Optimal VAR Control Considering Wind Farms Using Probabilistic Load-Flow and Gray-Based Genetic Algorithms

Techniques for distributed generations (DGs) have attracted increasing attention due to considerations of environmental sustainability. Wind farms are one of the DGs, and they have intermittent characteristics. This paper presents a method using wind generator voltages, static compensators, and transformer taps as controllers to regulate the voltage profile for operation planning in a distribution system. Wind power generations and bus loads are modeled with random variables. Through gray-based genetic algorithms (GAs), the MW loss in the system is minimized and the operational constraints are fulfilled. Moreover, this paper uses the cumulant method to calculate the bus voltage fluctuation by using the algebraic addition and multiplication to avoid convolution. The probability density function of the voltage fluctuation can be further expressed by the Gram-Charlier series expansion. Applicability of the proposed method is verified through simulation by using a 17-bus system and an autonomous 24-bus (Penghu) system.