Secondary grid network analysis

Secondary grid network analysis

General

The planning and operational challenge of secondary grids resides in its unique and complex topology, developed to ensure high power availability and reliability for sensitive and critical loads.

Such challenges bring along the need to model the grid with all its key components and to have robust algorithms to cater for heavily meshed networks.

Eaton's CYME Power System Analysis software brings the technologies together and is the perfect tool for any secondary grid network analysis.

The Secondary Grid Network Analysis module provides the capacity to model the important components of any spot network and secondary grid. It includes the representation of feeders, transformers, network protectors, cables and loads.

The complexity of secondary grid modelling is made easy through Eaton's CYME software user-friendly interface, its intuitive drag-and-drop operations and its many editing tools and functionalities. The secondary grid or the spot network can be presented in a separate view to offer better visualisation while maintaining the geo-referenced view of the rest of the distribution system.

Distribution system analysis

Once the secondary grids are modelled, the power, refinement and robustness of the CYME calculation engines is fully revealed:

• Unbalanced Newton-Raphson load flow method for the analysis of unbalanced heavily meshed networks
• Short-circuit analysis of secondary grids 
• Evaluation of the state of the network protectors with complete relay settings based on the operating condition (backfeed, contingency, etc.)
• Integration of distributed generation (DG) into the secondary grid
• Contingency scenario study
• Conductor resistance adjustment based on temperature is taken into account for both load flow and short-circuit analyses, making the calculations on spot networks and secondary grids more accurate

Network protector

The network protector is a key component of secondary grids and spot networks as it prevents back-feeding to the primary distribution circuits. Eaton's CYME Grid Network Analysis module provides the ability to model the network protectors with complete relay settings, which include trip functions and close functions.

Trip functions include:

• Insensitive
• Remote open/block open
• Sensitive
• Sensitive plus non-sensitive
• Time delay

Close functions include:

• Straight closing curve
• Circular closing curve

Polar plots are available to provide graphical visualisation of the trip and close regions.

Distributed generation

Extend the analysis capabilities

Load flow contingency

With the optional CYME N-p Load Flow Contingency module, the power engineer can create N-p type contingency events and single or multiple outage scenarios in a few mouse clicks.

Single or multi-contingency scenarios which take into account the automatic operation of network protectors can be simulated to study the effect of the loss of a combination of feeders, transformers, cables or any other network component.

Distribution state estimator

The optional CYME Distribution State Estimator module is a robust algorithm for the estimation of load and power flow in order to provide more detailed network models. It considers different measurement types, such as power and voltage meters, handles measurement redundancy and identifies errors in topology while performing the required load estimation. The module can solve issues for heavily meshed networks, such as secondary grid networks, and takes into account distributed energy resources.

Sub-network modelling

More accurate simulation results lead to more precise planning and management of distribution system expansion and maintenance and a greater facility to manage the integration of the distributed generation (DG) and distributed energy resources (DER) in the power grid, saving time and money.

The Sub-Networks Modelling module is included with any of the other CYME circuit/system modelling modules and shares similar features. It supports the creation of any sub-network, including utility vaults, switching cabinets and modular substations and DG and DER components in a nested representation connected to the overall grid.