Power System Control Centers Research Articles

Transportable simulator trains control center operators

The Electric Power Research Institute (EPRI) developed an advanced transportable operator training simulator (OTS) that features improvements over other simulators on the market. The OTS consists of four subsystems: power system modeling, educational, scenario building, and control center modeling. The interaction between the instructor and the OTS is supported by the instructor position man-machine interface (IPMMI) software and hardware. Control of the OTS, data entry into the database, and presentation of data on displays are performed by the IPMMI. All data requests and updates performed by the IPMMI relate to data resident in the power system model (PSM) database. The IPMMI also has the ability to initiate PSM tasks and to transmit program-generated messages to the instructor. OTS implementation and testing at a host utility are described. >

Observability analysis: a new topological algorithm

An efficient topological algorithm is presented for observability analysis. The algorithm has its roots in combinational optimization and relies on the concept of augmenting sequences. The correctness of the proposed algorithm is established by the proofs provided. The performance of the new algorithm is analyzed using two real-life networks. The authors comment on their experience with a numerical observability algorithm, which has been implemented in several power system control centers. Performance comparisons of the proposed topological algorithm with the numerical observability algorithm are also provided.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Scheme and design for advanced energy control centers

The concept and detailed design of advanced power system control centers that are highly integrated with all power system operations, planning, and management are presented. The latest examples of these designed control centers are also described. The results of these studies indicate that advanced power system control systems can be achieved in the near future and are essential to highly integrated systems for power system operations, planning and management, in order to secure a more economical and stable supply of electric energy. Integration of control systems into a total computer network system not only effectively reduces labor costs and software development but also greatly improves the quality and reliability of the control systems. Such integration also allows the application of upgraded and well-used analytical and optimizing offline program packages to online control. Such a well-integrated system will also result in various unexpected benefits to power system operations, planning, and management. >

Relay margins as a tool for dynamical security analysis

A new measure that quantitatively describes the dynamical response of a power system under large disturbances is proposed in this paper. The measure is named relay margin/relay space margin. The intention is to find a set of indicators which are well understood and informative enough for use in a power system control centre environment for dynamic security assessment (DSA). The protective system is included in the mathematical model of the power system. Current methods for DSA proposed in the literature ignore discrete devices such as the relays. It is the practice to update relay settings occasionally, depending on planned changes in the power system structure (new source, new load, new line, periodic checking). Thus the current operating state of the power system can be significantly different from the one for which the relay security are selected. The necessity for inclusion of relay models is illustrated by an example. For the dynamic security assessment of the power system it is not necessary to include all the relays present in the system. A set of relays which may trip for a given contingency can be isolated. This set is named the set of vulnerable relays and a procedure to identify them is proposed. The 10-machine, 39-bus system and 3-machine, 9-bus system are used to illustrate the basic idea of this work.

Using neural network to interpret multiple alarms

The problem of interpreting a large number of alarms in a power system control center under stress conditions is considered. A description is given of an experiment using a neural network to build and test an intelligent alarm processor, that can analyze the multiple alarms associated with a system problem and identify the particular problem causing the alarms. The offline test results, although preliminary, suggest that the neural network approach is promising in developing a generic intelligent alarm processor that could be implemented by various electric utilities with minimal customization effort.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A real time power system simulation laboratory environment

A laboratory environment for research, teaching and demonstration of power system behavior developed at Arizona State University is described. The main driver is a real-time digital simulation of a large power system. A full-graphic human interface made up of several levels of one-line diagrams, tables and other displays permits the observation of the power system behavior in real time; it also makes it possible to affect its behavior by introducing supervisory control actions. These programs operate on a database, which can be changed to represent different power systems. The simulation and the database are run on a VAX 11-785 mainframe computer, while the human interface is run on an Apollo DN570 workstation with a 19-inch full-graphic color display. The two computers are linked via a high-speed Ethernet data link. The program-to-program communication was specifically developed for this application. The total environment created is that of a power system control center. It can be used to demonstrate and teach power system behavior as well as to experiment with all facets of the energy management system. >

A high resolution digital frequency meter for low frequencies

A digital frequency meter using frequency multiplication is described. It can be used in utility power system control centers and other low-frequency applications where resolutions of the order of 1/100 Hz and almost instantaneous readouts are essential. Possible improvements of the circuit are suggested.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The present status and progress of energy management systems in China

The present status of energy control centers in China is described. The present status of the power industry is briefly examined. A short review of early control center developments in the late seventies and early eighties is presented. More emphasis is placed on recent development of energy management systems, and experiences with designing and developing a few typical control centers are summarized. A survey of power system control centers in China before 1991 is also included in this paper. It is noted that the total installed capacity of generation reached 122336 MW and the annual generation reached 543.0 TWh in 1988. The outlook for research and development work in the next few years in China is also examined. >

Survey on Excessive Alarms

In recent years a great deal of attention has been paid to the design of alarm processing hardware and software to guarantee that no alarms are lost when an event triggers a large number of alarms within a short period of time. The resulting systems are capable of filling alarm message displays much faster than human operators can read and comprehend them. The main objective behind conducting this survey was an attempt to answer the following questions: 1) Is there a problem with excessive alarms in modern power control centers? 2) If yes, what is the nature of the problem and what is the best way to cope with the problem? The idea for the project came as a result of a discussion in 1985 within the Joint Working Group on Power System Control Centers. An opinion was expressed that a problem existed with alarm processing in power system control centers and that perhaps the remedy for this situation ought to be studied. This opinion met with immediate agreement by some members and was disputed by others. The working group then decided to conduct a survey of control center operators to determine if problems existed with alarm processing. The survey contained many questions which required a simple yes, no or numerical response. In addition, the survey contained many questions which asked the respondent to express an opinion.

Survey on excessive alarms (power system control)

An overview is given of the results of a survey on excessive alarms that was conducted by the IEEE Power Engineering Society's Joint Working Group on Power System Control Centers. Results from the survey are tabulated by the number of responses as well as by opinions expressed. The majority of the respondents indicated that there were excessive alarms for their operators to deal with, particularly during emergencies. The most frequently proposed remedy was the use of alarm categories and priorities.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Computer-Administration of Hand Written Commentaries on Events and States in Power System Operation

In modern power system control centers computers are applied for information management and system control. Many operating states and events require commentaries which should also be entered into the computer.In control centres of nations with an alphabetic written language, a-numeric keyboards can be used for that purpose; in nations with non-alphabetic written language the problem gets a further dimension.Therefore methods have been studied to start such a text by signs, which have been input via functional keys, and to add up the commentary in handwriting on a digipad. So the computer is capable to administer the text using the first and unequivocally coded signs.In this paper, both roman-languge hand-writing (English) and non-roman language hand-writing (Chinese) are experimented with, using different output devices of power control centers.

Full-graphics man-machine interface for power system control centers

A description is given of a human factors analysis carried out on the man-machine interface (MMI) needs of energy management systems (EMSs), with focus on the applications of full-graphics display technology for these systems. The need for and purpose of human-factors analysis are discussed. Conclusions are presented regarding switching operations, screen management, automatic generation control, unit commitment, and security analysis. The results of the study demonstrate that advanced features such as world map, pan, zoom, and declutter applied to SCADA, network diagrams, and tabular applications displays enhance operator effectiveness. While some examples are drawn from an actual implementation, this is not a description of a specific MMI or a design description. >

Future role of high level languages in power system control centers

Four short reports are presented, each dealing with the attributes of different high-level computer languages and how they might perform in the specific application of a utility energy control center. The reports deal specifically with Fortran, Ada, Pascal, and the C environment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Recent Progress in Real-Time Network Security Analysis

Network security analysis forms the core of the advanced application software in modern power system control centers. Recent progress in network security analysis is reviewed in this paper. Topics include: On-line load flow, state estimation, observability analysis, bad data detection and identification, external network modeling, contingency selection and evaluation, and optimal power flow. Issues concerning modeling, assumptions and limitations, solution techniques, computational efficiency and solution accuracy are addressed.

The Finnish Power System Control Centre

The Finnish Power System Control Centre

Integrating Load Management into Energy Management System's Normal Operations???Primary Factors

This paper delineates the major considerations inintegrating loadmanagement intothe normal operations of powersystemcontrol centers' energy management systems(EMS). It showshowthe system operators wouldliketoutilize loadmanagement in conjunction withtheday-to-day scheduling and dispatch ofgeneration andinterchange resources inan electric utilitycompany.The paperpresents the results ofa surveyof utility companies andsystem vendors onthestate-of-the-art forintegrating load management intotheEMS. The survey wassponsored underanEPRIProject (RP2202-1). Thenthepapersets forththe primaryfactorsthatwouldaffectthe integration of load management intoEMS'normal operations.Theseprimaryfactorsbecomethe cornerstone for the formulation thatentailsthe integration ofloadmanagement. Theseresults provide insights intowhatto considerifutility engineers andoperators desire tointegrate loadmanagement into theEMS. anotherupcomingpaper,the authorswill present themathematical formulation for thisload management integration problem.Thepaperwillalso describethe prototypesoftwareentitledLoad Management Decision-Support System(LMDSS)that interfaces withtheapplication programsofEMSina hostutility company.Resultsof casestudies for thishostutilitycompanywillalsobepresented to illustrate howpractical the LMDSSisinintegrating loadmanagement intotheEMSfunctions andoperational planning.

Display Systems for Electrical System Control Centers

The Electric Power Research Institute (EPRI) sponsored a project that identified the display needs of power system control centers, evaluated currently available display systems, prepared a prototyped a display set, and wrote a handbook on the effective design of such systems. Project results are described, examples of currently used displays presented and analyzed. Improved and entirely new power system control center displays are presented along with the rationale for their design.

Integrating Load Management into Energy Management System's Normal Operations -- Primary Factors

This paper delineates the major considerations in integrating load management into the normal operations of power system control centers' energy management systems (EMS). It shows how the system operators would like to utilize load management in conjunction with the day-to-day scheduling and dispatch of generation and interchange resources in an electric utility company. The paper presents the results of a survey of utility companies and system vendors on the state-of-the-art for integrating load management into the EMS. The survey was sponsored under an EPRI Project (RP2202-1). Then the paper sets forth the primary factors that would affect the integration of load management into EMS' normal operations. These primary factors become the cornerstone for the formulation that entails the integration of load management. These results provide insights into what to consider if utility engineers and operators desire to integrate load management into the EMS. In another upcoming paper, the authors will present the mathematical formulation for this load management integration problem. The paper will also describe the prototype software entitled Load Management Decision-Support System (LMDSS) that interfaces with the application programs of EMS in a host utility company. Results of case studies for this host utility company will also be presented to illustrate how practical the LMDSS is in integrating load management into the EMS functions and operational planning.

The Finnish Power System Control Centre

The operating philosophy for controlling the Finnish power system is based on production conditions, which include hydro, nuclear and coal-fired power plants, and joint national and international operation. On top of the control hierarchy is the Control Centre which has eight District Centres under its command. The Control Centre system, which was placed in full operation in 1982, consists of three subsystems: the Main, the Front-End and the Automatic Generation Control Computer systems which together with the District Centre Computer systems form an extensive computer network. The Main Computer system includes the most common SCADA-functions and EMS features such as State Estimation, Operators Load Flow and Load Forecasting among others.

Reactive Switching Simulation in Security Analysis At Florida Power and Light System Control Center

This paper describes a method for simulating the switching of reactive devices in the Security Analysis function at Florida Power and Light Company System Control Center. The method closely simulates the automatic switching of reactive devices in the field, resolves problems of non-convergence of some highly critical contingencies, provides tools for a better VAR management and reactive device control, and thus relieves the system operator from the guesswork in interpreting Security Analysis results. Real time results are also presented to show the effectiveness of the method.