With power supply shortages becoming a thing of the past, the government is now focusing on providing quality power to consumers. Considerable generation capacity addition and transmission and distribution (T&D) network expansion over the last decade has played a key role in bridging the electricity demand-supply deficit in the country. Between 2012 and 2022, the country’s installed capacity and transmission line length have doubled to reach 409 GW and 4,463,758 circuit km respectively (as of November 2022). The distribution system has seen improvements too, with aggregate technical and commercial losses reducing from about 27 per cent to 17 per cent in the same period. As a result, the peak power demand-supply gap has reduced from over 10 per cent in 2011-12 to 1.2 per cent in 2021-22. The national average availability of power stood at around 20.89 hours in rural areas and 23.52 hours in urban areas as of 2021, as per government estimates. This is a significant increase over the average power availability of 12 hours in rural areas in 2015-16.
The next step is 24×7 quality power supply at affordable prices to all consumers. However, ensuring power quality (PQ) is challenging owing to the growing stress on the electricity grid with the increasing penetration of variable renewable generation, proliferation of electric vehicles (EVs) and charging facilities, as well as the rise in decentralised generation. This, coupled with underinvestment by distribution utilities in network upgradation and strengthening, affects the quality of power supply, which can lead to performance degradation and premature failure of electrical equipment as well as higher systemic and financial losses. Further, the quality of power supply is hampered by the effect of natural calamities on grid infrastructure and the increase in non-linear loads on the consumer side.
Technically speaking, an electrical system’s PQ relates to both the consistency of supply and the degree of distortion in the pure supply waveform. An ideal power supply has a sinusoidal waveform with no noise, is never interrupted, and operates consistently within voltage and frequency constraints. Low power factor, harmonic disturbances, load imbalances, and voltage changes are some of the most frequent signs of poor PQ.
Power factor, frequency, reliability (number of interruptions), and supply restoration (length of disruptions) are a few of the important power quality criteria. Supply interruptions, harmonic distortions, transients and imbalances in voltage and current, flickers, voltage sags and swells, frequency excursions, as well as issues with reactive power are some of the prevailing PQ issues. These disruptions each have unique causes and results. Customers connected to the same supply network may be impacted by upstream or downstream propagation of PQ faults.
The non-linearity of customer loads is the root cause of harmonics, one of the growing PQ problems. Harmonic voltage distortion is caused by harmonic currents that flow upstream from non-linear loads through the impedance of cables and transformers. Additionally, harmonic currents cause electrical cables to heat up more than usual, which causes premature ageing, overstressed electrical insulation, unintentional tripping of safety features, overheated conductors, etc. Further, brownouts, voltage problems and harmonics are just a few of the PQ issues that are becoming more prevalent as EV charging infrastructure expands. The distribution system is likely to witness higher incidences of harmonic fluctuations with the growing installation of EV chargers.
It must be noted that both utilities and customers are affected by power supply quality and reliability issues. While utilities suffer from additional expenses due to frequent maintenance, repair of damaged equipment, loss of revenue, etc., customers have to deal with increased repairing costs of consumer electronics and unscheduled power cuts. Also, PQ issues have varying degrees of significance for different stakeholders – consumers, utilities and equipment makers. A one-minute voltage sag, for example, could not be tolerable in a city like Delhi or Mumbai, but an hour-long outage in a village might be a regular thing. Within consumers too, different categories respond in different ways to PQ issues – for instance, PQ interruption for commercial and industrial consumers might translate into revenue losses, which would not be the case for domestic consumers.
Policy and regulatory landscape
At the central level, the Ministry of Power (MoP) notified the Electricity (Rights of Consumers) Rules, 2020 in December 2020 under Section 176 of the Electricity Act, 2003. These rules aim to empower consumers and emphasise that power systems exist to serve consumers and consumers have rights to get reliable services and quality electricity. The rules seek to ensure that new electricity connections, refunds and other services are provided in a time-bound manner and wilful disregard of consumer rights is penalised.
The government also recognises that the sub-transmission system plays an important role in quality power supply to consumers on a 24×7 basis. However, the sub-transmission system is riddled with high technical losses and outages. The MoP had, therefore, constituted a committee to suggest measures for reducing losses and ensuring reliability and efficiency in the sub-transmission system. The committee noted that losses at the 33 kV level stand at about 4.8 per cent, while losses at the 66 kV-220 kV levels are only 1.72-2.39 per cent. Further, the annual system availability at 33 kV is about 96.3 per cent while the same at the 66 kV-220 kV levels is 98.5-99.4 per cent. The committee, therefore, recommended bringing the 33 kV system, which is currently owned and operated by distribution utilities, under the state transmission utilities (STUs). Based on the committee’s recommendations, the MoP declared the 33 kV system a transmission element and the same was communicated to the states/union territories via a communication dated September 1, 2021, to begin the process of handover of these assets to STUs.
At the state level, PQ standards are typically covered under various regulations, standards of performance regulations and the grid code notified by the state electricity regulatory commissions (SERCs). These regulations prescribe limits for various quality- and reliability-related parameters such as the time duration for utilities to inform customers about scheduled outages, the amount of compensation to be paid by utilities for unscheduled outages, and limits for voltage variations, limits for indices such as the System Average Interruption Duration Index and the System Average Interruption Frequency Index. However, these regulations are not uniform across the states and do not provide a comprehensive mechanism for monitoring power quality and incentivising compliance, among other things. There are variations in similar power quality parameters specified by different SERCs. Also, the penalties prescribed for non-compliance are low and there is a general lack of information pertaining to the amount of compensation actually paid by utilities to customers on account of deficient services. Further, only a few states have initiated the process to notify PQ regulations. For instance, in 2019, the Kerala State Electricity Regulatory Commission notified the draft (Power Quality for Distribution System) Regulations, 2019. In December 2020, the Assam Electricity Regulatory Commission (AERC) notified the draft AERC (Power Quality for Distribution System) Regulations, 2020.
Consumer services rating of discoms
In April 2022, the power minister launched the first ever Consumer Services Rating of Discoms for 2020-21. The study was carried out by REC Limited on behalf of the MoP to develop a minimum set of parameters related to quality and reliability of electricity supply and consumer service. REC has developed discoms ratings across four key dimensions of operational reliability (hours of supply, interruption index and DT failure rate); connection and other services; metering, billing, collection-linked services; and fault rectification and grievance redressal. In the first ratings exercise, 60 discoms were covered and graded from A+ to D depending on their performance. The two Delhi discoms, BSES Rajdhani Power Limited (BRPL) and BSES Yamuna Power Limited (BYPL), ranked in the topmost category, earning an A+ grade. Five discoms – Tata Power Delhi Distribution Limited (TPDDL), Andhra Pradesh Southern Power Distribution Company Limited (APSPDCL), Andhra Pradesh Central Power Distribution Company Limited (APCPDCL), Telangana State Southern Power Distribution Company Limited (TSSPDCL) and Kanpur Electricity Supply Company – follow next with A grade. Grades B+, B, C+, C and D have 9, 15, 17, 5 and 7 discoms respectively.
The national average hours of supply (HoS) stand at 23.52 hours in urban areas and at 20.89 hours in rural areas. Several discoms are providing 24 hours of electricity, higher than the national average, such as APCPDCL, the Puducherry Electricity Department, Adani Electricity Mumbai Limited (AEML) and TPDDL in urban areas. Similarly, Uttar Gujarat Vij Company Limited (UGVCL), Dakshin Gujarat Vij Company Limited (DGVCL), Madhya Gujarat Vij Company Limited (MGVCL), KSEB Limited, APSPDCL and Andhra Pradesh Eastern Power Distribution Company Limited are providing 23.5 HoS in rural areas, which is higher than the national average. The DT average failure rate stands at 6.93 per cent with BYPL, BRPL, AEML, Tata Power Company Limited, and BEST Undertaking recording less than 1 per cent rate while Jammu Power Distribution Corporation Limited and Kashmir Power Distribution Corporation Limited are at the higher end with a DT failure rate of over 26 per cent.
The way forward
With rising consumer awareness and government initiatives in favour of reliable and quality electricity supply, addressing PQ issues will gain more prominence in the years to come. Further, as electrification of transportation accelerates, unwarranted peaks in power consumption and consequent PQ issues such as increased power flow in cables, transformer overloading, voltage drops, voltage imbalance and harmonic contamination are likely to increase. T&D utilities, therefore, need to invest in network upgradation and power conditioning equipment to ensure smooth electricity supply to consumers in the coming years.