Transformers In Distribution Systems Research Articles

Analysis of the Effect of Capacitor Placements at High and Low Voltage Transformer Sides as Voltage Profile and Total Cost in Distribution Systems

This study mentions the problem of determining optimal placements and sizes for capacitor banks by comparing different schemes that allow implemented buses at both high and low voltage side, only high voltage side or low voltage side of transformers in distribution systems. Criterions evaluated for each scheme are active and reactive power losses in whole system, voltage value at all buses, installation and operation cost and accumulative profit saving. Standard with and without transformer branches in distribution systems and Newton-Raphson method are introduced to make clear about the way to analyze power flows in whole system. Optimal placements and sizes for capacitor banks are determined by using a proposed algorithm and optimal capacitor placement tool in ETAP software. Simulation results can help to show the comparisons, evaluations and make decision about optimal capacitor placements and sizes. The contribution shows the best scheme that install capacitors at low voltage side of transformers because it has the lowest implemented capacity, highest economic factors while voltage quality is always in allowable range. Achieved results can be applied in any distribution system, help managers have overall review and decide optimal placements and sizes for capacitor banks. Keywords: Capacitor bank, OCP Tool, ETAP software, Optimal placement, Optimal size, Voltage quality, Optimal cost.

Advance technology using solid state transformer in power grids

In this paper we are going to discuss the solid- state transformer (SST) which is suitable alternative to the conventional transformer in distribution system. Further, the benefits of solid -state transformer is highlighted so as to improve problems that presently identified in distribution network. The solid state transformer (SST) is a new technology that has the potential to influence advances in a variety of fields, including smart grids, traction systems, and renewable energy systems. This research examines the SST topologies that are suitable for various voltage levels and stages, as well as their control operation. One of the most visible benefits of SST is the reduction in size and weight. Volume reduction of SST is beneficial from portability, low installation cost, and easy to assemble point of view. This study examines a variety of aspects, including current concerns and problems, and makes recommendations for future SST configuration and development.

Distribution network planning considering technology diffusion dynamics and spatial net-load behavior

This paper presents a data-driven spatial net-load forecasting model that is applied to the distribution network expansion problem. The model uses population census data with Information Theory-based Feature Selection to predict spatial adoption patterns of residential electric vehicle chargers and photovoltaic modules. Results are high-resolution maps (0.02 km2) that allow distribution network planners to forecast asymmetric changes in load patterns and assess resulting impacts on installed HV/MV substation transformers in distribution systems. A risk analysis routine identifies the investment that minimizes the maximum regret function for a 15-year planning horizon. One of the outcomes from this study shows that traditional approaches to allocate distributed energy resources in distribution networks underestimate the impact of adopting EV and PV on the grid. The comparison of different allocation methods with the presented diffusion model suggests that using conventional approaches might result in strong underinvestment in capacity expansion during early uptake and overinvestment in later diffusion stages.

Optimal Tap Setting of Voltage Regulation Transformers in Unbalanced Distribution Systems

In this paper, we propose a method to optimally set the tap position of voltage regulation transformers in distribution systems. We cast the problem as a rank-constrained semidefinite program (SDP), in which the transformer tap ratios are captured by 1) introducing a secondary-side “virtual” bus per transformer, and 2) constraining the values that these virtual bus voltages can take according to the limits on the tap positions. Then, by relaxing the non-convex rank-1 constraint in the rank-constrained SDP formulation, one obtains a convex SDP problem. The tap positions are determined as the ratio between the primary-side bus voltage and the secondary-side virtual bus voltage that result from the optimal solution of the relaxed SDP, and then rounded to the nearest discrete tap values. To efficiently solve the relaxed SDP, we propose a distributed algorithm based on the alternating direction method of multipliers (ADMM). We present several case studies with single- and three-phase distribution systems to demonstrate the effectiveness of the distributed ADMM-based algorithm, and compare its results with centralized solution methods.

Improving Transformers' Utilization Under Single Contingency Policy and Customer Reliability Requirements

During the past two decades, utilities have saved tremendous capital investments in new transformers by improving utilization of existing transformers in distribution systems. Meanwhile, in these highly-utilized systems, deteriorated reliability has been observed at the end-user level. This is mainly because utilities determine transformer utilization conventionally through the N-1 approach, which only guarantees reliability at the system level but not reliability requirements of customers. This paper presents an innovative method that balances the financial interest of utilities and service quality of customers by maximizing transformers' utilization while assuring reliability at the end-user level. The proposed method's advantages are enhanced by its capability of handling customer reliability requirements of a whole distribution system and/or of designated locations with critical loads. In addition to determining the maximum utilization of transformers, the proposed method can be extensively applied to other power delivery equipment in distribution systems.

1987年度秋季学術大会シンポジウム 情報化社会における地域システムの変容

Japanese society has come to be referred to as an information-oriented society, and it is infulenced by informations which is increasing significance whole to social and economic aspects. The purpose of this symposium is to clarify the transformations and characteristics of regional systems with the development of new technology on information distribution. Five reports were presented: 1) N. Takayanagi: Characteristics and areas of handbill advertisement with news papers deliverly as distribution of information 2) M. Sano: The transformation of distribution systems and the development of consummer-oriented enerpries 3) S. Namaizawa: The formation of network systems in commercial activities 4) Y. Wakabayashi: The diffusion of CATV and its impact on regional areas in Japan 5) T. Yamazaki: The development of information-oriented society and the locational change of central administrative functions All discussions are focussed on how changing information media affect the systems of existing society in a regional context. The location of every activity would be influenced if a new information technology, such as VAN systems, is widely introduced. A good example would be seen in the location of warehouse and wholesale activities. The development of “chain-store” systems is also expected even in small areal centers. As the highly centralized systems reduce the cost of spatial diffusion of information, leading urban centers like Tokyo will attract more headoffices of bigger firms. Then question is asked how we geographers should perceive the trends in intensifying urban congestion.