Emerging Electric Grid With Distributed Renewable Energy, Distributed Energy Storage And Packetized Energy Management

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Dibin Chandran

Average reading time for this story is 6 minutes

Opinion piece by Dibin Chandran, Senior Engineer- Power and Renewable

The overall purpose of power system operations is to supply energy in a cost-effective, efficient, and dependable manner. Decades of expertise with massive, synchronous generators have been used to manage the stability of electric power systems. In today’s electric power networks, unconventional sources such as wind and solar power, as well as energy storage technologies such as batteries, are becoming more prevalent. As electrification and decarbonization initiatives are followed, the amount of variable, renewable energy will rise, necessitating power system operators to think beyond supply and demand in order to accomplish the intended power system objectives.

Problem statement: Variable nature of Renewable Energy

These concerns are mostly about grid management, operation, and planning, especially where there is uncertainty in Renewable Energy System output owing to resource variability. Variability in PV irradiance, for example, is frequently noted as a key hurdle to high PV penetration into existing electricity networks. This fluctuation usually results in power curtailment and resource non-utilization; nevertheless, in such cases, we may have to employ traditional power resources to meet demand. Utility-scale energy storage devices are considered to be the solution to these issues, in which surplus power can be stored and can be utilized. However, the deployment of utility-scale energy storage is not linearly increasing like the deployment of utility RE. This is mostly due to a difference between projected and actual cost reductions for energy storage systems. Other obstacles limiting large-scale energy storage adoption include the volatile nature of battery costs, safety concerns in large-scale storage installations, and a lack of historical performance data, among others.

Utility-scale solar and energy storage installations are no longer a viable option due to the following factors:

  • Additional power evacuation infrastructure is required.
  • Losses in transmission and distribution are high.
  • The fluctuation of dynamic local resources will have a substantial influence on grid stability.
  • The power system’s stability will be harmed if centralized generation and stored energy supply are disrupted.
  • Utility-scale energy storage has a high initial investment cost.
  • The use of stored energy by emergency and non-emergency loads is challenging to optimize.
  • One of the solutions to these problems is Distributed Renewable Energy (DRE) deployment.
Figure 1: Utility-scale RE and energy storage (Source: PV Magazine)

Distributed Renewable Energy (DRE)

Distributed Renewable Energy (DRE) systems are receiving more attention than utility-scale systems due to their lower complexity levels. These co-benefits span across the following dimensions, notwithstanding their diversity and difficulty in valuing and monetizing them:

  • Cost savings when compared to the grid in many markets
  • Fuel availability and/or stability and predictability of prices
  • Modularity, flexibility and rapid construction times
  • Faster technological learning curves and rates of improvement compared to fossil fuels
  • Enhanced reliability and resilience
  • Improved health through reductions in indoor air pollution
  • Contribution to climate change mitigation
  • Reductions in deforestation and in environmental degradation
  • Positive effects on women’s empowerment
  • Reductions of poverty among vulnerable groups.
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It is expected that the deployment of DRE systems will get accelerated considering the above-listed benefits. Some of the other technical benefits that we can achieve by the DREs are:

  • Energy utilization near the generation: This will avoid transmission and distribution losses
  • Optimization of transmission and distribution infrastructures
  • Reduced local generation fluctuation: DRE can avoid the effect of dynamic power generation dip on the electric grid due to its distributed deployment.
  • Local grid issues due to environmental effects or natural calamities will not affect the generation. 
  • Anytime the DREs can be converted as a modern microgrid with energy storage and energy management.

DREs and Microgrid

Distribution network outages, especially as a result of catastrophic, devastating weather events, can affect huge regions and millions of customers and businesses. When grid segments are outfitted with distributed energy resources (DER), they can continue to service other loads on the same distribution network while also meeting local needs with on-site generating. Islanding is the term for this. Microgrids are electrical systems that may disconnect from the main grid and go off-grid for a specific reason.

Figure 2: Microgrid representation (Source: https//re-plus.events)

Microgrids come in many shapes and sizes, from single-customer microgrids to full-substation microgrids with hundreds of generators and electrical customers. Small-scale, off-grid power systems are not a novel concept. Ships, military installations, remote outposts, and isolated communities all over the world have long relied on local generation and power management to meet their energy needs. Because electricity-producing equipment is now more widely available and deployed in communities, DER makes microgrids a more viable option. Community-scale microgrids may provide resiliency and back up during and after natural disasters. Microgrid energy storage systems, or distributed energy storage (DES), will be used for such purposes. Energy storage systems that are deployed within the electricity distribution system and near to end users are referred to as distributed energy storage (DES). It may be more efficient to employ a number of small power energy storage systems in the microgrid instead of one or many big capacity energy storage units (utility-scale). This solution is ideal for the smart grid and energy market of the future.

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Consider a future electric grid with a significant number of DREs and DSEs; based on the problem statement above, the impact of RE sources’ fluctuating nature on the electric grid still exists. This influence may be mitigated by efficient energy management, which is simple in small-scale systems but more challenging as the system’s quantum grows. With the right energy management system in place, this problem might be solved in a factory, university campus, or community microgrid, for example (EMS). However, in the event of a surplus generation, the cure is power curtailment, which is not desirable.

So, let’s break down the microgrid architecture for the best option. The microgrid is designed with numerous DREs (Distributed Renewable Energy) and DESs (Distributed Energy Storage). The design of DRE and DES is dependent on energy demand, which might result in surplus power output owing to demand cycle changes. At this time, oversizing DESs is not a cost-effective solution, considering the economical feasibility.

Packetized Energy Management (PEM) is an advanced energy management approach that appears to offer a better answer to these challenges.

Packetized Energy Management (PEM)

Packetized Energy Management (PEM) is a real-time energy resource coordination system that reduces energy expenditures, lowers the need for energy infrastructure improvements, and increases the usage of renewable energy on the grid. Electrical equipment “request” energy packets in real-time, according to the requirement. Each request is coordinated by a centralized coordination entity, which can accept or reject the request based on market conditions at the time.

A bidirectional communication channel is a critical component of this system, and it also presupposes some degree of randomization, which means that not all devices would demand power at the same time, but rather at random and staggered intervals. Packetization and randomization are the two ideas that enable billions of devices to connect to the internet without the need for centralized scheduling or management.

Hundreds of billions of electrical loads contribute to the grid’s electricity consumption. Commercial and industrial loads, as well as residential loads, can be divided into two groups. As they go about their daily lives, most residential customers do not consider how to optimize their personal electrical loads. Furthermore, as the number of electric vehicles (EVs) on the grid grows, energy consumption is becoming more and more unpredictable on a daily basis. Here, we need to divide these loads into two categories, flexible and non-flexible loads. Unlike lighting or television, which you want to turn on right away, a flexible gadget may delay consumption and work whenever you want—as long as there’s hot water in the shower, your pool is clean, your electric vehicle has enough charge, and the inside temperature is suitable. 

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Figure 3: PEM- Packetization and Randomization (Source: UNIVERSITY OF VERMONT)

The PEM system will connect with the flexible devices over the internet, and the system will place the flexible load demand based on the power generating circumstances. This may bring load demand in line with the generation, or it may result in the most optimal use of RE generation with minimum wastage. Overall, this concept has the potential to improve the RE system’s stability and attract more private investment in energy storage and renewable energy. Even if the PME system rejects the request for power, consumers will always have the option to utilize the devices as normal.

Even though the tariff of the residential consumers is fixed throughout the day, in near future this may change to time-based. This is mainly due to electricity price/Unit cannot be same for a different type of resources, especially when the stored energy suppliers increasing. PME will allow the consumers to choose low-cost electricity. For example, with PEM residential washing machine/EV can operate during midnight or daytime as per the low tariff electricity availability. 

With the considerable addition of EVs, the relevance of PEM will get an increase in the near future. Also, this will improve the utilization of energy storage devices and PEMs will act as a virtual energy storage system. There are organizations like ‘Packetized Energy’ that have done considerable research and pilot projects in PEMs.

A considerable amount of policy and regulation amendments need to be adopted before implementing this new distribution philosophy. Regulators, utilities, and others will need to rethink and reinvent incentives and flexible-demand programs. Consumers will also need to be educated on how the system operates. We’ll need new technology and paradigms as we move to a new grid-based on distributed and renewable generation.

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