超导磁储能—限流器用于提高光伏并网发电系统暂态稳定性

Application of Superconducting Magnetic Energy Storage-current Limiter to Improve the Transient Stability of Photovoltaic Grid-connected Power Generation System

针对光伏并网发电系统转动惯量小,在受到不同的干扰时容易脱网运行的问题,提出了一种基于超导磁储能—限流器(superconducting magnetic energy storage-fault current limiter,SMES-FCL)装置的控制策略以提高光伏并网发电系统的暂态稳定性。SMES-FCL装置通过三相变压器串联在光伏电站与配电网间的公共耦合点,具有限流和储能的双重作用。但由于该装置具有高强度的非线性和耦合性,因此采用双闭环的滑模控制(sliding-mode control,SMC)方式控制,系统外环釆用SMC来稳定直流侧母线电压,内环采用SMC以实现电流的快速解耦。通过仿真算例分析验证了控制策略的有效性,仿真结果表明:外部增加SMES-FCL设备可以更有效地提高光伏并网发电系统的故障穿越的能力,减缓功率波动对配电网的冲击;与PI控制策略相比,所提出的SMC控制策略增强了SMES-FCL的抗扰动性。

In order to solve the problems that the instantaneous inertia of photovoltaic(PV)grid-connected power generation system is small and is easy to off-grid when suffering from different disturbances,a control strategy of a superconducting magnetic energy storage-fault current limiter(SMES-FCL)device is proposed to improve the transient stability of PV grid-connected power generation system.The SMES-FCL device is connected in series at the common coupling point between PV power station and distribution network through three-phase transformer,which has dual functions of current limiting and energy storage.However,due to the high-intensity nonlinearity and coupling of the SMES-FCL system,a double closed-loop sliding-mode control(SMC)method is adopted.SMC is used to stabilize the DC side bus voltage in the outer ring,and in the inner ring SMC is used to achieve rapid decoupling of current.The effectiveness of the control strategy is verified through simulations.The simulation results show that adding SMES-FCL devices outside can improve the fault-ride through(FRT)ability of PV grid-connected power generation system effectively,and reduce the impact of power fluctuations on the distribution network.Compared with PI control strategy,the proposed SMC control strategy enhances the disturbance resistance of SMES-FCL.