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AbstractWe present a stochastic programming model for informing the deployment of ad hoc flood mitigation measures to protect electric substations prior to an imminent and uncertain hurricane. The first stage captures the deployment of a fixed number of mitigation resources, and the second stage captures grid operation in response to a contingency. The primary objective is to minimize expected load shed. We develop methods for simulating flooding induced by extreme rainfall and construct two geographically realistic case studies, one based on Tropical Storm Imelda and the other on Hurricane Harvey. Applying our model to those case studies, we investigate the effect of the mitigation budget on the optimal objective value and solutions. Our results highlight the sensitivity of the optimal mitigation to the budget, a consequence of those decisions being discrete. We additionally assess the value of having better mitigation options and the spatial features of the optimal mitigation. [ABSTRACT FROM AUTHOR]

Electric power generated in a centralized station is transmitted through the transmission system and supplied to the consumer end through an electric distribution substation. Electric power losses are high in distribution network compared to the transmission system. The integration of decentralized generation (DG) units in electric distribution networks will reduce power losses. However, the integration of conventional DG is not appreciable due to various techno-economic and environmental concerns. Hence there is a need for the changeover from conventional to renewable energy sources (RES) for energy requirement. Because of vast availability, non-polluting nature, and sustainable character of RES are grasping significant attention over the years. At present most, viable RES are solar and wind energy systems in the world. It is observed that the output generation patterns of solar photovoltaic (PV) arrays and wind turbine generation units (WTGUs) are arbitrary. Hence there is a need for sophisticated method/technique for modeling these generated outputs. In the present paper, optimal modeling and allocation of RES are solved using a novel metaheuristic algorithm. The proposed algorithm is tested on 12, 15 and 85 - bus radial distribution networks (RDNs) and the simulation results obtained are outperforms other existing techniques in the literature. [ABSTRACT FROM AUTHOR]

With the growing interest in seismic hazards following the Gyeongju earthquake (ML 5.8; 2016), information on site amplification characteristics is essential for the effective analysis of seismic hazards in urban areas. To assess amplification characteristics, this study used three reference site methods. Two new modified reference methods were compared with the existing method, which relies on the horizontal/vertical (H/V) ratios of ground motions at the target and reference sites. For each type of seismic energy (S-wave, coda wave and background noise), similarities between the H/V spectral ratios (HVSR) for all three reference site methods were investigated. Site amplification characteristics were analysed using 216 acceleration ground motions of horizontal and vertical components for three earthquakes (Odaesan, Jeju and Gongju), observed simultaneously at four sites and having a magnitude > 3.4. Most electric substations showed similar HVSR behaviour for the three types of seismic energy and three reference site methods over a significant frequency range, with few exemptions. Although site amplification characteristics in the low- and high-frequency ranges, as well as the specific resonance frequency of each electric substation, varied greatly, the site amplification characteristics of the four sites could be classified into two groups: sites with a resonance frequency and those without. First, with the exception of New Taeback (NTB), the sites shared fundamental resonance frequencies in the range between ∼ 5 and ∼ 10 Hz. Second, NTB did not show any significant resonance, which may imply that it is located on a very firm rock formation. Considering all the resonance frequencies, the four sites can be classified as TB or harder rocks. By comparing the results with those from other regions, it is possible to provide insight into the site characteristics and the site classification methodology. [ABSTRACT FROM AUTHOR]

This paper presents an intelligent and integrated backup scheme based on artificial neural networks for current source converter-high voltage direct current (CSC-HVDC) systems. Taking advantage of the properties of ANNs to identify and classify patterns, the proposed scheme is able to detect and correctly locate a fault occurring either at the rectifier substation, the DC line or at the inverter substation. In this scheme, only local signals are used at the rectifier substation and no communication link is necessary, thus improving the system's protection reliability and reducing the required capital cost. Moreover, the proposed scheme could be promptly applicable in practical situations, as the hardware requirements and response times are not critical issues. All steps of the proposed scheme for the aforementioned purpose are accurately discussed in addition to all the information about the CSC-HVDC system under analysis. Finally, a detailed analysis of the influence of the main fault parameters on the algorithm's performance is also conducted. [ABSTRACT FROM PUBLISHER]

In this paper, application of gapless transmission line arresters (TLAs) in substation lightning protection is analyzed. Deterministic calculations in accordance with IEC 62305 are performed. Substations with non-standard configuration equipped with Gas Insulated Switchgear (GIS), long cables, and a direct cable connecting GIS and power transformer are considered. It is concluded that 220- and 400-kV substations lightning performance can be significantly improved by using TLAs at only one or two overhead line towers in front of the substation. In some cases, TLAs provide better lightning protection of power transformer than surge arresters installed in GIS. Positive effects of TLAs application are noticed both in the case of back-flashovers and in the case of shielding failures. TLAs energy stress increases with the decrease of the system rated voltage. Maximum estimated values in the analyzed substations are below 2.5 and 0.5 kJ/kVr for TLAs installed in 220- and 400-kV systems, respectively. [ABSTRACT FROM PUBLISHER]

This article presents a study on short-circuit current limiting using resistive superconducting fault current limiters, based on a melt cast processed BSCCO-2212. The application of the resistive superconducting fault current limiter was analyzed when installed downstream of a substation, protecting a distribution feeder. The studied power system is based on a dynamic model of the IEEE 13-node test feeder considering a power system expansion scenario, including renewable power generation. As a result of the power system expansion, fault current levels tend to increase, and the resistive superconducting fault current limiter device is used for fault current mitigation. The main contribution of this article is the performance assessment of superconducting fault current limiters and its effects on power quality due to different fault locations in the system and by accounting the complexity of the power system topology. Results obtained demonstrate that the system expansion does not significantly raise fault current levels. It also demonstrated that the resistive superconducting fault current limiter has a desirable operation zone, and unwanted power interruption may occur due to its operation outside this zone. [ABSTRACT FROM AUTHOR]

The aim was to investigate occupational exposure to electric and magnetic fields during tasks at ground or floor level at 110kV substations in Finland and to compare the measured values to Directive 2013/35/EU. Altogether, 347 electric field measurements and 100 magnetic field measurements were performed. The average value of all electric fields was 2.3 kV/m (maximum 6.4kV/m) and that of magnetic fields was 5.8 µT (maximum 51.0 µT). It can be concluded that the electric and magnetic field exposure at ground or floor level is typically below the low action levels of Directive 2013/35/EU. The transposition of the directive will not create new needs to modify the work practice of the evaluated tasks, which can continue to be performed as before. However, for workers with medical implants, the exposure may be high enough to cause interference. [ABSTRACT FROM AUTHOR]

Development of distributed generation has provided new opportunities in power system planning. In this article, distributed generation units are considered as an alternative for supplying the load of a sub-transmission system, and a new mathematical framework is presented for expansion planning of an optimal sub-transmission substation and allocation of distributed generation units as well as defining the associated service area. The proposed method focuses on dynamic expansion planning and operation of distributed generation units and substations in a way with lowest cost. Dynamic expansion planning of a sub-transmission system is inherently a mixed-integer non-linear programming problem due to the prevalent electrical and expansion constraints, cost indices in the objective function, and decision variables. This non-linear problem is simplified to a linear problem by the proposed method. The cost function of the developed method consists of investment, construction, and installation costs of sub-transmission substations as well as connection costs of substations to the upper network, new medium-voltage feeders, and distributed generation units. The costs of purchased energy from the upper network and distributed generation units forecasted as nodal prices are added to the objective function. Moreover, prevalent constraints are considered. The proposed approach is applied to a realistic case study. [ABSTRACT FROM AUTHOR]

High-voltage substations are fed by transmission lines with the earthing system solidly bonded to the substation earth grid. Under substation fault, both the substation earth grid and the pole grid resistance are exposed to voltage rise. This voltage rise could reach unacceptable and dangerous levels. Earthing system design ensures safety compliance for both the substation and transmission lines under fault conditions. This article analyses the relation between the substation earth potential rise and the transmission pole earth potential rises. The analysis shows that the poles located within the finite length from the substation form a solid input to the substation earth potential rise. The article reviews the existing literature and develops the formulas to assist the designer to compute the substation earth potential rise from the pole earth potential rise and vice versa. The article proposes modifications to IEEE earthing design block diagram. This modification ensures that the transmission line earthing system is always compliant to allowable safety limits under substation fault. Furthermore, the article shows the method to estimate the substation earth potential rise by measuring the pole earth potential rise with a case study. [ABSTRACT FROM PUBLISHER]

Large-magnitude earthquakes can damage high-voltage transformers, trigger power flow disruption and impact the economy and society. However, methods that enable large transformer vulnerability assessment in a practical and rigorous way are scarce. This paper proposes a probabilistic framework using Bayesian belief networks (BBNs) to predict the damage of high-voltage transformers subjected to seismic events. This framework incorporates major causes of transformer vulnerability at once, such as liquefaction, rocking response of the transformer, and interactions with interconnected equipment, which are otherwise commonly studied in isolation. To demonstrate the application of the framework, the paper elaborates on each step of the BBN framework, which is then validated with historical empirical data. Furthermore, the value of the proposed method is illustrated with high-voltage transformers in substations of the electric value BC Hydro in British Columbia, Canada. The paper also offers a sensitivity analysis that evaluates the effects of input variables on transformer damage. The proposed framework is simple to perform in practice, and the results are expected to support decisions on mitigation measures, seismic risk management, and to provide a step towards modelling the vulnerability of entire electrical substations. [ABSTRACT FROM AUTHOR]

Abstract—This article presents a stochastic methodology for volt/VAR/total harmonic distortion control to reduce power losses while satisfying the main recommended power quality standards and optimizing dispatch schedules for the switchable shunt capacitor and on-load tap-changer in distribution networks. The main aim is to find proper dispatch schedules for on-load tap-changer tap positions, substation capacitors, and along feeder capacitors. For this purpose, distribution network uncertainties, including load demand and wind power generation, are considered to provide a robust control scheme. A new scenario reduction method based on the highest potential cluster center is used to decrease the huge number of probable states. A new scenario-based probabilistic time-interval division framework, over a 24-hr period on both load curve and wind power output, is introduced to reduce effects of forecast plan uncertainty and switching operations in the on-load tap-changer. A genetic algorithm solution method is applied to find the best solution corresponding to various scenarios. To improve search ability, a method guaranteeing the suppression of maximum allowable daily substation capacitors switching and effectively correcting the convergence process is utilized. The proposed stochastic approach is tested on an IEEE 123-bus distribution network containing a number of non-linear loads and wind energy generation systems. [ABSTRACT FROM PUBLISHER]

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Optimal feeder routing is an important part of general optimal distribution network planning. This article proposes a new algorithm for optimal feeder routing using an easy step-by-step, radial path building algorithm, ensuring minimization of the total system planning cost. Furthermore, reliability assessment is carried out to obtain the most reliable feeder routing to acquire less interrupted network structure with different feeder configurations. The proposed approach is also tested for optimal feeder routing with variations in the number of substations, which provides information on the trade-off between optimality and reliability of the system configuration. Moreover, the concept of principle of optimality is effectively used to make the proposed approach computationally more efficient and useful. The extensive test results reflect the potential ability of the proposed approach for optimizing the network structure in power distribution networks. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a scalable multi-agent architecture to give support to smart grids, paying special attention to the intelligent monitoring of distribution substations. The data gathered by multiple sensors are used by software agents that are responsible for monitoring different aspects or events of interest, such as normal voltage values or unbalanced intensity values that can end up blowing fuses and decreasing the quality of service of end consumers. The knowledge bases of these agents have been built by means of a formal model for normality analysis that has been successfully used in other surveillance domains. The architecture facilitates the integration of new agents and can be easily configured and deployed to monitor different environments. The experiments have been conducted over a power distribution network. [ABSTRACT FROM AUTHOR]

This article presents novel fault-location algorithms for distribution systems by utilizing voltage and current measurements at the local substation. The methods extend from previously published algorithms by explicitly modeling feeder shunt capacitances so that the methods will be applicable to distribution feeders with significant capacitances, such as underground cables. The bus impedance matrix technique is harnessed to develop the relationship between the substation voltage and current and the fault location and fault resistances, based on which the fault location can be derived. To accommodate inherent unbalances in distribution systems, the methods are developed in the phase domain instead of the symmetrical component domain. The distribution network parameters and topology are assumed to be known for constructing the bus impedance matrix. Simulation studies have demonstrated that the methods can achieve very accurate results. [ABSTRACT FROM AUTHOR]

In this article, a novel approach is presented to study the impact of distributed generation on recloser–fuse coordination. This approach is based on the assessment of the recloser–fuse coordination due to the penetration of distributed generation with specified location and capacity for a given fault location. This assessment process acts as a classifier based on finding the operating sequence of all reclosers and fuses in the path from the faulted node to the substation. This sequence is compared with a pre-required sequence obtained from the protection coordination philosophy and then provides the distribution system operator with a result indicating whether the recloser–fuse coordination still holds or is lost. Consequently the operator can make the proper decision according to this classification process. One of the proper decisions that can be taken into account in the case of recloser–fuse miscoordination is to adapt the recloser setting such that the coordination can be re-attained. This new approach has been implemented on the IEEE 37-node test feeder using MATLAB-based developed software (The MathWorks, Natick, Massachusetts, USA), and the obtained results are presented and discussed. [ABSTRACT FROM PUBLISHER]

This article proposes a new method of grounding system analysis in the presence of a satellite electrode determining grounding resistance, step and touch voltages, and earth surface potential distribution considering the impact of depth of tie-wires. The impact of lateral variation of vertical fault has also been studied for safe and touch potentials along the length of tie-wire. A computer program called 'grounding system analysis in the presence of vertical fault' has been developed. The validation of the program has been carried out for the problem available in the literature. An experimental analysis has been carried out for a grounding system with ring and rod electrodes placed in soils of different resistivity separated by a vertical fault. A parametric study has been carried out on two square grids laid in the earth on both sides of the vertical fault connected together by an underground tie-wire and with the tie-wire only for comparison. The impact of the depth of the tie-wire and lateral variation of the vertical fault has been studied for determining ground resistance, step and touch voltages, and earth surface potentials near the square grids, as well as along the length of the tie-wire. [ABSTRACT FROM AUTHOR]

The Newcastle earthquake of 1989 had a signifi cant effect on the New South Wales high voltage grid. Multiple failures of large, porcelain insulators and operations of transformer Bucholz relays occurred in substations near the epicentre. Although unplanned, these operations correctly initiated a general and immediate loss of supply around Newcastle, resulting in both adverse and benefi cial outcomes. The Electricity Commission of New South Wales response was immediate and effective, with all bulk supply points energised after 2.5 hours. Full restoration followed in three weeks, but normal reliability of supply took months to recover. A third phase of review identifi ed areas where either the system or the response may have been improved. "Lifeline" studies to mitigate the effects of such extreme events are described and recommended for communities at risk. [ABSTRACT FROM AUTHOR]

This paper describes an application of the EMTP (Electromagnetic Transients Program) for the design of substation grounding systems. The power system circuit model is presented, as well as its EMTP implementation. Several case studies are used to show the suitability of the program for this task. [ABSTRACT FROM AUTHOR]

Substation-related failures can have an observable influence on the reliability of the individual load point connected to a distribution system. This paper investigates the impacts of station-originated, distribution-originated, and distribution-station–originated failures on the load point and system reliability indices of a distribution system. A hierarchical analysis approach incorporating reliability network equivalents is used to separately evaluate the effect of each system segment and to minimize the repeated calculations. Minimum path and cut set techniques are utilized in the evaluation. A recursive search algorithm is used to find minimum paths from the bulk supply point to the loads and the area affected due to a failure event. A test distribution system is utilized to illustrate the proposed technique. Results in the form of basic reliability indices and the expected customer outage costs are presented. [ABSTRACT FROM AUTHOR]

Numerous mathematical optimization methods have been used to obtain the optimal solution to the problem of distribution system planning, which often are time consuming and only restricted to small size distribution systems. In this paper, a novel heuristic method is developed to solve the problem of distribution system planning. The method is composed of three steps. First of all, an initial redundant network is formed by combining the existing network and the probable new additions. A new efficient two-stage load flow method is presented and integrated into a recursive process to determine the optimal combination of substations and derive their service areas. Secondly, a heuristic approach is used to obtain the radial network configuration of each substation. Finally, an algorithm based on branch exchange technique is implemented between elements of adjacent distribution zones to obtain the final planning scheme. A distribution system with 6 substations and 98 feeders is studied, which demonstrates the feasibility and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

This article discusses the U.S. vulnerability to terrorism. It is evident that a dedicated state-sponsored terrorist group in a strategically critical area could disrupt electric substations with relative ease. The interdependency of the U.S. networks is a major source of their vulnerability and thus lies at the center of emergency planning. Terrorists realize that such disruptions would affect large segments of the population for a variety of reasons. Both industry and government should be interested in prevention and countermeasures, since this new type of warfare could put some essential networks out of commission before the U.S. has realized that there was a war on.

The article reports on the first steam power plant launched in India. The first units of the $140,000,000 multi-purpose power system was modeled after the Tennessee Valley Authority. It represents the first major high pressure steam plant in the Far East. The plant involves three units: the steam power station, the Konar dam which will furnish the cooling water, and 477 miles of transmission lines and substations. An aerial ropeway will supply coal from the Bermo coal fields at the rate of 700,000 tons per year.

Earthquakes are one of the deadliest forces of nature that can shake structures to their limits. No comprehensive study has been done in Pakistan on seismic performance of electric supply substations and requires immediate attention as Pakistan is one of the highly seismic area in the world with potential of large earthquakes. Seismic qualification of electric supply substation equipment (132 kilo Volt surge arrester) by time history shake-table testing is presented in this paper. This equipment was tested under "Seismic Qualification Level Moderate" that is according to earthquake input requirements of this region. An artificial time history was generated that qualifies the Required Response Spectrum of Pakistan Electrical and Telecom Safety Code (PETSAC-2014) and IEEE Recommended Practice for Seismic Design of Substations (IEEE Std. 693-2005). Two types of measurements (displacement and acceleration) were recorded during time history shake-table testing at four different points using six accelerometers and four displacement transducers. Seismic qualification of electric supply substation equipment is totally a new dimension in Pakistan's electrical power system. [ABSTRACT FROM AUTHOR]