www.ijcrt.org © 2018 IJCRT | Volume 6, Issue 2 April 2018 | ISSN: 2320-2882 IJCRT1892413 International Journal of Creative Research Thoughts (IJCRT) www.ijcrt.org 505 VOLTAGE STABILITY IMPROVEMENT USING STATCOM WITH SUPER CAPACITOR Pranjali R. Nirvikar, Prof. Pratik Ghutke, Dr. Hari Kumar Naidu M-Tech scholar, Assistant Professor, HoD Electrical Engg TGPCET Mohgaon, Nagpur ________________________________________________________________________________________________________ Abstract: To maintain voltage stability of a power system, STATCOM is better solution which can provide the required amount of reactive power under various power system disturbances. This paper proposes a solution to enhance the performance of the STATCOM by adding supercapacitor which is a energy storage device to DC link of the conventional STATCOM. With the fast charge or discharge characteristics of the supercapacitor, the enhanced STATCOM can absorb and eject real and reactive power to the AC Power Grid instantaneously. In addition, this paper also proposes that the enhanced STATCOM can be applied to reduce instability and tripping due to the Rate of Change of Frequency (RCF) protection devices caused by large load impact. The amount of the energy required for the enhanced STATCOM to maintain the stability of the system is also discussed. In this paper, Static Synchronous Compensator (STATCOM) with energy storage system for wind power application has been implemented. This device was proposed to improve voltage stability and power transmission by offering reactive as well as active power compensation. The energy storage system used for this application was designed and simulation results were discussed. For active compensation for wind power, a bank of Super Capacitors for Energy Storage System(SCESS) was used. The super capacitor bank size was designed and used, based upon the short term fluctuations in wind power. These fluctuations are results of constructional factors of the turbines, variation and turbulence in the wind. A super capacitor bank was interface with the DC bus of the STATCOM with the normal half bridge boost converter, to convert voltage level of the bank while maintaining a constant DC bus voltage for good switching operation in the VSC. Keywords: STATCOM, Supercapacitor, Voltage profile, power losses. ________________________________________________________________________________________________________ I. INTRODUCTION STATCOM with supercapacitor which was demonstrated the change of dynamic and transient dependability and transmission capacity of the power system. Energy storage type STATCOM controls both active and reactive power absorption/injection to the power system. In a new structure of STATCOM with Super capacitors for improved power system dependability was designed to improve the voltage and system stability. For many cases in AC Power Systems disturbance during transient conditions, the lack of real power support from system compensators may lead to the failure due to low stability margins. A STATCOM with the ability to support both reactive and real power dynamically can provide significant improvement to the security of AC Power Systems, even if the real power is only supported for a short period of time. The main objectives of this paper are summarized as below: 1) To investigate the use of the STATCOM with energy storage for improving the stability within the system. 2) To investigate the Super Capacitor Energy Storage System (SCESS) applied for enhancing the performance of the conventional STATCOM. 3) To demonstrate the benefits of an AC Power System using the enhanced STATCOM with SCESS. A STATCOM is a reactive power compensator that exhibits a good dynamic response with a wide control of bandwidth and the capability of providing higher currents at low voltage levels. It is also desirable to use a STATCOM due to the possibility of working with decoupled control of the DC-link voltage and the reactive current. To compensate the voltage drop which is occurring across the AC transmission lines, lines which are compensated using shunt connected capacitors. Voltage compensation across AC transmission lines is one of the most notable advantages of STATCOM which replaces all the previous methods. The STATCOM is delivering the adequate amount of reactive power for dynamic voltage compensation. For this dynamic compensation STATCOM is controlling its three phase amplitude and phase angle on AC side. STATCOM acts as either inductor or capacitor while absorbing or injecting reactive power. STATCOM acts as an inductor while current flowing from AC side to capacitor and acts as capacitor while current flowing from capacitor to AC side. A capacitor with high capacity is used in STATCOM to deliver the adequate amount of DC power to the voltage source converter. Small signal transient stability and voltage stability of the system is achieved during Power System operations. However, one of the main drawbacks is the low energy density on the DC link capacitor installed in the STATCOM; this limits the reactive and active power capability of the STATCOM. An improved version of the STATCOM is called the STATCOM + ES (Energy Storage). This variant includes a storage device, usually batteries, Supercapacitors etc. The storage device provides more capabilities to the STATCOM, such as power oscillation damping or mitigation of phase-jump-related disturbances. Moreover, the STATCOM + ES can be used for reactive compensation when Low Voltage Ride Through system (LVRT) is implemented. II. DESIGN CONSIDERATIONS FOR STATCOM PLUS SCESS As the inverter and the DC-DC converter used in this paper are designed for utilizing the supercapacitors energy, the supercapacitor terminal voltage (Vsc) is then considered as the dominant rating that further defines the other voltage limitations. In order to make the use of the supercapacitor for the STATCOM, the bi-directional DC-DC converter is placed in between the