AST is an independent Latvian electricity Transmission System Operator, which operates the electric power transmission network and ensures security of electric power supply in Latvia, as well as fulfils the following mission: providing power transmission services based on the published transmission service tariffs and providing free third-party access to the transmission network. AST holds operational control of the transmission system and ensures its stable operation. Responsibilities of Augstsprieguma tīkls AS include: Development of transmission network and secure interconnection with neighbouring power systems; Operational control of power flows in the transmission network, ensuring exchanges of power with neighbouring power systems; Operational control of the power generation equipment connected to the transmission network; Supplying distribution network with energy in required amounts and according to the power quality requirements; Ensuring power supply security and stability of the transmission system; Provision of non-discriminating conditions on the transmission system usage for all transmission system users; Control procedures ensuring coordinated operation of power system; Provision of the information on the web-site, according to legislative requirements of EU.