Investigation on the dual functions of generator reactive power support

Open access permits all players to inject real power into a system with few restrictions. As generators also provide reactive power to the system, there is a general conception that their Q-outputs are supportive to system security and should be financially compensated. Our research results show, however, that a generator´s Q-output has double-applications. One is to support the shipment of its own active power, and the other is to support system security. Therefore, compensation should be made to the second component only. The main purpose of this paper is to introduce the problem and demonstrate the phenomena of the dual functions of generators Q-output. Simple systems are used to illustrate the phenomena. Analytical separation of the components is presented for these simple systems. Case-specific separation methods are also developed to demonstrate the problem. The paper contributes to introducing the phenomenon, as well as demonstrating its importance for defining fair compensation schemes for reactive power support services. It also shows that methods need to be developed to solve the problem for large-scale real-life power systems, Preliminary, but potential, ideas are discussed.