Simultaneous power quality analysis of feeders in MV utility power stations

The development of a low-cost, space saving device that could simultaneously take measurements from all (usually eight or up to twelve) outgoing three-phase feeders in a distribution substation is presented in this paper. To meet these requirements, at least 3 voltage measurements and 36 current measurements should be performed at the same time. In order to save space but not to reduce the measurement accuracy, a data acquisition system is designed based on real-time multiprocessing with a microcontroller and an FPGA circuit. Voltage and current measurements and their corresponding higher-order harmonics are calculated using a fast FPGA circuit, while other calculations (power, power factor, voltage and current phase angles, etc.) are performed in the microcontroller. Further savings are obtained using multichannel analog input modules with multiplexed inputs. Communication with the supervising computer is done using a GPRS modem or wireless network module depending of the station location. Results obtained in the laboratory and later in an industrial prototype confirm the proposed solution.