Abstract:
High PV penetration reduces stability tolerance due to the lower of system inertia and system ramp capability. To handle higher PV penetration issues, the system operator and PV owners should consider the operation improvement. For the system operator, critical system ramp capability with respect to PV penetration ratio can be useful to determine the lower bound of system ramp capability for handling N-1 contingency and expected disturbances. In the case study, test results reveal that the system can operate securely with PV penetration ratio up to 40%, in which it will require system ramp capability in the range of 0.05-0.09 p.u./min. In such case, when magnitude ratio of expected disturbance of aggregated PV output power is kept below 0.3, it will not need to impose a PV ramp limit on an individual PV plant. For PV owners, the grid-friendly dispatch strategy can partly compensate decreased revenue from energy payment by additional revenue from load frequency regulation ancillary service. Furthermore, the proposed method avoids unnecessary PV energy curtailment by providing load frequency regulation and frequency support, and avoids battery energy storage degradation by using internal active power reserve for frequency support component, instead. Overall, in so doing, system frequency security can be improved by 16.6%, when PV performance achieves day-ahead scheduled power compliance index at 94.3 % and load frequency power compliance index at 73.88%, respectively.
