necessary to test the noise characteristics of the power capacitors before delivery. Simulating the working condition of power capacitor in HVDC converter station effectively is the target of harmonic power supply researching. To ensure the accurate harmonic current injected into the power capacitor, the harmonic current frequency dividing detection and control strategy is proposed. Adapting the harmonic current detection method based on instantaneous reactive power theory and d-q transformation to single-phase harmonic current injection system, the current amplitude can be tracked timely and exactly by using random harmonic current detection method, so that the Proportional Integral (PI) regulator in d-q synchronous frame used directly to achieve zero-error control. The designed phase detection method can accurately detect the initial phase angle of each harmonic, accordingly calculating the compensation angle of the system. Through the accurate detection and control of the injected harmonic current and the more precise noise test result of power capacitor can be obtained. The simulation and experimental results validate the effectiveness of the current detection and control algorithm proposed in this paper.