Studding two indices of voltage stability in reliability constrained unit commitment in a day-ahead market

In an electricity market environment, market participants try to increase their profit. This attitude may lead to voltage instability and insecurity in operation of power systems. In this paper, unit commitment problem considering voltage stability is investigated. Benders decomposition is used to solve unit commitment problem. Some indices are used to describe voltage stability for each bus and all of the system. In other words, this paper tries to make comprise between cost and voltage stability in unit commitment (UC). Hence, the objective function was modified by adding a penalty factor. A sensitivity analysis is made to see the effect of this factor on voltage stability and cost. Based on this method, the penalty factor and cost of UC is defined in a way that voltage stability and cost are optimized. The effect of this improvement is investigated in spinning reserve and reliability. Spinning reserve was calculated by probabilistic criteria. A 6 bus system is used to evaluate this method.