交直流混合微电网接口变换器改进型双向下垂控制策略

Improved Bidirectional Droop Control of Hybrid AC-DC Microgrid Interface Converter

针对交直流混合微电网双向接口变换器(bidirectional interface converter,BIC)采用双向下垂控制存在惯性小、阻尼低等问题,提出一种适用于BIC的改进型双向下垂控制策略。通过改进有功环,引入惯性环节和限幅系数不仅能够给系统提供惯性,减小负荷波动对交流母线频率和直流母线电压的影响,改善交、直流子网间功率传输的动态响应,还能提高交直流混合微电网的抗干扰特性和动态响应特性。通过在电流环引入非线性干扰观测器,可以抑制负荷功率的瞬态波动,抑制外部功率扰动下母线电压的波动幅度。分析了关键参数对系统稳定性的影响,采用PSCAD/EMTDC仿真验证了所提控制策略的正确性和有效性,并针对不同控制策略下负载变化时交流频率和直流电压的动态响应以及功率传输的动态响应进行了对比分析,得出了所提控制策略的优越性。

Focusing on low inertia and low damping problems in the droop control for bidirectional interface converters(BICs)in hybrid AC-DC microgrid,an improved bidirectional droop control strategy applied to BICs is proposed.By improving the active power loop and introducing an inertia link and a limiting coefficient,the system can not only provide inertia,reduce the impact of load fluctuations on AC bus frequency and DC bus voltage,improve the dynamic response of power transmission between AC and DC subnets,but also improve the antiinterference and dynamic response characteristics of hybrid AC-DC hybrid microgrid.By introducing a nonlinear disturbance observer into the current loop,transient fluctuations in load power can be suppressed,and the amplitude of bus voltage fluctuations under external power disturbances can be suppressed.The article provides a detailed analysis of the impact of key parameters on system stability,and verifies the correctness and effectiveness of the proposed control strategy by PSCAD/EMTDC simulation.It also compares and analyzes the dynamic response of AC frequency and DC voltage as well as power transmission under different control strategies when load changes,highlighting the superiority of the proposed control strategy.