Loop‐Breaking 1 Method

This chapter shows in a stepwise manner how a three‐phase two‐level voltage source converter (VSC) can be modeled by the loop‐breaking 1 (LB 1) method. The LB 1 method requires the closed‐loop system at the connection point between blocks to be broken. Without loss of generality, the chapter considers the VSC operated as a STATCOM, where the dc current injection is neglected. As a typical VSC has three PI controllers (1 dc voltage controller and 2 ac current controllers), such a system must be subdivided into three solution blocks. Block 1 consists of the pattern generator and the model of the VSC. Block 2 is the “Current Control Block,” which contains the PI regulator for the ac currents. Block 3 is the “Voltage Control Block,” which contains the PI regulator for dc bus voltage. The chapter provides discussions on initialization and finding the Jacobian matrix.