4. Multiple-Virtual Inertia Synthesis for Interconnected Systems

In the previous chapter, the regulation of the interchange power and the implementation of multiple virtual inertia controls are not considered. In real practice, most of the power systems are interconnected to enable the power transfer between each area in the system for more efficient use of the available resources. With the increasing penetration of renewable energy sources (RESs)/distributed generators (DGs), the inertia of some areas will decrease and could lead to power system oscillations. In this regard, the regional inertia property is critical to managing the oscillations and avoiding system instability. To overcome this problem, this chapter investigates the coordination of multiple virtual inertia control systems to improve the frequency stability and responses of the inertia power and tie-line power in the interconnected power systems with RESs/DGs. The dynamic performance and frequency characteristics of an interconnected system with multiple virtual inertia, primary, and secondary control loops are explained. A dynamic response model of the interconnected system is linearized and investigated in detail. The role of interchange power between control areas is briefly described. The effects of control parameters affecting the system frequency response with respect to the implementation of multiple virtual inertia units in the interconnected system are discussed via the state-space representation.