Volume 55

Novel Virtual Synchronous Generation Control with Virtual Impedance Mir Nahidul Ambia, Yuchen Zhang, Ke Meng, Ahmed Al-Durra, Zhaoyang Dong

Abstract

In recent years, the power industry has seen a significant uptick in renewable energy integration, including solar and wind farms, accompanied by energy storage systems. While this has increased overall generation capacity, it has also posed challenges to grid security and vulnerability. Key issues such as low short circuit ratios due to renewable integration and the retirement of synchronous machines have weakened grids. Grid forming inverters therefore have emerged as a vital solution, aiding solar and wind farms in maintaining stability during low short circuit ratio conditions. However, traditional Virtual Synchronous Generation (VSG) controllers, while beneficial, often introduce oscillations during disturbances, threatening network stability. This paper introduces an innovative approach that integrates Virtual Synchronous Generation Control with a Virtual Impedance Strategy to address stability challenges in solar and wind farms under low short circuit ratio conditions. By eliminating the need for Phase-Locked Loops (PLL), this method effectively mitigates oscillations during faults and voltage disturbances, thereby ensuring grid stability, with compliance to grid codes such as those of NER and AEMO Australia serving as guidelines. Implementation in PSCAD, which is widely used in the power system industry, validates its capability to meet stringent grid code requirements.

Keywords Grid forming inverter (GFM), grid integration of renewable energy, virtual synchronous generator (VSG), weak grid, virtual impedance