Load-Side Voltage Flexible Control Based on Active Electric Spring

Electric spring (ES) is a device which can optimize the power quality of the grid. However, ES divides the load into critical load and non-critical load, realizing the protection of critical load while non-critical load operates at abnormal voltage. Besides, its voltage regulation ability is limited by line parameters. In order to solve the problem that the traditional ES regulates the load voltage in a passive way under the practical condition, this paper proposed an active electric spring (AC-AES) based on bipolar-Type direct AC-AC converter for distributed voltage regulation. AC-AES no longer distinguishes critical load from non-critical load, and protect them in a unified way, which makes its voltage regulation more active. The feasibility of AC-AES to regulate load power by voltage regulation and keep load voltage stable when the grid voltage fluctuates was verified by simulations and experiments respectively.