Reactive support allocation using improved Y-bus matrix method

In deregulated power systems ancillary services including reactive power supply are unbundled for transparency and accurate cost identification. Sufficient reactive power supply is essential for secure operation of power systems. Reactive power is supplied by generation-based and static reactive power sources and is used for two purposes: direct consumption at loads and system-wide voltage management. The task of the system operator is to identify which part of reactive power is supplied by any source and who consumes this. Accordingly, revenue is collected from consumers and distributed among reactive power providers. Therefore an appropriate and transparent reactive power pricing scheme will encourage more generators to participate in reactive power market, increasing stability of the system because of increased reactive power availability. However, existing reactive power allocation methods do not always provide unquestionable results. The proposed circuit theory-based method identifies different reactive power sources and allocates the amount of reactive power provided to different sources by using an improved Y-bus technique along with proportional or equal sharing principle. Line charging reactance present in transmission line supplies reactive power to the system, which is identified as a separate reactive power source for the first time in this study and the proposed method, offers a part of revenue to system operator for supplying reactive power to the system by means of this line charging reactance. By doing so, the proposed method eliminates some important drawbacks of existing allocation methods. The method is tested on different IEEE systems and also a 400 KV practical system.