Fuzzy controlled SMES unit for power system application

Abstract

This paper presents a new approach to control Superconducting Magnetic Energy Storage (SMES) unit for power system application. The SMES unit is used to improve the dynamic performance of P-f and Q-V loops of a power system. Two independent fuzzy controllers are assigned, one for the frequency control and another for the voltage control. Speed deviation (Δω) and acceleration of a synchronous generator are taken as the input signals to the Fuzzy Frequency Controller (FFC). The terminal voltage deviation (ΔVt) and its derivative are considered as the inputs to the Fuzzy Voltage Controller (FVC). To get the maximum benefit from the SMES unit, a supplementary control is generated by using the output of FFC and the inductor current deviation (ΔIsm) as inputs. ΔIsm is also used as a negative feedback signal to ensure the SMES energy is restored to its predisturbance level. The desired P-modulation from the SMES is obtained by adding this supplementary control signal to the output of FFC while the output of the FVC is the desired Q-modulation. The effective use of the SMES unit is verified for small as well as large disturbances for a single machine infinite bus system, and simulation results are presented and discussed.