International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-6, Issue-3, Mar-2020] https://dx.doi.org/10.22161/ijaems.63.8 ISSN: 2454-1311 www.ijaems.com Page | 154 Stability Enhancement of Pleiku Power System using a Distribution Static Synchronous Compensator (D-STATCOM) Nguyen Thi Mi Sa Hochiminh City University of Technology and Education, Vietnam Abstract— This paper presents the simulation results of using a static synchronous compensator (D-STATCOM) based on voltage source converter (VSC) to enhance voltage stability and improve the stability of the actual Pleiku Power System. The PI controller based D-STATCOM is applied to stabilize and improve voltage waveforms at load buses in the studied power system under three-phase short circuit fault. Simulation results in a time domain are presented to show effectiveness of using the D-STATCOM for stability and improvement of voltage quality when small disturbances occur, and of enhancing voltage magnitude, mitigating voltage oscillation in transient conditions under a severe disturbance in the power system. Keywords— D-STATCOM, VSC, PI. I. INTRODUCTION In recent years, power engineers are increasingly concerned over the stability of the electrical power. Presently in modern industries, load equipment uses electronic controllers which are sensitive to poor voltage quality and will shut down if the supply voltage is and may mal-operate in other ways if harmonic distortion of the supply voltage is excessive. Many efforts have been taken by utilities to fulfill consumer requirement, some consumers require a level of power quality higher than the level provided by modern networks of electricity. It shows that some measures must be taken in order to achieve higher levels of power quality. The Facts devices and Custom power devices are introduced to electrical system to improve the power quality of the electrical power. DVR, STATCOM/D-STATCOM, ACTIVE FILTERs, UPFC, UPQC etc are some of the devices used to improve the power quality of the current and voltage. By the help of these devices we are able to reduce the problems related to power quality. Under this work, among the different custom power devices D-STATCOM has been used to improve the quality of power under different conditions. The general theory about the D-STATCOM operation and its main components is discussed in next part. D-STATCOM [1] is a voltage source converter (VSC) that is connected in shunt with the distribution system by means of a tie reactance connected to compensate the load current. In general, a coupling transformer is installed between the distribution system and the D-STATCOM for isolating the D-STATCOM from the distribution system. In addition, the device needs to be installed as close to the sensitive load as possible to maximize the compensating capability. Being a shunt connected device, the D- STATCOM mainly injects reactive power to the system. The role of D-STATCOM is specifically appreciated in case of a weak AC system [2]. Application of D-STATCOM in distribution systems has gained considerable attention. While [3] discusses the dynamic performance of a D-STATCOM coupled with an energy storage system (ESS) for improving the power quality of distribution systems, [4] presents a study about the influences of a D-STATCOM on the dynamic behavior of distribution networks. The performance of a D- STATCOM as a voltage controller or a power factor controller is analyzed in [4]. To provide this voltage support, a D-STATCOM is connected to the micro-grid in [5]. It is well known that a D-STATCOM can provide reactive power support in normal operation. However, it can release the energy stored in it dc capacitor during transients to provide ride through to facilitate load shedding. In [5], the effect of sudden power loss is investigated with and without the D- STATCOM connection. A representative example of D- STATCOM is given in [6]. The goal of this paper is to investigate the main impacts of D-STATCOM on the