Resiliency-Oriented Microgrid Optimal Scheduling
TL;DR: A resiliency-oriented microgrid optimal scheduling model is proposed that is economically optimal, guarantees robustness against prevailing operational uncertainties, and supports a quick islanding with minimum consumer inconvenience and load curtailment.
Abstract: One of complementary value propositions of microgrids is to improve power system resiliency via local supply of loads and curtailment reduction. This subject is investigated in this paper by proposing a resiliency-oriented microgrid optimal scheduling model. The proposed model aims at minimizing the microgrid load curtailment by efficiently scheduling available resources when supply of power from the main grid is interrupted for an extended period of time. The problem is decomposed to normal operation and resilient operation problems. The normal operation problem solution, i.e., unit commitment states, energy storage schedules, and adjustable loads schedules, is employed in the resilient operation problem to examine microgrid capability in supplying local loads during main grid supply interruption. The schedule is revised via resiliency cuts if a zero mismatch is not obtained. Prevailing operational uncertainties in load, non-dispatchable generation, and the main grid supply interruption time and duration are considered and captured using a robust optimization method. The final solution, which is obtained in an iterative manner, is economically optimal, guarantees robustness against prevailing operational uncertainties, and supports a quick islanding with minimum consumer inconvenience and load curtailment. Numerical simulations demonstrate the effectiveness of the proposed resiliency-oriented microgrid optimal scheduling model applied to a test microgrid.
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TL;DR: This paper presents a review of issues concerning microgrid issues and provides an account of research in areas related to microgrids, including distributed generation, microgrid value propositions, applications of power electronics, economic issues, micro grid operation and control, micro grids clusters, and protection and communications issues.
Abstract: The significant benefits associated with microgrids have led to vast efforts to expand their penetration in electric power systems. Although their deployment is rapidly growing, there are still many challenges to efficiently design, control, and operate microgrids when connected to the grid, and also when in islanded mode, where extensive research activities are underway to tackle these issues. It is necessary to have an across-the-board view of the microgrid integration in power systems. This paper presents a review of issues concerning microgrids and provides an account of research in areas related to microgrids, including distributed generation, microgrid value propositions, applications of power electronics, economic issues, microgrid operation and control, microgrid clusters, and protection and communications issues.
875 citations
Cites background or methods from "Resiliency-Oriented Microgrid Optim..."
...In [294], an adaptive control strategy is proposed to augment the existing controllers and enhance their performance while monitoring the response of a controlled device and temporarily modulating its control set point to achieve close tracking of the set point in the presence of disturbances....
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...In [296], an adaptive control is presented for frequency regulation by using a combination of a classical PI controller and a PSO-fuzzy system....
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09 May 2017
TL;DR: It is concluded that networked microgrids in particular provide a universal solution for improving the resilience against extreme events in Smart Cities.
Abstract: This paper focuses on the role of networked microgrids as distributed systems for enhancing the power system resilience against extreme events. Resilience is an intrinsically complex property which requires deep understanding of microgrid operation in order to respond effectively in emergency conditions. The paper first introduces the definition and offers a generic framework for analyzing the power system resilience. The notion that large power systems can achieve a higher level of resilience through the deployment of networked microgrids is discussed in detail. In particular, the management of networked microgrids for riding through extreme events is analyzed. In addition, the merits of advanced information and communication technologies (ICTs) in microgrid-based distributed systems that can support the power system resilience are presented. The paper also points out the challenges for expanding the role of distributed systems and concludes that networked microgrids in particular provide a universal solution for improving the resilience against extreme events in Smart Cities.
393 citations
TL;DR: A microgrid planning model for determining the optimal size and the generation mix of distributed energy resources (DERs) as well as the microgrid type, i.e., ac or dc, is presented.
Abstract: This paper presents a microgrid planning model for determining the optimal size and the generation mix of distributed energy resources (DERs), as well as the microgrid type, i.e., ac or dc. Considering the growing ratio of dc loads and DERs, dc microgrids could be potentially more beneficial than ac microgrids by avoiding the need to synchronize generators, reducing the use of converters, facilitating the connection of various types of DERs and loads to the microgrid common bus with simplified interfaces, and reducing losses associated with the ac–dc energy conversion. The microgrid type is selected based on economic considerations, where the planning objective includes the investment and operation costs of DERs, cost of energy purchase from the main grid, and the reliability cost. Numerical simulations exhibit the effectiveness of the proposed model and investigate in detail the impact of variety of factors on planning results, including the ratio of critical loads, the ratio of dc loads, and the efficiency of inverters and converters.
342 citations
TL;DR: In this article, a robust optimization approach is adopted for considering forecast errors in load, variable renewable generation, and market prices, and the microgrid islanding is further treated as a source of uncertainty.
Abstract: This paper presents a model for the microgrid planning problem with uncertain physical and financial information. The microgrid planning problem investigates the economic viability of microgrid deployment and determines the optimal generation mix of distributed energy resources (DERs) for installation. Net metering is considered for exchanging power with the main grid and lowering the cost of unserved energy and DER investments. A robust optimization approach is adopted for considering forecast errors in load, variable renewable generation, and market prices. The microgrid islanding is further treated as a source of uncertainty. The microgrid planning problem is decomposed into an investment master problem and an operation subproblem. The optimal planning decisions determined in the master problem are employed in the subproblem to examine the optimality of the master solution by calculating the worst-case optimal operation under uncertain conditions. Optimality cuts sent to the master problem will govern subsequent iterations. Numerical simulations exhibit the effectiveness of the proposed model and further analyze the sensitivity of microgrid planning results on variety levels of uncertainty.
315 citations
09 May 2017
TL;DR: This paper provides an introduction to the fundamental concepts of power systems resilience and to the use of hardening and smart operational strategies to improve it, and introduces the resilience trapezoid as visual tool to reflect the behavior of a power system during a catastrophic event.
Abstract: Power systems have typically been designed to be reliable to expected, low-impact high-frequency outages. In contrast, extreme events, driven for instance by extreme weather and natural disasters, happen with low-probability, but can have a high impact. The need for power systems, possibly the most critical infrastructures in the world, to become resilient to such events is becoming compelling. However, there is still little clarity as to this relatively new concept. On these premises, this paper provides an introduction to the fundamental concepts of power systems resilience and to the use of hardening and smart operational strategies to improve it. More specifically, first the resilience trapezoid is introduced as visual tool to reflect the behavior of a power system during a catastrophic event. Building on this, the key resilience features that a power system should boast are then defined, along with a discussion on different possible hardening and smart, operational resilience enhancement strategies. Further, the so-called $\Phi \Lambda {E}\Pi $ resilience assessment framework is presented, which includes a set of resilience metrics capable of modeling and quantifying the resilience performance of a power system subject to catastrophic events. A case study application with a 29-bus test version of the Great Britain transmission network is carried out to investigate the impacts of extreme windstorms. The effects of different hardening and smart resilience enhancement strategies are also explored, thus demonstrating the practicality of the different concepts presented.
309 citations
Cites background from "Resiliency-Oriented Microgrid Optim..."
...Therefore, microgrids are proven to be one of the most effective ways of enhancing resilience to catastrophic events [33-37]....
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References
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TL;DR: The controller aims to optimize the operation of the microgrid during interconnected operation, i.e., maximize its value by optimizing the production of the local DGs and power exchanges with the main distribution grid.
Abstract: Microgrids are low-voltage (LV) distribution networks comprising various distributed generators (DGs), storage devices, and controllable loads that can operate either interconnected or isolated from the main distribution grid as a controlled entity. This paper describes the operation of a central controller for microgrids. The controller aims to optimize the operation of the microgrid during interconnected operation, i.e., maximize its value by optimizing the production of the local DGs and power exchanges with the main distribution grid. Two market policies are assumed including demand-side bidding options for controllable loads. The developed optimization algorithms are applied on a typical LV study case network operating under various market policies and assuming realistic spot market prices and DG bids reflecting realistic operational costs. The effects on the microgrid and the distribution network operation are presented and discussed.
932 citations
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24 Jun 2009TL;DR: In this article, the authors proposed a potential solution for sustainable, energy-efficient power supply to cater for increasing load growth, supplying power to remote areas, generation of clean power and reduction in emission of greenhouse gases & particulates as per Kyoto protocol.
Abstract: Microgrids and Active Distribution Networks offer a potential solution for sustainable, energy-efficient power supply to cater for increasing load growth, supplying power to remote areas, generation of clean power and reduction in emission of greenhouse gases & particulates as per Kyoto protocol.
754 citations
"Resiliency-Oriented Microgrid Optim..." refers background in this paper
...Themicrogrid islanding is typically performed to rapidly disconnect themicrogrid from themain distribution network in order to protect microgrid components from upstream disturbances, or to shield voltage sensitive loads from significant voltage drops in the main grid [8], [9]....
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TL;DR: The optimal ESS sizing problem is proposed which minimizes the investment cost of the ESS, as well as expected microgrid operating cost, and hence microgrid reliability criterion is satisfied.
Abstract: This paper presents a model for calculating the optimal size of an energy storage system (ESS) in a microgrid considering reliability criterion. A larger ESS requires higher investment costs while reduces the microgrid operating cost. The optimal ESS sizing problem is proposed which minimizes the investment cost of the ESS, as well as expected microgrid operating cost. Utilizing the ESS, generation shortage due to outage of conventional units and intermittency of renewable units is handled; hence microgrid reliability criterion is satisfied. A practical model for ESS is utilized. Mixed-integer programming (MIP) is utilized to formulate the problem. Illustrative examples show the efficiency of the proposed model.
413 citations
TL;DR: In this paper, a model for microgrid optimal scheduling considering multi-period islanding constraints is presented, where the objective of the problem is to minimize the microgrid total operation cost which comprises the generation cost of local resources and cost of energy purchase from the main grid.
Abstract: This paper presents a model for microgrid optimal scheduling considering multi-period islanding constraints. The objective of the problem is to minimize the microgrid total operation cost which comprises the generation cost of local resources and cost of energy purchase from the main grid. The microgrid optimal scheduling problem is decomposed into a grid-connected operation master problem and an islanded operation subproblem. The microgrid capability in operating in the islanded mode for multiple hours is scrutinized by a T-τ islanding criterion. The integer scheduling decisions determined in the master problem will be examined against the microgrid islanding feasibility in the subproblem. The scheduling decisions will be revised using proper islanding cuts if sufficient generation is not available to guarantee a feasible islanding. Islanding cuts will revise generating units, energy storage systems, and adjustable loads schedules. Any change in the schedule of adjustable loads outside the operating time interval specified by consumers is penalized by an inconvenience factor in the objective. Numerical simulations demonstrate the effectiveness of the proposed microgrid optimal scheduling model and explore its economic and reliability merits.
345 citations
Additional excerpts
...Microgrid components, including fixed and adjustable loads, dispatchable and non-dispatchable units, and energy storage, are identified and discussed in detail in the literature [22]....
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...The microgrid optimal scheduling model proposed in [22] is considered as the basis of this work and extended considerably to make the model applicable for resiliency applications....
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...The data for generating units, energy storage, and adjustable loads, as well as the forecasted values of microgrid hourly fixed load, non-dispatchable units’ generation, and market price are borrowed from [22]....
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TL;DR: In this paper, an algorithm for the microgrid planning as an alternative to the co-optimization of generation and transmission expansion planning in electric power systems is presented, which aims to minimize the total system planning cost comprising investment and operation costs of local microgrids, the cooptimized planning of large generating units and transmission lines, and the expected cost of unserved energy.
Abstract: This paper presents an algorithm for the microgrid planning as an alternative to the co-optimization of generation and transmission expansion planning in electric power systems. The integration of microgrids in distribution systems will offer a decentralized control of local resources for satisfying the network reliability and the power quality required by local loads. The objective in this paper is to minimize the total system planning cost comprising investment and operation costs of local microgrids, the co-optimized planning of large generating units and transmission lines, and the expected cost of unserved energy. The cost of unserved energy reflects the cost of load shedding which is added to the objective function for reliability considerations. The microgrid-based co-optimization planning problem is decomposed into a planning problem and annual reliability subproblem. The optimal integer planning decisions calculated in the planning problem will be examined against the system reliability limits in the subproblem and the planning decisions will be revised using proper feasibility cuts if the annual reliability limits are violated. Numerical simulations demonstrate the effectiveness of the proposed microgrid-based co-optimization planning in power systems and explore the economic and reliability merits of microgrid planning as compared to grid-based generation and transmission upgrades.
247 citations
"Resiliency-Oriented Microgrid Optim..." refers background in this paper
...Microgrids introduce unique opportunities in power system operation and planning such as improved reliability, higher power quality, reduction in carbon emission, utilization of less costly renewable energy sources, offering energy efficiency, reducing the total system expansion planning cost, and providing a quick and efficient response for supplying loads in remote areas [7]....
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