Small-disturbance stability of a concentrating solar power collecting system with multiple synchronous generators

This paper examines the small-disturbance stability in planning a concentrating solar power collecting system (CSPCS) with multiple concentrating solar power (CSP) generation plants, which are modelled as synchronous generators (SGs). The examination indicates that an oscillation mode of the CSPCS gradually moves to the right half of complex plane when the planned number of the CSP generation plants increases. Such oscillatory instability is different with the low-frequency electromechanical power oscillations (LEPOs) in a conventional multi-machine power system, because the unstable oscillation mode is associated with the excitation systems, rather than the electromechanical dynamics of the SGs. Analysis is carried out in the paper to explain why the instability risk found in the planning is associated with the excitation systems instead of electromechanical dynamics of the SGs. The analysis helps to understand the finding made in the planning. Furthermore, rules are proposed to adjust the gain of feedback loop of the excitation systems to eliminate the risk of oscillatory instability. This suggests that the parameters' setting of excitation systems recommended by the IEEE standard may need to be modified to accommodate the planning of CSPCS. Tests are presented to demonstrate and evaluate the analysis and conclusions made.