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Optimal load-side control for frequency regulation in smart grids
"... Abstract—Frequency control rebalances supply and demand while maintaining the network state within operational mar-gins. It is implemented using fast ramping reserves that are expensive and wasteful, and which are expected to grow with the increasing penetration of renewables. The most promising sol ..."
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Cited by 8 (3 self)
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Abstract—Frequency control rebalances supply and demand while maintaining the network state within operational mar-gins. It is implemented using fast ramping reserves that are expensive and wasteful, and which are expected to grow with the increasing penetration of renewables. 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 oper-ational constraints. Our controllers can rebalance supply and demand after disturbances, restore the frequency to its nominal value and preserve inter-area power flows. Furthermore, our controllers are distributed (unlike generation-side), can allocate load updates optimally, and can maintain line flows within ther-mal limits. We prove that such a distributed load-side control is globally asymptotically stable and illustrate its convergence with simulation. I.
Reverse and Forward Engineering of Frequency Control in Power Networks
"... Abstract — We reverse-engineer the frequency dynamics with general primary frequency control and show that it is a dis-tributed algorithm to solve a well-defined optimization problem. We further investigate the role of deadband in control, and show that if the aggregated uncontrolled load deviation ..."
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Cited by 6 (1 self)
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Abstract — We reverse-engineer the frequency dynamics with general primary frequency control and show that it is a dis-tributed algorithm to solve a well-defined optimization problem. We further investigate the role of deadband in control, and show that if the aggregated uncontrolled load deviation is nonzero the frequencies will be synchronized, and if however it is zero the frequencies may oscillate but within the deadband. The optimization based model does not only provide a way to characterize the equilibrium and establish the convergence of the frequency dynamics, but also suggests a principled way to engineer frequency control. By leveraging the optimization problem and insights from reverse engineering, we design a dis-tributed realtime frequency control scheme that does not only maintain the frequency to the nominal value, but also achieve economic efficiency. This is drastically different from the current hierarchical control approach that addresses frequency regulation and economic efficiency at different timescales and with centralized control, and is what is needed for future power system to cope with rapid and large fluctuations in supply/demand and manage a huge number of control points. This work presents a step towards developing a new foundation – network dynamics as optimization algorithm – for distributed realtime control and optimization of future power networks. I.
Fair load-side control for frequency regulation in smart grids
"... Abstract—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 non-renewable, and which are expected to grow with the increasing penetration of renewables. The most promising ..."
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Cited by 3 (2 self)
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Abstract—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 non-renewable, and which are expected to grow with the increasing penetration of renewables. 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 fre-quency control mechanism that can maintain the grid within operational constraints. Our controllers can rebalance supply and demand after disturbances, restore the frequency to its nominal value and preserve inter-area power flows. Further-more, our controllers are distributed (unlike generation-side), fair among participating loads, and can further maintain line flows within thermal limits. We prove that such a distributed load-side control is globally asymptotically stable and illustrate its convergence with simulation. I.
Distributed Frequency Control for Stability and Economic Dispatch in Power Networks
"... Abstract — We explore two different frequency control strate-gies to ensure stability of power networks and achieve economic dispatch between generators and controllable loads. We first show the global asymptotic stability of a completely decentral-ized frequency integral control. Then we design a d ..."
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Cited by 2 (1 self)
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Abstract — We explore two different frequency control strate-gies to ensure stability of power networks and achieve economic dispatch between generators and controllable loads. We first show the global asymptotic stability of a completely decentral-ized frequency integral control. Then we design a distributed averaging-based integral (DAI) control which operates by local frequency sensing and neighborhood communication. Equilib-rium analysis shows that DAI recovers nominal frequency with minimum total generation cost and user disutility for load control after a change in generation or load. Local asymptotic stability of DAI is established with a Lyapunov method. Simu-lations demonstrate improvement in both transient and steady-state performance achieved by the proposed control strategies, compared to droop control. I.
A unified framework for frequency control and congestion management in low-inertia power systems
- In preparation
"... Abstract—The existing frequency control framework in power systems is challenged by lower inertia and more volatile power in-jections. We propose a new framework for frequency control and congestion management. We formulate an optimization problem that rebalances power, restores the nominal frequenc ..."
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Cited by 1 (1 self)
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Abstract—The existing frequency control framework in power systems is challenged by lower inertia and more volatile power in-jections. We propose a new framework for frequency control and congestion management. We formulate an optimization problem that rebalances power, restores the nominal frequency, restores inter-area flows and maintains line flows below their limits in a way that minimizes the control cost. The cost can be squared devi-ations from the reference generations, minimizing the disruption from the last optimal dispatch. Our control thus maintains system security without interfering with the market operation. By deriv-ing a primal-dual algorithm to solve this optimization, we design a completely decentralized primary frequency control without the need for explicit communication among the participating agents, and a distributed unified control which integrates primary and secondary frequency control and congestion management. Simulations show that the unified control not only achieves all the desired control goals in system equilibrium, but also improves the transient compared to traditional control schemes. Index Terms—Congestion management, distributed control, frequency control, low-inertia systems. I.
Distributed Generator and Load-Side Secondary Frequency Control in Power Networks
"... Abstract—We design a distributed secondary frequency con-trol 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 netw ..."
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Abstract—We design a distributed secondary frequency con-trol 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. I.
Research on the Design and Implementation of Distributed Electrical Control Systems
"... Abstract. The consolidation of the applicability of the method of communication, has the ability to coordinate the internal mode conversion only rely on distributed PLS signal DEM system has been developed. It has been shown, this coordination can be used for a plurality of battery application and S ..."
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Abstract. The consolidation of the applicability of the method of communication, has the ability to coordinate the internal mode conversion only rely on distributed PLS signal DEM system has been developed. It has been shown, this coordination can be used for a plurality of battery application and Study on method of scalability, and at the same time management more units are discussed from the angle of the control more senior and brought from the viewpoint of system dynamics limitation. Our research focuses on distributed electrical control systems and the experimental analysis shows the feasibility of our research.
1Connecting Automatic Generation Control and Economic Dispatch from an Optimization View
"... Abstract—Automatic generation control (AGC) regulates me-chanical 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 so as to maintain the scheduled net interchanges between con ..."
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Abstract—Automatic generation control (AGC) regulates me-chanical 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 so as 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. I.
Distributed
"... optimization decomposition for joint economic dispatch and frequency regulation ..."
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optimization decomposition for joint economic dispatch and frequency regulation
