Study on Constraint Limits of HVDC Tie-line Based on Risk Assessment

The setting of HVDC constraints in the existing HVDC transmission plan takes into account the HVDC operation characteristic and equipment reliability, and ignores the constraints of system flexibility on HVDC operation. Based on this, a risk assessment model is proposed from the perspective of system flexibility to evaluate the flexibility of the sending and receiving ends affected by the (HVDC) regulation rate. A large number of scenarios are generated by modeling the renewable energy and load output at the sending and receiving ends, from which a set of extreme scenarios is extracted and clustered to obtain typical extreme scenarios for net load. A large number of HVDC scenarios are generated by changing the HVDC regulation rate limit value, and the flexibility risk indexes are calculated based on the AC current optimization model by combining the extreme scenarios of net load with HVDC scenarios. The values of risk indexes corresponding to different HVDC scenarios are compared to derive reasonable (HVDC) regulation rate limits. The reasonableness and validity of the evaluation method are verified through simulation analysis.