Custom Power Devices and the Benefits of their Application

CUSTOM POWER DEVICES

Initially for the betterment of power quality FACTS devices such as STATCOM ( inactive synchronal compensator ) , SSSC ( inactive synchronal series compensator ) , IPFC ( interline power flow accountant ) , and UPFC ( incorporate power flow accountant ) etc are introduced. These FACTS devices are planned for the transmittal system. However today more concentration is on the distribution system for the betterment of power quality, these devices are customized and known as usage power devices.

In 1995 N.G. Hingorani introduced the thought of custom power as an enlargement of FACTS impression to distribution system. The chief aim is to better power quality and enhance dependability of power supply. The construct of FACTS was besides proposed by Hingorani in 1988. The word `custom power ‘ illustrates the value added power that electric public-service corporations will offer their clients. The value add-on will supply the benefits of high power electronic accountants to distribution systems, on the supply terminal of industrial, commercial clients and industrial Parkss. The footings of usage power devices ( CPD ) are complementary to the entity terminal usage equipment at low electromotive forces ( such as UPS ( Uninterruptible Power Supply or standby generators ) .

Need OF CUSTOM POWER DEVICES

At present power quality is considered as one of the major concern. Distribution system is placed at the terminal of the power system and it is straight connected to the client, so dependability the power system chiefly depends on the distribution system. It has become important, chiefly with the debut of complicated devices, whose concert is highly sensitive to the quality of power supply. Power quality job is an incident manifested as an irregular electromotive force, current or frequence that effect in the failure of terminal usage setup. Any failure in the electrical distribution system will impact about 90 % of the mean client break. Since the customer’s demand for the dependability of power supply is lifting twenty-four hours by twenty-four hours, hence dependability of the distribution system has to be increased. Ideally, power distribution system should supply their client with a uninterrupted flow of energy at even sinusoidal electromotive force at the contracted magnitude degree and frequence. But, in pattern, peculiarly in the distribution system, incorporate several nonlinear tonss, which well affect the quality of power supplies. Due to the consequence of nonlinear tonss, the pureness of the supply wave form is lost. This may take to several power quality jobs. Although power perturbations will originate on all electrical system, the sensitiveness of today’s complicated electronic devices will do them more inclined to the quality of power supplies.

To work out this job, Custom power devices are used. One of those devices is Distribution Static Synchronous compensator ( DSTATCOM ) , which is the most efficient and effectual modern usage power device used in power distribution webs.

Categorization OF CUSTOM POWER DEVICES

Custom power devices are classified based on their power electronic accountants, which can be either of the web reconfiguration type or of the compensating type. The web reconfiguration devices besides called switchgear include the solid province and or inactive versions or current modification, current breakage and current transferring constituents. The counterbalancing type usage power devices either counterbalance a burden ( e.g. rectify its power factor, instability ) or better the quality of the supply electromotive force ( e.g. extinguish its harmonics ) . Custom power devices are classified as fallows

Network reconfiguration type of usage power devices include

• SSTS ( Solid province transportation switch )
• SSCL ( Solid province current clipper ) and,
• SSB ( Solid province ledgeman )

Compensation type of usage power devices include

• DVR ( Dynamic Voltage Restorer )
• DSTATCOM ( Distribution Static Synchronous compensator )
• UPQC ( Unified Power Quality Conditioner ) .

Distribution STATCOM ( DSTATCOM )

The distribution STATCOM is indistinguishable to a transmittal STATCOM which uses a VSC of the needed evaluation inside it. Though, the VSC employed in a DSTATCOM is a Type 1 convertor with PWM control above the magnitude of the injected AC electromotive force to prolong a changeless DC electromotive force across the capacitance. Rapid power semiconducting material devices like IGBT or IGCT are employed alternatively of GTO. The fast shift capableness given by IGBT ( or IGCT ) switches allow the usage of more complicated control methods to supply maps of active filtering ( by shooting harmonic currents ) , equilibrating ( by shooting negative sequence current ) and flicker relief. A DSTATCOM can be considered as a variable current beginning resolute by the control maps. To heighten the dynamic evaluation within the capacitive scope, a fixed capacitor/filter is connected in analogue with DSTATCOM. By affecting an energy storage device like SMES ( Superconducting Magnetic Energy Storage ) on the DC side during a DC/DC power conditioner, it is possible to interchange existent power with the system for a limited clip ( during fleeting breaks or big electromotive force droop ) .

Dynamic electromotive force refinisher / regulator ( DVR )

The Dynamic Voltage Restorer ( DVR ) is a series connected device indistinguishable to a SSSC. The chief purpose of a DVR is to take electromotive force droops perceived by sensitive tonss such as semiconducting material fabrication works or IT industry. Therefore the DVR that are installed till now have modular with evaluations of 2 MVA for each faculty. It has been designed to equilibrate the three stage electromotive force sags about 35 % if the continuance clip is less than half a 2nd. Typically the storage of energy in capacitance will lie between 0.2 to 0.4 MJ per MW of burden supplied. A DVR is connected in series along with the feeder by agencies of a transformer. The low electromotive force twist is associated to the convertor. The chief intent of a DVR is to command the electromotive force at the burden coach ; it will be in standby manner for the bulk of the clip through which the convertor is bypassed. The DVR injects a series electromotive force of the necessary magnitude merely when droop is identified. It is indispensable to protect a DVR from the mistake currents ( as in the instance of a SSSC ) . A DVR with IGBT/IGCT devices will be able to pull off to move as a series active filter so as to divide the burden from electromotive force harmonics on the beginning side. It is besides executable to command the electromotive force on the load side with the injection of negative and/or zero sequence electromotive forces in add-on to harmonic electromotive forces.

UNIFIED POWER QUALITY CONDITIONER ( UPQC )

Unified power quality conditioners are feasible compensation devices and are used to verify that the power delivered will fulfill all necessary criterions and specifications at the installing point.

The ideal UPQC can be identified as the combination of a electromotive force beginning convertor ( shooting shunt current ) and a common DC nexus ( connected to a DC capacitance ) .UPQC consist of combined series active power filter that regulate electromotive force harmonics of the power supply, and shunt active power filter that regulate harmonic currents of a nonlinear burden. Due to double functionality, UPQC is considered as one of the most appropriate devices that can work out the jobs of both consumers every bit good as of public-service corporation. Hence UPQC will assist to heighten electromotive force profile of power distribution system.

Benefits WITH THE APPLICATION OF CUSTOM POWER DEVICES

The usage power devices like DVR, DSTATCOM and UPQC etc, are employed to heighten the dependability of the distribution system by giving electromotive force support at the critical coachs in the system ( with series connected accountants ) and to command the power flow in the critical lines ( with shunt connected accountants ) . Both power flow and electromotive force are regulated by the combined series and shunt accountants known as UPQC.

As the power electronic control is comparatively fast, this allows ordinance under both steady province and dynamic conditions as compared to other accountants when the system is caused to perturbations. The benefits due to custom power devices are listed below.

1. They assist to outdo possible system operation by diminishing power losingss and heightening electromotive force profile.
2. The power flow in critical lines can be improved as the operating borders can be decreased due to fast controllability.
3. The power transporting ability of lines can be raised to values up to the thermic bounds ( imposed by current transporting ability of the music directors ) .
4. The transeunt stableness bound is improved hence bettering dynamic security of the system and diminishing the incidence of blackouts affected by cascading outages.
5. The steady province or little signal stableness country can be improved by supplying subsidiary stabilising accountants to muffle low frequence oscillations.
6. FACTS accountants such as TCSC can react to the job of Sub synchronal Resonance ( SSR ) experienced by agencies of fixed series capacitances connected in lines to take power from thermic power Stationss ( with turbo generators ) .
7. The job of electromotive force fluctuation and moral force over electromotive forces can be overcome by these accountants.