Optimization for Unit Commitment Considering Operational Flexibility of Back-to-Back VSC-HVDC
Due to the promising advantages of reducing short-circuit currents and achieving fast power flow reversal,the back-to-back voltage source-converter-based high voltage direct current(VSC-HVDC)is gradually being applied to deal with the practical power system problems.However,the study on the back-to-back VSC-HVDC-embedded power system decision-making issues is still very limited.This paper,closely combining the practical engineering background and taking a typical unit commitment problem in power systems as an example,proposes an optimization method for the unit commitment that fully takes into account the operational flexibility of back-to-back VSC-HVDC.Firstly,a back-to-back VSC-HVDC model based on the equivalent virtual generators is introduced,incorporating various control requirements for power adjustment during operation.This model encompasses constraints of power adjustment directions,adjustment times,power flip requirements,and power delivery modes.It not only avoids the issue of shortened lifespan due to frequent device operations but also guarantees the on-site practical feasibility of model optimization results.Secondly,a unit commitment model considering the back-to-back VSC-HVDC is presented,and the corresponding reformulation method is given.Finally,the effectiveness of the proposed model is verified by the modified IEEE 14-bus,the IEEE 118-bus,and a certain power grid test systems in China.The simulation results show that the developed model is able to improve the economy of system operations while ensuring safety.
back-to-back VSC-HVDCunit commitmentpower flipelectricity marketequivalent virtual unit