Power-imbalance allocation control for secondary frequency control of power systems

To balance the power supply and demand with optimized control cost and nominal synchronized frequency, we propose a secondary frequency control approach, named Power-Imbalance Allocation Control (PIAC), for power systems with lossless networks, consisting of synchronous machines, frequency dependent power sources and passive loads. With Proportional-Integral control, the power imbalance is estimated by a coordinator with aggregated frequency deviations and the control inputs are optimally allocated to the controllers after solving an economic power dispatch problem on-line. The advantage of the approach is that the estimated power imbalance converges to the actual power imbalance exponentially with neither overshoot of control inputs nor unnecessary oscillations of the frequency. In addition, the convergence speed only depends on a control coefficient which is independent of any other parameters of the power systems and of the economic power dispatch problem.