This paper investigates the optimal resource management in a microgrid under various operating conditions. A two-level optimization system is proposed for the distributed optimal resource management based on a multi-a...
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This paper investigates the optimal resource management in a microgrid under various operating conditions. A two-level optimization system is proposed for the distributed optimal resource management based on a multi-agent system framework. The proposed strategy generates a reference of the optimal power output at the top level through local communication. This strategy only requires the information among neighboring participants without a central control coordination, and simultaneously accomplishes resource optimization in a finite time while maintaining the supply-demand balance. The bottom-level control is responsible for the reference tracking of each corresponding participant in a microgrid. The convergent rate of the proposed algorithm is compared with other consensus-based algorithms through simulation studies. Simulation results in the IEEE 14-bus system and an actual islanded system are also presented to demonstrate the overall effectiveness of the proposed strategy.
This paper investigates the fixed-wing aircraft flocking problem with nonholonomic constraints, speed limits, conflict avoidance, and the efficient use of airspace taken into account. It is challenging to simultaneous...
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This paper investigates the fixed-wing aircraft flocking problem with nonholonomic constraints, speed limits, conflict avoidance, and the efficient use of airspace taken into account. It is challenging to simultaneously address all of these issues with less restrictive requirements on the initial configuration of the aircraft, and yet, there are few theoretically rigorous works explicitly considering the fixed-wing aircraft flocking problem. Proposed here is a hybrid flocking control algorithm with three modes of decentralized flocking control protocol and a state-dependent switching logic. The three modes of control protocol are designed using artificial potential fields to address the collective flight behavior subject to the constraints of fixed-wing aircraft. The mode switching logic is designed based on the invariance principle, such that the desired convergence properties are guaranteed to be achieved. In addition, the proposed hybrid flocking control algorithm avoids undesirable fast mode switching.
The voltage rise problem in low voltage distribution networks with high penetration of photovoltaic (PV) resources is one of the most important challenges in the development of these renewable resources since it may p...
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The voltage rise problem in low voltage distribution networks with high penetration of photovoltaic (PV) resources is one of the most important challenges in the development of these renewable resources since it may prevent the maximum PV penetration considering the reliability and security issues of distribution networks. In this paper, the battery energy storage (BES) systems are used in order to solve the voltage rise during the peak PV generation as well as the voltage drop while meeting the peak load. A coordinated control strategy is proposed to regulate the charge/discharge of BESs using a combination of the local droop-based control method and a distributed control scheme which ensures the voltages of feeder remain within allowed limits. Therefore, two different consensus algorithms are used: the first algorithm determines the BESs participation in voltage regulation in terms of their installed capacity whereas the second one modifies the BESs performance in terms of their state of charge to prevent the excessive saturation or depletion of batteries. The proposed controller enables the effective use of storage capacity in different conditions. Finally, the simulation results based upon real data of a radial distribution feeder validate the effectiveness of this approach.
In this paper, we investigate the perfect consensus problem for second-order linearly parameterised multi-agent systems (MAS) with imprecise communication topology structure. Takagi-Sugeno (T-S) fuzzy models are prese...
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In this paper, we investigate the perfect consensus problem for second-order linearly parameterised multi-agent systems (MAS) with imprecise communication topology structure. Takagi-Sugeno (T-S) fuzzy models are presented to describe the imprecise communication topology structure of leader-following MAS, and a distributed adaptive iterative learning control protocol is proposed with the dynamic of leader unknown to any of the agent. The proposed protocol guarantees that the follower agents can track the leader perfectly on [0,T] for the consensus problem. Under alignment condition, a sufficient condition of the consensus for closed-loop MAS is given based on Lyapunov stability theory. Finally, a numerical example and a multiple pendulum system are given to illustrate the effectiveness of the proposed algorithm.
We consider the distributed maneuvering target tracking in the wireless sensor network (WSN), where the maneuvering target may appear in or disappear from the surveillance region at random instances. We first develop ...
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We consider the distributed maneuvering target tracking in the wireless sensor network (WSN), where the maneuvering target may appear in or disappear from the surveillance region at random instances. We first develop a multi-model Bernoulli filter, which is based on the interacting multiple model method and the Bernoulli filter. Then, we present a centralized implementation (CI) of the multi-model Bernoulli filter, where a fictitious fusion center (FC) has the information of all sensors and is responsible for the CI. Finally, we present a consensus-based distributed implementation of the multi-model Bernoulli filter, where no FC exists in the WSN. Each sensor only communicates with its neighbors which enables the scalability in the network. By using average-consensus algorithms, each sensor iteratively diffuses its private information to the whole network. Numerical results illustrate that the distributed estimate at each sensor can be close to the global estimate at the FC.
In this Paper, we present a complete, proof-of-concept sense-and-avoid solution for small unmanned aircraft systems, including a small low-cost ground-based radar system, multitarget tracking and estimation, collision...
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In this Paper, we present a complete, proof-of-concept sense-and-avoid solution for small unmanned aircraft systems, including a small low-cost ground-based radar system, multitarget tracking and estimation, collision detection, and an avoidance planner. We describe the development of a small frequency-modulated continuous-wave phased-array radar system that provides a three-dimensional surveillance volume. The radar measurements are processed using the recursive random sample consensus algorithm, producing tracks for the intruders and the ownship. We propose a collision-detection algorithm based on the geometric relationship between encountering aircraft. If a collision threat is detected, a collision-free new path is generated for the ownship using a two-step path-planning algorithm. In the first step, an initial suboptimal path is generated using an A* search. In the second step, the path is refined using a variant of the potential fields technique, adapted to the sense-and-avoid scenario. The performance of the complete system is demonstrated with flight-test experiments.
This paper proposes a distributed model predictive control (MPC) approach for a family of discrete-time linear systems with local (uncoupled) and global (coupled) constraints. The proposed approach is based on the dua...
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This paper proposes a distributed model predictive control (MPC) approach for a family of discrete-time linear systems with local (uncoupled) and global (coupled) constraints. The proposed approach is based on the dual problem of an overall MPC optimization problem involving all systems, which is then solved distributively using a modified distributed Nesterov-accelerated-gradient algorithm. To further reduce the computational requirement, this approach allows for early termination of the distributed gradient algorithm. This is made possible via a consensus algorithm that determines the satisfaction of the termination condition and by appropriate tightening of the coupled constraints. Under reasonable assumptions, the approach is able to produce a suboptimal solution as long as the network of the systems is connected while ensuring recursive feasibility and exponential stability of the closed-loop system. The performance of the proposed approach is demonstrated by a numerical example.
This work presents a management strategy for microgrid (MG) operation. Photovoltaic (PV) and wind generators, as well as storage systems and conventional units, are distributed over a wide geographical area, forming a...
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This work presents a management strategy for microgrid (MG) operation. Photovoltaic (PV) and wind generators, as well as storage systems and conventional units, are distributed over a wide geographical area, forming a distributed energy system, which is coordinated to face any contingency of the utility company by means of its isolated operation. The management strategy divides the system into three main layers: renewable generation, storage devices, and conventional units. Interactions between devices of the same layer are determined by solving an economic dispatch problem (EDP) in a distributed manner using a consensus algorithm (CA), and interactions between layers are determined by means of a load following strategy. In this way, the complex behaviour of PV and wind generation, the battery storage system, and conventional units has been effectively combined with CA to solve EDP in a distributed manner. MG performance and its vulnerability are deeply analysed by means of an illustrative case study. From the observed results, vulnerability under extreme conditions could be reduced up to approximately 30% by coupling distributed renewable generation and storage capacity with an energy system based on conventional generation.
The growth in installed solar photovoltaic (PV) capacity and the ever-increasing power demand due to the use of energy-hungry appliances have caused voltage issues. In this paper, a hierarchical dispatch strategy is p...
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The growth in installed solar photovoltaic (PV) capacity and the ever-increasing power demand due to the use of energy-hungry appliances have caused voltage issues. In this paper, a hierarchical dispatch strategy is proposed for coordinating multiple groups of virtual energy storage systems (VESSs), i.e., residential houses with air conditioners, to regulate voltage in low-voltage (LV) grids with high solar PV penetration. Specifically, the two levels of the proposed model are: 1) in the lower level, VESSs within each intelligent residential district are controlled locally by individual aggregator;2) in the upper level, multiple aggregators are coordinated to achieve voltage regulation through a consensus control strategy. By exchanging information through sparse communication links, each aggregator shares the required active power adjustment among all participating groups, without compromising users' thermal comfort. Simulation result demonstrates that the proposed control scheme can effectively regulate voltage in LV grids with greater robustness and scalability.
In islanded microgrids, traditional droop control tends to make the total operating costs higher as the power is distributed by capacity ratios of distributed energy resources (DERs). According to equal increment rate...
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In islanded microgrids, traditional droop control tends to make the total operating costs higher as the power is distributed by capacity ratios of distributed energy resources (DERs). According to equal increment rate criteria, to minimize the whole expenses, an interesting marginal costs-based economic droop control is proposed in this paper, and the active power can be distributed by identical marginal costs among DERs under economic droop control. If some DERs have arrived at the maximum or minimum power, consensus-based "virtual" controller is applied to make marginal costs still be the same among the rest of DERs. Moreover, distributed secondary frequency controller (DSFC) is proposed to rapidly restore system frequency to the nominal value. As an ancillary service, the whole design can easily realize the transition between economic and non-economic operation only by altering the type of droop control. The above controllers only need to interact with neighbor DERs by sparse communication network, so that eliminating the necessity of a central controller. An islanded microgrid incorporating renewable generators, storage devices and conventional generators are presented to verify the effectiveness of the above controllers. Simulation results show that the proposed controllers can successfully make islanded microgrids realize economic operation and the above transition. (C) 2018 Elsevier B.V. All rights reserved.
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