Robust type-2 fuzzy fractional order PID controller for dynamic stability enhancement of power system having RES based microgrid penetration

摘要

The increased penetration of renewable energy sources (RES) based microgrid (MG) to the power system can affect the system stability due to the difference in dynamic characteristics of this kind of MG from the conventional generators. The reduction in system inertia caused by these power electronics interfaced renewable power generations introduces a negative effect in the dynamic stability of the system and may cause ensuing instability problems. On the other hand, power injection of RES based MG improves the damping performance with the reduction of transmission line congestion and power loss. Thus it becomes imperative to analyze the new dynamic stability concerns and control performance of a power system in the context of increased MG penetration. This study thoroughly investigates the impact of RES based MG penetration on the dynamic stability and control of a multi-machine multi-area system under varying operating conditions. The design of a novel type-2 fuzzy fractional order PIO based power system stabilizer (PSS) using a meta-heuristic hybrid algorithm is presented in this paper for improving the electromechanical oscillation damping performance of the power system to enhance the dynamic stability. The large bandwidth, memory effect and flat phase contribution in the frequency response of fractional-order PID controllers are exploited to make the controller perform well against a wide range of system uncertainties in the presence of an MG. First, the parameter tuning problem of the type-2 fuzzy fractional order PID controller is transformed to an optimization problem that is solved using a hybrid algorithm by combining a dynamic genetic algorithm (DGA) with a bacteria foraging algorithm (BFA). The capability of the proposed controller in damping the low-frequency oscillations in the system with various MG penetration ratios is assessed through non-linear time-domain simulations and some performance indices under different disturbances and operating conditions.