基于改进频率微分运算的虚拟惯量控制策略

Virtual Inertia Control Strategy Based on Improved Frequency Differential Operation

可再生能源通过快速功率变换器接口接入电网受到广泛关注,但往往会引起电网等效惯量减小的频率稳定性问题。文中分析了2种现有解决方案:利用锁相环频率直接进行微分运算的方法,其动态响应速度慢,易引起谐波放大的问题;利用二阶广义积分器-锁频环(SOGI-FLL)评估频率微分信号的方法避免了频率微分运算,但在抑制电网电压扰动方面的能力有限。为此,提出一种基于级联二阶广义积分器-锁频环(CSOGI-FLL)准确评估频率信号的虚拟惯量控制策略,即将基于二阶广义积分器原理的频率自适应滤波器加入SOGI-FLL的控制回路中,增强SOGI-FLL的扰动抑制能力。最后,建立柴储微网系统的仿真模型和实验平台,仿真和实验结果共同验证了所提控制策略的有效性。

The renewable energy sources accessed to the power grid through fast-response power converters has received widespread attention,but they often cause frequency stability problems due to the reduction of power system equivalent inertia.This paper analyzes the effectiveness of two existing solutions.The direct differential operation method using phase-locked loop frequency has a slow dynamic response and causes noise amplifications.And the evaluation method of frequency differential signal using the second-order generalized integrator based frequency-locked loop(SOGI-FLL)can avoid the frequency differential operation.Nevertheless,the SOGI-FLL has a limited ability in suppressing the grid voltage disturbances.To solve this problem,this paper proposes a virtual inertia control strategy with the cascaded SOGI-FLL to accurately evaluate the frequency signal.The frequency self-adaptive filter based on SOGI is added to the SOGI-FLL control loop to enhance the disturbance suppression capabilities.Finally,both simulation and experimental platforms of the microgrid with diesel and energy storage system are established,and the simulation and experimental results verify the effectiveness of the proposed control strategy.