Tie-line bias control and oscillations with variable generation in a two-area power system

Integrating variable generation sources such as utility-scale photovoltaic (PV) plants into the transmission grid is desirable with the increasing quest for cleaner sources of electric power generation and reducing cost of utility-scale PV. In a multi-area power system, inter-area flows have to be controlled according to some power purchase agreements and transaction contracts. Automatic generation control (AGC) with knowledge of PV plant generation is introduced for variable tie-line bias control and maximum utilization of PV power in the power system. Typical results to illustrate the proposed real-time tie-line bias control are presented on a two-area four machine power system with a utility-scale PV plant. Furthermore, an analysis of the tie-line power oscillations due to cloud cover and disturbances for different levels of PV power penetration are carried out and the presence of low frequency modes are pointed out.