Method for regulating terminal voltage by reactive power support of double-fed wind generator unit and system thereof

The invention relates to a method for regulating terminal voltage by reactive power support of a double-fed wind generator unit and a system thereof. The method includes steps of initializing the system, measuring terminal voltage and calculating errors e, judging whether the errors e is in a dead zone or not and calculating reactive power reference QPI, calculating the maximum reactive power capacity Qmax, defining reactive power control commands Qout according to the QPI and Qmax, and driving the double-fed wind generator unit to send out corresponding reactive power according to the reactive power control commands Qout. The system comprises an electric energy mass module, a dead zone hysteresis comparator, a PI (proportional plus integral) controller, a reactive power capacitor calculation module, a current converter and the double-fed wind generator unit. The decoupling control characteristics of active power and reactive power of the double-fed wind generator unit are given full play, dynamic regulation of voltage of the double-fed wind generator unit is realized, and the quality of the power grid is improved. Meanwhile, capacity of an SVC (static var compensator) and an SVG (static var generator) of existing reactive regulating equipment are decreased and cost is reduced.