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NOVEMBER 3,2020 - timesofindia
Mumbai needs a large sized battery storage solution

Last month’s power outage in Mumbai was of a scale rarely seen by the metropolis – a perfect storm with demand rising when a critical line was down for maintenance. But a technology relatively new to India, large-scale batteries, working as “virtual transmission” could prove critical for preventing similar future outages.

How this week’s power outage occurred

Early Monday, power demand was at 2400 MW in the morning, not unusually high for a city where peak demand goes up to 3400 MW. About half the power was flowing through transmission lines owned and operated by MahaTransco, a State owned transmission company. The Kalwa-Padhge line 1 was down for maintenance and the backup Kalwa-Padhge line 2 was carrying 600 MW of load, above its normal capacity. At 9:58am, Kalwa-Padhge line 2 tripped due to a technical fault. As a result, load on the Pune-Kharghar line jumped to over 900MW and at 10:02 am this line was tripped as well due to overloading.

Mumbai’s electricity supply system is capable of “islanding” – separating from the larger network in the case of grid failure and switching to embedded power generators located within the city’s network. However, over the years with a reliable grid, more economic generation sources have become available outside the network. In addition, due to environmental concerns in the Mumbai area, the use of embedded generation has decreased. As a result, the islanding capability was not available to the extent needed, making the outage worse, with 3508 MW of load dropping off the network and 1375 MWs of generation tripping. The accountability for this large-scale outage, damage to the network and the economic cost of millions losing power are still being assessed.

This was the second major power outage in Mumbai in last 2 years. The inadequacy of transmission capacity to Mumbai is a known issue to network planners. Addition of more transmission capacity to bring more power into Mumbai are under consideration for some time. This option has run into the issues of limitations of land availability, access, social permit to build such infrastructure and long lead times. There have been proposals to add more embedded generation in Mumbai but these have run into the issue of environmental impact of a power plant in the city and its standby costs. Fast responding Battery-based energy storage of MW scale with durations that can run upto six hours offer a solution to both of these seemingly insurmountable problems in Mumbai.

Battery Storage as “virtual transmission” – a scalable, embeddable solution

BloomberNEF (BNEF), a research organization reported 10.79GW of Energy Storage Systems installed globally at the end of 2019. BNEF projects this number to increase to 306GW by 2030. India’s own 10MW project owned by AES Corporation and Mitsubishi Corporation and supplied by Fluence, has been operational for over eighteen months at a substation in northern Delhi. During the “Lights Out” event, this 10MW system was put into action ramping up and down autonomously to its full available capacity in sync with the change in frequency within milliseconds.

Other battery storage projects totaling hundreds of MW are being developed in India to meet the peak power needs of cities across the country. Mumbai should seriously evaluate the option to install Battery Storage to address the risk of similar power outages occurring in the future.

Built for rapid deployment

Energy storage systems can be deployed faster than transmission lines—in as little as one year for assets 100 MW or larger. Storage systems are not subject to the same arduous permitting and easement processes required for transmission lines. In the case of Mumbai, faster speed of deployment is particularly useful because the local grid conditions are acute, and a solution has to be put in place before the next emergency.

As much as 80% smaller footprint than new power lines

Because battery-based energy storage projects have compact footprints—housed in either data center-like buildings or containerized solutions—they do not have the typical environmental impacts of transmission projects. Avoided impacts include right-of-way and easement issues, visual impacts across large tracts of land, wildlife preservation issues, or the need to cross water or protected lands, as well as the communal benefit of fewer high-voltage cables crisscrossing local communities. A 200 MW energy storage project could fit onto a site equivalent in size to only 600 meters of 220 kV transmission line, including easement.

Highly scalable

Storage assets can be scaled dynamically in terms of size, operations and applications over different planning horizons to flexibly adapt to network conditions. A 200MW battery storage for Mumbai can be split into two deployment of 100MW at two different substations. Storage can also be configured in a wide variety of ways to adapt to siting constraints. No other transmission asset class can provide this level of flexibility.

Augmentation and transportability

Unlike poles-and-wires projects, storage can be augmented in place or potentially moved to a new location if load or generation patterns change over a project’s lifespan. This attribute adds key option value for network owners and operators in how they deploy capital.

Can serve as a regional resource

Battery storage working as virtual transmission can receive instructions and be controlled from multiple points in the network – from local controls at the substation level, from regional dispatch or even from the overall transmission system’s controls in coordination with other transmission assets.

Ability to provide additional services

In addition to enabling greater dispatchability of generation, storage can also provide reactive power, enabling network operators to better preserve system performance in the event of temporary transmission outages or, in more extreme circumstances, prevent blackout/system black conditions or rolling brownouts. Battery storage in transmission projects can also provide a range of ancillary services, including frequency and voltage control and special protection schemes, to name a few.

For Mumbai’s regional grid, a path to lower risk, greater benefits

All of these attributes add up to less risk for network owners in a sector that is dealing with huge risks of potentially stranded conventional generation assets and the supporting infrastructure. Further, energy storage can provide either the network owner or market participant with revenue streams, while concurrently offering network support, such as ancillary services, capacity payments or arbitrage (depending on configuration and local ring-fencing regulatory restrictions).

In a number of markets, congestion on transmission corridors is forcing operators to “redispatch” generation—that is, paying generators to ramp down on one side of congestion and others to ramp up closer to load. Storage deployed along a congested corridor can mimic line flows and reduce the need to redispatch generation, minimizing excessive ramping.

Energy storage is frequently a less costly option, which can be advantageous in cost-benefit tests. Although energy storage will not always supplant traditional poles-and-wires projects, in the short to medium term it offers networks and network planners a powerful and flexible new tool for addressing network issues. For the Mumbai region, this offers a way to reinforce the network far faster than with traditional solutions. The recent grid failure calls for urgent interventions, and the State and Central Governments should roll out a coordinated plan to implement solutions on a priority basis.

The below image illustrates one of the ways to place a battery in Mumbai’s transmission network that could have prevented last month’s outage. Through detailed power flow simulations and optimization studies, planners can model energy storage’s impact on transmission and distribution system in Mumbai and identify where it would best support the local grid through direct interconnection, as well as provide positive cascading impacts on adjacent substations via their interconnections. This is an analysis that should be taken up proactively for Mumbai.

Read more: https://timesofindia.indiatimes.com/blogs/voices/mumbai-needs-a-large-sized-battery-storage-solution-to-address-its-power-problems/