The Experts below are selected from a list of 243219 Experts worldwide ranked by ideXlab platform
Frede Blaabjerg - One of the best experts on this subject based on the ideXlab platform.
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autonomous economic operation of grid connected dc microgrid
International Symposium on Power Electronics for Distributed Generation Systems, 2014Co-Authors: Inam Ullah Nutkani, Poh Chiang Loh, Wang Peng, Frede BlaabjergAbstract:This paper presents an autonomous power sharing scheme for economic operation of grid-connected DC microgrid. Autonomous economic operation approach has already been tested for standalone AC microgrids to reduce the overall Generation Cost and proven a simple and easier to realize compared with the centralized management approach. In this paper, the same concept has been extended to grid-connected DC microgrid. The proposed economic droop scheme takes into consideration the power Generation Cost of Distributed Generators (DGs) and utility grid tariff and adaptively tunes their respective droop curves. The scheme can be realized with the local information (terminal voltages and currents) without centralized controller and high bandwidth communication links. Microgrid voltage can be maintained within the define limit (±5%), which, if required, can be restored back to the nominal value through the proposed secondary control. The performance of the proposed scheme has been verified for the example grid-connected DC microgrid.
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Cost based droop scheme with lower Generation Costs for microgrids
Iet Power Electronics, 2014Co-Authors: Inam Ullah Nutkani, Poh Chiang Loh, Frede BlaabjergAbstract:In an autonomous microgrid where centralised management and communication links are not viable, droop control has been the preferred scheme for distributed generators (DGs). At present, although many droop variations have surfaced, they mainly focus on achieving proportional power sharing based on the DG kilovolts ampere (kVA) ratings. Other factors like Generation Costs, efficiencies and emission penalties at different load demands have not been considered. This omission might not be appropriate if different types of DGs are present in the microgrids. As an alternative, this study proposes a Cost-based droop scheme, whose objective is to reduce a Generation Cost function realised with various DG operating characteristics taken into consideration. Where desired, proportional power sharing based on the DG kVA ratings can also be included, whose disadvantage is a slightly higher Generation Cost, which is still lower than that produced by the traditional droop schemes. The proposed droop scheme therefore retains all advantages of the traditional droop schemes, whereas at the same time, keeps its Generation Cost low. These findings have been validated in experiments.
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autonomous droop scheme with reduced Generation Cost
IEEE Transactions on Industrial Electronics, 2014Co-Authors: Inam Ullah Nutkani, Poh Chiang Loh, Peng Wang, Frede BlaabjergAbstract:Droop schemes have traditionally been applied to the control of parallel synchronous generators in power systems. It has subsequently been brought over to the control of distributed generators (DGs) in microgrids with the same retained objective of proportional power sharing based on ratings. This objective might, however, not suit microgrids well since DGs are usually of different types, unlike synchronous generators. Other factors like Cost, efficiency, and emission penalty of each DG at different loading must be considered since they contribute directly to the total Generation Cost (TGC) of the microgrid. To reduce this TGC without relying on fast communication links, an autonomous droop scheme is proposed here, whose resulting power sharing is decided by the individual DG Generation Costs. Comparing it with the traditional scheme, the proposed scheme retains its simplicity and it is hence more likely to be accepted by the industry. The reduction in TGC has been verified by experiment.
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Cost based droop scheme with lower Generation Costs for microgrids
IEEE ECCE Asia Downunder, 2013Co-Authors: Inam Ullah Nutkani, Poh Chiang Loh, Frede BlaabjergAbstract:In an autonomous microgrid where centralized management and communication links are not viable, droop control has been the preferred scheme for power sharing among distributed generators (DGs). At present, although many droop variations have been proposed to achieve proportional power sharing based on the DG kVA ratings. Other operating characteristics like Generation Costs, efficiencies and emission penalties at different loadings have not been considered. This makes existing droop schemes not too well-suited for standalone microgrids without central management system, where different types of DGs usually exist. As an alternative, this paper proposes a Cost-based droop scheme, whose objective is to reduce a Generation Cost realized with various DG operating characteristics taken into consideration. The proposed droop scheme therefore retains all advantages of the traditional droop schemes, while at the same time keep its Generation Cost low. These findings have been validated through simulation and scaled down lab experiment.
Simone Baldi - One of the best experts on this subject based on the ideXlab platform.
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distributed reinforcement learning algorithm for dynamic economic dispatch with unknown Generation Cost functions
IEEE Transactions on Industrial Informatics, 2020Co-Authors: Pengcheng Dai, Guanghui Wen, Simone BaldiAbstract:In this article, the dynamic economic dispatch (DED) problem for smart grid is solved under the assumption that no knowledge of the mathematical formulation of the actual Generation Cost functions is available. The objective of the DED problem is to find the optimal power output of each unit at each time so as to minimize the total Generation Cost. To address the lack of a priori knowledge, a new distributed reinforcement learning optimization algorithm is proposed. The algorithm combines the state-action-value function approximation with a distributed optimization based on multiplier splitting. Theoretical analysis of the proposed algorithm is provided to prove the feasibility of the algorithm, and several case studies are presented to demonstrate its effectiveness.
Inam Ullah Nutkani - One of the best experts on this subject based on the ideXlab platform.
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autonomous economic operation of grid connected dc microgrid
International Symposium on Power Electronics for Distributed Generation Systems, 2014Co-Authors: Inam Ullah Nutkani, Poh Chiang Loh, Wang Peng, Frede BlaabjergAbstract:This paper presents an autonomous power sharing scheme for economic operation of grid-connected DC microgrid. Autonomous economic operation approach has already been tested for standalone AC microgrids to reduce the overall Generation Cost and proven a simple and easier to realize compared with the centralized management approach. In this paper, the same concept has been extended to grid-connected DC microgrid. The proposed economic droop scheme takes into consideration the power Generation Cost of Distributed Generators (DGs) and utility grid tariff and adaptively tunes their respective droop curves. The scheme can be realized with the local information (terminal voltages and currents) without centralized controller and high bandwidth communication links. Microgrid voltage can be maintained within the define limit (±5%), which, if required, can be restored back to the nominal value through the proposed secondary control. The performance of the proposed scheme has been verified for the example grid-connected DC microgrid.
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Cost based droop scheme with lower Generation Costs for microgrids
Iet Power Electronics, 2014Co-Authors: Inam Ullah Nutkani, Poh Chiang Loh, Frede BlaabjergAbstract:In an autonomous microgrid where centralised management and communication links are not viable, droop control has been the preferred scheme for distributed generators (DGs). At present, although many droop variations have surfaced, they mainly focus on achieving proportional power sharing based on the DG kilovolts ampere (kVA) ratings. Other factors like Generation Costs, efficiencies and emission penalties at different load demands have not been considered. This omission might not be appropriate if different types of DGs are present in the microgrids. As an alternative, this study proposes a Cost-based droop scheme, whose objective is to reduce a Generation Cost function realised with various DG operating characteristics taken into consideration. Where desired, proportional power sharing based on the DG kVA ratings can also be included, whose disadvantage is a slightly higher Generation Cost, which is still lower than that produced by the traditional droop schemes. The proposed droop scheme therefore retains all advantages of the traditional droop schemes, whereas at the same time, keeps its Generation Cost low. These findings have been validated in experiments.
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autonomous droop scheme with reduced Generation Cost
IEEE Transactions on Industrial Electronics, 2014Co-Authors: Inam Ullah Nutkani, Poh Chiang Loh, Peng Wang, Frede BlaabjergAbstract:Droop schemes have traditionally been applied to the control of parallel synchronous generators in power systems. It has subsequently been brought over to the control of distributed generators (DGs) in microgrids with the same retained objective of proportional power sharing based on ratings. This objective might, however, not suit microgrids well since DGs are usually of different types, unlike synchronous generators. Other factors like Cost, efficiency, and emission penalty of each DG at different loading must be considered since they contribute directly to the total Generation Cost (TGC) of the microgrid. To reduce this TGC without relying on fast communication links, an autonomous droop scheme is proposed here, whose resulting power sharing is decided by the individual DG Generation Costs. Comparing it with the traditional scheme, the proposed scheme retains its simplicity and it is hence more likely to be accepted by the industry. The reduction in TGC has been verified by experiment.
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Cost based droop scheme with lower Generation Costs for microgrids
IEEE ECCE Asia Downunder, 2013Co-Authors: Inam Ullah Nutkani, Poh Chiang Loh, Frede BlaabjergAbstract:In an autonomous microgrid where centralized management and communication links are not viable, droop control has been the preferred scheme for power sharing among distributed generators (DGs). At present, although many droop variations have been proposed to achieve proportional power sharing based on the DG kVA ratings. Other operating characteristics like Generation Costs, efficiencies and emission penalties at different loadings have not been considered. This makes existing droop schemes not too well-suited for standalone microgrids without central management system, where different types of DGs usually exist. As an alternative, this paper proposes a Cost-based droop scheme, whose objective is to reduce a Generation Cost realized with various DG operating characteristics taken into consideration. The proposed droop scheme therefore retains all advantages of the traditional droop schemes, while at the same time keep its Generation Cost low. These findings have been validated through simulation and scaled down lab experiment.
Steven H Low - One of the best experts on this subject based on the ideXlab platform.
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distributed generator and load side secondary frequency control in power networks
Conference on Information Sciences and Systems, 2015Co-Authors: Changhong Zhao, Enrique Mallada, Steven H LowAbstract:We design a distributed secondary frequency control scheme for both generators and controllable loads. The proposed scheme operates via local sensing and computation, and neighborhood communication. Equilibrium and stability analysis of the closed-loop system is performed with a power network model including turbines and governors of generators and nonlinear AC power flows. After a change in power supply or demand, the proposed scheme is able to stabilize the system, restore bus frequencies and net inter-area power exchanges, and minimize total Generation Cost minus user utility at equilibrium.
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exact convex relaxation of optimal power flow in radial networks
IEEE Transactions on Automatic Control, 2015Co-Authors: Lingwen Gan, Ufuk Topcu, Steven H LowAbstract:The optimal power flow (OPF) problem determines a network operating point that minimizes a certain objective such as Generation Cost or power loss. It is nonconvex. We prove that a global optimum of OPF can be obtained by solving a second-order cone program, under a mild condition after shrinking the OPF feasible set slightly, for radial power networks. The condition can be checked a priori, and holds for the IEEE 13, 34, 37, 123-bus networks and two real-world networks.
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optimal power flow in direct current networks
Conference on Decision and Control, 2013Co-Authors: Lingwen Gan, Steven H LowAbstract:The optimal power flow (OPF) problem seeks to control power Generation/demand to optimize certain objectives such as minimizing the Generation Cost or power loss. Direct current (DC) networks (e.g., DC-microgrids) are promising to incorporate distributed Generation. This paper focuses on the OPF problem in DC networks. The OPF problem is nonconvex, and we study solving it via a second-order cone programming (SOCP) relaxation. In particular, we prove that the SOCP relaxation is exact if there are no voltage upper bounds, and that the SOCP relaxation has at most one solution if it is exact.
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exact convex relaxation of optimal power flow in radial networks
arXiv: Optimization and Control, 2013Co-Authors: Lingwen Gan, Ufuk Topcu, Steven H LowAbstract:The optimal power flow (OPF) problem determines power Generation/demand that minimize a certain objective such as Generation Cost or power loss. It is nonconvex. We prove that, for radial networks, after shrinking its feasible set slightly, the global optimum of OPF can be recovered via a second-order cone programming (SOCP) relaxation under a condition that can be checked a priori. The condition holds for the IEEE 13-, 34-, 37-, 123-bus networks and two real-world networks, and has a physical interpretation.
Derek Abbott - One of the best experts on this subject based on the ideXlab platform.
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Cost based droop schemes for economic dispatch in islanded microgrids
IEEE Transactions on Smart Grid, 2017Co-Authors: Feixiong Chen, Minyou Chen, Kaikai Meng, Yongwei Zheng, Josep M Guerrero, Derek AbbottAbstract:In this paper, Cost-based droop schemes are proposed, to minimize the total active power Generation Cost in an islanded microgrid (MG), while the simplicity and decentralized nature of the droop control are retained. In Cost-based droop schemes, the incremental Costs of distributed generators (DGs) are embedded into the droop schemes, where the incremental Cost is a derivative of the DG Cost function with respect to output power. In the steady state, DGs share a single common frequency, and Cost-based droop schemes equate incremental Costs of DGs, thus minimizing the total active power Generation Cost, in terms of the equal incremental Cost principle. Finally, simulation results in an islanded MG with high a penetration of intermittent renewable energy sources are presented, to demonstrate the effectiveness, as well as plug and play capability of the Cost-based droop schemes.