English

Abstract

In recent years, voltage instability and voltage collapse have been observed in power systems of many countries. Such problems have occurred even more often in developed countries because of utility deregulation. Currently, voltage security is of major importance for successful operation of power systems. Assessment of voltage security is needed to utilize power transmission capacity efficiently and to operate the system uninterruptedly. In our research work, we study voltage security of on power system of IEEE20 bus system. We assess voltage security of these systems using P-V curve In other words, we compute margins of real power(P) . To achieve what we promise, we first obtain the power-flow solution for the given data by running the power-flow program that we have coded using MATLAB. The solution is taken as the base case. Second, we choose candidate buses at which we incrementally change real power for plotting P-V curves. The candidate buses are of load buses so that P margins are computed against increase in demand. Third, we run the power-flow program for incremental changes in real power at the candidate bus. The point at which power-flow convergence is no more available is the critical point. Up to the critical point, we obtain voltages at the candidate bus corresponding to changing realpower at the same bus.Fourth, we plot PV curves using voltages versus P .Finally, the difference between the real power demanded the candidate bus at the critical point and that at the base case gives us the P-margin computed for the candidate bus. This paper proposed that Our investigation of power-flow solutions, P-V curves of the 20 bus IEEE system -shows that we obtain power-flow solution using Newton-Raphson method and compute margins of voltage security with predefined tolerance using MATLAB. Such computations provide us indispensable information for the secure and efficient operation of power systems.