PRISM Energy Management System






ACS’ first EMS 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 PTI, 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. The issues of transmission stability and transfer capability are a major concern.
  • 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 EMS and DMS capabilities now manage the power network as the integrated entity that it is. ACS offers a new generation EMS solution in our PRISM real-time system environment. Our solution is based on a best of breed partnership using a powerful suite of field proven applications.  The applications are integrated with the ACS PRISM system using 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 EMS 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.


 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.



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.


Security Analysis

Dispatcher Power Flow

PRISM Dispatcher Power Flow (DPF) 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.

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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.

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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.

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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.

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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.

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More Information

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