A Measurement Method to Solve a Problem of Using DG Interfacing Converters for Selective Load Harmonic Filtering

Flexible control of interfacing converter has been utilized to compensate the harmonics from nonlinear loads in a power distribution system. However, the site selection of a DG unit is mainly determined by the location of renewable energy resources that might be far away from the nonlinear load. This can degrade the performance of conventional nonlinear load current measurement methods using current transformers and shielded twisted-pair wires, and accordingly, make the harmonic compensation less effective. To solve this issue, the fundamental components of the PCC voltage and the DG installation point voltage are utilized to establish links between the DG unit controller and the power quality (PQ) meter for PCC nonlinear load monitoring. With this method, the harmonic current waveform can be accurately sent from the PQ meter to the DG unit controller with a very low bandwidth communication system, and it is not required to have any clock synchronization at the sending and the receiving ends of the communication system. Simulated and experimental results are provided to verify the correctness of the proposed measurement method.