• Energy Research

AbstractThe paper deals with a digital‐signal‐processor (DSP)‐based implementation of a Fuzzy control algorithm for a three‐phase active filter (AF). The laboratory prototype model of the AF uses voltage source inverter (VSl) with pulse‐width modulation (PWM) current control technique. The AF is employed to compensate harmonics and reactive power of a non‐linear load. A three‐phase diode bridge rectifier with resistive‐inductive load is taken as a non‐linear load. With a view to obtain the steady‐state and transient response of the AF system, its mathematical model is developed. Experimental verification of simulated results is carried out to validate the proposed fuzzy control technique for AF systems.

This paper deals with the analysis, design and control of Distribution Static Compensator (DSTATCOM) for power quality improvement in an AC distribution system. Various design criteria are considered for the design of DSTATCOM for a variety of possible functions such as voltage regulation, power factor correction and load balancing. Conventional AC power capacitors are considered in conjunction with DSTATCOM for reducing the rating of DSTATCOM. The design of DSTATCOM is carried out and the ratings of its DC bus capacitor, AC filter inductor, current and voltage ratings of solid-state devices are determined along with AC capacitors to reduce the rating of DSTATCOM.

In this paper, hardware-in-the-loop (HIL) implementation of solar photovoltaic (PV) array feeding autonomous load, without dump load, is investigated. Two control algorithms based on the sliding mode approach are designed to guarantee a fast and finite-time convergence without adjustment of the system parameters. The dc-dc boost converter and the current controlled-voltage source converter (CC-VSC) are controlled to maximize the power from the PV, to protect the battery energy storage system (BESS) from overcharging, and to regulate the voltage and frequency at the point of common coupling (PCC). An accurate stability analysis of the system is presented and discussed in this work. The effectiveness and the robustness of the developed controllers are validated by simulation and experimental results during the load perturbation and varying climate conditions.

Abstract This work presents a frequency integrated approach on a multi-order generalized integrator and a self-tuned discrete proportional plus integral regulator (PIR) for three-phase double-stage grid tied photovoltaic (PV) energy system, where the peak power is extracted from PV system and feed to the load and the grid. The function of this novel frequency integrated multi-order generalized integrator (FIMOGI) is to attenuate the higher-order and sub-order harmonic components from distorted load currents, even when the load currents are linear or nonlinear and balanced or unbalanced. Integrated frequency approach removes the switching frequency variation of VSC without addition of a FLL and improves the synchronization of VSC power fed to the grid. Moreover, self-tuned PIR is used to regulate the DC-link voltage under different dynamic and disturbance conditions. To improve the transient performance, a PV power feed-forward term is included in the implemented control. The proposed FIMOGI controller is modelled and the control is developed in Simulink environment as well as its performance is validated on a developed laboratory prototype. The simulated and experimental performance is carried out under nonlinear balanced and unbalanced load, and solar insolation increase and decrease. The grid current condition measured in terms of total harmonics distortion, during Simulation and validation are found under the restrained of IEEE-519 standard in different working condition, which exhibits the efficacy of the implemented control.

This paper deals with the performance of distribution static synchronous compensator (DSTATCOM) connected to an alternator of 42.5 kVA rating feeding four-wire linear loads. Simulation of DSTATCOM connected such weak system is carried out using standard MATLAB environment and power system toolbox. Results are simulated for linear resistive-inductive lagging power-factor loads for power factor correction, voltage regulation and load balancing for improving the power quality of the system isolated from the power grid.

This paper deals with the simulation of distribution static synchronous compensator (DSTATCOM) for improving power quality of a distribution system feeding linear as well as non-linear loads. Nowadays, there are an increasing number of non-linear loads which inject harmonics into the system. A three-phase insulated gate bipolar transistor- (IGBT-) based current controlled voltage source inverter with a DC bus capacitor known as a DSTATCOM is used for power factor correction, harmonic compensation and for providing required reactive power to the load. A model of DSTATCOM connected to a power distribution system feeding linear and non-linear loads (diode bridge rectifier with R and R-C) is developed for predicting the behaviour of system under transient conditions. Simulation is carried out in standard MATLAB environment using Simulink and power system blockset toolboxes. Control algorithm is made flexible so that it can correct supply power factor, eliminate harmonics and provide load balancing. The control algorithm utilises one closed loop PI controller for regulating the DC link voltage of DSTATCOM and second PI controller for regulating the AC voltage at point of common coupling. Results are presented for a variety of linear and non-linear balanced as well as unbalanced loads, which demonstrate power factor correction, voltage regulation, harmonic elimination and load balancing capabilities of DSTATCOM.

With rapid industrialization the use of electrical machines is increasing exponentially. The use of these machines includes their application as continuous duty and intermittent duty. The intermittent duty applications have become very popular for their applications in automation, but assessment of power and power factor of such application has not been clearly defined, which has drawn attention of researchers in recent years. The paper discusses a method for assessment of power factor for intermittent duty load conditions. The method adopts the concept of energy losses corresponding to every power component (active, reactive, distortion and unbalance power) for the total period (light load period and heavy load period respectively). The discussion includes application for single phase and three phase unbalanced intermittent duty loads having harmonics, using the theory of symmetrical components followed by instantaneous reactive power theory (IRPT). Analysis is carried out mathematically and results are simulated under MATLAB.

This paper describes the use of series capacitor in rating reduction of static compensator (STATCOM) for voltage regulation of three-phase self-excited induction generator (SEIG). A SEIG driven through a constant speed prime mover such as gasoline engine requires an appropriate combination of shunt and series capacitors to improve its voltage regulation under varying load conditions. Inclusion of fixed value of series capacitor provide additional VARs with increasing load to enhance the voltage regulation of the SEIG. However, the SEIG being a weak power supply system with limited kVA experiences large voltage dip with variable output power and fixed excitation in stand-alone applications. The problem of voltage dip arising from varying loads is reduced with use of STATCOM along with fixed excitation. The shunt excitation capacitor needs to supply the reactive power of demand of SEIG to generate rated voltage at no-load. In the present study the transient performance of series capacitor compensated SEIG-STATCOM system has been analyzed through simulation in MATLAB/Simulink environment. The simulation results have revealed that with inclusion of series capacitors along with STATCOM improves the voltage regulation of SEIG under varying loads. Moreover, the use of fixed value of series capacitor has resulted in significant reduction in the rating of STATCOM.

This paper presents the modelling of Distribution Static Compensator (D-STATCOM) used in isolated power systems. The model of D-STATCOM is developed using Power System Block-set (PSB) and Simulink toolboxes of standard MATLAB software. Two proportional integral PI controllers are used to control DC bus voltage and AC bus voltage regulation at the point of common coupling. Results are presented for D-STATCOM used in an isolated distribution system fed from an alternator. It is observed from results that D-STATCOM is able to improve power factor, provide voltage regulation, balance the loads and reduce harmonics.