The steady state voltage stability

The steady state voltage stability analysis is extremely important to the security of power systems. The continuation power flow (CPF) is one of the important tools for the steady state voltage stability analysis. However, its computation load is very large. To improve the analysis performance in DC power systems, a basic technique is used to explore the exact relationships between injected currents, buses voltages, lines currents and lines voltages. Based on the basic technique, the computation loads can be separated and some repeated computation can be avoided. In this paper, two new methods to calculate critical point are proposed. One is by combining the basic technique and a correctness method for CPF. The method improves the calculation speed by avoiding the repeated computation of same topology and buses types analysis. Another method is a direct method. The direct method is based on the novel view to understand power systems and the physical (and mathematical) essence of critical point and voltage collapse. Most CPF is discussed in AC system. The corresponding CPF in DC system will be studied to get standard results for comparison. Compared with CPF in DC systems, the numerical verification shows that the proposed methods can reduce most computation loads of CPF method in DC systems.