Optimising Power System Frequency Stability Using Virtual Inertia from Inverter-based Renewable Energy Generation

This paper addresses the impact of high penetration of renewable energy sources (RES), in particular wind and solar power generation on the western transmission network of the South African (Eskom) power system. The study focuses on the power system’s stability, specifically the frequency dynamics. With a decline in power system inertia, inertial response emulated by inverter based RES, is considered as a means to restore the system’s inertia. Virtual inertia is seen as a valuable ”resource”, but comes at the cost of active power generation. In addition virtual inertia also provides an additional degree of control, which must be used in an optimal manner to provide maximum system stability at a reasonable cost to power generation. This paper utilizes an optimal virtual inertia placement and allocation method, for the western transmission network considering a trip of the Koeberg nuclear power plant in the Western Cape province. Simulation test results show that the virtual inertia and optimal allocation improves the system stability significantly. This in return gives additional incentive for RES integration.