Research on impact of synchronous condenser excitation strategy based on PIDA controller and feedforward voltage control on transient voltage of grid

Abstract

As grid-connected renewable energy and HVDC transmission grow in China, maintaining stable power grid operation is essential to avert system collapse caused by insufficient reserves of dynamic reactive power. Network topology and dynamic reactive power compensation device settings influence the transient voltage stability. Synchronous condenser (SC) serves as a dynamic reactive power source in modern energy AC/DC grids. However, the traditional SC excitation control strategy causes significant voltage overshoot during the voltage recovery process of the grid. This paper proposes a proportion-integral–differential-acceleration (PIDA) excitation controller which considers grid voltage feedforward for SC to improve FV type excitation control strategy to suppress transient voltage fluctuations, and the fruit fly optimization algorithm (FOA) is employed to tune the PIDA parameters. To verify the control effect, an improved IEEE14-node AC/DC hybrid system is proposed by using the PSCAD/EMTDC simulation platform, and variations in SC excitation voltage, DC transmission active power, reactive power output of SC (Qsc), and AC bus voltage on the inverter side are compared and analyzed in three different excitation control strategies under three fault conditions. Simulation results show that the improved SC excitation control strategy proposed can not only suppress system bus voltage drop effectively and reduce the risk of DC commutation failure, but also reduce voltage overshoot by 6 % and voltage drop by 10 % compared with those of traditional excitation control strategies of SC, and make the system recover faster and effectively improve the power system voltage level and voltage stability.

Keywords

• Synchronous condenser
• Excitation system
• AC/DC hybrid power system
• PIDA controller
• Dynamic reactive power compensation