You can use EMTDC in its multiple run mode to determine an optimal set of parameters. Vary a set of parameters either sequentially or randomly for each run and plot the set of values against a objective function such as peak over voltage, integral square error, etc. The objective function can be built in PSCAD using standard blocks available in the master library or you can custom write one using the standard interface.
This feature allows you to run an EMTDC simulation many times - each time with a different set of parameters. For example you can run the case several times, each time with different fault or a different gain for a controller. This batch feature is ideal for parametric optimization, determining worst point on wave fault over voltage, determining optimal relay settings etc.