Preparing power distribution network for EV charging needs

In this guest article for EVreporter, Chandana Sasidharan presents her take on the preparedness required at the DISCOM’s end to accommodate for expanding Electric Vehicle Charging Infrastructure requirements in the country.

Introduction

The simplest way to look at electrification of transportation is that it eventually leads to an increase in electricity demand. Every electric vehicle (EV) is effectively a new consumer for the electricity distribution company (DISCOM).

When it comes to electricity connection for EV charging facilities, one of the key questions that needs to be answered is ‘who will bear the cost of the grid upgradation?’. Will the DISCOM bear the cost of upgradation? Should the charging service provider or the consumer bear the cost? As I see it, there are some unavoidable costs associated with the procurement ‘wires and poles’ to get the connection. But then again, I believe it is possible to limit the expenditure on the grid upgradation. 

Decoding electricity distribution

Before talking about electric vehicles, it is essential to understand how electricity distribution works. The job of DISCOMs is to supply electricity to its consumers. If you examine it closely you can see that a DISCOM is technically an intermediary between the power generator and the consumer. The DISCOMs need to buy electricity from the generators according to consumer demand before supplying it to consumers. Since the transfer of electricity to the consumer cannot take place without wires, the DISCOM also has the responsibility to provide and maintain the ‘wires, poles, transformers and other paraphernalia’, which constitutes the electricity distribution grid. 

Though electricity is practically everywhere, the capacity of the grid is not the same everywhere. Every wire and associated equipment in the network have an inherent limit to how much power it can carry. This means that for any geographical location, the power that the DISCOM can provide depends on the wires or grid around it. The DISCOM is bound by law to provide electricity to the consumer. So, when the number of consumers increase or existing consumers demand more power at a particular location, the DISCOM is often left with no choice but to increase the capacity of its distribution network. As you would expect, this network augmentation process is not a new thing. Every DISCOM already has a grid expansion plan in place. It is just that it takes some time to lay the new ‘poles and wires’ and there is always an associated cost. Nevertheless, there is a range of other possible solutions that the DISCOMs can explore for EV consumers.

The new electric vehicle consumer

Rules governing the current electricity supply and network upgradation process of DISCOMs was created long before EVs came into the picture. With the advent of EVs, DISCOMs are in for a new set of consumers on wheels. The problem with the new EV consumer is three-fold: 

DISCOM has to provide the poles and wires of adequate capacity at the places where the electric vehicles will charge.

DISCOM has to provide buy and supply the additional electricity needed for the electric vehicle

DISCOM has to maintain the grid so that the electricity supply to other consumers is not impacted by the new consumer

This is a new set of consumers who can pop up anywhere on the grid and demand electricity. What makes this really challenging is that DISCOM cannot precisely pinpoint ‘when, where and how much’ EV charging demand will arise.

Secondly, at the specific location where the electric vehicle is demanding power, the grid may not have the adequate capacity to provide it. It is also likely that there are no ‘poles and wires’ in the region where the EV is to be charged. However, it is not a problem without solutions. It is better to visualize the problems and solutions with examples. If I were to buy an EV tomorrow, I have two options to charge it- charge it at my home or at a public charging facility.

Home charging

The easiest option to charge my electric vehicle is using my electricity connection at my home. In fact, all over the world the majority of electric vehicle charging happens at home using the electricity connection that is already there. Now here, with home charging, the problem for the DISCOM is that this is an extra load, on top of my existing load. That is, I still need to use my AC, microwave, washing machine as I was using earlier. On top of it, I also need extra electricity to charge my electric vehicle. It is a piece of cake if the DISCOM is able to give me enough power to perform electric vehicle charging and along with running my home through the existing wires. If it is not possible, then the straight forward solution is to change the wire that is coming to my home. But it is important to remember that the DISCOM may need to upgrade the grid equipment in the upstream also if many consumers start demanding more power.

But there is always a middle path and there are many smart solutions without upgrading the wires. I can always charge my EV when I am not using much power. I can limit the power I am using to charge the EV. I can also let DISCOM have control over the charging of my EV. DISCOM can change the rate of my power use according to its capacity. There could be an endless list of solutions which can be called as smart charging. All that should be ensured is that there is enough charge in the battery for my travel the next morning. 

car charging

Public charging

The second option available to me is to recharge the vehicle at a public charging station. A public charging station is similar to a petrol pump: the electric vehicle consumer comes in, gets the battery charged and leaves. But there are marked differences, which makes it difficult for the DISCOM. The fuel is not stored and pumped from tanks for one. It is always possible to provide energy storage devices along with charging facilities. However, in this case with electricity grid connection, the operation is like very much similar to one with a fuel pipeline.

Though the DISCOM has some idea about ‘where’ the demand is going to come from, it does not have much clue on ‘when and how much’ electricity is required.

The ‘when’ or time factor is important because it is the same ‘pipeline’ everywhere. India has one electricity grid, and there is no separate electricity network to serve electric vehicle consumer. There is a problem if everyone asks for power at the same time. If the electric vehicle consumer is demanding power at a peak demand time, it becomes a serious issue for the DISCOM. In this case, the DISCOM needs to add more wires or change the existing wires at a cost.  

The second aspect is about ‘how much’ power is needed at that location. As we have seen, the capacity is dependent on the grid elements at that location. The best-case scenario is when the DISCOM is able to provide the sufficient capacity that the consumer is demanding. Reverse engineering of this fact is one way to solve the charging infrastructure problem. The chargers can be installed at locations where the DISCOM can easily provide a connection of adequate capacity. If there is not enough capacity in the grid, the straight forward solution is to upgrade the network to the required capacity. There will be unavoidable time delays and costs associated with this process.

It is essential to explore what else is possible. In reality, it is possible that the grid might have sufficient capacity at certain periods of time, if not all the time. The fact is the power demand in the grid varies with time and location. The peak demand happens only for a few hours in a day. So, it is most probable that the DISCOM has no problem with electric vehicle charging except for few hours in a day. 

The full picture is that ‘how much’, ‘when’ and ‘where’ are interconnected factors. The extra capacity that is available in the grid to supply to the consumer will depend on how much power is being used in that area. Even if one location is experiencing a peak load, there could be another location nearby where the DISCOM can easily provide the needed power. If the power usage or grid loading is less, then the DISCOM can supply more at that time. So, the strategy is to plan to change charging power according to the available grid capacity. 

The DISCOM can approach this problem directly or indirectly. The indirect method is to increase energy charges when electricity usage is more. The goal is to discourage users from charging when there is already a peak demand. One of the ways this can be devised is similar to the surge prices of Ola/Uber when the demand is more. The other side of this coin is that during times when the demand is less the DISCOM can encourage the users to charge more. This could be when there is a lot of cheap Solar based electricity generation.

The alternate approach to solve the problem involves DISCOM taking direct control of the situation. This can be called a controlled charging or smart charging strategy. The DISCOM can control the charging power according to the capacity of the grid. This is not an easy task as the DISCOM needs to have full awareness to control the situation. To achieve this type of control the measuring, monitoring, control and communication aspects are of paramount importance. For this, the distribution network needs to upgrade itself to become a smart grid.

As the number of charging facilities increases, there are practical difficulties for the DISCOM to control each and every charging point. Hence, a new set of middlemen called Aggregators might be needed to achieve this task.

Concluding thoughts

In summary, electric vehicles are ultimately good news for the DISCOM as it presents a chance to sell more power. This is particularly important because we are living in an age where the consumer can generate his own power. The reduction in energy sales of the DISCOMs is an unavoidable aftereffect of increase rooftop solar penetration. Having said all that, the DISCOM still needs to buy additional power from the generator to sell to the electric vehicle consumer. The DISCOM has to become smart and be able to forecast ‘when, where and how much’ electricity demand from electric vehicles will come. 

DISCOM will only have problem with EV charging if it has no control over it. We have to remember that technological advancement has made control of EV charging as a practical option. This is important because it is then possible to limit the addition of new ‘poles and wires’ to deal with electric vehicle charging. It also makes it possible to create win-win situations for the DISCOM and consumer. The consumer is happy if the DISCOM can provide cheaper electricity during lean loading periods. Additionally, as peak power procurement is typically expensive for a DISCOM, it makes sense to discourage charging at peak. Overall, the final choice of the approach the DISCOM should adopt to deal with electric vehicle charging will depend on weighing the costs against the benefits. 

About the Author

Chandana is an electrical and electronics engineer and not an expert in EV or batteries. She is a renewable energy and clean mobility enthusiast who loves to learn and teach. She is passionate about her research at Alliance for an Energy Efficient Economy on Energy Resources in the Distribution system. This article is a summary of her notes from multiple sources. 

Disclaimer – The views and opinions expressed here is that of the author and does not necessarily reflect the official policy or position of Alliance for an Energy Efficient Economy.

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