Interactive Grid Synchronization-Based Virtual Synchronous Generator Control Scheme on Weak Grid Integration

Abstract

While high volume of power electronic converters with renewable energy are being integrated into the grid, low system strength of grid causes reduction in system inertia and loss of synchronization with power converters. This paper proposes a novel interactive control scheme of voltage source converter (VSC) connected to weak grid. Firstly, a grid synchronization approach is performed using VSC side voltage transformed on rotating reference frame with respect to grid voltage, which is carried out based on lowest short circuit ratio (SCR) as approved by utilities such as Australian Energy Market Operator’s system strength report. The transformed voltage is then fed into the active power and reactive power control through PLL. Secondly, the grid synchronization approach through PLL is made interactive by adding virtual synchronous generator (VSG) control into the outer loop, which generates virtual inertia to mimic the synchronous generators of a power system. The design of the VSG control parameters is realized based on small signal stability analysis. Furthermore, the control method is evaluated as per the National Electricity Rules clauses S5.2.5.1-S5.2.14 under AEMO and National Service Providers of Australian strict Industry guidelines. The time-domain simulation results are conducted on PSCAD platform.