Yi-Kyu Kang, “대용량 풍력발전 시스템 설계를 위한 파라미터 계측 및 제어 알고리즘 개발,” 아주대학교 공학석사 학위 논문, 2010. > Paper

This paper proposes two algorithms for driving in a wind power system using an IPMSG (Interior Permanent Magnet Synchronous

Generator). First of all, this paper presents a simple scheme to estimate the initial rotor position and the d-, and q-axis inductances

for an effective Maximum Torque per Ampere (MTPA) operation. An IPMSM essentially requires an exact coordinate transformation

and accurate inductance values to use a reluctance torque caused by the saliency characteristic. In the proposed high-frequency

voltage testing method, there is no voltage drop caused by the resistance and the electromotive force. The initial rotor position and

the inductance can be measured through the analysis of the stator current without turning the rotor. A power conversion system in

a wind turbine using a Permanent Magnet Synchronous Generator (PMSG) is directly connected between a generator and a grid. The

capacity of power semiconductor switches and filters should be selected regarding the overall system rating and the output power

quality. The use of an LCL-filter and n-parallel power conversion devices can be the best solution for these problems in a high power

system. However, the resonant pole introduced in the LC part produces resonance in the system leading to the stability problem.

The voltage difference between the parallel back-to-back converters generates a zero-sequence circulating current. In this paper, a

novel control method using a PQR transformation for simultaneously compensating of both the LCL-filter resonance and the zero-

sequence circulating current in a wind power system driven by 3-parallel back-to-back converters is proposed. The effectiveness of

the proposed algorithms is verified by simulations and experimental results.