De Mystifying PQ: Interrelation with Power Supply Reliability, AT&C Losses, Energy Efficiency

Published On: Aug 31, 2016

The Indian electricity network is undergoing considerable change that is brought about by new technological advancement and the desire to make it smarter and more efficient. In today’s scenario, the key strategies for Power Distribution System reforms are ensuring Reliability of Supply, reducing AT&C losses and thereby leading to improving Energy Efficiency

While distribution utility professionals focus on implementing the aforementioned strategies however at times the importance of Power Quality and its interrelationships with these ultimate objectives is not given due consideration. This blog focuses on helping Indian Utility professionals demystify the facts of PQ and considering PQ, since it is critical to achieve the desired results for distribution utilities. 

At first, let us attempt to understand the key strategic areas of the distribution system/network reforms and why they are important to the extent that they attract almost the entire focus of distribution utility professionals.


A major concern for Indian electrical power system is maintaining ‘Reliable power supply’. Reliability of supply implies that power is made available to the customer in right manner and without unplanned outage or interruptions disturbing normal life. Reliability and quality of supply were rarely considered as issues in the past and hence a little or no attention was paid towards it. However, Modern economies are highly dependent on reliable and secure electricity services. In recent times the end customer has become more demanding and conscious about interruption free supply. Shortage of reliable supply impacts their normal life, thereby impacting economic and social growth.

In India, in accordance to world standards and law “Standards of Performance” is driven through State Electricity Regulatory Commissions and CEA. The reliability of power supply is captured through reliability indices like Customer Average Interruption Duration Index (CAIDI), System Average Interruption Frequency Index (SAIFI) and System Average Interruption Duration Index (SAIDI). Hence, monitoring and maintenance of reliable supply has been an important parameter to comply with in the minds of the management of distribution utilities. In India there are approximately 4 Million Distribution Transformers with capacity in excess of 3 lakhs (0.3 Millions) MVA in the power distribution network. The failure rate for DTs is 15-20% in public sector utilities, which leads to the failure of about 6 to 8 Lakhs (0.6 to 0.8 Millions) DT each year and adds huge financial loss to the utilities. Such high failure rates of Distribution Transformer (DT) – which form a critical piece of the distribution network reduces quality and reliability of supplied power. Failure of other network equipment is also possible thus leading to further impact of reliability of power supply.


Power Distribution Utilities in India are facing critical challenge of loss reduction so as to improve their financial performance and operate viably. Public Distribution Companies are facing huge burden of losses (~Rs. 2.4 lakh Cr. (Rs. 2400 billion)) and high average AT&C losses (~28%). Of this, the standard technical loss component is around 17% in India, while remaining constitutes un-metered supply, pilferage, etc.

Figure 1 shows approx. state wise AT&C loss (in %). It can be seen that most states has high cumulative AT&C losses. This loss has created an inefficient distribution systemcontributing to poor quality and reliability of power supply to consumers.
Loss reduction is core to the utilities and is being driven by targets set by regulation. Distribution companies are exploring and investing in all areas including network improvement, IT and business process improvement to meet their loss reduction targets.


Energy Efficiency emerged as a key policy priority in India’s energy sector since the enactment of Energy Conservation Act, 2001. Subsequently, Bureau of Energy Efficiency (BEE) set up by Government of India, is assisting in developing strategies and policies to reduce the energy intensity of the Indian economy. The government estimates that the energy efficiency market in India has an investment potential of USD $10 billion and that improving energy efficiency could save up to 184 billion kilowatt-hours (kWh) of generated electricity.
Distribution Transformer is one of the key equipment of power distribution network. Efficiency of the Distribution Transformers in various Indian Power Distribution utilities is very poor. Poor efficiency increases losses and reduces the quality and reliability of power supplied. Various State Regulatory bodies have given directives to improve the efficiency of the DTs to improve the overall efficiency of power distribution network. Implementing/Adopting Energy Efficiency measures decreases the overall energy demand and also peak demand, leading to higher reliability of supply. However, many devices that improve power reliability and quality – such as an inverter, a storage device, an Uninterruptable Power Supply (UPS), or a Dynamic Voltage Restorer (DVR) have possible negative impact on energy efficiency. Poor EE also affects the environment and the profitability of the utility consequently Indian economy.


Now, that we have seen the strategic areas individually, it would be interesting to note that these are interrelated not only between themselves but also with Power Quality. Below causal loop diagram shows the relationships between these and various other key elements in the power distribution system.

For e.g. it can be seen from above diagram that investing in ‘Network Improvement’ improves Power Quality, Reliability of Supply (via other elements in the system), which in turn will reduce technical losses and improveenergy efficiency. 

Reliability and quality of the electrical power remains the major concerns. There is a need to understand that improving PQ is nothing but ensuring continuity of supply. PQ can be key differentiator for tomorrow’s utility business model that is fast changing and it is no more about 24X7 supply alone.


Maharashtra State Electricity Distribution Company Limited (MSEDCL) is the leading power distribution utility in India, having an installed capacity of more than 23000 MW, distribution losses 16% and AT&C losses 18.36%. It supplies electricity to nearly 1.93 Cr. (19.3 Million) categories of consumers (as of 2012).

It can be observed from above snapshot of the company’s infra plans (i.e. capital works) aimed to reduce distribution losses, improve network reliability and to a certain extent improve Power Quality through Power Factor improvement. It is critical to note that PQ improvements although limited in this case are to be considered while making larger infrastructural changes in the distribution networks from the point of view of reliability of supply and loss reduction. Apart from only capacitor bank, various technological improvements like use of rightly located load Centre oriented

substations, use of DTs with right load balancing, use of OLTC for voltage profile improvement, use of filters (reactors) at right locations to avoid supply of distorted waveforms to consumers at large, use of means to ‘measuring for managing’ are few components, use of auto reclosures / sectionaliser / online capacitor, automatic fault location detector, undergrounding at high load density locations etc. should be considered for PQ improvement plans.


In today’s rapidly expanding and evolving electrical power system environment, utilities must manage electrical grid assets effectively and efficiently. Properly managed assets will significantly reduce operational costs; improve service levels and financial controls. With Smart Grids coming into the picture, the future electrical system designs will focus more on reliability, sustainability and energy efficiency considerations. 

While a Utility’s main focus remains on achieving improved customer service through the above key points, it must start considering Power Quality as one of the important aspect in the utility’s Capex and Opex plans.Power Quality is not different from the identified strategies for Utilities. In fact, it is interrelated with and further facilitates the success of supply reliability, loss reduction and energy efficiency for utilities.


  1. Central Electricity Authority (CEA) – RELIABILITY OF POWER SUPPLY
  2. PHD Chamber and Arthur D. Little – Restructuring Debts of Discoms’ for Sustainable Power Growth
  3. By Hans De Keulenaer – Does efficiency come at the expense of reliability?
  4. Mahadiscom Infra plans
  5. SheoliPargal and Sudeshna Ghosh Banerjee – More Power to India – The Challenge of Electricity Distribution
  6. Report on Distribution Transformer – Idam Infrastructure Advisory Pvt Ltd, November 2013
  7. Energy Intensity – is used as a measure of a nation’s economy. It is computed as units of energy per unit of GDP.
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