Feeder Automation System Research Articles

Efficient cloud-based digital-physical testing method for feeder automation system in electrical power distribution network

Efficient cloud-based digital-physical testing method for feeder automation system in electrical power distribution network

Risk assessment in distribution networks considering cyber coupling

With the continuous development of information and communication technologies and their wide application in distribution networks, which have evolved into cyber-physical distribution systems (CPDS). Yet, interactions between cyber and physical systems mean power systems face a greater potential risk. Since feeder automation (FA) systems in a CPDS can quickly isolate faults and restore services, to reduce customer outage times, the potential effect of cyberattacks on FA systems is massive. This paper proposes a risk assessment method for cyberattacks in distribution networks considering cyber coupling. The proposed method takes into account the impacts of cyber systems on power systems, and vice versa. Regarding the cyberattack, an attack method to mislead the judgment of FA systems by tampering with monitoring data of remote terminal units (RTUs) is analyzed, and a Bayesian attack graph (BAG) model is adopted to quantify the successful probability of RTUs. To calculate the attack consequences, a power supply restoration model considering the interdependence of cyber and physical systems is developed, which is measured in scale and in duration to full restoration. The proposed methodology is tested and validated using the modified IEEE 33-node and CPS 62-node test systems. This study highlights the importance of assessing distribution network security from the cyber-physical point of view.

Research on Acceptance and Testing Scheme of Intelligent Distributed Feeder Automation System

The intelligent distributed FA uses the peer-to-peer communication network between distribution terminals to realize the information exchange between terminals, and uses the line fault state quantity differential and bus fault state quantity differential to realize the fault monitoring, fault isolation and non-fault area restoration of power supply. In the distribution automation system, the proportion of terminals with intelligent distributed FA function is increasing. How to test and accept such terminals has become a research hotspot. This paper introduces the basic test contents of testing intelligent distributed FA through simulation system, and expounds the ideas and methods of test and acceptance in detail. Some suggestions are given for the test and acceptance of intelligent distributed FA terminal, which can be used for reference to improve the test standard and batch test.

Half-Interval Method Applied in Feeder Terminal Unit Overcurrent Detecting Curve Setting

Currently, self-healing is one of the most important functions in the smart grid. Meanwhile, fault detection, isolation, and restoration of feeder automation systems dominate the self-healing function in power distribution systems. The steps of the aforementioned function depend on the fault flag status of the feeder terminal unit. The conditions for setting this flag are judged by the feeder terminal unit overcurrent detecting curve. This paper found an efficient approach to calculate this curve via a half-interval method. Versatile application software with the curve plotting capability was also developed and deployed on the web server of the information-management department of Taiwan Power Company and is running successfully.

Performance Evaluation of Multiagent Systems for Navy Shipboard Power System Restoration

A multiagent-based feeder automation system is developed for the service restoration of power systems in a navy ship after fault contingencies. In the system, power-electronic-building-block agents of the multiagent system (MAS) are used to derive the proper restoration plan after the faulted location is identified and isolated. To assure that the restoration plan complies with operation regulation, heuristic rules based on standard operation procedures of the shipboard power system (SPS) are included in the best first search of the MAS. Two control schemes for SPS restoration are investigated, and their performances are evaluated and compared using a discrete event simulation technique with respect to restoration time. For fault contingency when the capacity reserves of supporting feeders are not enough to cover the fault restoration, the load shedding strategy is derived for the MAS to restore service power to as many key loads as possible. A navy SPS with 72 feeders is selected for computer simulation to demonstrate the effectiveness of the proposed methodology. The study concludes that, to cover feeder automation functions, a MAS with distributed processing capability provides better reliability performance than the centralized control.

The Research of 10 kV Feeder Automation Based on the Upper PC System

As the basis of power distribution network automation, the feeder automation plays an important role in the distribution network. The traditional feeder automation system has a long fault isolation time, the frequent switching and outgoing and then overlap power filter troubleshooting repeatedly. 10 kv feeder automation system in the thesis is controlled by the upper PC computer system and the lower machine system, and the lower machine system's intelligent controller collects the operation information of the voltage and current of the line being monitored in real time with AC-sampling technology, and through the GPRS wireless communication network will field data is passed to the remote control center. When the short circuit faults occur, the controller will immediately disconnect the switch, and the incorrect information will be sent to the remote control center, the remote control center to collect incorrect information from all the controllers, then provide the fault judgment and control strategy through relevant logic. Practices have proved that the system could improve the level and reliability of power distribution network effectively.

Design and Implementation of a Stand-Alone Remote Terminal Unit

A Remote Terminal Unit (RTU) plays a vital role in substation automation. It consists of various sections that can handle different types of field parameters. This paper discusses a stand-alone RTU on a single board and its various sections: analog inputs section, digital inputs section and digital outputs section. The main objective of this paper is to check the accuracy of measurement of field inputs by the controller. A number of testing is done on each type of analog input to prove its accuracy. RTUs were once dumb devices that served as an extension of the central computer to the local Input/output. They had no intelligence but could only read the inputs and activate the control outputs. With the development and use of 8 -bit, 16-bit and 32-bit microcontrollers, RTUs are now dedicated microcomputers with stand-alone capability (3). With the RTUs sharing data base management with the central computer, the central computer becomes an operator interface device. Chen Qi.et.al developed a low-power remote terminal unit (RTU) based on GPRS/GSM (general packet radio service / global system for mobile communication) hybrid communications for data acquisition and transmission from distributed monitoring points in industrial environments. During the GPRS network congestion problem, the Short Message Service (SMS) mode is used for data transmission with guaranteed integrity. The ultra-low powered MSP430 microprocessor is used in this RTU. Thus, power consumption obtained during the working cycle was 200 milliWatts (mW) and 0.2 mW during the low power mode. Also, no data losses were obtained with the hybrid communication system during a 48 h test (4). Chen Peijiang and Jiang Xuehua designed and implemented a remote monitoring system based on GSM. The system includes two parts: monitoring centre and the remote monitoring station. The communication between these two parts is done using a TC35 communication module of GSM. MSP430F149 MCU is used in the monitoring station. The result of demonstration showed that the system can monitor and control the remote communication between the monitoring centre and the remote monitoring station (5). Chang.et.al developed a DNP3.0 protocol based on the high performance remote terminal unit (RTU) which was applied to the feeder automation system of substations. The Harvard architecture advanced microcontroller using pipeline processing technology would be used as the control core, to improve the system efficiency. The RTU proposed in this paper could measure the voltage and current of the feeder, monitor the

Study on the Key Distribution Mechanism of Feeder Automation System

Along with the development of information technology, the information security of power industry is becoming an important problem in the stability of power systems. In order to solve the key distribution problems of feeder automation system, a key agreement and mutual authentication scheme based on elliptic curve cryptograph techniques is proposed. The mutual authentication and agreement on a secure session key is realized, between feeder terminal unit (FTU) and regional substation. By using the ECC techniques, greater security with fewer bits is provided. As the result, the requirement of bandwidth is decreased, furthermore, computational burden and storage requirement is also lowered on the FTU.

Optimal Coordination of Automatic Line Switches for Distribution Systems

For the Taiwan Power Company (Taipower), the margins of coordination times between the lateral circuit breakers (LCB) of underground 4-way automatic line switches and the protection equipment of high voltage customers are often too small. This could lead to sympathy tripping by the feeder circuit breaker (FCB) of the distribution feeder and create difficulties in protection coordination between upstream and downstream protection equipment, identification of faults, and restoration operations. In order to solve the problem, it is necessary to reexamine the protection coordination between LCBs and high voltage customers’ protection equipment, and between LCBs and FCBs, in order to bring forth new proposals for settings and operations. This paper applies linear programming to optimize the protection coordination of protection devices, and proposes new time current curves (TCCs) for the overcurrent (CO) and low-energy overcurrent (LCO) relays used in normally open distribution systems by performing simulations in the Electrical Transient Analyzer Program (ETAP) environment. The simulation results show that the new TCCs solve the coordination problems among high voltage customer, lateral, feeder, bus-interconnection, and distribution transformer. The new proposals also satisfy the requirements of Taipower on protection coordination of the distribution feeder automation system (DFAS). Finally, the authors believe that the system configuration, operation experience, and relevant criteria mentioned in this paper may serve as valuable references for other companies or utilities when building DFAS of their own.

Value-based distribution feeder automation planning

In a competitive electric energy market, service quality and reliability are two of the essential issues of the business. Distribution automation has been chosen by many utilities around the world as one of the most reliable measures for reducing outage time in their distribution networks. Considering network reliability data and the customer interruption costs, a value-based planning method is proposed in this paper to find the optimal numbers and locations of switches in feeder automation systems. The proposed method takes reliability costs, maintenance and investment costs into account to obtain a feeder automation plan that has a maximum benefit and a proper system reliability requirement. Three stages are involved in the search for optimal solution. Using minimum feeder data and assume equally distributed feeder loads, stage 1 gives initial estimates of reliability indices and costs, and benefit/cost ratios of different feeder automation options. To gain the maximum benefits from feeder automation with reasonable costs, results of stage 1 are used to select feeders with highest priorities for automations. Stage 2 determines the optimum locations of switches that minimize feeder outage costs, and in stage 3, the best locations for tie switches in the automated network are determined. Numerical processing procedure is described and the solution efficiency and results are compared with those obtained from a genetic algorithm.

Installation of Hydro-Quebec's distribution feeder automation system

A pilot project involving feeder automation is discussed. The advantages of a decentralized approach are discussed, and guidelines for system design are given. The Hydro-Quebec feeder automation system is then described. A testing procedure for remote terminal unit prototypes is described. System cost, network characteristics, and field experience are covered. It is shown that the flow of electrical energy to the customers through distribution feeders can be managed more efficiently and reliably by automation of the feeders, at an affordable cost to utilities, for years to come.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>