Inclusion of robustness into design using optimization-enabled transient simulation

This paper presents an approach to the design of robust power-electronic systems (i.e., those which have optimal operation over a range of operating configurations). Designing nonlinear systems, such as power-electronic converters, to be robust is a challenging task as settings that may be optimal for a given operating configuration may be inadequate for another. This paper extends the method of combining nonlinear optimization with electromagnetic transient simulation, which has previously been successfully applied to the design of optimal systems at only one operating point; to an approach which simultaneously considers a range of operating points. The method is exemplified using two examples. In the first example, a dc power supply is designed to operate optimally over a range of current order settings. The second is the case of an HVdc system, which is optimized to work well with a range of possible ac system configurations.

I. Introduction

Modern power networks are large-scale nonlinear systems that exhibit complicated dynamic behavior. This complexity often prohibits the use of analytical methods for the analysis and design of power systems. As an alternative tool, electromagnetic transient simulation programs [Electromagnetic Transients Program (emtp)-type programs], which simulate the behavior of power systems by numerically integrating the time-domain differential equations of the system, can be used [1], [2]. Since these programs make use of detailed models for power system components, they are computationally intensive, and completion of the simulation can take a long time.