Article records
https://feeds.library.caltech.edu/people/Zhao-Changhong/article.rss
A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenTue, 16 Apr 2024 14:35:44 +0000Optimal Load Control via Frequency Measurement and Neighborhood Area Communication
https://resolver.caltech.edu/CaltechAUTHORS:20131203-091918486
Authors: {'items': [{'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Topcu-U', 'name': {'family': 'Topcu', 'given': 'Ufuk'}}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven H.'}, 'orcid': '0000-0001-6476-3048'}]}
Year: 2013
DOI: 10.1109/TPWRS.2013.2261096
We propose a decentralized optimal load control scheme that provides contingency reserve in the presence of sudden generation drop. The scheme takes advantage of flexibility of frequency responsive loads and neighborhood area communication to solve an optimal load control problem that balances load and generation while minimizing end-use disutility of participating in load control. Local frequency measurements enable individual loads to estimate the total mismatch between load and generation. Neighborhood area communication helps mitigate effects of inconsistencies in the local estimates due to frequency measurement noise. Case studies show that the proposed scheme can balance load with generation and restore the frequency within seconds of time after a generation drop, even when the loads use a highly simplified power system model in their algorithms. We also investigate tradeoffs between the amount of communication and the performance of the proposed scheme through simulation-based experiments.https://authors.library.caltech.edu/records/wdh99-fkz82Design and Stability of Load-Side Primary Frequency Control in Power Systems
https://resolver.caltech.edu/CaltechAUTHORS:20140529-094709292
Authors: {'items': [{'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Topcu-U', 'name': {'family': 'Topcu', 'given': 'Ufuk'}}, {'id': 'Li-Na', 'name': {'family': 'Li', 'given': 'Na'}}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven'}, 'orcid': '0000-0001-6476-3048'}]}
Year: 2014
DOI: 10.1109/TAC.2014.2298140
We present a systematic method to design ubiquitous continuous fast-acting distributed load control for primary frequency regulation in power networks, by formulating an optimal load control (OLC) problem where the objective is to minimize the aggregate cost of tracking an operating point subject to power balance over the network. We prove that the swing dynamics and the branch power flows, coupled with frequency-based load control, serve as a distributed primal-dual algorithm to solve OLC. We establish the global asymptotic stability of a multimachine network under such type of load-side primary frequency control. These results imply that the local frequency deviations on each bus convey exactly the right information about the global power imbalance for the loads to make individual decisions that turn out to be globally optimal. Simulations confirm that the proposed algorithm can rebalance power and resynchronize bus frequencies after a disturbance with significantly improved transient performance.https://authors.library.caltech.edu/records/srhae-p5128Distributed power flow loss minimization control for future grid
https://resolver.caltech.edu/CaltechAUTHORS:20150925-092242544
Authors: {'items': [{'id': 'Nakayama-Kiyoshi', 'name': {'family': 'Nakayama', 'given': 'Kiyoshi'}}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Bic-L-F', 'name': {'family': 'Bic', 'given': 'Lubomir F.'}}, {'id': 'Dillencourt-M-B', 'name': {'family': 'Dillencourt', 'given': 'Michael B.'}}, {'id': 'Brouwer-J', 'name': {'family': 'Brouwer', 'given': 'Jack'}}]}
Year: 2015
DOI: 10.1002/cta.1999
In this paper, a novel decentralized algorithm is proposed to minimize power flow loss in a large-scale future grid connecting with many real-time-distributed generation systems by which power flows bi-directionally. The DC-power loss at each link is defined as the product of resistance and the square of current that can be considered as a quadratic flow cost. We employ the notion of tie-sets that reduces the complexity of the power flow loss problem by dividing a power network into a set of loops that forms a linear vector space on which the power loss problem can be formulated as a convex optimization problem. As finding a solution in each tie-set enables global optimization, we realize parallel computing within a system of independent tie-sets by integrating autonomous agents. Simulation results demonstrate the minimization of the power loss on every link by iteratively optimized power flows and show the superiority against the traditional centralized optimization scheme.https://authors.library.caltech.edu/records/cbjtp-33b08Connecting Automatic Generation Control and Economic Dispatch From an Optimization View
https://resolver.caltech.edu/CaltechAUTHORS:20160921-122049751
Authors: {'items': [{'id': 'Li-Na', 'name': {'family': 'Li', 'given': 'Na'}}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Chen-Lijun', 'name': {'family': 'Chen', 'given': 'Lijun'}}]}
Year: 2016
DOI: 10.1109/TCNS.2015.2459451
Automatic generation control (AGC) regulates mechanical power generation in response to load changes through local measurements. Its main objective is to maintain system frequency and keep energy balanced within each control area in order to maintain the scheduled net interchanges between control areas. The scheduled interchanges as well as some other factors of AGC are determined at a slower time scale by considering a centralized economic dispatch (ED) problem among different generators. However, how to make AGC more economically efficient is less studied. In this paper, we study the connections between AGC and ED by reverse engineering AGC from an optimization view, and then we propose a distributed approach to slightly modify the conventional AGC to improve its economic efficiency by incorporating ED into the AGC automatically and dynamically.https://authors.library.caltech.edu/records/4cpmz-54x80Optimal Load-side Control for Frequency Regulation in Smart Grids
https://resolver.caltech.edu/CaltechAUTHORS:20171101-115726975
Authors: {'items': [{'id': 'Mallada-E', 'name': {'family': 'Mallada', 'given': 'Enrique'}, 'orcid': '0000-0003-1568-1833'}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven'}, 'orcid': '0000-0001-6476-3048'}]}
Year: 2017
DOI: 10.1109/TAC.2017.2713529
Frequency control rebalances supply and demand while maintaining the network state within operational margins. It is implemented using fast ramping reserves that are expensive and wasteful, and which are expected to become increasingly necessary with the current acceleration of renewable penetration. The most promising solution to this problem is the use of demand response, i.e., load participation in frequency control. Yet it is still unclear how to efficiently integrate load participation without introducing instabilities and violating operational constraints. In this paper, we present a comprehensive load-side frequency control mechanism that can maintain the grid within operational constraints. In particular, our controllers can rebalance supply and demand after disturbances, restore the frequency to its nominal value, and preserve interarea power flows. Furthermore, our controllers are distributed (unlike the currently implemented frequency control), can allocate load updates optimally, and can maintain line flows within thermal limits. We prove that such a distributed load-side control is globally asymptotically stable and robust to unknown load parameters. We illustrate its effectiveness through simulations.https://authors.library.caltech.edu/records/p6tpf-bzs41Profit Maximizing Planning and Control of Battery Energy Storage Systems for Primary Frequency Control
https://resolver.caltech.edu/CaltechAUTHORS:20170810-105250761
Authors: {'items': [{'id': 'Zhang-Ying-Jun', 'name': {'family': 'Zhang', 'given': 'Ying Jun'}}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Tang-Wanrong', 'name': {'family': 'Tang', 'given': 'Wanrong'}}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven H.'}, 'orcid': '0000-0001-6476-3048'}]}
Year: 2018
DOI: 10.1109/TSG.2016.2562672
We consider a two-level profit-maximizing strategy, including planning and control, for battery energy storage system (BESS) owners that participate in the primary frequency control (PFC) market. Specifically, the optimal BESS control minimizes the operating cost by keeping the state of charge (SoC) in an optimal range. Through rigorous analysis, we prove that the optimal BESS control is a "state-invariant" strategy in the sense that the optimal SoC range does not vary with the state of the system. As such, the optimal control strategy can be computed offline once and for all with very low complexity. Regarding the BESS planning, we prove that the the minimum operating cost is a decreasing convex function of the BESS energy capacity. This leads to the optimal BESS sizing that strikes a balance between the capital investment and operating cost. Our work here provides a useful theoretical framework for understanding the planning and control strategies that maximize the economic benefits of BESSs in ancillary service markets.https://authors.library.caltech.edu/records/xjzab-d1m36Distributed plug-and-play optimal generator and load control for power system frequency regulation
https://resolver.caltech.edu/CaltechAUTHORS:20180327-084750901
Authors: {'items': [{'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Mallada-E', 'name': {'family': 'Mallada', 'given': 'Enrique'}, 'orcid': '0000-0003-1568-1833'}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven H.'}, 'orcid': '0000-0001-6476-3048'}, {'id': 'Bialek-J', 'name': {'family': 'Bialek', 'given': 'Janusz'}}]}
Year: 2018
DOI: 10.1016/j.ijepes.2018.03.014
A distributed control scheme, which can be implemented on generators and controllable loads in a plug-and-play manner, is proposed for power system frequency regulation. The proposed scheme is based on local measurements, local computation, and neighborhood information exchanges over a communication network with an arbitrary (but connected) topology. In the event of a sudden change in generation or load, the proposed scheme can restore the nominal frequency and the reference inter-area power flows, while minimizing the total cost of control for participating generators and loads. Power network stability under the proposed control is proved with a relatively realistic model which includes nonlinear power flow and a generic (potentially nonlinear or high-order) turbine-governor model, and further with first- and second-order turbine-governor models as special cases. In simulations, the proposed control scheme shows a comparable performance to the existing automatic generation control (AGC) when implemented only on the generator side, and demonstrates better dynamic characteristics than AGC when each scheme is implemented on both generators and controllable loads. Simulation results also show robustness of the proposed scheme to communication link failure.https://authors.library.caltech.edu/records/37nnq-6dv36Distributed Frequency Control with Operational Constraints, Part II: Network Power Balance
https://resolver.caltech.edu/CaltechAUTHORS:20170726-155035857
Authors: {'items': [{'id': 'Wang-Zhaojian', 'name': {'family': 'Wang', 'given': 'Zhaojian'}, 'orcid': '0000-0002-4998-6339'}, {'id': 'Liu-Feng', 'name': {'family': 'Liu', 'given': 'Feng'}, 'orcid': '0000-0003-2279-2558'}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven H.'}, 'orcid': '0000-0001-6476-3048'}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Mei-Shengwei', 'name': {'family': 'Mei', 'given': 'Shengwei'}, 'orcid': '0000-0002-2757-5977'}]}
Year: 2019
DOI: 10.1109/TSG.2017.2731811
In Part I of this paper, we propose a decentralized optimal frequency control of multi-area power system with operational constraints, where the tie-line powers remain unchanged in the steady state and the power mismatch is balanced within individual control areas. In Part II of this paper, we propose a distributed controller for optimal frequency control in the network power balance case, where the power mismatch is balanced over the whole system. With the proposed controller, the tie-line powers remain within the acceptable range at equilibrium, while the regulation capacity constraints are satisfied both at equilibrium and during transient. It is revealed that the closed-loop system with the proposed controller carries out primal–dual updates with saturation for solving an associated optimization problem. To cope with discontinuous dynamics of the closed-loop system, we deploy the invariance principle for nonpathological Lyapunov function to prove its asymptotic stability. Simulation results are provided to show the effectiveness of our controller.https://authors.library.caltech.edu/records/7dpz2-fda60Distributed Frequency Control with Operational Constraints, Part I: Per-Node Power Balance
https://resolver.caltech.edu/CaltechAUTHORS:20170726-160828931
Authors: {'items': [{'id': 'Wang-Zhaojian', 'name': {'family': 'Wang', 'given': 'Zhaojian'}, 'orcid': '0000-0002-4998-6339'}, {'id': 'Liu-Feng', 'name': {'family': 'Liu', 'given': 'Feng'}, 'orcid': '0000-0003-2279-2558'}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven H.'}, 'orcid': '0000-0001-6476-3048'}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Mei-Shengwei', 'name': {'family': 'Mei', 'given': 'Shengwei'}, 'orcid': '0000-0002-2757-5977'}]}
Year: 2019
DOI: 10.1109/TSG.2017.2731810
This paper addresses the distributed optimal frequency control of multi-area power system with operational constraints, including the regulation capacity of individual control area and the power limits on tie-lines. Both generators and controllable loads are utilized to recover nominal frequencies while minimizing regulation cost. We study two control modes: 1) the per-node balance mode and 2) the network balance mode. In Part I of this paper, we only consider the per-node balance case, where we derive a completely decentralized strategy without the need for communication between control areas. It can adapt to unknown load disturbance. The tie-line powers are restored after load disturbance, while the regulation capacity constraints are satisfied both at equilibrium and during transient. We show that the closed-loop systems with the proposed control strategies carry out primal-dual updates for solving the associated centralized frequency optimization problems. We further prove the closed-loop systems are asymptotically stable and converge to the unique optimal solution of the centralized frequency optimization problems and their duals. Finally, we present simulation results to demonstrate the effectiveness of our design. In Part II of this paper, we address the network power balance case, where transmission congestions are managed continuously.https://authors.library.caltech.edu/records/4d9wj-z6b42Decentralized Provision of Renewable Predictions Within a Virtual Power Plant
https://resolver.caltech.edu/CaltechAUTHORS:20201105-145616008
Authors: {'items': [{'id': 'Chen-Yue', 'name': {'family': 'Chen', 'given': 'Yue'}, 'orcid': '0000-0002-7594-7587'}, {'id': 'Li-Tongxin', 'name': {'family': 'Li', 'given': 'Tongxin'}, 'orcid': '0000-0002-9806-8964'}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Wei-Wei', 'name': {'family': 'Wei', 'given': 'Wei'}, 'orcid': '0000-0002-1018-7708'}]}
Year: 2021
DOI: 10.1109/TPWRS.2020.3035174
The mushrooming of distributed energy resources turns end-users from passive price-takers to active market-participants. To manage massive proactive end-users efficiently, virtual power plant (VPP) as an innovative concept emerges. It can provide some necessary information to help consumers improve their profits and trade with the electricity market on behalf of them. One important information desired by consumers is the prediction of renewable outputs inside this VPP. Presently, most VPPs run in a centralized manner, which means the VPP predicts the outputs of all the renewable sources it manages and provides the predictions to every consumer who buys this information. We prove that providing predictions can boost social total surplus. However, with more consumers and renewables in the market, this centralized scheme needs extensive data communication and may jeopardize the privacy of individual stakeholders. In this paper, we propose a decentralized prediction provision algorithm in which consumers from each subregion only buy local predictions and exchange information with the VPP. Convergence is proved under a mild condition, and the demand gap between centralized and decentralized schemes is proved to have zero expectation and bounded variance. Illustrative examples show that the variance of this gap decreases with more consumers and higher uncertainty.https://authors.library.caltech.edu/records/dvfdb-8jr58Approaching Prosumer Social Optimum via Energy Sharing With Proof of Convergence
https://resolver.caltech.edu/CaltechAUTHORS:20210113-163505633
Authors: {'items': [{'id': 'Chen-Yue', 'name': {'family': 'Chen', 'given': 'Yue'}, 'orcid': '0000-0002-7594-7587'}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven H.'}, 'orcid': '0000-0001-6476-3048'}, {'id': 'Mei-Shengwei', 'name': {'family': 'Mei', 'given': 'Shengwei'}, 'orcid': '0000-0002-2757-5977'}]}
Year: 2021
DOI: 10.1109/tsg.2020.3048402
With the advent of prosumers, the traditional centralized operation may become impracticable due to computational burden, privacy concerns, and conflicting interests. In this article, an energy sharing mechanism is proposed to accommodate prosumers' strategic decision-making on their self-production and demand in the presence of capacity constraints. Under this setting, prosumers play a generalized Nash game. We prove main properties of the game: an equilibrium exists and is partially unique; no prosumer is worse off by energy sharing and the price-of-anarchy is 1−O(1/I) where I is the number of prosumers. In particular, the PoA tends to 1 with a growing number of prosumers, meaning that the resulting total cost under the proposed energy sharing approaches social optimum. We prove that the corresponding prosumers' strategies converge to the social optimal solution as well. Finally we propose a bidding process and prove that it converges to the energy sharing equilibrium under mild conditions. Illustrative examples are provided to validate the results.https://authors.library.caltech.edu/records/8gdt7-0wv71An Energy Sharing Mechanism Considering Network Constraints and Market Power Limitation
https://resolver.caltech.edu/CaltechAUTHORS:20230502-727238500.2
Authors: {'items': [{'id': 'Chen-Yue', 'name': {'family': 'Chen', 'given': 'Yue'}, 'orcid': '0000-0002-7594-7587'}, {'id': 'Zhao-Changhong', 'name': {'family': 'Zhao', 'given': 'Changhong'}, 'orcid': '0000-0003-0539-8591'}, {'id': 'Low-S-H', 'name': {'family': 'Low', 'given': 'Steven H.'}, 'orcid': '0000-0001-6476-3048'}, {'id': 'Wierman-A', 'name': {'family': 'Wierman', 'given': 'Adam'}, 'orcid': '0000-0002-5923-0199'}]}
Year: 2023
DOI: 10.1109/tsg.2022.3198721
As the number of prosumers with distributed energy resources (DERs) grows, the conventional centralized operation scheme may suffer from conflicting interests, privacy concerns, and incentive inadequacy. In this paper, we propose an energy sharing mechanism to address the above challenges. It takes into account network constraints and fairness among prosumers. In the proposed energy sharing market, all prosumers play a generalized Nash game. The market equilibrium is proved to have nice features in a large market or when it is a variational equilibrium. To deal with the possible market failure, inefficiency, or instability in general cases, we introduce a price regulation policy to avoid market power exploitation. The improved energy sharing mechanism with price regulation can guarantee the existence and uniqueness of a socially near-optimal market equilibrium. Some advantageous properties are proved, such as the prosumer's individual rationality, a sharing price structure similar to the locational marginal price, and the tendency towards social optimum with an increasing number of prosumers. For implementation, a practical bidding algorithm is developed with a convergence condition. Experimental results validate the theoretical outcomes and show the practicability of our model and method.https://authors.library.caltech.edu/records/npwrx-d8m85