The Impact of High Penetration of Renewable Energy Generation to Locational Marginal Price and Security of Supply: Case Study at Mae Hong Son City Thailand

As the dramatically increasing power supply of renewable energy (RE) generation penetrates the distribution network, the security of the supply of the network, such as voltage level, is affected by the uncertain power output. The unstable voltage is caused by the tap of the distribution transformer, which is usually a fixed tap. In addition, the locational marginal price (LMP) depends on the number of power supplies from RE generation. The LMP of the whole local system is not lower, although the selling price of RE generation is lower than that of others, which results from the oversupply of RE generation to the network. The Provincial Electricity Authority (PEA) distribution network in Mae Hon Son City is also affected by the high penetration of renewable energy generation (RE generation). Currently, the proportion of power supply from RE generation is approximately 38% (in May) and 143% (in October) of total power supply to the load. During an oversupply of RE generation, the excess power reverses to PEA transmission network at approximately 8.79 MWh, which results in the security of supply and cost efficiency of distribution network companies such as PEA. The locational marginal price (LMP) in case of high penetration of RE generation is, however, slightly the same price as the non-penetration of RE generation under the Thailand electricity market condition. Therefore, the local generation management and dispatching are consequently considered for local power supply and demand balancing, maintaining the security of supply and reducing power losses and locational marginal price.