One of the biggest challenges facing distribution utilities is high level of network losses. As per the latest estimate of Power Finance Corporation of India Limited, the all-India aggregate technical and commercial (AT&C) losses stand at 22.7 per cent (as of March 2014). High loss levels adversely affect the health of the discoms and consequently impair their ability to undertake investments in network improvement and augmentation. In the recent past, various technologies have been adopted by discoms to reduce their loss levels. These include the use of automated meter reading (AMR), aerial bunched cables (ABCs), high voltage distribution systems (HVDS), and feeder segregation.
Metering plays a crucial role in reducing the AT&C losses of distribution utilities through improvements in billing and collection efficiency as well as a reduction in power theft. Improvement in metering infrastructure has been the focus of various government schemes, including the Integrated Power Development Scheme (IPDS) and the Deendayal Upadhyaya Gram Jyoti Yojana (DDUGJY).
Distribution utilities are providing electronic meters for all new connections as well as replacing the existing electromechanical meters with electronic ones. The use of electronic meters significantly lowers the incidence of meter tampering and theft.
AMR is one of the technologies that is gaining traction in the country. It allows quick identification of theft and pilferage and helps in the identification of metering defects and tampering. Further, by eliminating manual intervention, AMR reduces errors and promotes transparency, leading to increased customer satisfaction. AMR also improves the utilities’ billing efficiency, as the issue of inaccessibility in hostile areas is eliminated and consumers can be billed according to their actual consumption. In addition, AMR technology assists utilities in activities including outage management, data analytics, tamper detection and network management.
Some of the other metering technologies that aid in loss reduction are meters with infra-red ports and prepaid meters. In meters with infra-red ports, data is collected from the meter through a handheld device for accounting purposes. These meters are usually used in rural areas for domestic and commercial consumers. Meanwhile, in the case of prepaid meters, consumers are required to pay prior to actual consumption. Traditionally, these have been targeted at low-income segments, with consumers approaching payment kiosks to recharge their meters.
Another technology widely deployed by discoms for loss reduction is ABCs. ABCs are overhead power lines consisting of several insulated phase conductors bundled tightly together, with a bare neutral conductor. In contrast, as per the traditional practice, the uninsulated conductors are separated by air gaps.
One of the key benefits of this technology is protection against power theft due to the absence of hooking in the distribution lines. The technology also entails negligible losses due to the leakage of power. Further, as the ACBs are insulated with a dielectric material, these are less prone to faults caused by high winds, falling trees or birds. As such, these cables offer greater reliability and are extensively being deployed in areas where the reliability of supply is a prime concern.
ABC is also advantageous in areas with a large number of trees, narrow streets, and hilly and mountainous terrain. ABCs offer benefits such as less inspection and maintenance time, safety to linesmen, low level of maintenance, ease of installation, and less cluttered appearance. Besides, ABCs can withstand close proximity to trees and do not spark upon being touched. Further, in the case of ABCs, multiple circuits of power and telephone cables can be used on the same poles or any other support, including walls.
However, some of the challenges in the implementation of ABCs include the degradation of the external insulation with exposure to the sun (though the insulation between the wires remains shielded from the sun), and the short spans and greater number of poles needed to withstand the weight of the cables.
Another technology adopted by distribution utilities for loss reduction is the use of three-phase HVDS. This improves the reliability of power supply to the consumers as well as helps the discoms in maintaining better voltage profiles. In March 2015, the Kerala State Electricity Board adopted HVDS at Manjadi, which was witnessing high levels of power theft and frequent electricity line snapping.
In HVDS, power is distributed through high voltage lines and single-phase small capacity distribution transformers (usually a 10 kVA copper-wound transformer is used). With HVDS, distribution losses are reduced and the incidence of overloading and distribution transformer failure is lowered significantly.
Further, in HVDS, the chances of running illegal motors through unauthorised hooking of loads is prevented as the system comprises short and insulated low-tension lines. This minimises pilferage and improves the quality of power supply. Further, due to a reduction in the kVA capacity of the transformers, the voltage drop on low-voltage lines is negligible, thereby improving the voltage profile of the power supply. In an event of fault, only a limited number of customers will be affected and hence, the reliability of the system increases significantly.
HVDS can be single phase one neutral (continuous neutral from substation), two-phase two-wire (rigidly earthed natural system), or three-phase with small rating transformers. With the single-phase one neutral system, a continuous earth wire is required to be drawn from 33 kV/11 kV substations and the earth wire is to be earthed at all the poles. The neutral of the distribution transformer is also earthed on the high and low-voltage sides. This conversion does not require the acquisition of additional land and there is no depletion of cultivable or forest land as the conversion to HVDS can be done on the existing poles. Therefore, there is no additional right-of-way requirement for the erection of lines.
Another loss reduction technology deployed by distribution companies is feeder segregation. In rural areas, feeder segregation entails the separation of the distribution infrastructure of agricultural consumers from non-agricultural consumers. Notably, Gujarat’s discoms have recorded a significant improvement in performance with the implementation of feeder segregation, which has enabled them to improve the power supply scenario in the state. Many states are emulating the Gujarat model for feeder segregation.
Through feeder segregation, the power supply to agricultural and non-agricultural consumers can be regulated independently. However, in case all rural consumers are connected on the same feeder (wires that emerge from substations and carry electricity to transformers for distribution to consumers), the power supply to non-agricultural consumers, including households, schools and dispensaries, also gets switched off when agricultural supply is not needed.
Feeder separation helps utilities in managing the load and reducing network losses through efficient distribution of power. It helps them in flattening the load curve by distributing agricultural load during off-peak periods. The loss reduction, in turn, contributes to a reduction in peak load. This results in saving costly peak power procurement by the utility.
To improve the health of the distribution segment, it is vital to lower the loss levels. Although there are various technologies that target reductions in network losses, it is important for utilities to select the ones that meet their specific requirements. Meanwhile, significant support is being offered by the government to reduce losses through schemes such as DDUGJY and IPDS. Timely implementation of loss reduction technologies and adequate cost-benefit analysis, along with government support are expected to yield positive results in the coming years.