Search

This paper introduces the development and actual test results of the Korean Smart Distribution Management System (KSDMS). The KSDMS has been designed and developed to cope with the lack of interconnection capability of the Dispersed Energy Resource (DER), to provide standardization and compatibility, and to implement automatic processing of service restoration, in the existing Distribution Automation System (DAS) in Korea. First, real-time system analysis and control application programs were developed, to solve the problems of the existing DAS; and the Distribution Management System (DMS) platform was developed, to run the developed application programs. Second, international standard-based communication, platform, and database structures were adopted, for standardization and compatibility. Third, a platform and application program functions were developed to process faults automatically; and a communication device and an intelligent electronic device (IED) were developed to automate fault restoration, through communication between devices. The KSDMS was evaluated by three tests: unit function test, platform and application program integration test, and empirical test. The first two were conducted on both small and large demonstration systems. The empirical test was performed at the Power Testing Center (PTC) in Gochang, and on a real system, at the Korea Electric Power Corporation (KEPCO), on Jeju Island. The test results verified that the KSDMS can actively resolve the problems of the existing DAS.

Recently, a distribution management system (DMS) that can conduct periodical system analysis and control by mounting various applications programs has been actively developed. In this paper, we summarize the development and demonstration of a database structure that can perform real-time system analysis and control of the Korean smart distribution management system (KSDMS). The developed database structure consists of a common information model (CIM)-based off-line database (DB), a physical DB (PDB) for DB establishment of the operating server, a real-time DB (RTDB) for real-time server operation and remote terminal unit data interconnection, and an application common model (ACM) DB for running application programs. The ACM DB for real-time system analysis and control of the application programs was developed by using a parallel table structure and a link list model, thereby providing fast input and output as well as high execution speed of application programs. Furthermore, the ACM DB was configured with hierarchical and non-hierarchical data models to reflect the system models that increase the DB size and operation speed through the reduction of the system, of which elements were unnecessary for analysis and control. The proposed database model was implemented and tested at the Gochaing and Jeju offices using a real system. Through data measurement of the remote terminal units, and through the operation and control of the application programs using the measurement, the performance, speed, and integrity of the proposed database model were validated, thereby demonstrating that this model can be applied to real systems.

Implementing automation system in distribution networks needs a huge investment that usually cannot be funded entirely in a short period of time. So distribution companies (DISCOs) should develop long-term plans to equip their network with automation technologies as far as economically justifiable. Aiming to provide a methodology for development such plans, this paper presents a novel multistage planning model for implementing distribution automation system considering all main hardware and software infrastructures. The proposed method optimally determines the type, location, and time in which an equipment or infrastructure must be added to network considering the network capacity expansion plan. The objective function of the planning problem is to maximize the net present value of the DISCO's profit in the planning time horizon. In this method, the optimization problem is solved using the genetic algorithm approach as a promising technique in solving the mixed integer nonlinear programming problems. The proposed method is evaluated on an illustrative test network and the obtained results are presented and discussed. [ABSTRACT FROM PUBLISHER]

To date, power system analysis has been performed separately for transmission and distribution systems. Due to the small influence of distribution systems on transmission systems, separate analyses have had no accuracy problems in existing power systems. However, as the amount of distributed generation (DG) in distribution systems increases, neighboring distribution systems and even transmission systems can be affected by the distributed generation. Therefore, a power system operator needs a new system to analyze the power system, one that considers the mutual interactions between the transmission and distribution systems. This paper presents with applications and case studies a transmission and distribution integrated monitoring and analysis system for high DG penetration. The integrated system analyzes the mutual interaction between the transmission and distribution systems due to DG. The preliminary evaluation of the DG connections is automated in this system, using real time online data. Case studies with practical data show the need and effectiveness of transmission and distribution integrated monitoring and analysis for real power systems with high DG penetration. [ABSTRACT FROM AUTHOR]

This paper introduces a multi-objective fault indicator (FI) placement method in electric distribution systems. The prevalent FI placement problem formulation is extended by considering effects of existing protection and control devices on customers' restoration time. Moreover, the customers' average restoration time index (CARTI) is proposed, as a new technical objective function with respect to uncertainties of automatic switching. Furthermore, a multi-objective solution approach is developed to simultaneously minimize indispensable economic and technical objectives. The resultant optimization problem is solved through a multi-objective particle swarm optimization (MOPSO) based algorithm, accompanied by a fuzzy decision making method to select the best result among the obtained Pareto optimal set of solutions. Assuming SAIDI and CARTI as technical objectives, the proposed method is applied to bus number four of the Roy Billinton test system (RBTS4), as well as a real-life distribution network with about 5500 customers, followed by a discussion on results. [ABSTRACT FROM PUBLISHER]

In a smart-grid environment, more intelligent, distributed control devices will be deployed in the distribution network to significantly enhance reliability and flexibility. Distributed fault localization, isolation, and supply restoration (FLISR) are examples of such important applications. These devices need a standard model to share information with each other and support interoperability of intelligent electronic devices from different manufacturers. IEC 61850 has been developed as a series of standards to facilitate interoperability of substation automation systems (SAS). Earlier efforts focus on the application of IEC 61850 to a distributed FLISR system. However, the difference between SAS and FLISR has not been addressed. In this paper, an IEC 61850 model expansion toward a distributed FLISR system is proposed based on the requirement analysis of a variety of distributed FLISR modes. Moreover, a typical breaker-level switch-mode FLISR algorithm is studied as an example to demonstrate the benefits of the proposed model. The correctness and security of the proposed model and algorithm are verified by the model checker and tested in an intelligent distribution simulation system. [ABSTRACT FROM AUTHOR]

This paper proposes an algorithm for determining the optimal composition which means number of links and section switches in a feeder and placement of automatic switches in a distribution automation system (DAS). A DAS is configured by automatic switches and reclosers on a power distribution line. The composition and placement of switches affect the operational applications of a DAS. More switches lead to better DAS operation but also to increased cost and maintenance. Thus, this paper proposes an approach to determining the optimal composition and placement of automatic switches. Additionally, the proposed algorithm is developed considering various system topologies in a real field. The algorithm was tested on an example power distribution system with eight-feeders and on a real power distribution system operated by KEPCO in Young-Deung-Po and Jeju, South Korea. [ABSTRACT FROM PUBLISHER]

A distribution automation system (DAS) is a power automation system to operate a power distribution network efficiently through remote control and monitoring. The most important function of the DAS is the restoration of a stable power supply to the customer when a fault occurs. Since the DAS has a centralized structure, the restoration time of the DAS takes place in about 5 min. This is too long for a customer in the digital age, so a distributed restoration system, which can shorten the restoration time from 5 min to less than 1 min is proposed in this paper. The concept of a multiagent system (MAS) for a distributed control system is applied to the proposed system to enhance its operational reliability, but there is a belief that the MAS-based distributed operations system is just a future technology. So an application method is proposed in this paper for an MAS-based distributed restoration system without significant changes to the existing DAS. The proposed system was applied to an existing DAS and tested in the Gochang Power Testing Center. The test results showed that in the most complex case, the DAS restoration time was 48 s using a code-division multiple-access module and 10 s using an Ethernet communication module. [ABSTRACT FROM PUBLISHER]

When a high-impedance fault (HIF) occurs in any zone of a distribution system, it is very difficult to detect the fault because the fault current is very small and the time of its occurrence cannot be ascertained. This paper proposes a self-isolation method for an HIF zone in which the feeder remote terminal unit (FRTU) experiencing nil-voltage can identify and isolate autonomously an HIF zone by exchanging voltage and current information with the neighbor FRTUs on the feeder when an HIF occurs under the network-based distribution system. Also, the method was devised to enhance the reliability of hF identification from the voltage sensor error. Furthermore, new and simple heuristics are proposed, which are required to classify the nil-voltage due to an HIF with nil-voltage caused by general fault outage, scheduled outage, and outage due to the reclosing operation of a protective device (circuit breaker or recloser). [ABSTRACT FROM AUTHOR]

A communication system plays an important role in distribution automation system (DAS), and various communication media have been applied to meet the utility's objective. Distribution automation technology using code division multiple access (CDMA) wireless communication network have been developed and shown its cost effectiveness and durability through the field test. Several system components for CDMA such as gateway, packet assembly disassembly and modem had been newly developed and their interfaces are standardized. Establishing a separate control channel for interworking function from central station, system reliability is significantly improved in the case of event processing. CDMA network would be applied to a small-scale DAS which could have a difficulty in constructing a communication net- work in an economic way, while fiber-optic cable would be applied to a large-scale DAS which needs high speed and reliability in a big city. [ABSTRACT FROM AUTHOR]

To enhance the cost effectiveness of the distribution automation system (DAS), this paper proposes the immune algorithm (IA) to derive the optimal placement of switching devices by minimizing the total cost of customer service outage and investment cost of line switches. The reliability index of each service zone defined by the boundary switches is derived to solve the expected energy not served due to fault contingency, and the customer interruption cost is then determined according to the customer type and power consumption within the service zone. To demonstrate the effectiveness of proposed IA methodology to solve the optimal placement of line switches, a practical distribution system of Taiwan Power Company (Taipower) is selected for computer simulation to explore the cost benefit of line switch placement for DAS. [ABSTRACT FROM AUTHOR]

The diminishing trend of reliability owing to possible power system failures has become a serious concern for the power system as a whole. It has necessitated the development of advanced protection methodologies employing advanced information technology and substation monitoring system (SMS) constitutes an integral part of such methodologies. The proposed scheme for condition monitoring of insulators, which serves as an augmented feature of SMS, aims at alleviating overall system reliability as well as power quality because cracked insulators cause disruption of power, thereby incurring heavy loss to the power system utilities. The image processing based video surveillance (VS) is incorporated to dispense with the cumbersome and time consuming conventional manual on-site detection using discrete orthogonal S-transform (DOST) in conjunction with some intelligent classification algorithms to ascertain the condition of the insulators. [ABSTRACT FROM AUTHOR]