Smart Grid Technology for Better Integration of Renewable Energy Resources

Transcription

1 Smart Grid Technology for Better Integration of Renewable Energy Resources Dr.Ibrahem A. Elagtal 1 and Abdussalam A. Khamis 2 1 Faculty of Engineering Technology - Hoon, Libya elagtal52@yahoo.com 2 Faculty of Engineering Technology - Hoon, Libya abdussalam.khamis@yahoo.com Abstract Smart grid technology and its complex digitalized system is relatively a new concept in power systems. One of the potential advantages of this technology is its ability to make the connection of renewable resources into working electricity grids possible. This paper discusses two scenarios of implementing smart grid technology to facilitate integration of renewable energy into the Libyan electricity grid. The first scenario proposes some techniques that would play significant roles in connecting large-scale renewable energy plants into the Libyan national electricity grid. The second scenario discusses the roles that smart grid can play in order to support electrification services at distribution networks by supplying them with distributed generations. The validity of these two proposed scenarios are concluded in the end of the paper. Index Terms Smart Grid, Renewable Energy, Distributed Generation. I. INTRODUCTION Many electrical engineers like to define electricity grids as the most significant technological accomplishment of the 20th century. The electrical grid, however, still remains its 19th century construction with central generating stations, electromechanical power delivery systems, and central loads. The whole electric system is monitored from central control rooms with no actual communication between electricity providers and their clients. As an obligation, utilities have to satisfy their clients needs of energy whensoever by adjusting the power supply and demand on real-time bases. The 21th century has brought lots of challenges to the present electricity companies throughout the world. In addition to the limited available amounts of conventional energy sources (oil and natural gas), electricity companies are ordered to seriously address emission reduction of greenhouse gases, and deal with other regulatory that associated with climate change [1]. Moreover, penetration of intermittent resources of energy into the existing power grids is another challenge which has to be addressed more precisely. Obviously, todays electricity grids cannot function with high efficiency to correspond with these challenges because of the described old fashion infrastructure. In order to deal with future energy challenges, utilities must fundamentally modernize their strategies. Utilities, for instance, ought to create channels to communicate with their costumers. Furthermore, the utilities have to be able to secure the future of electrification by integrating renewable energy supplies within their Total Primary Energy Supply. It is highly recommended for Libyan electricity grid to take necessary measures to be in the same technological level with other countries. That would guarantee continuity of electrification services in future when conventional energy supplies are limited, and the demand for the energy is incredibly high. The objective of this paper is to discuss two potential scenarios of using smart grid technology to facilitate the integration of renewable energy resources into the Libyan national electricity network. The first scenario addresses largescale integration of renewable energy resources into the grid and the roles of smart grid technology. The second scenario discusses how smart grid technology assists in including power from distributed generation to support electrification services in distribution networks. II. LIBYAN RENEWABLE ENERGY CURRENT SITUATION Libya is an oil-exporting country. The total proven oil in the country is approximately 43 billion barrels, and it has increasing proven natural gas [2]. Consequently, Libya is relying on oil and natural gas as the primary sources of income as well as depending on them to produce electricity. Figure(1) illustrates the types of fuel that are used to produce electricity in Libya. As can be seen from Figure (1), up to 80% of the electricity comes from heavy and light fuels, and 20% comes from natural gas. clearly, the present contribution of renewable energy resources into the generated electricity is almost zero; nevertheless Renewable Energy Authority of Libya (REAOL) has attempted to implement some solar energy applications such as water pumping in rural areas and electrifying some security check points [3]. The total energy that can be obtained from renewable energy is estimated by 157 TWh/year. Figure (2) shows the main

2 Light Fuel Heavy Fuel Natural Gas 42% 20% 38% the governmental subsidization of the electricity prices. III. THE CONCEPT OF SMART GRID The term Smart Grid can be best defined as a unified communications and control systems on the existing power delivery infrastructure to provide the right information to the right entity at the right time to take the right action [1]. similarly, the Smart Grid is introduced as the integrated array of technologies, devices and systems that provide and utilize digital information, communications and controls to optimize the efficient, reliable, safe and secure delivery of electricity [2]. Fig. 1. Types of Fuel for Libyan Electricity production renewable energy resources in Libya, and their percentage from the total estimation. Ultimately, the both definition are serving same goal, which lead to digitalizing a traditional electricity grid to enhance its efficiency, reliability, and modernize customer services. Figure (3) demonstrates how smart grid technology facilitates information flow within an electricity network. Solar Energy Wind Energy Biomass 1% 10% 89% Fig. 3. Smart Grid and Information flow, Source (EPRI) Fig. 2. Renewable Energy Resources in Libyan It is obvious from Figure (2) that solar and wind energy are the main promising renewable energy resources in Libya. The solar energy represents 89% and the wind represents 10%. This encouraging amounts of solar energy could produce 140 TWh/year which can tremendously change the electrification landscape in the country. By the year of 2020, Libya is looking for 10% of the total produced electricity to come from renewable resources. In order to make this plan more realistic, the whole Libyan electricity national grid should be reconstructed. Yet, there are some challenges that can be considered as serious obstacles for achieving this goal, for instance. Old fashion construction of the Libyan electricity network, lack of awareness of importance of renewable energy, weakness in regulatory and policy for renewable energy, and The reality behind the Smart Grid is that this technology is not an individual devices or equipments that are equipped into a conventional electricity network to make it smarter, rather it is a combination of integrated devices and techniques to obtain the goal of modernization of electrification services.thus, the bulk of smart grid technologies and devices can enable utilities as same as consumers to[2]: Reduce the peak demand, shift usage to off-peak hours, lower total energy consumption, enhance system reliability, actively manage electric vehicle charging, actively manage other usage to respond to solar, wind, and other renewable resources, 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, and

3 downsize the monthly electricity bills In the marks there are many devises and techniques that can be used to accomplish the previous goals such as smart meters, dynamic pricing devices, smart thermostats, automated control of equipment, real-time next day energy information feedback to electricity users, usage by appliance data, and scheduling and control of loads. IV. SMART GRID TECHNOLOGY FOR INTEGRATION OF RENEWABLE RESOURCES Since utilities have no control over the variable electric load, electricity networks are designed to provide power instantaneously. In order to do so efficiently, electricity companies implement various load forecasting methods to predict the electric daily and monthly loads based on historical data. There is one obvious challenge to integrate renewable energy into a working electricity grid. The problem is that utilities can not guarantee the instantaneous power delivery because of the renewable resources changeable natural. That is, utilities cannot increase or decrease power from renewable energy resources whensoever needed. Fortunately, the new advanced devices and techniques of smart grid facilitate these sort of challenges by making arrangement between variability of intermittent energy resources and energy demand. The technical advanced for connecting large wind and solar farms into an electricity grid or energizing an isolated house from standalone wind turbine and rooftop solar panel are already known. However, the challenge in this matter is how even a small amount of integrated renewable energy can be notice in terms of its impacts on the whole electricity system, and ultimately reduce our dependency of fossil fouls as the only source of power. It is believed that without adapting smart grid technology and its ability to open two-way communication between costumers and utilities in order to shift usage to off-peak hours and influence costumers behaver for using energy, the objective of moving toward green energy can be hardly to accomplish. In this section we introduce two scenarios for integrating renewable energy into the Libyan electricity network, and the roles that smart grid technology can potentially play to make this integration possible and effective. A. Smart Grid for centralized Large-Scale Renewable Energy Integration In order for General Electric Company of Libya (GECOL) to achieve 10% renewable energy sharing by the year of 2020, the whole Libyan traditional electricity gird must be re-constructed. Also, the new electricity grid should be accompanied with new technological improvements which enable smooth integration of renewable resources in largescale levels. In another perspective, smart grid is capable of smoothingdown the intermittently natural of renewable energy resources. This advantage can be achieved by providing real-time information about renewable resources availability to both energy providers and energy consumers. Therefore, the large-scale integration is now possible due merely to the information provided by smart devices to adjust the demand side of the energy to the supply one. In the Libyan future electrification schemes both traditional power stations and centralize green power stations are connected to the same electrical grid. The techniques of realtime information, costumers dynamic pricing and scheduling and control of loads would accelerate the process of including renewable resources into the gird. Customers will have the privilege to choose the source of energy they want to use. Likely, utilities would inform ahead their clients about sources of energy they use, associated with the intermittent natural of renewable energy resources and their participation on the present power supply. Thus, customers might choose to consume more power when, for instance, a solar plant at its higher efficiency. In addition, when customers choose to change their energy consumption behavior, they will definitely participate in diminishing polluted gases; and therefore, save the environment as well as expand the penetration of renewable energy in the electricity marks. To evaluate these techniques, let s take the Libyan residential load as an example. Figure (4) demonstrates the daily residential load for one summer day. MW/day Hours Fig. 4. Total Daily Energy Consumption and Residential Daily Energy Consumption, Source (GECOL) As can be seen in Figure (4) the energy demand is at its lowest levels in the time period between 1 AM to 10 AM. Then it increases to reach its peak demand of 1789 MW at 9 PM. For the conventional power system operation, utilities do not have influence on consumers energy consumption behavior. Thus, in the traditional situation the supply side of energy is always modified to meet the demand, which makes it unpractical under such circumstances to integrate renewable resources because of their intermittently. However, smart grid

4 technology can facilitate integration of large-scale renewable energy resources into the grid and increase the reliability by shifting the load side to meet the available generated energy, which comes from renewable resources; therefore, variable energy supplies, solar and wind, can operate at their maximum efficiencies to serve part of the energy demand. The study in [6] shows that by sending certain messages through smart grid devices the energy generation side and demand side can be moved to a particular point of serving, rather than follow the old fashion methods of serving electric loads. Informed customer of such information as real-time pricing, environmental impacts of their energy use, and type of energy they use are more likely to decide to change their energy uses. Let s assume that the Libyan energy provider uses lifetime display, which allocated in every residential point on the distribution networks, to inform costumers with information such as: Reduction of electricity price if customers operate some of their appliances in off-peak times. Daily forecasting of solar and wind energies and the percentage of their contribution in the total supplied energy. Environmental impacts of using energy that comes from oil and natural gas. The expected responses of these messages would be positive and helping to crease the sharing of renewable energy in the total generated energy. However, there are many factors that might affect clients response to these sort of messages. Some of these factors are the level of eduction, whether a family is a working-family or not, and level of awareness of issues like climate change and reduction of greenhouse gases. Nevertheless, in some level Sending the appropriate messages at the right time to a big number of consumers would encourage them to change their energy uses to the point that make shifting the part of the load demand the available renewable energy possible, and also highlight the importance of renewable energy resources as energy supply. Some of householders may decide to do some home activities like laundry and ironing... etc in the morning instead of the evening where is the peak load, motivated by pricing intensives whensoever the solar and wind energies are available. Also, customers may decide to contribute in greenhouse gases reduction by using energy which has high percentage of solar energy at noon to operate some of their house appliances. It is worth mentioning that the actual motivation behind the expected corresponding with smart grid messages cannot be accurately predicted. What is important here, however, is knowing how much of the residential sector energy demand would increase or decease due to costumers response toward the information signals. Figure (5) illustrates three scenarios of response to smart grid messages which reduce the power consumption in the peak demand with 2.5%, 5%, and 10%, associated with 2.5%, 5%, and 10% increasing when renewable energy is available. MW / Day Smart Grid and Modification of Residential Daily Energy Consump- Fig. 5. tion Normnal Load Curve 2.5 % response to smart grid messages 5 % response to smart grid messages 10 % response to smart grid messages Hours of a Day It is obvious from Figure (5) that the peak Load, which accrues between 8 PM to 10 PM, would be noticeably diminished due to communication process between costumers and utilities. Therefore, a lot of distribution networks problems such as black-out and brown-out, which affect power quality, would be avoided or at least limited to the minimum values. Table (1) summarize the peak load reduction and the amounts of saved power due to real-time communication between a power provider and its clients. TABLE I PEAK LOAD REDUCTION DUE TO SMART GRID SIGNALS Response % OriginalP eakload(mw ) P eakloadreduction(mw ) SavingP oweratp eakload(mw ) The major benefit of the previous operation is reducing the peak demand to lower levels. The another benefit of the smart grid technology is informing costumers with best and efficient option of using energy. In this study, smart grid would inform costumers with times of the day when solar and wind energies are at their highest contribution on the generated energy. Therefore, costumers would cease using some of their houses appliances on the peak periods, and use them in the times that guarantee both clean and cheap energy. Table (2) shows the average amounts of power that generated from both Conventional and renewable resources.

5 TABLE II RENEWABLE ENERGY PARTICIPATION TO SERVE AN ELECTRIC LOAD Response % T otalaveragep owerdemand(mw ) CnventionalP ower(mw ) RenewableP ower(mw ) In time period 9 AM to 12 AM, the renewable energy participation on the produced power is considered to be 2.5%, 5%, 10% respectively. The communication ability of smart grid guides costumers to shift consume power at the peak load, where the power is expensive, and operate some of their appliances in this time where subsidized-clean energy is available. B. Smart Grid for Integrating Distributed generation resources Distributed generation combined with smart grid technology at the distribution networks would play a significant role in terms of enhancing the electrification services in the whole electricity system. Rooftop solar panels and standalone wind turbines, and in some cases plug-in vehicles, are considered the most common used technologies as distributed generation at distribution systems [7]. Figure (6) shows a model for future distribution system. loads at several points on the distribution network. The second power flow is from distributed generation in the distribution network into the whole distribution system for the electrification ancillary. Here are examples of messages that are proposed to convey through smart grid two-way of communication in terms of integrating distributed generation at the distribution network. Timing when utilities need power from distributed energy resources. Timing when costumers can provide power to the local electricity grid. Monterey values of providing energy to the grid at the peak demand. Reliability and sustainability benefits of enhancing the electrification services by the distributed sources. In order for costumers to be energy providers, they have to produce energy with the standardized voltage and frequency of the local distribution system. Otherwise, the load control devices will prevent the power comes from a particular house to enter the system. Smart meters will read the flow of power in the two directions. Hence, whenever costumers provide power to the network, the smart meters will count in the opposite direction, which mean money saving and using clean energy by other loads on the distribution system. V. CONCLUSION Fig. 6. Smart Grid and Distribution System, Source ( Benefits of the technologies of smart grid will be noticeable to costumers when they become energy providers. Smart meters and load control devices are proposed technologies for this scenario. Enabling customers to become energy providers is not an easy task. In addition to take the necessary political regulations, the whole construction of the distribution system should be modified and digitalized in the future in order to handle a such two-way of power flow. The first power flow is the traditional one where the power flows from the substation and distribution transformers to In this paper a hypothetical discussion has been made to study two different scenarios of how smart grid technology would assist in achieving the Libyan plan for 10% of renewable energy sharing of the total produced energy by the year of It has been concluded that the technology of smart grid can make the connection of large-scale renewable energy plants into the national grid possible by partially shifting the electric load from peak load period, which occurs in the evening in this study, to periods of time where renewable energy is available. That would overall reduce the dependency on fossil fuel as the only source of energy as well as cut down the peak load. Then, scenario of including distributed generation to distribution networks has been discussed. It was concluded that two-way communication ability of smart grid technology will provide a great assistance in terms of enabling rooftop solar panels and standalone wind turbines to support electrification services in distribution networks. REFERENCES [1] The Green Grid Energy Savings and Carbon Emissions Reductions Enabled by a Smart Grid. EPRI, Palo Alto, CA: [2] Methodological Approach for Estimating the Benefits and Costs of Smart Grid Demonstration Projects. EPRI, Palo Alto, CA: [3] GECOL Annual Report, GECOL, [4] GECOL Annual Report, GECOL, [5] Dr. Mohamed A. Eklat, Renewable Energy in Libya: Potential, Current situation, and Way forward. Libyan Ministry of Electricity and Renewable Energy, Presentation, May 2012.

6 [6] FPL, GE, Cisco, Silver Spring Rolling Out 1M Smart Meters: Cleantech News and Analysis. Smart Grid Miami: Earth2tech.com, ( ). Retrieved on [7] A. Bracale, P. Caramia, and D. Proto Optimal Operation of Smart Grids Including Distributed Generation Units and Plug in Vehicles. International Conference on Renewable Energies and Power Quality, Las Palmas de Gran Canaria (Spain), April, 2011