不对称条件下的储能虚拟同步发电机低电压穿越控制技术

A Low Voltage Ride Through Control Technique for Energy Storage Virtual Synchronous Generator Under Asymmetric Condition

虚拟同步发电机技术能够使逆变器模拟同步发电机的运行机制并网运行,有利于改善系统稳定性。而为了真实模拟同步发电机的工作特性,要求虚拟同步发电机装置必须具备低电压故障穿越能力。当发生不对称故障时,由于电压、电流中存在大量负序分量,严重影响输出电压和电流质量。为解决上述问题,首先,从控制系统数学模型出发,分析三相电压源型逆变器常规d-q旋转坐标系下的电压前馈本质,提出基于α-β坐标系下的电压前馈策略。然后,采用电压相位补偿技术实现负序电流抑制。最后,通过5 MW储能虚拟同步发电机实时数字仿真仪模型,模拟单相和相间接地故障,验证了控制算法的正确性和有效性。

The technology of virtual synchronous generator（VSG）enables the inverter to simulate the operation mechanism of synchronous generators connected to the grid,which is beneficial to improve the stability of the power system.In order to truly simulate the working characteristics of synchronous generators,it is required that the VSG must have low voltage fault crossing capability.When an asymmetrical fault occurs,there are a large number of negative sequence components in the voltage and current,which seriously affect the quality of output voltage and current.In order to solve the problem mentioned above,firstly,based on the mathematical model of the control system,the voltage feedforward nature of the three-phase voltage source inverter is analyzed in the conventional d-q rotating coordinate system,and the voltage feedforward strategy based on theα-βcoordinate system is proposed.Then,the voltage phase compensation technique is adopted to suppress the negative sequence current.Finally,through real time digital simulator model of the 5 MW energy storage VSG,single-phase and phaseto-ground fault is simulated,which verifies the correctness and effectiveness of the control algorithm.