Energy Management Systems

Energy Management Systems

ACS offers a new generation EMS solution in our PRISM real-time system environment. Our solution is integrates best of breed technologies using a powerful suite of field proven applications.

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Energy Management Systems

ACS offers a new generation EMS solution in our PRISM real-time system environment. Our solution is integrates best of breed technologies using a powerful suite of field proven applications.

ACS’ first Energy Management System was delivered in 1991 with a transmission state estimator, dispatcher’s load flow and contingency analysis application. The Security Network Analysis applications were tightly integrated into the real-time SCADA platform using a suite of applications from PSI, Inc. Since ACS’ first delivery the market has witnessed major evolutions in T&D:

  • Transmission operations have dramatically evolved due to power marketing operations and the need for voltage stability considerations in the network analysis. 
  • Distribution operations have radically changed from simple SCADA operations within substations to fully functional feeder network automated and optimized systems.

From a control center perspective the individual systems that used to provide Energy Management System and Distribution Management System capabilities now manage the power network as the integrated entity that it is. The ACS PRISM system uses industry standard interfaces in a modular architecture. The SecureSuite application represents a state-of-the-art implementation based on patented technology which greatly increases the likelihood of a convergent solution when compared with competing technologies that often fail to converge. ACS is proud to be able to offer this powerful field proven Energy Management System application suite together with our industry-leading PRISM real-time operation platform.

ACS’ first Energy Management System system was delivered in 1991 with a transmission state estimator, dispatcher’s load flow and contingency analysis application. The Security Network Analysis applications were tightly integrated into the real-time SCADA platform using a suite of applications from PSI, Inc. Since ACS’ first delivery the market has witnessed major evolutions in T&D:

  • Transmission operations have dramatically evolved due to power marketing operations and the need for voltage stability considerations in the network analysis. 
  • Distribution operations have radically changed from simple SCADA operations within substations to fully functional feeder network automated and optimized systems.

From a control center perspective the individual systems that used to provide Energy Management System and Distribution Management System capabilities now manage the power network as the integrated entity that it is. The ACS PRISM system uses industry standard interfaces in a modular architecture. The SecureSuite application represents a state-of-the-art implementation based on patented technology which greatly increases the likelihood of a convergent solution when compared with competing technologies that often fail to converge. ACS is proud to be able to offer this powerful field proven Energy Management System application suite together with our industry-leading PRISM real-time operation platform.

Component Based Architecture

ACS offers the strengths of a component architecture approach rather than the classical tightly integrated EMS approach. The advantages of the PRISM approach is that components can be replaced or enhanced without affecting the operation of other components on the system.

Leveraging this architecture has enabled ACS to deliver a “plug in” a best of breed EMS analysis engine, combined the ACS DASmap unified editor for the model/display builder and the PRISM real-time platform for SCADA and DMS. This modular approach has enabled the components such as OMS and EMS to be plugged into other ACS platform solutions worldwide. The integration at the user interface level in the proposed architecture is seamless. PRISM displays the results of the Security Network Analysis (SNA) on the SCADA /EMS one-line diagram.

ACS’ EMS solution provides utilities with the following unique strengths:

  • ACS supports a fully redundant EMS architecture. ACS‘ approach is to loosely couple the redundant components of the SCADA/AGC real-time system from the EMS security analysis applications to provide the greatest degree of modularity. In this way changes to one component does not affect the other. This also provides the greatest flexibility in providing an isolated component to the planning department for the ISO model exchange and for planning evaluation scenarios. The SCADA/EMS components will share the same model with the planning EMS component.
  • ACS supports a loosely coupled non–redundant back up emergency control center and Quality Assurance system for NERC CIP compliance.
  • A non redundant Program Development System is supported as a separate component.

To meet the NERC CIP requirements the component approach offers greater testing prior to implementation as changes to one component minimizes the interaction with other system applications.

Component Based Architecture

ACS offers the strengths of a component architecture approach rather than the classical tightly integrated EMS approach. The advantages of the PRISM approach is that components can be replaced or enhanced without affecting the operation of other components on the system.

Leveraging this architecture has enabled ACS to deliver a “plug in” a best of breed EMS analysis engine, combined the ACS DASmap unified editor for the model/display builder and the PRISM real-time platform for SCADA and DMS. This modular approach has enabled the components such as OMS and EMS to be plugged into other ACS platform solutions worldwide. The integration at the user interface level in the proposed architecture is seamless. PRISM displays the results of the Security Network Analysis (SNA) on the SCADA /EMS one-line diagram.

ACS’ EMS solution provides utilities with the following unique strengths:

  • ACS supports a fully redundant EMS architecture. ACS‘ approach is to loosely couple the redundant components of the SCADA/AGC real-time system from the EMS security analysis applications to provide the greatest degree of modularity. In this way changes to one component does not affect the other. This also provides the greatest flexibility in providing an isolated component to the planning department for the ISO model exchange and for planning evaluation scenarios. The SCADA/EMS components will share the same model with the planning EMS component.
  • ACS supports a loosely coupled non–redundant back up emergency control center and Quality Assurance system for NERC CIP compliance.
  • A non redundant Program Development System is supported as a separate component.

To meet the NERC CIP requirements the component approach offers greater testing prior to implementation as changes to one component minimizes the interaction with other system applications.

Network Topology Processor

PRISM Network Topology Processor (NTP) serves the dual propose of identifying electrical buses in the network, based upon the present status of the network switching devices, and of identifying the islands in the network. The other analysis modules use the power system model built by NTP.

Network Topology Processor

PRISM Network Topology Processor (NTP) serves the dual propose of identifying electrical buses in the network, based upon the present status of the network switching devices, and of identifying the islands in the network. The other analysis modules use the power system model built by NTP.

Unified T&D Graphical Editor

PRISM offers a unified T&D graphical editor. The same editor, DASmap, is used for the creation and maintenance of both Transmission and Distribution network model and graphics. DASmap supports various import models and file formats for the creation of bus and breaker oriented models:

  • Manual editing to graphically add lines and devices from a tool bar
  • GIS import to build the distribution network
  • Import model parameter information from an existing model

The user is able to create the model in a geographic or a schematic view as desired since the DASmap editor support a geo-spatial database. Geo-spatially accurate models can be optionally overlaid in a using aerial or Google maps (see GridVu product). DASmap exports a conversion set of files for the support of in house planning and analysis systems (such as PSS/E, PSLF), as well as the following EMS component modules.

  • CIM breaker model
  • PSS/E bus model (optional)
  • PRISM breaker real-time model with SCADA DB
  • PRISM real-time topology model
  • Historical archive
  • Simulator model (XpertSim)
  • Distribution (DMS) model for three-phase unbalanced analysis

DASmap includes AutoCAD Map 3D 2013 and Oracle Spatial technology with PRISM network topology building tools. The advantage of DASmap is that in a single editing session all system files and databases are created. This design considerably reduces the maintenance effort due to the intuitive nature of graphically drawing the network, importing existing models for merging networks and by exporting the various graphics, real-time database point, simulator and historical data points.

Unified T&D Graphical Editor

PRISM offers a unified T&D graphical editor. The same editor, DASmap, is used for the creation and maintenance of both Transmission and Distribution network model and graphics. DASmap supports various import models and file formats for the creation of bus and breaker oriented models:

  • Manual editing to graphically add lines and devices from a tool bar
  • GIS import to build the distribution network
  • Import model parameter information from an existing model

The user is able to create the model in a geographic or a schematic view as desired since the DASmap editor support a geo-spatial database. Geo-spatially accurate models can be optionally overlaid in a using aerial or Google maps (see GridVu product). DASmap exports a conversion set of files for the support of in house planning and analysis systems (such as PSS/E, PSLF), as well as the following EMS component modules.

  • CIM breaker model
  • PSS/E bus model (optional)
  • PRISM breaker real-time model with SCADA DB
  • PRISM real-time topology model
  • Historical archive
  • Simulator model (XpertSim)
  • Distribution (DMS) model for three-phase unbalanced analysis

DASmap includes AutoCAD Map 3D 2013 and Oracle Spatial technology with PRISM network topology building tools. The advantage of DASmap is that in a single editing session all system files and databases are created. This design considerably reduces the maintenance effort due to the intuitive nature of graphically drawing the network, importing existing models for merging networks and by exporting the various graphics, real-time database point, simulator and historical data points.

CIM Compliance

PRISM EMS delivers a common T&D transmission model which is Common Information Model (CIM) compliant to IEC 61970 and 61968 standards. The CIM compliant model is available for export (i.e. to ISO) or for import for model building in DASmap.

CIM Compliance

PRISM EMS delivers a common T&D transmission model which is Common Information Model (CIM) compliant to IEC 61970 and 61968 standards. The CIM compliant model is available for export (i.e. to ISO) or for import for model building in DASmap.

Third Party Model Support

PRSIM EMS offers support for planning system applications or NERC ISO by exporting a model such as a PSS/E compliant model from the PRISM EMS model and real-time database. PSS/E is frequently used as the model format for ISO model exchange as is included in the base offer.

Other model formats such as PSLF are available as an option.

Third Party Model Support

PRSIM EMS offers support for planning system applications or NERC ISO by exporting a model such as a PSS/E compliant model from the PRISM EMS model and real-time database. PSS/E is frequently used as the model format for ISO model exchange as is included in the base offer.

Other model formats such as PSLF are available as an option.

SecurityAnalysis

SecurityAnalysis

Power Flow

PRISM Power Flow (PF) software is part of the EMS software suite.

It can be executed either in real-time or in off-line study mode. Through the PRISM Graphical Operator Interface, the user can specify what case is to be evaluated. These can be either the real-time data, a set of previously saved cases, data input manually or imported through a file.

PF supports three load flow solution algorithms:

  • Full Newton-Raphson solution
  • Fast Decoupled Solution
  • Gaussian Solution

All three solutions are available at all times, employ the same database and user dialogue, and can be used interchangeably. PF provides a full set of tools for quick creation of operating scenarios in the study mode.

All PF solution algorithms support the following features:

  • Transformer and generator adjustment to control voltage at local or remote buses
  • Switched reactive power devices adjusted to hold a scheduled voltage
  • Two-terminal and multi-terminal DC transmission lines
  • Interchange control between areas
  • Limit checking and violation alarming of branch flows and bus voltages

Power Flow modules are supported by a number of display facilities, each dedicated to a particular application in the control center environment:

  • All system voltages and power flows can be compared to specified limits; PRISM SecureSuite will alarm any values, which violate their assigned limits.
  • All system operating quantities can be transferred to the PRISM Interface module, from which they can be accessed by the standard Operator Interface.
  • Summary reports are available for individual buses, for specified groups of buses, or for the entire system.
  • On an area or island basis, PF can display summary information that shows the characteristics of subdivisions of the power system.

State Estimator

Any real-time Real Time Market and Security Assessment component of an Energy Management System (EMS) is dependent on a fast and robust State Estimator.

This includes Nodal Price Computing and Contingency Analysis. With operating conditions constantly being stressed near their limits, the demand for more accurate real-time snapshots of our power networks is greater than ever. The State Estimator addresses the concerns that current operator’s face with state of the art solutions.

Measurement data that are received by SCADA systems are bound to contain errors, either small or large in magnitude. Within the high redundancy of measurements, sufficiently corrupted data must be identified and removed. This is a key process in finding an accurate estimate of the network state. However, the manner of identifying this “bad data” is dependent on the optimal formulation of the desired solution. By offering multiple formulations, we can provide different solutions that are tailored to the criteria of the system operator. For example, if the operator desires to see a state estimation that corresponds to a smaller maximum measurement residual compared to the solution of other products, the SE can provide such an answer.

Current State Estimation installations do not guarantee system operators the quality level of their routine estimation results. SE provides analysis that provides a “metric of confidence” about how well the results satisfy their functional requirements.

The State Estimator’s user-friendly interface is readily adaptable to your preferred EMS. The features of SE are:

  • Topology Assessment of Real Time Models
  • Accurate Modeling of Interconnected Networks
  • Fast Bad Data Detection and Detailed Analysis of Measurement Errors
  • Computational Efficiency for Complex Large Scale Systems
  • Parameter Errors and Correction

The SE processes telemetered power system measurements to obtain an estimate of the system voltages, flows, generation, and load.

Four key processes are involved:

  • An observability processor identifying the observable buses in the system
  • An advanced, constraint-based solution module using a new block structured algorithm for faster, more robust solutions
  • Facilities for identifying and removing bad telemetry points from the measurement set
  • Tools for assessing the adequacy of an existing or a proposed telemetry configuration. Among other uses, these tools identify areas where additional telemetry is needed for redundancy

PRISM State Estimator (SE) processes telemetered power system measurements to obtain an estimate of the system voltages, flows, generation, and load.

Four key processes are involved:

  • An observability processor identifying the observable buses in the system
  • An advanced, constraint-based solution module using a new block structured algorithm for faster, more robust solutions
  • Facilities for identifying and removing bad telemetry points from the measurement set
  • Tools for assessing the adequacy of an existing or a proposed telemetry configuration. Among other uses, these tools identify areas where additional telemetry is needed for redundancy

Contingency Analysis

On-line Study Contingency Analysis (CA) is an integrated package for voltage security assessment to provide voltage assessment for large-scale power networks under base case and contingency case scenarios in real-time and on-line study environments.

The strategy of using effective schemes to rank a comprehensive list of all credible contingencies and of applying detailed analysis programs only to critical contingencies is widely accepted. In order to identify critical contingencies, which will severely violate static security constraints, CA employs two look-ahead ranking schemes, which are to be incorporated into the tool. The first look-ahead scheme ranks the set of all credible contingencies in terms of branch MVA violation and selects the top few critical contingencies. The second look-ahead scheme all credible contingencies in terms of bus voltage violation and selects the top few critical contingencies.

CA implements the most robust commercially available Continuous Power Flow (CPFLOW). CPFLOW can generate P-V Curves, Q-V Curves, or P-Q-V Curves in a reliable and fast manner. These curves are generated under the condition that the constant P-Q load component of a bus (or a collection of buses) varies, with the constant current load and constant impedance load being kept indeed constant. The nonlinear load model, ZIP-model, is popular in modeling nonlinear behaviors of load. ZIP-V curves can better trace power system steady-state stationary behavior due to load and generation variations.

A contingency is composed of a single or multiple items. Line, transformer, shunt, load and generator outages are considered in the contingency. Multiple outages of up to 60 pieces of equipment are allowed in a contingency. Contingency definitions for Remedial Action Schemes and Special Protection Schemes are supported as a package option.

Generation

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Generation

Automatic Generation Control

PRISM AGC is an application that uses feedback loop control to regulate the power output of electric generators within a prescribed area in response to changes in system frequency, tie line loading, and the relation of these to each other.

AGC monitors and controls power generation with these overall objectives:

  • Minimize area control error
  • Minimize operating costs, in conjunction with economic dispatch calculation software
  • Maintain generation at fixed (baseload) values
  • Ramp generation in a linear fashion, according to a schedule specified by the operator

PRISM AGC supports four states, which are dispatcher-selectable and/or automatically implemented by the AGC function listed below in increasing order of restrictions placed on them:

  • ON: All AGC functions are performed.
  • MONITOR: All AGC functions are performed except issuance of control action.
  • ENTRY: Used for data entry when several quantities are to be entered, which would affect the output of the AGC function.
  • SUSPEND: A state that is not selectable by the dispatcher but is implemented solely by AGC due to the sustained non-update condition of critical telemetered quantities.

AGC provides the following five operational control modes, each using a different method for calculating the area control error (ACE):

  • Tie-Line Bias (TLB) Control Mode
  • Constant Frequency (CF) Control Mode
  • Constant Net Interchange (CNI) Control Mode
  • Tie-Line Bias with Inadvertent Payback (TLB-IB) Control Mode
  • Tie-Line Bias with Time Error Correction (TLB-TEC) Control Mode

PRISM AGC allows the definition of up to four restricted (prohibited) operating regions for each unit. Each region is defined by upper and lower boundary values and permissible time value.

PRISM AGC supports the NERC CPS 1&2, DCS reporting and control requirements, as well as the ERCOT SCE (Scheduling Control Error) reporting and control requirements.

Economic Dispatch

The PRISM Economic Dispatch Calculation (EDC) subsystem is a program that dispatches the available generation of an electric power system (one control area) to supply a given load in the most economic manner in real–time operation.

The following characteristics apply to EDC:

  • Consideration of incremental transmission losses is considered indirectly by imposing penalty factors on the dispatchable units
  • Calculation of optimal economic megawatt base points and economic participation factors for all the generating units under economic dispatch in the system
  • Calculation of optimal economic megawatt base points for all dispatcher selected generating units
  • Real–time and study mode operation

The dispatch is based on the principle of operating all dispatchable generating units at the same incremental cost of generation. Incremental transmission losses are considered indirectly by imposing penalty factors on the dispatchable units. Penalty factors are defined as manual points in the real–time data base and initialized with unity value, which can be updated manually or by other programs in real–time operation to represent the effects of incremental transmission losses.

The EDC program calculates the optimal economic megawatt base points and economic participation factors for all the generating units under economic dispatch in the system. The resulting dispatch is a system–wide optimum on the basis of individual generating units.

The EDC program also calculates the optimal economic megawatt base points for all dispatcher selected generating units in a study mode. The resulting dispatch provides recommendations to the dispatcher of the optimal megawatt levels of base points for all the selected units in AGC mode (1,2,3,4,5).

EDC is a slave program of Automatic Genration Control. It can only be scheduled by AGC or an operator only in real–time operation. In normal operation, AGC schedules EDC once every two minutes. It may be scheduled more frequently when a unit changes its AGC control mode or when the Base Load Deviation (BLD) exceeds a pre–specified threshold.

Going Smart At Scale

Your smart grid rollout should go live everywhere, right from the start.