Q16Power Quality and FACTS

Impact on System Efficiency

Poor power quality directly reduces the efficiency of both the supply network and connected equipment. Harmonic currents cause additional I2R losses in conductors, transformers, and cables due to skin effect and increased RMS current, while eddy current and hysteresis losses rise in transformer cores. Reactive power flow caused by poor power factor increases line current for the same real power delivered, further raising transmission and distribution losses. Voltage imbalance causes negative-sequence currents in induction motors, producing additional heating and reduced motor efficiency.

Impact on Reliability

Voltage sags, swells, and transients can cause nuisance tripping of adjustable-speed drives, PLCs, and contactor-controlled equipment, leading to unplanned production stoppages. Harmonic resonance between line inductance and power factor correction capacitor banks can cause capacitor failure or fuse blowing, reducing overall system reliability. Repeated overheating from harmonics and imbalance accelerates insulation aging in transformers, cables, and motors, shortening equipment life and increasing failure rates and unplanned outages.

Impact on Operation

Protective relays and metering equipment that rely on accurate voltage/current waveforms may mis-operate under harmonic distortion or notching, causing false tripping or failure to trip when needed. In sensitive electronic and computing equipment, sags and transients can cause data loss, memory corruption, and processor resets. In industrial processes, momentary interruptions can cause loss of entire batches, requiring costly restart procedures. Overall, poor power quality translates into higher operating costs, reduced plant availability, increased maintenance expenditure, and financial losses from lost production and equipment damage.

• Efficiency loss: increased I2R and core losses, reduced motor efficiency
• Reliability loss: nuisance tripping, capacitor/fuse failure, accelerated insulation aging
• Operational impact: relay mis-operation, data loss, production downtime, financial loss