An aging grid…Haneea Isaad
In the early hours of January 23, the frequency at one of the 500 KV transmission systems in the south went up to 50.75 Hz, followed by severe voltage fluctuation and a tripping of the Muzaffargarh, DG Khan and Guddu circuits. The tripped circuits in turn led to cascading outage of more than 21 generating units resulting in almost 11356 MW of capacity being taken offline and a nationwide rolling blackout.
Despite consistent attempts to re-energize the grid, the system kept tripping repeatedly and almost the whole nation was without power for over fourteen hours, bringing economic and commercial activity to a halt.
This is neither the first incident of its kind, nor will it be the last, but it points to a deeper problem that needs to be addressed on a systemic level; an ageing and a highly centralized transmission network.
The National Transmission and Despatch Company (NTDC) was established in 1998 and acquired most of its transmission assets from Wapda in the form of 550 kV and 220 kV lines. As of 2021, the company operates an interconnected system of eighteen 500 kV and forty-nine 220 kV grid stations and a sprawling mass of 8388Km of 500 kV and 11645Km of 220 kV transmission lines.
Regional Distribution Companies (DISCOs) operate lower voltage 132 kV and 66 kV lines. Although the company has expanded and augmented the transmission network over the years, the technology employed in its upkeep and maintenance is still outdated, with some parts of the grid dating as far back as 25 years.
DISCOs also operate on high transmission and distribution (T&D) losses, with almost 18 per cent of the power transmitted being lost this way. The Supervisory Control and Data Acquisition (SCADA) system has only been deployed to a limited extent, which prevents most of the power plants on the grid being connected from main control rooms and automation.
The grid itself follows an elaborate system of interconnectivity, with major load centers located far away from generation sources. Seasonal variation in generation adds another layer of complexity, as major flows during summer are met by hydel in the north and in winters by thermal power in the south. This interdependence means that when a problem occurs in one area of the grid, it cannot be isolated from the rest, resulting in a cascading failure of the entire grid, which is what happened on January 23.
Only digitization and modernization can completely rid the grid of the many problems it faces. Technologies which allow for real-time automated monitoring, two-way communication and far greater interaction amongst human operators, control systems and communication networks need to be deployed. Intelligent processors which are able to automatically sense the precursors to a blackout and reconfigure power flows should be installed.
To transform the existing transmission network into such a self-healing grid would not only take time but would also require significant investment in technology and training of human resources. Given the current dire economic state of our country and its state-owned enterprises, it can be safely assumed that the achievement of these goals will take many years if not decades. Meanwhile, we must explore more decentralized and bottom-up solutions to our energy dilemma.
Clean distributed energy resources (DERs) such as rooftop solar PV, or mini/micro grids based on solar and wind energy are small and modular technologies which allow power to be generated and consumed at or near the source, thus reducing reliance on efficient long-distance transmission and distribution networks.
These technologies come with an array of advantages that not only offer a cleaner and cheaper alternative to imported fossil fuel-based power but can also add diversity and resilience to the existing power system. They can be a great source of relieving pressure on the grid during times of high electricity demand and providing back up in case there is a blackout. Traditional power systems such as the national grid in its present state may not always be able to match electricity supply and demand, resulting in frequency fluctuation and subsequent blackouts. Microgrids on the other hand may be able to provide cost-effective battery storage.
As technologies evolve and the grid becomes smarter, distributed renewable energy resources may have a larger role to play by contributing to the generation needs of the country in a more dynamic and responsive way. Development of DERs along with the grid offers a chance at energy affordability, independence and security.
Courtesy The News