Evolution of the LV Network

University essay from KTH/Elektriska energisystem

Author: Pierre Croce; [2013]

Keywords: ;


Providing reliable electricity to everyone is a very important matter nowadays. Both thetransmission system operator and the distribution system operator are acting on the grid inorder to insure it. The latter sometimes has to deal with problems regarding the voltage,especially in rural areas. Those issues are crucial because they might lead to a bad functioning ordamage some appliances, so they lower greatly the quality of supply. Moreover, the installationof new small producers such as wind power plants and solar panels to this network hasworsened the situation by complicating and multiplying the constraints. New methods are thusneeded to bring more flexibility to the distribution grid and consequently solve the voltageproblems and possibly others.The aim of this project was to test possible solutions to voltage problems in the lowvoltage network which is the part of the distribution grid directly connected to the finalconsumers. The main ones were the use of an on-load-tap-changer, capacitors and the controlof the producers connected at this level. At first, statistical models for the loads and theproducers were developed. The simulation itself was then designed and programmed. It isbased on Monte Carlo using a load flow procedure and takes into account a 30 years evolutionof the network. Finally, many cases were run to observe various behaviors and the mostinteresting ones were selected for the conclusions.The results showed that the on-load tap-changer is the possibility that adds the mostflexibility to the system and seems thus the best option due to the high randomness of theevolution of such networks. The other options tested are efficient in specific cases and cheaperso they might be interesting when it is possible to forecast the new customers and producers ofthe area, which is unfortunately not often the case. Finally, the negative effect of unbalance onsuch networks has been highlighted and it would be very good idea to develop procedures ableto give the best repartition of consumers among the phases at every bus in order to optimizeparameters such as voltage and losses.

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