Comparison of Algorithms for Control of Loads for Voltage Regulation

Autonomous flexible loads can be utilized to regulate voltag e on low voltage feeders. This paper compares two algorithms for controllin g loads: a simple voltage droop, where load power consumption is a varied in proportio n to RMS voltage; and a normalized relative voltage droop, which modifies the simpl e voltage droop by subtracting the mean voltage value at the bus and dividing by the standard deviation. These two controllers are applied to hot water heaters simul ated in a simple residential feeder. The simulation results show that both controllers r educe the frequency of undervoltage events. The simple droop controller delivers a widely different response depending on where the load is located on the feeder. In contr ast, all of the loads with the normalized relative droop controller have a similar res ponse