Fuzzy controlled SMES unit for power system application

This paper presents a new approach to control a 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 (Δω) of a synchronous generator are taken as the input signals to the fuzzy frequency controller (FFC). The terminal voltage deviation (ΔV₁) and its derivative (ΔV₁) 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 (ΔI_sm) as inputs. ΔI_sm is also used as a negative feedback signal to ensure the SMES energy is restored to its pre-disturbance 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