On-Line Load Dispatching Control with Security Constraints at the Tohoku Electric Power Company

This paper presents an on-line load dispatching control system with security constraints which will start to operate in 1984 at the Tohoku Electric Power Company in Japan. One of these authors had developed a novel technique for an optimal power flow problem which was formulated based on the Decoupled Newton Load Flow method well recognized in bulk power systems. That is, the optimal power flow problem was formulated into P-0 active power and Q-V reactive power networks. Quadratic programming was employed to solve the OPF problem. The main algorithm of the developed system comprises the only P-0 active power network of the OPF problem. The system is able to minimize either generation costs or sum of squares of deviations between generator outputs and desired ones by controlling generators. The constraints consist of generator operating limitations and of power flow limitations which are restricted by thermal capacities or transient stability. If the problem has not a solution to satisfy the constraints, this system gives a solution which minimize sum of squares of the power flow violations. This on-line system is capable of dealing with a problem size of up to 180 buses, 200 lines, 26 controlling generators and 3 phase-shifting transformers.