Distribution system analysis (CYMDIST)

Distribution System Analysis package (CYMDIST)

General

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 specialised analyses. New modules are developed regularly to meet the evolving needs of the distribution engineers.

Accurate modelling and representation

The modelling capabilities of Eaton's CYME software network editor include the detailed representation of all portions of a distribution network, including the MV primary system and 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 customisable graphical user interface provides the representation, results and reports at the required level of detail.

Load flow with CYMDIST

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 optimised 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.

Fault analysis with CYMDIST

Comprised of a number of applications, the fault analysis functions in CYMDIST support 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

Additional analyses included in CYMDIST

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/invoicing data or existing calculated load data.

Load balancing

The load balancing analysis is used to determine which loads or lateral taps can be reconnected to different phases so as to minimise 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 capacitor 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.

Alternatively, 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

Eaton's CYME software comprises several add-on modules for detailed modelling and in-depth simulations, bringing the analysis of any power system to a whole new level.

The modelling modules allow the creation of 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 optimise grid efficiency.