The integration of the energy system of the Republic of Bulgaria within the European Network of Transmission System Operators (ENTSO-E) began in 2009. The ENTSO-E was established and mandated by the EU's Third Legislative Package for the Internal Energy Market, which aims to further liberalize the EU's gas and electricity markets. The ENTSO-E is responsible for the management of the electricity transmission system and for the authorization of trade and supply of electricity across EU…