Improved dynamic security assessment for AC/DC power systems using energy functions

A method is presented to integrate the dynamics of DC power flow into calculations of transient energy functions of AC/DC power systems. This method treats the generator input power as a function of the parameters and the input, output variables of the DC control system. By using this transient energy function, the accuracy of the stability prediction of AC/DC power systems is improved. The new transient energy function is validated using 12-bus and 30-bus test systems by comparing the stability results with those obtained from time simulation. The new transient energy function is used in a number of studies to establish its effectiveness.