The energy storage virtual synchronous generator (VSG), which can provide inertial support for the grid, has attracted wide attention. However, there is a problem that the dynamic characteristics and the characteristics of primary frequency modulation of grid-connected active power cannot be satisfied at the same time. Therefore, the dynamic oscillations suppression strategy of energy storage VSG grid-connected active power based on frequency feedforward compensation is proposed in this paper. This strategy uses the rated frequency to feed forward to the grid-connected active power closed-loop modulation loop through the compensation link and increases the transient damping of the system without affecting the characteristics of primary frequency modulation of the energy storage VSG, to effectively suppress the dynamic oscillations of its grid-connected active power. Finally, the effectiveness and superiority of the proposed strategy are verified by the Matlab/Simulink simulation model of the energy storage VSG grid-connected system.

The grid-forming virtual synchronous generator (GFVSG) with large virtual inertia can provide a friendly grid-connected operational mode for power electronic converters, but it may also introduce the active power dynamic oscillation problems similar to traditional synchronous generators. In view of this, the dynamic equivalent circuit model of the GFVSG grid-tied active power-angle is established firstly, and, then, the understanding of the GFVSG active power oscillations under variable disturbances is revealed from the perspective of circuit energy flow in this paper. On this basis, an active power dynamic oscillation damping method based on an energy reshaping mechanism for the GFVSG is proposed, and a parameter design method using the second-order equivalent reduced-order control model is given. The MATLAB 2016a simulation as well as experimental test platforms of a 100 kV·A GFVSG grid-connected system are established, then, both the feasibility and effectiveness of the proposed active power dynamic oscillation damping method are verified by using the simulation and experimental comparison results.

基于电压源型整流器(VSR)与电压源型逆变器(VSI)整合而成的VSR-VSI双PWM变换器已在电梯能量回馈系统中得到应用.本文围绕VSR-VSI系统的直流母线电压可控与能量可双向流动的特点,首先阐述了基于VSR-VSI电梯永磁同步电机驱动系统在dq坐标系下的PI双闭环控制结构与参数设计方法,分析了VSR-VSI系统直流母线电压与并网电流存在谐波畸变的机理,在此基础上提出了基于PI+谐振(PI plus resonant,PIR)调节器的VSR电流内环改进控制策略以抑制并网电流谐波,最后利用仿真结果验证了上述理论分析的准确性与有效性.

基于前端电压源型整流器(voltage source rectifier,VSR)与后端电压源型逆变器(voltage source inverter,VSI)级联的VSR-VSI双三相脉冲宽度调制(pulse width modulation,PWM)变换器已在电梯能量回馈系统中得到广泛应用,但前端三相VSR采用传统比例积分(proportional integral,PI)双闭环控制结构通常存在中端直流母线电压无法兼顾抗干扰性和跟踪性的问题.为此,文中提出一种基于二自由度比例积分微分(proportional integral differential,PID)的三相PWM整流器调压改进策略.首先,阐述基于VSR-VSI双三相PWM变换器级联系统的结构和工作原理,并给出前端三相VSR的传统PI双闭环控制方案及其参数设计过程,分析该方案不能兼具良好的抗干扰性与跟踪性的原因.在此基础上,给出基于二自由度PID的前端三相VSR直流调压优化策略及其参数设计方法.最后,利用软件仿真与实验测试对比结果共同验证了所述三相PWM-VSR直流调压改进策略的有效性与优越性.

The energy storage virtual synchronous generator (VSG) can provide certain inertia support for the renewable energy power generation system, but its virtual damping coefficient is coupled with the primary frequency modulation coefficient, so the dynamic oscillation and the steady-state error of its grid-tied active power cannot be eliminated simultaneously when the active power command and the grid frequency are disturbed. Therefore, a dynamic response optimization strategy based on the improved virtual impedance for the energy storage VSG is proposed in this paper, which introduces the virtual impedance into the voltage control link in the conventional VSG control strategy. The proposed method can not only improve the system damping but also suppress the dynamic oscillation of grid-connected active power without any steady-state deviation. The correctness of the theoretical analysis and the effectiveness of the proposed control strategy are verified by simulation results.

A virtual synchronous generator (VSG) has a good adaptability to the weak grid but its grid-connected active power (GCAP) has the problem of a slow dynamic response under the active power command step. An optimization strategy of the GCAP dynamic response for the VSG based on the virtual negative impedance combined with the active power transient damping control algorithm is proposed in this paper. The optimization strategy first uses the virtual negative impedance control method to reduce the VSG equivalent output impedance and the GCAP dynamic response time of the VSG. Then, the transient damping as well as the inhibition ability of the GCAP dynamic oscillation for the VSG are enhanced by the active power transient damping control algorithm. The Matlab/Simulink simulation software is used to study the GCAP dynamic response performances of the VSG in the condition of the active power command step, and the experimental test platform of a VSG grid-connected system is established. The simulation and experimental results jointly verify the feasibility and superiority of the proposed strategy in improving the GCAP dynamic response characteristics of the VSG under a weak grid.

为解决传统储能虚拟同步机(virtual synchronous generator,VSG)的并网有功由于其一次调频系数与虚拟阻尼系数相互耦合而存在稳态偏差与动态振荡难以兼顾的问题,提出一种基于有功前馈补偿的储能VSG并网有功动态振荡抑制策略.该策略利用有功经一阶低通滤波器后前馈至并网有功闭环控制回路,通过调节前馈系数优化储能VSG并网有功的动态性能且无需进行微分运算,同时不影响储能VSG的一次调频特性.然后,建立基于有功前馈补偿的储能VSG并网有功闭环的小信号模型,并给出前馈系数的整定方法.最后,利用仿真与实验测试对比结果共同验证了所述策略在有功指令与电网频率2种阶跃扰动下可有效消除储能VSG并网有功的稳态偏差及其动态振荡,且不存在频率过冲的风险.

The phase difference between the grid voltage and current in grid-connected current source inverter is affected by the PI controller parameters, filter inductor and equivalent resistance. To eliminate the phase difference, three phase compensation strategies are proposed: phase compensation based on phase detection, phase compensation based on output power detection, and filter inductance regulation. The inverter mathematical model is established firstly. Then, the compensation principle and its parameters design method are given. Finally, the feasibility and effectiveness of the proposed strategies in eliminating phase difference and improving power factor are verified by using the Matlab/Simulink simulation model and experimental platform.