Bidirectional Power Flow Control of Grid-Connected Converter Using Resistance-Emulating Approach

Resistance-emulating control is a cost-effective control scheme for grid-connected converters. However, it is not suitable for the case in which bidirectional power flow is required. To overcome this limitation, a new resistance-emulating control scheme is presented in this article. The emulated resistance is composed of a notch filter and a band-pass filter. Compared with the conventional resistance-emulating control, two extra degrees of freedom are introduced into the proposed one. By choosing the degrees of freedom properly, both the steady and dynamic performance of the system can be enhanced. In addition, the operating range of the grid-connected converter is extended greatly. Meanwhile, the advantages of no grid voltage sensor and phase-locked loop are retained in the proposed method. Experimental results verify the effectiveness and correctness of the proposed method.