Available Transfer Capability Calculation for AC/DC Systems with VSC-HVDC

In this paper, the voltage source converter is equivalently represented by voltage source model, thus the model of voltage source converter--high voltage direct current (VSC-HVDC) system suitable for optimal power flow is established. Each control mode could be considered by the model which can be applied to multiterminal VSC-HVDC. Moreover, internal and external operating limits can be taken into account with ease. The mathematical model of ATC for AC/DC systems with VSC-HVDC in which various methods for optimizing control variables can be used is set up. Sequential quadratic programming method is applied to calculate the ATC. Numerical results illustrate the viability of the proposed model and method as applied to the modified CEPRI-36 bus system.