An Improved Grid Voltage Feedforward Compensation Scheme of Grid-Connected Inverter in Weak Grid

The grid voltage feedforward control strategy is widely used in the grid-connected inverter, aiming to reduce the disturbance of grid voltage distortion and suppress the impulse current of inverter at startup. However, an extra positive feedback channel will be introduced into the current control loop in weak grid, bringing low harmonics and even instability in the inverter. In order to solve this problem, several blocks including weighting coefficient, low-pass filter (LPF) or second-order generalized integrator (SOGI) are added in the grid voltage feedforward control strategy. In this paper, the above improved algorithms are compared and it is concluded that the steady-state and dynamic performance of the system cannot be balanced with the existing method. Therefore, an improved voltage feedforward compensation control strategy is given. Compared with existing scheme, the proposed scheme in this paper has better steady state performance. Meanwhile, the dynamic performance of the proposed scheme is better than that of the SOGI technique. The effectiveness of the proposed scheme is verified by theoretical analysis and experiments.