• Electrical India
  • Sep 5, 2016

The Promising Transition

Electricity demands increase day by day causing imbalance in the present power grid system, which results in various problems like load shedding and unbalanced voltage, ultimately affecting consumers. To avoid all such situations, the only option is to meet increasing demand for electricity by generating more power. However, since we lack conventional natural resources, the use of renewables may perhaps be the only way out...


A smart grid provides power utilities with digital intelligence to the power system network. It comes with smart metering techniques, digital sensors, and intelligent control systems with analytical tools. It enables the two-way flow of energy from power to plug to be automated, monitored and controlled.

  The smart grid has been described as the ‘Energy Internet’, which can turn the electric power infrastructure into a two-way network built on a standard Internet Protocol (IP) network. It uses a large number of smaller, discrete distributed plants instead of single high-producing plants, so reduces the risk of attacks and natural disasters. Even if such a major problem should occur, the smart grid, being a self-healing network, will restore itself quickly by isolating the particular line and re-routing the power supply.

  Increasing renewable electricity generation is an essential component in achieving a doubling of the renewable energy share in the global energy mix. Such a transition is technically feasible, but will require upgrades of old grid systems and new innovative solutions to accommodate the different nature of renewable energy generation. In particular, smart grids are able to incorporate the following characteristics:

Variability: Some forms of renewable electricity, notably wind and solar, are dependent on an ever-fluctuating resource (the wind and the sun, respectively). As electricity supply must meet electricity demand at all times, efforts are required to ensure that electricity sources or electricity demand is available that is able to absorb this variability.

• Distributed generation: Distributed renewable generation—smaller-scale systems, usually privately owned and operated—represent a new and different business model for electricity. Traditional utilities are often uneasy about allowing such systems to connect to the grid due to concerns over safety, effects on grid stability and operation, and the difficulties in valuing and pricing their generation.

• High initial cost: Renewable electricity generating technologies typically have higher first costs and lower operating costs than fossil-fuelled electricity generating technologies. Although renewables may be 'cost-effective' on a lifecycle basis, some electricity systems—particularly in developing countries—simply do not have access to sufficient capital to invest in renewables. Smart grid technologies can directly address these three challenges of renewable electricity generation. In addition, smart grids have added benefits that can further ease the transition to renewables.

Smart Grid

Smart Grid

Smart grid technologies are divided roughly into three groups:

• Well-established: Some smart grid components, notably distribution automation and demand response, are well-established technologies that directly enable renewables and are usually cost eff-ective, even without taking into consideration the undeniable benefits of sustainability related to renewable energy integration.

• Advanced: Smart inverters and renewable forecasting technologies are already used to increase the efficiency and productivity of renewable power generation, yet tend to entail additional costs. These devices start to help noticeably when capacity penetration for renewables reaches 15% or more (on any section of the grid) and become essential as this capacity penetration approaches 30%, although there is little downside to choosing smart inverters even at low penetration levels.

• Emerging: Distributed storage and micro-grids are generally not 'entry level' smart grid technologies, and thus are less well developed. Most utilities should focus on other technologies first, except in special circumstances (such as with grant funding, high reliability requirements, or remote locations).

  Historically, integration of small-scale renewable energy sources into a traditional grid causes problems. These include voltage fluctuations and harmonic distortions, which require synchronisation of the sources with the grid. Smart grid, on the other hand, optimises these problems by preventing outages and allowing consumers to manage energy usage. This technology enables various options to add energy to the grid at transmission and distribution levels through distributed generation and storage.

Smart Grid

  In other words, the smart grid makes better use of renewable energy resources. It gives grid operators new tools to reduce power demand quickly when wind or solar power dips, and it has more energy storage capabilities to absorb excess wind and solar power when it isn't needed, then to release that energy when the wind and solar power dips. In effect, energy storage will help in smoothing out the variability in wind and solar resources, making them easier to use.

  One of the principal challenges in operating an electricity system is ensuring that the demand for electricity is always exactly equal to the supply. It is difficult to store electricity (although the technologies to do so are steadily improving – and thus electricity system operators must continually adjust the output of power plants to match demand.

  Most traditional fossil-fuelled power plants will operate at a set output level – and so electricity system operators can generally depend on these plants to provide a steady and predictable amount of electricity. In addition, power plants fuelled by diesel and natural gas are often designed to allow for continual fine-tuning of their electricity output. This makes the challenge of matching electricity supply and demand manageable. Some forms of renewable electricity, however – notably wind and solar PV – are dependent on a continually fluctuating resource. If the wind slows or clouds obscure the sun, then the output of these plants drops, leaving electricity system operators scrambling to find other sources of electricity. When wind and solar PV provide a small fraction of total electricity – in the order of a few percent – it is usually straightforward to manage the fluctuations. However, when these 'variable resources' begin to provide a significant fraction of the system’s total electricity, maintaining system reliability can become increasingly challenging. Even when renewables provide a small fraction of a system’s total electricity, they may be providing a large fraction of electricity on a smaller time scale or larger geographic area.

  Smart grid technologies can do much to help meet that challenge. In essence, a smart grid makes it possible to integrate renewables with a wide range of diverse electricity resources. For instance, imagine a PV system and a set of commercial and industrial electricity consumers on an interruptible rate, all tied together with smart grid communication and control technologies. If the PV system output drops due to a cloud, then the smart grid interrupts service to those customers on the interruptible rate. When the cloud moves on, their service resumes.

  Demand response provides an opportunity for consumers to play a significant role in the operation of the electric grid by reducing or shifting their electricity usage during peak periods in response to time-based rates or other forms of financial incentives. Demand response programs are being used by electric system planners and operators as resource options for balancing supply and demand. Such programs can lower the cost of electricity in wholesale markets, and in turn, lead to lower retail rates.

  The smart grid offers multiple opportunities to develop demand response programs. For example, sensors can perceive peak load problems and utilise automatic switching to divert or reduce power in strategic places, removing the chance of overload and the resulting power failure. Advanced metering infrastructure expands the range of time-based rate programs that can be offered to consumers and smart customer systems.

Benefits of integration

  Leading characteristics of renewable resources that impact their integration into power grids are their size (generation capacity as compared to other sources of power generation on a system), their location (both geographically and with respect to network topology), and their variability (minute-by-minute, daily, seasonally, and intermittently).Renewable integration - reducing our nation’s dependence on foreign coal by enabling the seamless integration of cleaner, greener energy technologies into our power network. Normally, renewable resources are connected at the distribution level and as larger resources (wind farms, solar farms) are connected at the transmission level.

1. Future energy sustainability: Renewable energies are making a significant contribution to climate protection, diversify resources, ease dependence on fossil resources, not produce any type of contamination, domestic energy carriers and therefore contribute to regional value creation and help in securing employment. Hence, renewables as future energy provides sustainability.

2. Empowering grid in peak hours: Integration of more renewables and storage support the smart grid with real time information and substituting renewable energy sources whenever possible. Increasing proportion of renewables in generation mix not only improves operational efficiency but also reduces peak demands.

3. Energy management: Smart metering helps in adopting energy management techniques, such as demand side management at consumer level, demand response usage leads to optimum utilisation and results into saving of energy.

4. Independent systems: RE system works as an isolated system during grid failure, and reduces impact on customer. Industrial and commercial consumers adopt grid connected RE systems, which help in reducing power demand. Sometimes isolated systems in residential areas conserves the energy.

5. Upgrading electrical market: Power exchange provides an electronic platform to facilitate trading of electricity at national level. It initiated renewable energy trade since 2011. India ranks fourth for its market potential in renewable energy.

  Distributed renewable generation, notably rooftop PV, is a particularly promising renewable technology. Smart grid technologies can do much to promote greater use of distributed renewable generation. They can provide system operators with continual, real-time information on how these systems are operating and allow full control over these systems. This information and control can be used in several ways, including, for example:

• Reducing output of, or even disconnecting, distributed generation as needed to maintain reliability, match load, or protect workers.
• Providing real-time data on distributed generation electrical output.
• Supporting the distribution system through, for example, tighter control of voltage.

  Utility system operators may be uncomfortable with electricity generation that they cannot monitor and control. Smart grids can provide this monitoring and control – and thus encourage utilities to consider distributed renewable generation as an alternative to traditional utility-scale power plants. Smart grids can also make it possible to more accurately price and value distributed renewables. Distributed generation can have multiple impacts on distribution systems, from voltage regulation to administrative cost. Detailed data on distributed renewables’ output and performance, such as that available from a smart grid, can help the utility or system operator put an accurate figure on the value of the distributed renewables. Similarly, the data can help the utility determine the proper price to pay the distributed renewable system owners or operators for their systems’ output.

Challenges in integration of renewable with smart grid

  Variable generation, provided by many renewable-energy sources, is a challenge to electric grid operations. But when used in integration with smart grid as responsive distributed generation, it can be a profit to system operations if coordinated to relieve stress in the system (e.g., peak load, line overloads etc.). Smart grid approaches can reduce barriers and facilitate integration of renewable resources. The challenges can be categorised as technical, financial, business and societal issues.

Technical

1. Advanced Control Strategies: Solar and wind power plants exhibit changing dynamics, non-linearities, and uncertainties. Hence, smart grids require advanced control strategies to solve effectively. The use of more efficient control techniques would not only increase the performance of these systems, but would increase the number of operational hours of solar and wind plants and thus reduce the cost per kilowatt-hour (KWh) produced.

2. Wind and solar energy are both intermittent resources. Wind behaviour changes daily and seasonally, and sunlight is only available during daylight hours. Both wind and solar energy can be viewed as aggregate resources from the point of view of a power grid, with levels that vary within a 10 minute to 1 hour time frame, so they do not represent the same form of intermittency as an unplanned interruption in a large base-load generator.

3. Research in technology is still in progress. Hence, existing generation and delivery infrastructure (i.e., legacy) of RE systems must be adaptive to work with new technologies.

4. Being flexible to changing technologies require identifying the vital interface between technology components.

5. Achieving association across service providers, end-users and technology suppliers is difficult particularly in the growing international market place. Exchange of knowledge and information can allow multiple parties to connect their devices and system for proper interaction, but attaining interoperability is difficult.

Business and financial
1. Understanding and communicating the value proposition of a smart grid deployment for each stakeholder in the electricity supply chain is scary.

2. The financial environment risk and reward can challenge business plan for smart grid investments as well as in Renewable energy system.

3. Regulatory understanding and sensitivity to providing an appropriate environment for smart grid investment takes place. Regulatory decisions (or lack of decisions) can create new challenges.

4. Developing an appropriate incentive structure that aligns economic and regulatory policies with energy-efficiency and environmental goal needs to be tailored to each member economy.

Societal
1. Strategies need to account for a variety of policy objectives (affordability, sustainability, growth and cultural values).

2. Assigning value to externalities, such as environmental impacts, is difficult, but necessary, in balanced decision-making.

3. Understanding and accounting for the beneficial aspects of smart grid investments as a mechanism for job creation and advancing a technically skilled workforce needs development.

4. Greater awareness about capabilities of smart grid and there benefits for improving energy-efficiency and renewable resource integration policies.

5. Research and development activities: the speed with which new ideas and deployment tactics are being generated.

Conclusion

  Renewable generation has the benefit of enhancing sustainability (reducing environmental impacts), reducing Greenhouse Gas (GHG) emissions, reducing dependence on local or imported fossil fuels, and increasing energy security through diversification of energy sources. Smart grid technology can control renewable resources to effect changes in the grid’s operating conditions – and can provide additional benefits as distributed generation assets or when installed at the transmission level. Distributed generation can support weak grids, adding grid voltage and improving power quality. In certain circumstances, distributed generation can be used in conjunction with capacitor banks for management of power flows or to manage active and reactive power balance.

If harvested and taken care of control system,
“Renewable Resources will act as Smart Grid Assets.”


AUTHOR CREDIT & PHOTOGRAPH

Amrita Tandon

Amrita Tandon
Assistant Manager
L&T – Technology Services