This chapter explains the meaning of basic terms and concepts related to expert systems, describes the architecture and functions of an expert system, and the conditions under which the building or purchase of an expert system is feasible. The benefits and disadvantages attached to the use of expert systems will be analysed. Also included are a description of the tools and methods used for building expert systems plus the criteria used to evaluate and compare these tools. Finally the reader will gain an understanding of the difficult process of knowledge acquisition and an awareness of the legal implications of the use of expert systems.

Expert systems

In this paper, a novel algorithm, based on dc link voltage, is proposed for effective energy management of a standalone permanent magnet synchronous generator (PMSG)-based variable speed wind energy conversion system consisting of battery, fuel cell, and dump load (i.e., electrolyzer). Moreover, by maintaining the dc link voltage at its reference value, the output ac voltage of the inverter can be kept constant irrespective of variations in the wind speed and load. An effective control technique for the inverter, based on the pulsewidth modulation (PWM) scheme, has been developed to make the line voltages at the point of common coupling (PCC) balanced when the load is unbalanced. Similarly, a proper control of battery current through dc-dc converter has been carried out to reduce the electrical torque pulsation of the PMSG under an unbalanced load scenario. Based on extensive simulation results using MATLAB/SIMULINK, it has been established that the performance of the controllers both in transient as well as in steady state is quite satisfactory and it can also maintain maximum power point tracking.

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Permanent Magnet Synchronous Generator-Based Standalone Wind Energy Supply System

This paper addresses the issue of robust fuzzy sliding mode control for continuous-time nonlinear Takagi–Sugeno fuzzy systems with semi-Markovian switching. The focus is on designing a novel fuzzy integral sliding surface without assuming that the input matrices are the same with full column rank and then developing a fuzzy sliding-mode controller for stochastic stability purpose. Based on Lyapunov theory, a set of newly developed linear matrix inequality conditions are established for stochastic stability of the sliding-mode dynamics with generally uncertain transition rates, and then extended to where the input matrix is plant-rule-independent, as discussed in most existing literatures. Furthermore, finite-time reachability of the sliding surface is also guaranteed by the proposed fuzzy sliding-mode control laws. A practical example is provided to demonstrate the effectiveness of the established method numerically.

A Novel Robust Fuzzy Integral Sliding Mode Control for Nonlinear Semi-Markovian Jump T–S Fuzzy Systems

Active power filters (APFs) have been developed to solve the problems of harmonic suppression and reactive power compensation simultaneously, In this paper, a three-phase four-wire power filter comprising a three-phase three-wire APF and a Zig-Zag transformer is developed. A hardware prototype is implemented and tested to verify the performance of the proposed power filter under various ideal and non-ideal power conditions. Experimental results show that this three-phase four-wire power filter has the desired performance under limited zero sequence utility voltage.

A Three-Phase Four-Wire Power Filter Comprising a Three-Phase Three-Wire Active Power Filter and a Zig–Zag Transformer

In this study, the design and analysis of a fuzzy logic (FL) controlled dynamic voltage restorer (DVR) are presented and extended to perform fast fault detection. A new control method for DVR is proposed by combining FL with a carrier modulated PWM inverter. The proposed control scheme is simple to design and has excellent voltage compensation capabilities. The proposed method for voltage sag/swell detection has the ability of detecting different kinds of power disturbances faster than conventional detection methods. Effectiveness of the proposed detection method is shown by comparison with the conventional methods in the literature. Simulation results under unbalanced supply voltage are presented to evaluate the performance of the designed DVR.

Fast sag/swell detection method for fuzzy logic controlled dynamic voltage restorer

Summary form only given. The paper describes the application of Takagi-Sugeno (TS) type fuzzy logic controller to three-phase shunt active power filter (APF) for the power quality improvement and reactive power compensation required by a non-linear load. The advantage of fuzzy logic control is that it does not require a mathematical model of the system. The application of Mamdani type fuzzy logic controller to three-phase shunt active power filter have been investigated earlier but it has the limitation of more number of fuzzy sets and rules. Therefore, it needs to optimize large number of coefficients, which increases the complexity of the controller. On the other hand, TS fuzzy controllers are quite general in that they use arbitrary input fuzzy sets, any type of fuzzy logic, and the general defuzzifier. Moreover, TS fuzzy controller could be designed by using less number of rules and classes. Further, in this paper hysteresis current control mode of operation is implemented for PWM switching signal generation. Computer simulation results show that the dynamic behavior of TS fuzzy controller is better than the conventional Pl controller and is found to be more robust to changes in load and other system parameters compared to the conventional Pl controller.

S. Mishra

Papers

TS-fuzzy controlled active power filter for load compensation