Design and implementation of fault tolerant fractional order controllers for the output power of self-excited induction generator

Abstract

In this paper, a static volt-ampere-reactive compensator (SVC) composed of fixed capacitor-thyristor controlled reactor (FC-TCR) is employed to regulate the terminal voltage of self-excited induction generator (SEIG) in the purpose of controlling the output power. In addition, the speed of the generator is adjusted by robust proportional-integral-derivative (PID) in order to regulate the frequency. Fractional order PID (FOPID) and Tilt-PID (T-PID) controllers are proposed to adjust the triggering angle of FC-TCR. The objectives of the paper are to design the optimal voltage controller with a robust PID frequency controller and to maintain the output power at a desired level in case of voltage sensor faults. In this regards, nonlinear autoregressive network with exogenous inputs (NARX) and small signal models of the SEIG are constructed where triggering angle and generator speed are inputs, whereas terminal voltage and frequency are outputs, respectively. Training of the NARX model is achieved with a high regression value (R2 = 0.99) where the accuracy of the small signal voltage model is 82%. After comparing the accuracy of the models, NARX-based fault detection architecture and fault tolerant controller are designed in order to avoid incorrect control of the output power. To establish the effectiveness of proposed fault tolerant controllers, simulation studies are conducted using particle swarm optimization (PSO). The designed controllers are performed experimentally on three-phase 5.5 kW, 400 V, 50 Hz, balanced loaded SEIG to confirm the effectiveness. The system is tested with proposed controllers under the healthy sensor, faulty sensor and dynamic reference conditions. Results give good agreement with simulation results and designed fault tolerant T-PID controller performs better tracking dynamics with small deviations whether the voltage sensor is faulty or not.