A new method to compute reactive power margin

For a long time, the research about the impacts of reactive power compensation devices on reactive power margin and voltage stability in power system has been important. Under the electrical market environment, the reactive power margin computation becomes even more necessary. By adopting the idea of heuristic energy function, this paper formed the energy models of two-bus and multi-bus system. Based on this, the paper successfully computed the critical voltage and the critical energy value in load nodes before and after compensation through adopting the power flow of retaining nonlinearity algorithm integrating the optimal multiplier (PFRNAIOM) . According to these critical values, this paper not only gains reactive power margin of load node before and after compensation, but also logically analyzes the impact of shunt compensation on voltage stability and the changes of voltage phase angle and required energy in every load node with the increase of reactive load proportion. By comparing with the results of continuation algorithm, the simulations of two-bus system and multi-bus system demonstrate the validity and feasibility of the approach proposed in this paper.