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APPLICATION OF D-STATCOM IN POWER SYSTEMS N. RAVI KIRAN ( 13881D5407 ) BYUNDER THE GUIDENCE OF Mr. B. RAMU M.TECH (Assistant Proff)

OBJECTIVE To exhibit high speed control of reactive power to provide voltage stabilization

To protect the utility distribution system from voltage dip.

To provide leading or lagging reactive power during transient conditions.

INTRODUCTION D-STATCOM (Distribution Static Compensator) is a shunt device which is generally used to solve power quality problems in distribution systems. D-STATCOM is a shunt device used in correcting power factor, maintaining constant distribution voltage and mitigating harmonics in a distribution network. D-STATCOM is used for Grid Connected Power System, for Voltage Fluctuation, for Wind Power Smoothening and Hydrogen Generation etc. This paper D-STATCOM is used in Electrical Power System for Power Quality Improvement. Relevant solutions which applied nowadays to improve power quality of electric network according to the five aspects of power quality- harmonics, fluctuation and flick of voltage, Voltage deviation, unbalance of 3- phase voltage and current frequency deviation.STRUCTURE OF D-STATCOM

It is comprised of three parts.

Voltage Source Converter Step-up coupling transformer ControllerDC storage element

VOLTAGE SOURCE CONVERTER (VSC) A VSC is a power electronic device, which can generate a sinusoidal voltage with any required magnitude, frequency and phase angle. The converter is normally based on some kind of energy storage, which supply the converter with a DC voltage.

STEP -UP COUPLING TRANSFORMER The output voltages of VSC are in phase and coupled with the ac system through the reactance of the coupling transformer. CONTROLLER The aim of control scheme is to maintain constant voltage magnitude at the point where a non-linear load is connected, under system disturbances. The controller input is an error signal and such error is processed by a PI controller and output is angle .

BLOCK DIAGRAM REPRESENTATION OF D-STATCOM

PRINCIPLE OF OPERATION

The D-STATCOM is a three phase and shunt connected power electronics based reactive power Compensation equipment, which generates and /or absorbs the reactive power whose output can be varied so as to maintain control of specific parameters of the electric power system.COMPENSATION SCHEMES General compensation scheme

Reactive power compensation scheme

GENERAL COMPENSATION SCHEME In this D-STATCOM, they can exchange both reactive power and real power with the AC system.

They can be control independently of each other and any combination of real power generation/absorption or With VAR generation/absorption is possible. a) shunt connected synchronous voltage source .

Reactive power compensation scheme In this scheme the power exchange between the DSTATCOM and the AC system can only be reactive.

a) synchronous voltage source operated as the static condenser

APPLICATIONS OF DSTATCOM D STATCOM is used in non conventional power generation system for improve the quality of power

In order to improve the survivability of a navy ship in battle condition, DSTATCOM or Distribution Static Compensator can be used, which reduces the impact of pulsed loads on the bus voltage and thus keeps the bus voltage at desired level.

DSTATCOM is a voltage-source inverter (VSI) based shunt device generally used in distribution system to improve power quality. The main advantage of DSTATCOM is that, it has a very sophisticated power electronics based control which can efficiently regulate the current injection into the distribution bus.

The second advantage is that, it has multifarious applications, e.g. a). Cancelling the effect of poor load power factor,

b). Suppressing the effect of harmonic content in load currents,

c). Regulating the voltage of distribution bus against sag/swell etc., compensating the reactive power requirement of the load and so on.

CONCLUSION This paper has presented the power quality problem such as voltage dips, consequences, and mitigation techniques of custom power electronic device D-STATCOM. A new PWM-based control scheme has been implemented to control the electronic valves in VSC that are used in the D-STATCOM. It was also observed that the capacity for power compensation and voltage regulation of D-STATCOM depends on the rating of the dc storage device.

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