ADJUSTING CONVERTER CONTROLS FOR PARALLELED DC CONVERTERS USING A DIGITAL TRANSIENT SIMULATION PROGRAM
A description of how accurate system modelling of a dc system with an electromagnetic transient simulation program can be used to study and correct interbipole oscillations between converters connected into a parallel multiterminal system is given. The paper shows how to decide on the detail of modelling that is required, and demonstrates that it is often not enough to use prepackaged , generic HVDC control models, supplied with these programs. The detail of control models that are used in the electromagnetic simulation programs are shown to have a significant impact, in some cases, on the simulation results. In particular, a case of six hertz oscillations, in the dc currents of two converters on the Nelson River System, is accurately simulated, and it is shown that control modifications suggested by the simulation actually do eliminate the interbipole oscillations.
In this paper we analyze the impact of systematic errors in TRL calibration on the extracted equivalent circuit parameters of the measured device. We mainly focus on extraction of RLCG-parameters (resistance, inductance, capacitance, conductance) of transmission lines and inductors. We show how the uncertainties in measured S-parameters and in determined characteristic impedance propagate into RLCG-parameters. In particular, we emphasize the importance and the difficulty of an accurate determination of the imaginary part of characteristic impedance. We use the results of our sensitivity analysis to estimate the accuracy of RLCG-parameter extraction of a coplanar transmission line and a 2.2 nH spiral inductor. Finally, we propose an alternative method for determination of certain RLCG-parameters based on causal relationships.