PRESENTED BY
THUSHARA.K.P

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POWER QUALITY ENHANCEMENT BY COMPENSATING CUSTOM POWER DEVICES
INTRODUCTION
 The term power quality refers to maintaining a sinusoidal waveform of bus voltage at rated voltage and frequency.
 Over the last 20 years the number of PQ problems are experienced in industrial and commercial sites are increased dramatically.
 The waveform of electric power at generation stage is purely sinusoidal and free from any distortions. There are many devices the distort the waveform that propagate all over the electrical network.
TYPES OF DISTURBANCES
 SHORT DURATION
VOLTAGE VARIATIONS
 LONG DURATION VOLTAGE
 TRANSIENTS
 VOLTAGE IMBALANCE
 WAVEFORM DISTORTIONS
 VOLTAGE FLUCTUATIONS
 POWER FREQUENCY
VARIATIONS
PASSIVE FILTER
 Passive filters are used to provide a low impedance path for harmonic currents so
that they flow in the filter and not the supply
 The filter may be designed for a single harmonic or for a broad band depending on requirements.
DRAW BACKS
 Passive filter is designed only to particular harmonic frequencies. That is for fixed compensation.
 In some installation harmonic content is less predictable.
 They are prone to resonances.
custom power specification
 No power interruption.
 Tight Voltage regulation including short duration sags or swells .
 Low harmonic Voltages .
 Acceptance of fluctuating and non linear loads without effect on terminal voltage.
custom power devices
 These are power electronics controllers that are used for power quality improvement.
 2 types
 Network reconfiguration type.
 Compensating type.
Network reconfiguration type
 These devices changes the configuration of power system network for power quality enhancement.
 3 Types
 SSCL (Solid State Current Limiter)
 SSCB (Solid State Circuit Breaker)
 SSTS (Solid State Transfer Switch)
 Compensating type cpd
 Main functions
 Active filtering
 Load balancing
 Power factor correction
 Voltage regulation
Classification
 DSTATCOM (Distribution Static compensator)
 DVR (Dynamic voltage restorer)
 UPQC( Unified power quality conditioner )
DSTATCOM
 VSC
 Dc energy storage device
 Coupling transformer
PRINCIPLE OF OPERATION
 The D-STATCOM is a shunt connected power electronics based reactive power compensation equipment.
 The D-STATCOM provides operating Characteristics similar to a rotating Synchronous compensator without the mechanical inertia.
 The D-STATCOM employs solid state power switching devices and provides rapid controllability of the three phase voltages, both in magnitude and phase angle.
 The D-STATCOM employs an inverter to convert the DC page link voltage Vdc on the capacitor to a voltage source of adjustable magnitude and phase. Therefore the D-STATCOM can be treated as a voltage controlled source.