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Abstract: Distribution network reconfiguration problem is simply aimed at finding the best set of radial configurations among a huge number of possibilities. Each solution of this set ensures optimal operation of the system without violating any prescribed constraint. To solve such problem, it is important to count on efficient procedure to enforce radiality. In this paper, we propose a reliable approach to deal properly with topology constraint enabling algorithm convergence toward optimal or quasi-optimal solutions. A simple and practical codification of individuals used in evolutionary algorithms to solve the generalized reconfiguration problem is detailed in this paper. Mathematical formulation, algorithm, and simulation results are presented for the distribution reconfiguration problem, incorporating a new representation scheme which is immune to topologically unfeasible possibilities. The individual interpretation procedure is straight and it demands no additional data structure or graph preprocessing. Comparisons are made for five well-known distribution systems to demonstrate the efficacy of the proposed methodology. It is also demonstrated that optimal configurations are properly surveyed when single or multiple sources are dealt. [Copyright &y& Elsevier]

The method of absolute nodal coordinate formulation (ANCF) is used to solve the problem of determining the cable sags and the forces during the cable stringing and sagging process for overhead lines. The problem of calculating the sagging tables due to the temporary supporting cable sheave deflection during the construction phase is emphasized on hilly terrain. Two different models for the contact point between the cable and the sheave are analyzed. The most important advantage of this newly proposed approach is that it opens up the possibilities for analyzing more complex overhead-line structures that are a consequence of the line compaction, e.g., using unconventional insulating applications. The paper describes the basic steps of an ANCF algorithm to solve the presented problem. It also provides numerical examples in order to verify the ANCF method by comparing it with the results of other known approaches based on catenary equations. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an agent-based simulation of a Financial Transmission Rights (FTR) auction for both types of point-to-point FTRs, obligation and option, is presented. Each auction participant is simulated as an adaptive agent who has the ability of evaluating its environment and acting accordingly, following the decision rules of the naïve reinforcement learning algorithm presented in the paper. Initially, a Locational Marginal Pricing (LMP) based ex-ante energy market is assumed. From the solution of the ex-ante energy market the agents calculate their initial FTR bid prices. Subsequently, the ISO solves the FTR auction problem and the agents profits equal the reimbursement they receive in the ex-post energy market for holding the FTR. The agent-based simulator repeats the FTR auction under the same conditions; in each repetition the agents update their bids according to the implemented algorithm and they “learn” their bidding strategies, through exploration by repetition. A five bus test system with five agents is used to illustrate the presented method. The results demonstrate the impact of contingency constraints and the effect of speculation in FTR auctions. Furthermore, the difference between bidding for FTR-obligations and FTR-options is shown. [Copyright &y& Elsevier]

Abstract: This paper proposes a novel methodology for the optimal location and sizing of shunt capacitors in radial distribution systems. This method is based on a fuzzy decision making which using a new evolutionary method. The capacitor placement optimization problem includes: minimizing the cost of peak power, reducing energy loss and improving voltage profile. The installation node is selected by the fuzzy reasoning supported by the fuzzy set theory in a step by step procedure. Also an evolutionary algorithm known as bacteria foraging algorithm (BFA) is utilized in solving the objective multivariable optimization problem and the optimal node for capacitor placement is determined. The proposed approach is applied to 34-bus distribution system as a test study and the results are compared with previous method. The results show that this method provides more economic solution by reducing power losses, energy loss, total required capacitive compensation and show a good improvement in nodes voltage to be in the requested range. Comparison between the proposed method in this paper and similar methods in other research works shows the effectiveness of the proposed method for solving optimum capacitor planning problem. [Copyright &y& Elsevier]

• Distribution Management Systems enable the real-time operation of Volt/VAr Control. • A Software-In-the-Loop strategy allows the real-time testing of automation functions. • Clonal Selection Algorithm allows the optimization of coordinated Volt/VAr control. • The random behavior of metaheuristic techniques is a challenge in real-time control. With the advent of smart grid technologies, modern Distribution Management Systems (DMSs) enable the real-time operation of advanced automation functions such as Coordinated Volt/VAr Control (CVVC). Typically, control rule-based techniques have been proposed to efficiently carry out this important function in Distribution Networks (DNs). In this paper, a novel adaptation of the clonal selection theory of immune systems (CLONALG - Clonal Selection Algorithm) is proposed for real-time optimal solution of CVVC problem in radial DNs composed of multiple control equipment. To do this, a Software-in-the-Loop (SIL) strategy is developed, through the use of the Real-Time Digital Simulator (RTDS) and Matlab® program. Implementation details of the referred strategy and the corresponding adaptation of the CLONALG-based CVVC are discussed in this paper. Simulations results demonstrated that the proposed adaptation of the CLONALG technique is suitable to solve the CVVC problem in a maximum time of less than 10 min, in accordance with the Brazilian electric utilities' need. On the other hand, the developed SIL strategy proved to be effective to analyzing the time domain behavior of CVVC algorithms, designed to operate in real time in a modern DMS. [ABSTRACT FROM AUTHOR]

• The relationship between apparent soil resistivity and soil parameters. • A high-efficiency and accurate PSO-DE algorithm for soil parameters estimation was proposed. • The initialization method of PSO-DE and other heuristic algorithms for improving the calculation accuracy was proposed. The grounding grid is buried in horizontal multilayer soils, so accurate parameters (resistivity , thickness, the number of soil layers) estimation of the soil is the basis for accurately calculating the grounding parameters and design of grounding grids. At present, the parameters estimation is usually solved by non-heuristic algorithms and heuristic algorithms. However, existing non-heuristic algorithms depend too much on the initial value and conventional heuristic algorithms could deviate from the correct solution too far, which would easily fall into local optimal solution, causing calculation errors. To solve the above problem, this paper first studies the relationship between the apparent soil resistivity and soil parameters based on the Wenner's method. Then, an innovative PSO-DE (Particle Swarm Optimization-Differential Evolution) optimization algorithm and its initialization method are proposed. The results of PSO-DE, conventional heuristic intelligent optimization algorithms, CDEGS, and literatures are compared, which verifies the superiority and accuracy of the PSO-DE. Therefore, the contribution of this work can lay a solid theoretical foundation for grounding parameters calculation. [ABSTRACT FROM AUTHOR]

Highlights: [•] The paper presents a novel solution for distance relay third zone load encroachment problem. [•] A multi-agent based adaptive relaying algorithm is used to propose the solution. [•] The proposed algorithm was examined on radial and loop network configurations. [•] The results showed the superiority of the proposed algorithm in mitigating the load encroachment problem compared to traditional Mho and Quad settings. [ABSTRACT FROM AUTHOR]

• A fast single-end relaying algorithm is developed for fault protection using bus-voltage change rate and fault component current. • It solves the problem the protection of the emerging fault between the DCCB and line reactor. • The wall bushing fault can be identified to avoid erroneous openings of healthy lines. • The method is with high selectivity, sensitivity, and reliability. Fault protection for a modular multi-level converter (MMC)-based high voltage direct current (HVDC) grid with dc circuit breakers (DCCBs) is a great challenge, because faults need to be isolated fast to prevent the collapse of the grid and overcurrent damage to the equipment. Before clearing faults, faults must be detected as soon as possible. However, the fast rising speed of fault currents and the emerging fault between the DCCB and line reactor increase the difficulty of fault protection. A fast and reliable fault detection and protection method relying on bus-voltage change rate and fault component current is proposed in this paper. It requires the measurements with local sensors and makes use of a lower number of voltage sensors. The proposed algorithm is applied to a four-terminal MMC HVDC grid. Results show that the proposed method can identify the fault type and discriminate bus faults, line faults, and wall bushing faults. It can detect faults quickly and does not generate erroneous and unnecessary trip signals. [ABSTRACT FROM AUTHOR]

Abstract: An improved mixed-integer linear program for determining the tree of minimum active power losses in balanced large medium voltage systems is presented and assessed throughout this paper. The proposed approach depends on a number of parameters, which can be tuned for each specific system, ensuring a desired level of accuracy in relation to the final obtained solution. Eight systems were tested with the new algorithm to highlight the efficiency and accuracy of the proposed model. The model is mainly designed for large systems with a high number of switches whose statuses need to be determined. [Copyright &y& Elsevier]

Abstract: We present a novel transmission expansion planning model that explicitly considers a multi-year planning horizon. The proposed formulation is a mixed-integer linear problem that can be solved using commercially available software. The algorithm determines the best overall transmission expansion plan, reflecting both investment and operational costs. To analyze the results obtained from the model, we use a set of efficiency metrics to appraise the effect of the expansion among generators and demands, as well as congestion metrics to measure changes in nodal prices and line congestions. This paper also provides a case study that considers the expansion plan for a transmission system based on the one of mainland Spain. [Copyright &y& Elsevier]

Abstract: An effective heuristic graph-based approach is proposed in this paper for solving the service restoration problem in distribution networks. Minimisation of the de-energised consumers’ load and reduction of the number of switching operations were considered in this service restoration application. A suitable assignment of the weighting coefficient to all branches in a de-energised area was used to decrease the number of switching operations. Prim''s algorithm for finding of the minimum spanning tree logic was used to realise this approach. Other applications necessary for the optimal performance of the service restoration application were also developed and tested in this study (e.g., load flow, load reallocation of overloaded network elements, generation of the sequence of switch actions, etc.). [Copyright &y& Elsevier]