Since the CCSR software calculate the compatible settings for relay’s secondary, so now there is some requirement for calculating and predicting proper settings for primary relays transmission and sub-transmission substations. Based on this requirement and also considering special features of DIgSILENT software for simulation, calculation and coordination of relay settings, this software has been selected as a protection studies core. While DIgSILENT cannot study the systems automatically, FASBA developed proper tools called DPAT (DIgSILENT Protection Analysis Tools) to add this capability to mentioned software.

Preparing this tools considering conditions of power grids especially in sub-transmission networks and also requirements to support different network topologies and possibility of fault investigation, take time around 5 years. The result now created fundamental changes in protection studies methods.

Considering all above capabilities, now we can do protection studies for both transmission and sub-transmission networks with the best accuracy in minimum time and prepare detail report to the customer on calculation methods and relay settings in primary and secondary.

Mentioned software is capable of calculating the relay settings for all transmission and sub-transmission substation equipment. This tools executed in part of transmission and sub-transmission substation equipment of Fars and Sistan-Baluchistan regional Electric Companies.

FASBA continuously updated software libraries to add different types of relays; overcurrent relays and longitudinal differential lines, overcurrent, and REF differential transformers, reactors and capacitor banks to cover all equipment and scenarios. Naturally this procedure will continue for new equipment also.

The current methods used for relay setting calculation are manually or using defined applications in Excel or Mathcad environments that use substation short circuit states in a specified operational mode and defined algorithms. At the end, relay settings codified.

Based on feedback and experience in Iran's electricity grid, the following items should be considered:

• If you consider calculation accuracy, it will be time consumable to calculate proper relay settings
• In absence of adequate technical knowledge, we have some calculation errors
• The lack of uniformity computing strategy and apply different personal style make it in some cases, lack of coordination in protection system
• In this way, the effect of operational modes could not be considered in settings calculation
• Evaluation of relay coordination in adjacent positions and different levels of voltage will not be possible
• Relay settings update in case of topological changes in the network (pipeline and new posts), is difficult and time-consuming. This the same that done in Iran’s power grid because of some problems like time consuming processes

DPAT in addition of solving above problems has the capability of:

• The exact calculation of the distance relay settings, longitudinal differential, overcurrent relay coordination of sub-transmission networks and also overcurrent relays and differential transformers
• Step by step report in process of performing calculations in a manual of calculation relay settings
• Evaluation of the quality and accuracy of the calculation settings and relay coordination using complementary studies and simulation of possible disorders and assess the relay coordination
• Calculation of settings for implementing relay in the secondary. In this regard, the software library of CCSR for distance relays for sub-transmission networks, longitudinal differential and overcurrent relay transformer has been updated and compatible with  more than 50 new relay, now
• Rapid identifying system protection weaknesses using relay settings data gathering and transferring them to software automatically to investigate the settings are correct
• In case of certain changes in the configuration of network, utilization and the Establishment of the new line, DPAT doing the new relay setting calculation, to identify and calculate the relay settings that are improving this medium to maintain consistency
•  Ability to evaluate the performance and coordination of relay network in a variety of operating conditions
• The possibility of a more appropriate analysis of network events and assess and identify weaknesses and evaluate strategies to improve
• Many other studying facilities and capabilities provided by DIgSILENT software