Evaluation of Synchronous Generators Reactive Power Output During Transient Process

Abstract

Due to the insufficient short-term voltage security margin of many large scale receiving-end power grids in China, it is necessary to install new dynamic reactive power devices or increase the dynamic reactive power reserve of the system by adjusting the operating point of different devices. However, the actual reactive power output of the generators during transient process may not be related to the dynamic reactive power reserve. Besides, the common method can't explain the mechanism of the transient reactive power output. Therefore, based on the mathematical model of synchronous generators, we derive the analytical expression of the reactive power output during the transient process, and then establish the relationship between the steady-state operation conditions and the transient reactive power output. Next we analyze the impact of some key parameters on generator transient reactive power output. Finally, simulation is conducted based on the IEEE 39-bus system, which verifies the correctness and effectiveness of the evaluation method and the conclusions drawn in this paper.