02-11-2016, 03:09 PM
1463573592-1Introductionstatcom.docx (Size: 14.27 KB / Downloads: 4)
INTRODUCTION:
Modern power system is complex power network, where hundreds of generating loads and thousands of loads are interconnected through transmission or distribution networks. The main concern to the customer is to provide reliable and quality of power supply.
In this world there are three different categories of nations which are developed, developing and under developing. Peoples in these three nations, mostly everyone using advanced and hands on technologies for their everyday work progress in which major equipment’s or utilities are developed with the electronics and power electronics based technology. All the power electronic based utilities are very sensitivity in nature because of its switching condition; due to this most of the harmonics are generated. During unbalanced, sudden increase in load power quality issues like voltage distortions, sag/swell will arise due to this utility equipment’s may get damaged, so some external devices has to be used to compensate the issues. The voltage source inverter based dynamic voltage restorer is connected with three phase transmission line to compensate the variations in voltage like voltage sag/swell by injecting three phase voltage into the transmission line.
The magnitude and phase angles of the injected three-phase voltage can be varied, thereby allowing control of real power and reactive power exchanged between the DVR and the distribution system. The amount of real power and reactive power provided by the DVR depends on the type of voltage disturbance occurred due to load variations, the power requirements of the protected load and the direction and magnitude of the injected three phase voltage. The mitigation of the voltage sag/swell is mainly depends on device connected in series with the line and the energy storage to supply when DVR comes in to operation. DVR is compensating the voltage sag even for long duration very effectively, but it requires appropriate energy capacity. The magnitude and phase angle of injected three phase voltage are variables which result in variable real and reactive power exchange between the DVR and transmission line to supply the sensitive load or the distribution system network.
The injected three phase voltage of the DVR depends on the accuracy and dynamic behavior of the pulse width modulated (PWM) voltage synthesis scheme and control system used. This paper also presents an extensive analysis to develop suitable control schemes for voltage sag compensation and THD minimization. The general requirement of such control scheme is to obtain an ac waveform with low total harmonic distortion (THD) it can be minimized using STATCOM and good dynamic response against supply and load disturbance whether the DVR in IDVR system operates in voltage compensation control mode. Usually the control voltage of the DVR in mitigating voltage sag/swell is derived by comparing the supply voltage against a reference waveform. In this paper a shunt connected FACTS device called STATCOM in also used to minimize the THD generated due to electronic loads. STATCOM is used because of its simplicity, low cost, effective reactive power compensation. Reactive power compensation is mainly for the grid connected wind energy system. And also analyzing the common DC link energy storage capacity.