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Distribution System Analysis


The evolution of the distribution systems now requires the engineers to perform from planning analyses to expert simulations supporting operations, including protection studies and DER interconnection assessments.

The CYME software is a focused and powerful tool to model the whole distribution system and address the simulation needs for capacity, contingency, power quality and optimization analyses.

Distribution System Analysis

CYMDIST is the distribution system analysis base package of the CYME software. It bundles all the modeling and analysis tools required to perform the various types of simulations involved in electric distribution system planning. The calculation engines support balanced or unbalanced distribution models that are built with any combination of phases and operated in radial, looped or meshed configurations.

The following analyses are included in the CYMDIST package:

  • Load flow
  • Load allocation and estimation
  • Fault analysis
    • Short-circuit/fault flow
    • Fault locator
    • Series and simultaneous fault
    • Voltage sag
  • Load balancing
  • Optimal capacitor placement and sizing
  • Motor starting
  • Batch analysis

Optional modules can be added to CYMDIST to extend the functionality to perform more in-depth and specialized analyses. New modules are developed regularly to meet the evolving needs of the distribution engineers.

Accurate modeling and representation

The modeling capabilities of the network editor of the CYME software include the detailed representation of all portions of a distribution network, including the MV primary system, the LV secondary system (radial or meshed) as well as the subtransmission system.

Simulations with CYMDIST

The CYMDIST base package is a comprehensive tool providing distribution engineers with key applications to perform system planning studies, simulations and analysis on a daily basis.

At the core of the software are extensive libraries, detailed models and algorithms in line with industry best practices and standards; and based on innovative engineering technologies. Its fully customizable graphical user interface provides the representation, results and reports at the level of detail needed.

Load flow

The steady-state performance of the power system under various operating conditions is simulated using the load flow analysis of CYMDIST. It is the basic analysis tool for the planning, design and operation of any electrical power system.

  • Unbalanced and balanced voltage drop – It features an iterative technique that is specifically designed and optimized for radial or weakly meshed systems; and includes a full three-phase unbalanced algorithm that computes phase voltages.
  • Unbalanced Newton-Raphson load flow – Takes into account for underground secondary networks (urban grid systems or spot networks), low voltage installations, and sub-transmission systems tied to the distribution systems.

The comprehensive analysis results include voltage, current, power factor, losses, abnormal conditions and unbalanced factors. The results can be viewed for the whole system or for individual locations.

Load allocation and estimation

This analysis assists in developing an accurate load model by allocating feeder demands across the network based on transformer connected capacity, consumption/billing data or existing calculated load data.

Fault analysis

Comprised of a number of applications, the fault analysis functions in CYMDIST support in the assessment of issues related to faults in the distribution system.

It includes three short-circuit calculation methods: Conventional, ANSI, IEC 60909© and IEC 61363©, All methods are based on multiphase models to solve complex balanced/unbalanced, single/two/three phase systems and radial/highly meshed power systems.

The fault analysis applications of CYMDIST also include:

  • Series fault analysis – Evaluates open circuit or asymmetrical line impedance conditions on the distribution system.
  • Simultaneous fault analysis – Studies the impact of having faults at different locations simultaneously on the network.
  • Fault locator – Evaluates possible locations of a fault on the network.
  • Voltage sag analysis – Studies the impact of a sudden reduction of voltage magnitude caused by network faults, or other disturbances such as motor starting or overloads.

Load balancing

The load balancing analysis is used to determine which loads or lateral taps can be reconnected to different phases so as to minimize kW losses or balance the current, the load, or the voltage. It reports a series of individual changes to the network and the objectives improvement with each change.

Optimal capacitor placement and sizing

This analysis helps in determining the ideal location and size of shunt capacitors banks to reduce kW losses or to improve the system voltage while maintaining a desired power factor. The user can provide guidance regarding the size, number and appropriate locations of the capacitor banks, and approve whether the recommended banks should be installed or not.

Alternately, the analysis can provide an exhaustive list of all possible capacitor placement locations with associated impacts on voltages and kW losses.

Motor starting

The motor starting functionality of CYMDIST determines the impact of induction or synchronous motors starting on the system by evaluating voltage flicker. An estimation tool also provides the largest single- or three-phase motor size for all locations based on the maximum voltage dip allowed.

Batch analysis

The batch analysis function allows users to run multiple user-defined scenarios on a selection of studies, self-contained files and multiple networks available in the database. Each scenario is configurable and can include several analysis simulations; each of these using configurable parameters.

This function is even more powerful when coupled with the Advanced Project Manager module and/or the Automated Network Forecast Analysis module to run analyses on user-defined project scenarios.

Additional Modules

The CYME software comprises several add-on modules for detailed modeling and in-depth simulations bringing the analysis of any power system to a whole new level.

The modeling modules allow creating a very detailed model of the distribution system from subtransmission to the customer meter, including secondary networks.

The CYME advanced analysis modules help engineers to perform system-wide distribution capacity planning studies, assess distributed generation interconnection impact, improve system reliability and optimize grid efficiency.


  • Enhanced Substation Modeling: to model all the major components of the distribution substation and any sub-network such as the detailed modeling of an industrial facility.
  • Low-Voltage Secondary Distribution Modeling: to model in detail low-voltage distribution systems within a one-line diagram.
  • Secondary Grid Networks Modeling and Analysis: allows the power flow and short circuit analyses of heavily meshed secondary network distribution systems for any voltage level.
  • Geographic Overlay: to display raster or vector map images (geographical land-base such as DWG, DXF, SHP, etc) as layers directly underneath the electrical model.
  • Online Maps Service: complements the CYME Geographic Overlay module and provides the capability to display Google™ maps and MapQuest™ Open maps as layers underneath the geographical view of your electrical network model.


  • Advanced Project Manager: extensive tool that supports the collaborative and detailed preparation of a project that consists in modifications to the network with related simulations.
  • Automated Network Forecast Analysis: to create, view and modify time-dependent projects (using the CYME Advanced Project Manager) consisting in modifications to the network such as the addition of any load at a given date, change/replacement of power transformers within a substation, a rephasing/reconductoring project, network switching or reconfiguration, etc.
  • Techno-Economic Analysis:facilitates the evaluation of the feasibility and the profitability of a project based on the factual system model.

Distributed Energy Resources (DER)

  • Integration Capacity Analysis: addresses DER and load interconnection issues by determining the maximum allowable capacity that can be added at any point of the network without violating a set of constraints. Allows to quickly assess the hosting capacity of the network and filter out interconnection requests that are non-compliant.
  • DER Impact Evaluation: assists engineers in their generation interconnection system impact studies. The analysis automates a series of time-consuming, repetitive and error-prone verifications and returns insightful results that clearly identify violations.
  • Network Disturbance Assessment D-A-CH-CZ: to determine the acceptability of a new load or generator interconnection by evaluating its impact on a series of power quality criteria.
  • EPRI DRIVE™: the calculation method provides aggregate and granular hosting capacity results for each distribution feeder and considers numerous circuit-specific attributes.


  • Distribution State Estimator: To analyze the unbalanced power flow and the voltages at every level of a distribution power system.
  • Contingency Assessment and Restoration: to study the impact of forced or planned outages on the electrical distribution system and find the optimal switching plan to restore electrical power to priority customers and to recover the maximum possible load in the affected areas.
  • Load Flow Contingency (N-p): to assist in power flow related static contingency analysis. To create contingency events and single- or multiple-outage scenarios and compare to a base case.
  • Advanced Fault Locator: Reports all the possible fault locations taking into account multiple monitoring points with several readings , fault indicator statuses and field measurements extracted from COMTRADE files.


  • Protective Device Analysis: provides engineers with a wide range of tools to efficiently and accurately design and validate the coordination scheme of their power system.
  • Arc Flash Hazards Analysis: to analyze and promote the electrical safety for employees working on or near electrical equipment. It computes the necessary parameters required to assess the risk level and adopt the adequate safety procedures.
  • Distance Protection Analysis: helps engineers design and verify their protection scheme, and address different coordination issues in any power system.

Power Quality

  • Reliability Assessment:provides a framework within which predictive and historical reliability assessment scenarios are run and the impacts of the related investment such as DA (Distribution Automation) can be evaluated and understood.
  • Harmonic Analysis: to perform harmonic penetration analysis in electric power systems. It features single phase and full three-phase modeling capabilities and includes a large library of pre-defined models for network equipment and harmonic current sources. The Frequency scan capability included in this module is also available as an independent module. This analysis provides full impedance scan results and allows the user to see problematic areas even before installing harmonic devices.



  • Long Term Dynamics: time-series simulation to study the impact of insolation variations, wind fluctuations and load variations on network controls.
  • Steady State Analysis with Load Profiles: to perform time range analysis based on a combination of historical consumption patterns and real-time monitoring.
  • Transient Stability Analysis: to simulate the dynamic behavior of distribution systems with distributed generation under various transient events (fault application/clearing, large motor starting, disconnection of co-generation units, islanding, etc.)


  • CYME Scripting Tool with Python®: Python® scripting has been integrated into the CYME power system analysis software for the users to extend the customization of the CYME capabilities based on specific needs. The latest data model is always available so the scripting can take advantage of the CYME analyses, but also allow the users to create their own algorithms and analyses.

Complementary Solutions and Modules

  • CYME Gateway: CYME Gateway is the CYME solution for the creation and maintenance of the network data model. The connectivity network extracted from the GIS is accurate, electrically complete, with actual loads and switch status; and this network model can be updated easily.
  • CYME for ArcGIS Desktop™: this solution is an out-of-the-box toolbar that seamlessly integrates into the ArcGIS Desktop™ framework to embed power systems analytics into your GIS environment. Along with the CYME Server solution, it offers powerful analytical ability, meeting the need for answers in a prompt manner.
  • CYME Server: brings the CYME network model and analysis engines into your IT environment to facilitate the widespread and efficient use of this powerful engineering analysis tool. These advanced applications allow system operators to respond quickly and decisively to changing network conditions and threats while driving significant improvements in network efficiency and reliability.
  • CYMTCC: addresses Time Over-Current protection for Industrial, Commercial and Distribution Power systems. Features a direct interface to CYMDIST to verify the coordination of protective devices, the maximum permitted operating time («Reach») and the maximum permitted continuous load current. The Arc Flash Hazards analysis module can be added to CYMTCC.

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