With the increasing use of electrical equipment, discoms need to focus not only on the quantum of power supply, but also on its quality and reliability. Power quality may suffer due to harmonic distortions, dips and surges, and under/overvoltage, etc. Any deviation in voltage, current and frequency can result in failure or malfunction in the electricity network system. It is, therefore, crucial that such deviations are monitored and standards for power quality are specified. In India, the Central Electricity Authority (CEA) and the Central Electricity Regulatory Commission (CERC) have put in place regulations for power quality at the central level. Meanwhile, the state electricity regulatory commissions (SERCs) have specified regulations at the state level. Although various aspects of power quality are covered under the current regulations, there is no well established monitoring and implementation framework to ensure power quality in the country.
Power quality regulations and standards
The power quality regulations in India mainly include provisions for frequency and power factor. The common aspects covered under the various regulations include voltage (variation and unbalance), current (unbalance) and harmonics (total harmonic distortion). The power factor is largely maintained at similar levels across states through incentives and penalties in tariffs determined by the SERCs. In addition, reliability indicators such as the system average interruption frequency index, the system average interruption duration index and the consumer average interruption duration index are also taken into account under the regulations specified by the SERCs. Standardisation organisations such as the Institute of Electrical and Electronics Engineers (IEEE) and the International Electrotechnical Commission have taken measures to regulate the minimum power quality level that utilities have to provide to their consumers. Most states in India refer to the IEEE 519-1992 standards for harmonic limits.
Most of the states that have specified voltage harmonic limits do not have prescribed limits for current harmonics.
There are also inconsistencies in the standards prescribed for harmonics at the state level. Within a state too, there are instances of differences in the limit specified for harmonic distortions under various regulations. For extra high transmission voltage levels, certain states (such as Karnataka and Madhya Pradesh) have a harmonic level different from that specified in the central regulations. Further, the harmonic limits determined by the central authorities are higher than those recommended in the IEEE standards. Lastly, there is no clarity on the consequences of non-compliance.
The way forward
Various regulatory interventions are required to improve the approach to power quality in India. To begin with, it is crucial to ensure consistency in the central and state regulations and align the relevant parameters with internationally recognised norms. Further, key performance indicators such as interruption at the point of supply and neutral voltage variation need to be considered while evaluating the standards of performance of discoms. The regulators need to establish procedures for monitoring different aspects of power quality. The deployment of power quality monitoring instruments should be made mandatory at substations. The regulations should also introduce penalties to ensure compliance with the power quality norms.
Given the changing power scenario in the country, the existing power quality regulations and standards also need to evolve so as to improve the performance of the discoms and achieve customer satisfaction.
Based on inputs from a white paper on “Power Quality Regulations in India for the Forum of Indian Regulators” by Asia Power Quality Initiative