A System-Level Harmonic Control Method Based on Multibus Voltage Detected APF Without Exact Phase Synchronization

Abstract

The decentralized distribution of nonlinear harmonic loads drives the trend of harmonic control from local compensation to system-level mitigation. Based on the active power filter (APF) with multi-bus harmonic detections, comprehensive control of harmonic distortions in multiple buses achieves, which is so-called system-level harmonic mitigation. However, existing system-level harmonic mitigation methods require high-speed data exchange for real-time phase synchronization among multiple buses, which reduces the feasibility of the methods. To reduce the burden of communication, a system-level harmonic mitigation method without inter-bus phase synchronization is proposed in this paper. Firstly, the phase synchronization problem is analyzed, and control system of multi-bus detected APF is proposed, in which the reference phase of each detector could be set locally. Then, a new online system-level harmonic mitigation model is introduced and solved to obtain the optimal APF current reference. Subsequently, the closed-loop control strategy of multi-bus detected APF is raised and four control stages are designed to cope with different situations. Finally, an eight-bus network with dynamic harmonic loads is designed in simulation and experiment. According to the results, multi-bus harmonic voltage distortions in the network could meet the standard. The proposed method contributes to achieving good harmonic compensation performance without multi-bus phase-synchronization.