The optimal power flow (OPF) problem for active distribution networks with distributed generation (DG) and a variety of discretely adjustable devices (e.g. on-load tap-changers, OLTCs) is essentially a non-convex, non...
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The optimal power flow (OPF) problem for active distribution networks with distributed generation (DG) and a variety of discretely adjustable devices (e.g. on-load tap-changers, OLTCs) is essentially a non-convex, non-linear, mixed-integer optimisation problem. In this study, the quadratic model of three-phase OLTCs is proposed by adding branch currents as unknown variables, which guarantee a constant Hessian matrix throughout iterations. This study proposes a three-phase OPF model for active distribution networks, considering a three-phase DG model. The OPF model is solved by an interior point method incorporating a quadratic penalty function as opposed to a Gaussian penalty function. Furthermore, a voltage regulator is also incorporated into the OPF model to form an integrated regulation strategy. The methodology is tested and validated on the IEEE 13-bus three-phase unbalanced test system.
This study presents a probabilistic model to determine the optimal expansion of transmission network under uncertainties of demand, wind power generation, and energy price. The Benders decomposition approach and the p...
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This study presents a probabilistic model to determine the optimal expansion of transmission network under uncertainties of demand, wind power generation, and energy price. The Benders decomposition approach and the point estimate method (PEM) are used to solve the developed mixed-integer optimisation problem and tackle the uncertainties, respectively. The proposed market-based expansion problem is a two-stage model in which the master problem optimises the investment cost, and the sub-problem (SP) includes the cost of energy not served, congestion cost and congestion rent. A new objective function is proposed to consider the congestion rent in the Benders algorithm. In the SP, a two-step optimisation process is then proposed to generate proper Benders cuts. The proposed model has been applied to the Garver's, and modified IEEE 24-bus and IEEE 118-bus test systems. Furthermore, to validate the accuracy of the proposed PEM, a Monte Carlo simulation method (MCSM) has been used and the results of PEM have been compared to the MCSM.
In this study, the authors propose an energy-efficient user association scheme to maximise the overall energy efficiency for downlink heterogeneous cellular networks, and formulate it as a non-linear and mixed-integer...
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In this study, the authors propose an energy-efficient user association scheme to maximise the overall energy efficiency for downlink heterogeneous cellular networks, and formulate it as a non-linear and mixed-integer optimisation problem. Such a problem includes user association problem and power control problem. Since the formulated problem is in a fractional and mixed-integer form, it is challenging for designers to achieve the optimal solutions of this problem. To this end, they design an effective three-layer iterative algorithm. In the first layer, the energy efficiency parameter is found via bisection method. In the second layer, association index and transmit power are optimised alternately. In the third layer, the user association problem is solved via dual decomposition method and the transmit power is updated by employing a power update function. In addition, they further give some convergence analyses for some parts (user association algorithm and power control algorithm) of the proposed algorithm, and also give some complexity analyses for the whole algorithm. Numerical results show that, compared with non-energy-efficient association, the energy-efficient association has significant superiorities on load balancing level, system throughput and energy efficiency.
This paper discusses the reactive coordination of generation and transmission planning in a competitive electricity market. The transmission planner is assumed as a social cost minimizing entity and the behavior of ge...
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ISBN:
(纸本)9781467366922
This paper discusses the reactive coordination of generation and transmission planning in a competitive electricity market. The transmission planner is assumed as a social cost minimizing entity and the behavior of generators is modeled as the Nash equilibrium of a strategic game. Reactive coordination forms a mixed-integer optimisation problem which can be solve by commercially available softwares. This problem is solved for two cases of with and without transmission charges. Efficient coordination of transmission and generation planning is considered as the benchmark in this study. The developed model is implemented for a 6-node illustrative example and IEEE-RTS96 test system and the results are compared.
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