Optimisation of the voltage regulation in the Dutch MV-grid

Voltage regulation in Medium Voltage networks is approached in two main different ways: load-dependent (compounding) and load-independent regulation. In order to adopt a unified method for the utility Nuon, both have been compared. Because of its sensitivity to load patterns, cogeneration is a distortion factor for compounding. This is why there are different visions on whether or not compounding should be applied. The research covers the question whether compounding is effective with the current degree of cogeneration in the Dutch MV-grid. A couple of 50/10 kV transformers were modeled, as well as the outgoing MV-feeders. The behavior of each transformer was simulated both with load-independent regulation and compounding. Within the utility Nuon measurements of the load patterns (P and Q) from the transformers and the current of each feeder are available, as well as the maximum load of all low-voltage substations. Using this data and varying the compounding degree, load flow simulations on these networks were performed to determine the optimal tuning of the voltage regulation on the transformers. A statistical analysis of the results shows that by a moderate degree of cogeneration a small amount of compounding does not give any problems, whereas by a large degree of compounding the problems are considerable. Conclusion of this study is that on the greater part of the network the voltage profile at the low-voltage substations as a result of compounding is notably better than the one gotten by independent-load voltage regulation. This means less investment on voltage improvement in the net. On this moment the implementation phase within the utility Nuon is been carried out.