Electrical Project on Unified power quality conditioner (UPQC). UPQC is one of the best custom power device used to compensate both source and load side problems. It consists of shunt and series converters connected back to back to a common dc link. A UPQC that combines the operations of DSTATCOM (Distribution Static Compensator) & DVR (Dynamic Voltage Regulator)
Different Power Quality Issues are
- Voltage sags - Happens when there is reduction in rms voltage( 10 and 90 percent of nominal voltage for one half cycle to one minute). Voltage Sag can be caused by short circuit, starting of electric motors or overload.
- Voltage Swells - Is a short term problem during which there is a reduction in the RMS voltage magnitude. Sometimes sags can adversly affect equipment performance. Sags can be caused by switching loads, voltage drop caused by long runs of wire, poor wiring and overloaded branch circuits.
- Voltage unbalance - Unbalanced voltages usually occur because of variations in the load. When the load on one or more of the phases is different than the others, unbalanced voltages will appear. This is caused by different impedance's, or type and value of loading on each phase.
- Flicker - In a weak distribution system, when heavy loads are periodically turned on and off, flicker occurs . If the distribution system’s short circuit capacity is not large enough, voltage fluctuations will occur. This can impact sensitive electronic equipment's very badly
- Reactive currents - Can cause overloading effects on the line, circuit breakers, transformers, relays and insulation's
- Current harmonics - Due to non linear electric loads, certain electric voltages and currents that appear on the electric power system.
Power Quality Solutions
- Tuned Filters - Filter contains a variable inductor which consists of main winding, auxiliary windings and switching circuitry along with each auxiliary winding. Auxiliary windings are arranged in such a way that, they act as inductive series with respect to the main winding. The switching circuitry is used to selectively connect the auxiliary windings in electrical series with the main winding, so allowing the inductance of the inductor to be varied.
Upcoming Solutions –Custom Power devices
- Shunt Active Filters
- Dynamic Voltage Restorer (DVR)
- Unified Power Quality Controller (UPQC)
Shunt Active Filter
An ideal shunt compensator can be considered as a voltage source, controlled in magnitude and phase angle, with the same frequency of the system to which it is connected. Compensates Reactive current and Harmonic current
UPQC can mitigate Voltage sag, swell and Unbalance. UPQC can supply VAR to load. UPQC isolates the load current harmonics from flowing to the utility. It maintains unity input power factor at all conditions. Fast Dynamic response.
Please go through the attached Electrical project Report for more info