A Circuit Approach for the Computer Modelling of Control Transfer Functions

This paper presents a technique which uses circuit components, such as resistances, capacitances, and ideal operational amplifiers, for the computer modelling of control transfer functions. This approach can be used by any EMTP-type electromagnetic transients program or by similar simulation programs, independently of the method used for the time-domain integration, because of its generality and flexibility. For an efficient digital computer implementation, it is assumed that resistances and capacitances can be assigned negative values. Ideal operational amplifiers could be solved with the modified nodal analysis (MNA) method, which would result in an unsymmetric nodal conductance matrix. The compensation method with an iterative NewtonRaphson algorithm is used here, because nonlinear effects can then be easily handled as well. With this compensation method, a simultaneous solution of the control and electric power system equations is obtained at every time step of the digital computer simulation.