A comprehensive approach to fixed-step simulation of switchedcircuits

摘要

Because of its reduced calculation effort and deterministicnexecution time, fixed-step simulation is a prerequisite for real-timenperformance. However, when simulating switched circuits, it introducesnerrors in the form of switching delays and inconsistent initialnconditions. In order to eliminate these errors, the present paperndescribes a physically sound method for accurate and efficientnfixed-step/real-time simulation of switched circuits. Assuming thatnswitching is instantaneous and respecting the conservation of energynprinciple, the simulation method provides simple and straightforwardnprocedures for eliminating switching delays and for calculatingnconsistent initial conditions, even though the switching time may notncoincide with a calculation time-step and the circuit may pass through anseries of simultaneous switchings. Furthermore, the simulation methodnproposes a simple decoupling technique to isolate parts of the circuitnwhere the switching occurs, in order to reduce the effort required fornthe calculation of initial conditions. Implementation of the proposednsimulation method in the nodal approach and in the state space approachnis shown. A 12 pulse thyristor rectifier and a PWM inverter are used tonhighlight simulation accuracy. Simulation results, with and without thensimulation method, are compared to variable-step simulation and to otherndocumented methods. Finally, the simulation of a full HVDC system servesnto demonstrate real-time simulation performance