Vector Control of Three-Phase Solar Farm Converters Based on Fictive-Axis Emulation

Abstract

In this paper, a new method for adjusting the current of three-phase voltage source DC-AC converter in orthogonal (DQ) reference frame is presented. In the DQ reference system, AC variable appears in the constant form of DC, making the controller design the same as the DC-DC converter [1]. It provides controllable gain benefits at the steady-state operating point, and finally realizes zero steady-state error [2]. In addition, the creative analytical model is dedicated to building up a series of virtual quantities orthogonal to the actual single-phase system. In general, orthogonal imaginary numbers get the reference signal by delaying the real quantity by a quarter period. However, the introduction of such time delay makes the dynamic response of the system worse. In this paper, orthogonal quantities are generated from a virtual axis system parallel to the real axis, which can effectively improve the dynamic performance of traditional methods without increasing the complexity of controller structure. Through PSCAD simulation, the ideal experimental results are obtained.