Trans Power has replaced two distributed Area SCADA’s with centralized the system of SCADA. It is likely that the comparative performance of these architectures, found in the IEEE RTS results described previously. However this gives no absolute indication of reliability worth for Trans Power System’s area was analyzed. This followed the model construction and analysis detail described previously for the IEEE RTS with the addition as following:
• The model comprised an Area SCADA covering 13 busses within New Zealand’s North Island grid (the DC power flow model for this system comprises 116 busses and 232 circuits). The power system model was simplified by making generation 100% available. Though forced by data lack was considered as a reasonable approximation given that generation in the New Zealand Power system is highly reliable.
• Much of the load curtailment in Trans Power system results from supply transformer tripping. However the large number of circuits and busses needed to include these transformers in the OPF model caused excessive computational overhead. Instead the loads were broken into one or more components connected to HV bus with each component having a defined probability of being connected.
• Only preliminary data reliability was available for the Power System. Based on this the composite model predicted approximately 39 system minutes compared with an actual value of around 10 system minutes. It is likely that this would lead to an over estimate of reliability worth.
• A single power system load value was used of around 60% of full load.
A single simulation run of 10 million samples was made giving a result of j=0.0038 joint system minutes, this is required around 14 days on a 166 MHz Pentium PC. This equates to US$ 6,942 per annum based on Trans Power CDF of US$ 2/kWh. This figure is substantially lower than the equivalent figures for the IEEE RTS because the Trans Power system is at least two orders of magnitude more reliable.