Introduction
Power quality is an essential factor as far as performance of the electrical machines and equipment are concerned. Quality plays an integral role in ensuring reliability and satisfactory service by improving the transmission and distribution of electric power. In order to serve a huge section of the world with electrical power, quality is paramount in order to reduce losses during transmission and distribution. IEEE defines power quality as the deviation of current and voltage from the ideal to the actual realization. It factors in the concept of ensuring high standard powering and grounding of the electrical equipment for the purpose of high-efficiency performance.
The deterioration of power quality majorly depends on the presence of nonlinear loads in the electrical system as well as power electronic systems that are incorporated during both transmission and distribution of power. The mentioned type of load and power electronic equipment result in distortion of current and voltage waveforms. Distortion interferes with phase angle as well as power factor of the transmitted power.
In order to improve the quality of power, manufactures and designers concentrated on attempts to produce high-efficiency electrical machines and appliances. Total harmonic distortion and issue of reactive loads have been taken into consideration. Some of the important electrical issues that result due to poor power quality include power frequency disturbance, power factor and grounding. Several techniques have been developed to sort out those issues resulting in poor power quality (Chattopadhyay, Mitra, & Sengupta, 2011).
Power factor correction banks
Power factor in electrical aspect is defined as the ratio of real power to the apparent power. Electrical machines especially motors have coils leading to inductance. The inductance in machines results in reactive power in the electrical system. The increase in reactive power results in power deterioration due to the fact that it increases the amount of reactive power. When the reactive power increases, the active power reduces leading to more losses. Through transmission, distribution and consumption of power, increase in reactive power due to the presence of inductance reduces power quality. With the aim of reducing the power losses and improve the quality, capacitors banks have been designed to restore the required quality. Capacitor banks introduce the capacitance into the power system to cancel out the inductance. The introduction of capacitors results in the change of power factor. The recommended power factor that results in required quality of power is in the range of 0.75 to 0.95. Within this range, reactive power is reduced leading to less reactive power. The variation of inductance in the electrical power system should be accompanied with the continuous capacitance variation to ensure minimal power losses. The current technology has led to the development of automatic power factor correction banks (Schlabbach, Blume, & Stephanblome, 2011). The connection of the capacitors in the system is varied automatically in response to the amount of inductance in the electrical system. The coordination is based on the set point of the required power factor.
Power frequency disturbance: voltage sag and swells are known as the variation voltage. The voltage variation is caused by increased current and impedance imbalance in the electrical system. Variation of voltage results in power disturbance leading to power of poor quality. The introduction of new load into the power supply is one cause of power disturbance. It leads to malfunction of other machines connected to the power system. The rise of impedance due to new load introduced into the electrical system is also a cause of power disturbance. Fault due to short circuit can lead to power supply fluctuation compromising the quality of power. The current technology has led to the design and development of new equipment that can be used to improve the quality of electrical energy. The equipment include;
Voltage regulators; the voltage regulators are devices that output constant and stable power to the electrical appliances. The devices ensure no fluctuation of power that can compromise the quality of power delivered to the appliance in connection. The connection of other loads and even electric faults leads to power fluctuation but the supply of the appliances through voltage regulator is stable. The use of voltage regulators improves the efficiency of the electrical appliances hence improve the durability.
Variable speed drives; this is an electrical device that is used to control the speed of the motor by varying the voltage and frequency of the supplied power. Variable speed drive plays an integral role in ensuring stable power supply to other devices. It is noted that motors require high starting current and this leads to reduction of voltage causing power instability in the electrical system. In order to overcome the condition, variable speed drives are introduced into the system. The drive can be varied to avoid high current at the start of the motor. The motor is started at control speed to avoid more current withdrawal. When this device is used, the current variation the electrical system is avoided hence improvement in power quality.
Soft switching line conditioner; this is a device that adopts the technology of thyristor and filters (LC filters) to control the power supplied to the appliances. The device is connected in between the power supply and the electrical appliances. Soft switching line conditioner is manufactured with the technology is also used for high switching inverter. The device protects the appliances from the power variation hence increasing their lifespan and maintaining the efficiencies. Fault protection to the appliances is also incorporated in such device (Schlabbach, Blume, & Stephanblome, 2011).
Flywheels and Motor-Generator (M-G) Sets; flywheel is a device that is used to link motor and generator and store energy for a short duration. It uses electromechanical technology. The charge and discharge of flywheel is carried out through motor generator. The power from the grid is drawn by the motor generator and is supplied to the flywheel to charge it. In cases of voltage sags and swells, generator motor provides the required power. The rotation attained by flywheel is converted to DC power that is then supplied to appliances through inverters and filters.
Uninterrupted power supply devices; to avoid power fluctuation and blackout, uninterrupted power supply device is used. It involves the use of battery and inverter to form back up for the consumers. The electrical power from the grid is supplied to the inverter that supplies DC power to the battery. The power from the battery is supplied to the appliances via converters. Due to the fact battery is able to store energy in DC form, power interruption will not affect the devices (Chattopadhyay, Mitra, & Sengupta, 2011). It results in quality power by ensuring a constant supply of electrical with required specifications.
Conclusion
Power quality is essential in the current world. The current technology has helped to eradicate problems the crop in due to low-quality power. The electric power quality helps in reducing power losses hence reducing the cost of production.
References
Chattopadhyay, S., Mitra, M., & Sengupta, S. (2011). Electric power quality. Dordrecht: Springer.
Schlabbach, J., Blume, D., & Stephanblome, T. (2011). Voltage quality in electrical power systems. London: Institution of Electrical Engineers.
