International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 07 | July 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 2219 Power Quality Improvement by using DSTATCOM with PSO Tuned PI Controller S. Karuna 1* , P.V. Prasad 2 1* EEE Department, CBIT, Gandipet, Hyderabad, India 2 EEE Department, CBIT, Gandipet, Hyderabad, India ---------------------------------------------------------------------------***--------------------------------------------------------------------------- Abstract - The Distribution static synchronous compensator (DSTATCOM) is used for reactive power compensation, Power factor correction, reduction in total harmonic distortion and to stabilize the source and PCC currents. DSTATCOM is a parallel connected device connected at a point of common coupling (PCC). The Controlling algorithm for DSTATCOM is developed by using synchronous reference frame theory (SRF) and which is utilized for generating the reference currents. The DSTATCOM comprises of VSI, dc link capacitor and control circuit. The dc link capacitor voltage is regulated by using the PI controller. The Kp, KI values obtained with conventional method may not give accurate results. Hence, In this paper a PSO based technique is proposed to obtain optimal results. The simulation representation is progressed using MATLAB simulation software. Keywords: DSTATCOM; voltage source inverter (VSI); SRF Theory; PI controller; PSO. 1. INTRODUCTION In current years because of new advancement in technology most of the industries and commercial customers prefer the usage of Power electronics devices. Because of these non-linear loads distribution system is facing power quality (PQ) problems such as poor power factor, harmonics injection, voltage sag, voltage swell, high neutral current, unbalance in three phase loading, distortions in source currents. These distortions may pass through the entire network. These PQ problems may responsible for increase of power losses, violates the power flow limits, and reduce the system response time [1]. Various custom power devices such as DSTATCOM (Distribution Static Synchronous Compensator), Unified Power Quality Conditioner (UPQC), and Dynamic Voltage Regulator (DVR) are operating for power quality (PQ) improvement [2-3]. Among these devices DSTATCOM is preferred because of its features such as low power losses, generating few harmonics, ability of high regulatory, less cost, and compact size. For controlling of DSTATCOM various methods are used such as Synchronous Reference Frame (SRF) Theory, Instantaneous Reactive Power (IRP) Theory [4], and Instantaneous Symmetrical Component (ISC) Theory [5]. The performance of DSTATCOM depends on the reference currents generation. DSTATCOM is a VSI based custom device. For switching of VSI Hysteresis current controller [6-8] is used. Among the other PWM current controllers, Hysteresis controller gives the fast response, reduce peak current and shows better performance. PI controller is operated for regulating the DC link voltage [9-11]. For tuning of PI controller trial and error method is the simplest but it consume more time and the performance is also not good. Instead of Trial and error if soft computing techniques are used such as Ant colony Optimization, Genetic Algorithm (GA), Ziegler-Nichols technique and Particle Swarm Optimization (PSO) [12-15] technique, better results can be obtained. In this paper PSO which gives the best global gains for PI controller is applied for obtaining gains and DSTATCOM is simulated using MATLAB/SIMULINK software. 2. CONFIGURATION OF DSTATCOM DSTATCOM is a practice power device connected at PCC through interfacing inductor. DSTATCOM is used for injecting or absorbing the reactive power into system to stabilize the voltages in the system due to variation of the load. It is also used to inject the compensating currents into the system. I sa, Isb, and Isc are the source currents and Vsa, Vsb and Vsc are the source voltages of phase a, b, c, Ila, Ilb and Ilc are the load currents and compensating currents are symbolized as I fa, Ifb and Ifc. Non linear load is supplied with the system source voltage of 11kV, 50Hz. Transformer is used for step down the voltage from source to load in distribution system, and this non linear load develop harmonics in the system. In order to compensate these harmonics DSTATCOM is connected at the Point of Common Coupling (PCC) to inject the compensating currents into the system to make the system balance. DSTATCOM configuration consists of VSI, dc capacitor, and control circuit. PI controller is operated to maintain the dc capacitor voltage constant. SRF theory is used for controlling the DSTATCOM by generating the reference currents and then actual currents and reference currents are compared, the initiated error signal is given to the VSI for switching of IGBT’s [2]. DSTATCOM representation is shown in Fig .1.