Saturday, January 22, 2011

why smart grid?

The title makes a presumption that the reader is already aware of what a smart grid is. But I will take a couple of paragraphs to explain just what it is, why was it conceived and how it will help the world at large, if at all.

The term 'smart grid' was introduced in 2005 and like the elephant story, it means different things to different people. And that has also been the main source of confusion for its acceptance. I met a senior expert in the field last week and he said they have been doing the automation related work for decades now. No one noticed it till the catch-phrase 'smart grid' was introduced. But it is not that grids have been non-existent or even dumb before that time. So we will see what is so smart about it and what makes it different from earlier grids. But let us understand first what a grid really is. Let us trace the journey of power as it generated in a power plant till it reaches you for use. Power plants can be of many types, thermal, coal, hydro- or nuclear. Be that as it may, the generated power from the power plant is fed through power transformers. From the power transformers, it is received by the transmission substation. The journey of transmission grid terminates here. From here, the power is fed into the distribution substation. From the distribution substation, the power is transmitted to distribution transformers and to residences or commercial or industrial outfits.

Transmission lines mostly use three phase alternating current (AC), although single phase AC is sometimes used in railway electrification systems. High-voltage direct current (HVDC) technology is used only for very long distances (typically greater than 400 miles, or 600 km); submarine power cables (typically longer than 30 miles, or 50 km); or for connecting two AC networks that are not synchronized.

Electricity is transmitted at high voltages to reduce the energy lost in long distance transmission. Power is usually transmitted through overhead power lines. Underground power transmission has a significantly higher cost and greater operational limitations but is sometimes used in urban areas or sensitive locations. Power transformers are up transformers and transform the voltage from typically 12KV to 380KV. Through distribution substations this is down transformed to 220KV to 110KV, 25KV, to 20 KV and eventually to 230V that most of us use.

A key limitation in the distribution of electricity is that, with minor exceptions, electrical energy cannot be stored, and therefore it must be generated as it is needed. A sophisticated system of control is therefore required to ensure electric generation very closely matches the demand. If supply and demand are not in balance, generation plants and transmission equipment can shut down which, in the worst cases, can lead to a major regional blackout, something we are used to in India. To reduce the risk of such failures, electric transmission networks are interconnected into regional, national or continental wide networks thereby providing multiple redundant alternate routes for power to flow should (weather or equipment) failures occur. Much analysis is done by transmission companies to determine the maximum reliable capacity of each line which is mostly less than its physical or thermal limit, to ensure spare capacity is available should there be any such failure in another part of the network.

Energy demand is expected to grow by 55% by 2030. CO2 emissions grow faster than energy demand. An inefficient energy chain with 2/3rd of primary energy lost mostly due to power conversion. Between 7 and 15% of the electricity generated is lost on all networks.

Four major power regions of the country namely, North-Eastern, Eastern, Western and Northern are now operating as one synchronous grid (same frequency). Southern Regional grid is connected to this synchronous grid through HVDC links. For overall improvement and better grid management in the country, Power Grid Corporation of India has modernized all the Regional Load Dispatch Centers (RLDCs). The RLDCs correspond to the region and namely are : southern RLDC, northern RLDC, western RLDC, eastern RLDC and north-eastern RLDC besides the national LDC. These modernized RLDCs are greatly contributing to bring quality and economy in the operation of the power system besides improving data availability, visibility and transparency. With the adoption of state-of-the-art operational practices, proactive preventive maintenance, implementation of availability-based tariff, the modernization of RLDCs coupled with training & deployment of expert manpower and round the clock vigil for grid management, no major grid disturbances in the country have been encountered for the last 6½ years. Further, tripping of lines and minor grid disturbances in regional grids have come down so significantly that it can be reckoned as a benchmark achievement. For overall co-ordination, National Load Dispatch Center (NLDC) at Delhi,with back up at Kolkata, has been successfully commissioned. The power grid has spearheaded the implementation of Availability Based Tariff (ABT) across the country, which has a built-in commercial mechanism to reward proper grid behavior. This has significantly stabilized vital grid parameters, i.e. voltage and frequency thereby improving the quality of power.

So much about what it is. Why need to make it strong? In its present form, is it dumb? No it is not. But maybe, the answer lies in the meaning of the word smart. As per the dictionary, when used as an adjective it primarily means to be 'capable of quick and prompt action'. That is what is the crux of the function of smart grid. A 'quick and prompt action' requires a quick and prompt input to take an action. Smart grid enables this through a two-way communication between distribution and customers. A smart grid is a form of electricity network utilizing digital technology. A smart grid delivers electricity from suppliers to consumers using two-way digital communications to control appliances at consumers' homes; this saves energy, reduces costs and increases reliability and transparency. It overlays the ordinary electrical grid with an information and net metering system, that includes smart meters. Smart grids are being promoted by many governments as a way of addressing energy independence, global warming and emergency resilience issues. A smart grid is made possible by applying sensing, measurement and control devices with two-way communications to electricity production, transmission, distribution and consumption parts of the power grid that communicate information about grid condition to system users, operators and automated devices, making it possible to dynamically respond to changes in grid condition. Of course, I have given the definition which primarily stems from the distribution requirement of the transmitted power. You will hear totally different definition of smart grid from transmission experts and it is important to be aware of the distinction.

So just why it is important to have a smart-grid and why its existence is inevitable today than ever before? Reasons are many

  1. Response to many supply-demand conditions: A smart grid could respond to events which occur anywhere in the power generation, distribution and demand chain. Events may occur generally in the environment, e.g., clouds blocking the sun and reducing the amount of solar power or a very hot day requiring increased use of air conditioning. They could occur commercially in the power supply market, e.g., customers change their use of energy as prices are set to reduce energy use during high peak demand. Events might also occur locally on the distribution grid, e.g., an MV transformer fails, requiring a temporary shutdown of one distribution line. Finally these events might occur in the home, e.g., everyone leaves for work, putting various devices into hibernation, and data ceases to flow to an IPTV. Each event motivates a change to power flow. Latency of the data flow is a major concern, with some early smart meter architectures allowing actually as long as 24 hours delay in receiving the data, preventing any possible reaction by either supplying or demanding devices.
  2. Smart energy demand - Smart energy demand describes the energy user component of the smart grid. It goes beyond and means much more than even energy efficiency and demand response combined. Smart energy demand is what delivers the majority of smart meter and smart grid benefits. Smart energy demand is a broad concept. It includes any energy-user actions to enhancement of reliability, reduce peak demand, shift usage to off-peak hours, lower total energy consumption, actively manage electric vehicle charging, actively manage other usage to respond to solar, wind, and other renewable resources, and buy more efficient appliances and equipment over time based on a better understanding of how energy is used by each appliance or item of equipment. All of these actions minimize adverse impacts on electricity grids and maximize consumer savings. Smart Energy Demand mechanisms and tactics include: smart meters, dynamic pricing, smart thermostats and smart appliances, automated control of equipment, real-time and next day energy information feedback to electricity users, usage by appliance data, and scheduling and control of loads such as electric vehicle chargers, home area networks (HANs), and others.
  3. Peak load management and time of day pricing - To reduce demand during the high cost peak usage periods, communications and metering technologies inform smart devices in the home and business when energy demand is high and track how much electricity is used and when it is used. To motivate them to cut back use and perform what is called peak curtailment or peak leveling, prices of electricity are increased during high demand periods, and decreased during low demand periods. It is thought that consumers and businesses will tend to consume less during high demand periods if it is possible for consumers and consumer devices to be aware of the high price premium for using electricity at peak periods. This could mean making trade-offs such as cooking dinner at 9pm instead of 5pm. When businesses and consumers see a direct economic benefit of using energy at off-peak times become more energy efficient, the theory is that they will include energy cost of operation into their consumer device and building construction decisions.
  4. Real-time monitoring of grid performance will improve grid reliability and utilization, reduce blackouts, and increase financial returns on investments in the grid.
Finally, it boils down to whether we have sufficient electricity to meet demand. The answer is an affirmative no and hence focus shifted on optimal use of electricity. Starting from simple things like switching off lights and fans and AC when not required to shifting to CFLs and LEDs, each one of us can contribute a lot. From the utility side, the smart-grid will also offer similar benefits to the end-user while offering a platform for the utility to manage demand side requirements. The business case is clear for smart-grid and many Indian utilities are now looking at moving into smart grid implementations, not just because it makes the grid smart, it makes the business smarter too.

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