Research On Static Voltage Stability Of Thevenin Equivalent When Considering Generator Power Balance

The voltage stability of power system is a problem and a key study at home andabroad all the time. Especially in recent several decades, voltage collapse occursfrequently with the constantly expanding power grid of long distance and super highvoltage in our coutry. Based on this issue, a new method of static voltage stabilityanalysis is presented based on the Thevenin’s equivalent circuit in this paper.Firstly this paper introduces the background and significance of the topicselection, and the definition and classification of the power system voltage stability,then introduces the existing methods of voltage stability analysis and index of staticvoltage stability in detail. In order to analyze the voltage stability of load buses morequickly, this paper presents a analysis method to simplify the power grid structure.The core idea is tracing the equivalent electric network frame.The Theveninequivalent circuit has clear and simple structure, which is a hot topics in recent years.Based on the research of Thevenin theorem, a novel algorithm for the analysisand calculation of voltage stability with the sensitivity method to get the Theveninequivalent parameters is proposed.At first,the voltage and power of researched loadbuses is obtained through power flow calculation.Each sensitivity which is used tocalculate Thevenin equivalent parameters is then found through the partial derivativesof voltage to power. At last the voltage stability of load buses can be rapidly judgedthrough the resistance module margin index and voltage instability proximityindex.The calculation process and results show that the proposed method gets rid ofrepeated iterative calculations and avoids no solution condition at Jacobin matrixsingular place.Finally the proposed method is verified on IEEE10system and IEEE118system.The results show that the voltage stability of load buses is improved whenpredicting generators to participate in power balance.The proposed method can beused for quick analysis of load buses voltage stability and predict the effect ofimproving voltage stability relative to the buses when some generator is with differentcoefficient so that it can be used as a tool for real-time supervising power systemstability and preventive control in power dispatching center.