Assam Electricity Grid Corporation Limited (AEGCL), which was incorporated in 2003, is the largest state transmission utility in the north-eastern region. It has managed to significantly expand its network over the years. However, a key challenge for it today is its transmission losses, which are not at par with other major state transcos in the country. Further, with Assam expected to see significant solar power capacity addition over the next few years, the transco will need to augment the grid’s capability to manage the integration of infirm energy sources. Grid modernisation initiatives such as geographic information systems (GIS), substation automation systems and remote monitoring are, therefore, of key importance to the transco. At Power Line’s recent workshop in Guwahati, S.N. Kalita, managing director, AEGCL, shared his perspective on the challenges before the transco as well as its grid modernisation and strengthening plans. Excerpts…
Existing network and capabilities
As per the 19th Electric Power Survey, the peak load of Assam by 2021-22 is expected to reach 2,713 MW. Today, the average peak load during summer is about 1,750 MW and the off-peak load is about 1,150 MW. The peak and off-peak load again varies during the winter, with the peak load being around 1,415 MW and the off-peak load being around 900 MW. So the difference during the winter is substantial. Our transmission system is capable of handling a peak load of about 1,800 MW. In fact, in October 2017, we handled a load of almost 1,745 MW. The grid can, however, safely handle around 1,900 MW. In the next four years, we need to prepare the grid for handling a 55 per cent increase in load from 1,900 MW to 2,713 MW.
Modernisation drivers and initiatives
Most of the existing assets are in a very poor condition. Also, out of the 63 grid substations that we currently own, the majority (52) are at the 132 kV level. Further, out of the 5,117 km of transmission lines in our network, 2,800-2,900 ckt. km are at the 132 kV level. This has a direct linkage with the loss levels in our network. Today, the transmission losses are quite steep, which does not augur well for a transmission company. The loss levels in 2016-17 were 3.54 per cent, compared to 3.64 per cent in 2015-16. About five years back, the losses were around 4.5 per cent. We need to bring these losses down further.
Our system also needs to be made more modern and new technologies must be brought in, not only for the existing network but also for additional assets that we plan to build. In the next three to four years, we are planning to add at least 59 grid substations as well as 7,000 ckt. km of transmission lines to our network. We are planning to build a highway of transmission lines in the north bank and south bank of the River Brahmaputra at the 220 kV level. Overall, we have sorted out our proposed plans by component and funding requirements as well.
It is not enough to just have a robust network; it is also important that the network delivers. This is where modernisation plays a role. Currently, under the Power System Development Fund (PSDF), we have implemented substation automation systems. However, some of the substations are still not covered under the scheme and we need to take forward these systems for those substations as well.
Also, aside from good software and IT equipment, it is important to have modern and updated infrastructure in the substations. For this, under the PSDF, we are setting up kiosk buildings within the switchyards with all the necessary services at various substations.
We are also planning on introducing an asset management system. This system would cover not only IT-based systems but also, more importantly, GIS mapping. Within the next one year, we are planning to complete GIS mapping of our entire line infrastructure.
We already have some experience in GIS implementation. Two additional GISs will be commissioned by the end of March 2018 at Kamakhya and Sonari. At a few sites, at least in the city areas, we plan to go in for GIS technology.
To address the connectivity issues, we have already installed 1,373 km of optical ground wire (OPGW) network. Over the next one and a half years, we will be adding another 740 km of OPGW network. Thereafter, we will be covering almost 90 per cent of our substations through the OPGW network.
We also plan to take up remote monitoring. This is important as the grid today is integrated but, at the same time, we are talking about a distributed grid with distributed generation sources. We do not have immediate plans, but in the future we are looking to set up at least four remote command centres in different localities, which will communicate with the central control room at Kahilipara.
We are also in discussions with manufacturers to look at monopole solutions as well as towers that have much lesser land requirements for our upcoming projects. We are also planning to introduce high temperature low sag (HTLS) conductors for two or three transmission corridors in the next one year.
We have a lot of issues specific to the north-eastern region in terms of the quality of implementation of projects and their timely completion. From ensuring that the scheme is implemented properly to monitoring the personnel implementing the project, these are challenges that we are looking into. We face significant challenges particularly in the implementation of transmission lines and following up on right-of-way (RoW) issues. We are taking up RoW issues with authorities at the state government level.
Another key challenge that is likely to come up in the near future would be the integration of renewables. We need to look at ways to integrate the huge amount of solar energy that is expected to come up in the north-eastern region into our grid. We also need to look at ways to reduce the uncertainty associated with infirm energy sources. Even though during the last four to five years many new technologies have come in that aim to lower the uncertainties, the quantum of renewable energy has gone up.
Another key challenge is the transportation of equipment. There is significant reliance on equipment manufacturers located outside the state and hence, transportation becomes a major constraint. For instance, transporting materials/transformers from Mumbai to Guwahati takes up to two months. We need to look at ways to reduce the time taken for transportation. We could request manufacturers to set up manufacturing bases in the north-eastern region around Guwahati. This will benefit them too, as they would be serving not only the Assam market and other north-eastern states but also the neighbouring countries.
“Our system needs to be made more modern and new technologies brought in, not only for the existing network but also for the additional assets that we plan to build.”