In this chapter, a new technique has been proposed for reducing the harmonic content of a three-phase PWM rectifier connected to the networks with a unit power factor and also providing decoupled control of the active and reactive instantaneous power. This technique called direct power control (DPC) is based on artificial neural network (ANN) controller, without line voltage sensors. The control technique is based on well-known direct torque control (DTC) ideas for the induction motor, which is applied to eliminate the harmonic of the line current and compensate for the reactive power. The main idea of this control is based on active and reactive power control loops. The DC voltage capacitor is regulated by the ANN controller to keep it constant and also provides a stable active power exchange. The simulation results are very satisfactory in the terms of stability and total harmonic distortion (THD) of the line current and the unit power factor.
Top1. Introduction
Recently, different control approaches have been proposed for designing nonlinear systems for many practical applications, such as optimal control, nonlinear feedback control, adaptive control, sliding mode control, nonlinear dynamics, chaos control, chaos synchronization control, fuzzy logic control, fuzzy adaptive control, fractional order control, and robust control and their integrations (Azar & Vaidyanathan, 2015a,b,c, 2016; Azar & Zhu, 2015; Azar & Serrano, 2015a,b,c,d, 2016a,b, 2017; Boulkroune et al, 2016a,b; Ghoudelbourk et al., 2016; Meghni et al, 2017a,b,c; Azar et al., 2017a,b,c,d; Azar 2010a,b, 2012; Mekki et al., 2015; Vaidyanathan & Azar, 2015a,b,c,d, 2016a,b,c,d,e,f,g, 2017a,b,c; Zhu & Azar, 2015; Grassi et al., 2017; Ouannas et al., 2016a,b, 2017a,b,c,d,e,f,g,h,I,j; Singh et al., 2017; Vaidyanathan et al, 2015a,b,c; Wang et al., 2017; Soliman et al., 2017; Tolba et al., 2017).
The increasing use of electronically powered and controllable systems in the industrial sector, motivated by improved performance, has led to a proliferation of static converters. Today, the number of these devices connected to electricity grids is constantly increasing. The switching operation of the semiconductor components constituting these converters is the reason why their behavior with respect to the power source is non-linear. Indeed, they take non-sinusoidal currents and for the most part consume reactive power, which poses serious problems for electrical networks. Static converters have become the most important sources of harmonics on the network. The uncontrolled diode and controlled thyristor rectifier is the most polluting and widespread static converter in both industry and domestic appliances. Under certain operating conditions, it can introduce a harmonic distortion rate (THDi) of current greater than 30%. For this reason, some recent adapted international standards, such as IEEE Standard 519, IEC 61000 and EN 50160, impose limits on the THD of currents and voltages within the supply network (5% for currents and 3% for voltages). In view of this state of affairs, and in order to limit the harmonic disturbance caused by the power electronics systems connected to the network, it is necessary to develop curative devices such as active filtering on one side and the other to design preventive actions such as non-polluting converters, equipped with a control device making the current drawn on the network as sinusoidal as possible.