高压直流输电系统用SHE多脉冲逆变器

SHE Multi-pulse Inverter Used for HVDC Transmission System

高压直流输电损耗小、纹波小、灵活性好、可靠性高,可实现不同频率网互联等,已被广泛应用于长距离架空和电缆输电。通过对SHE-PWM原理的分析,推导出了SHE-PWM数学模型。在高压直流输电用逆变器拓扑结构的基础上应用SHE-PWM技术进行Matlea和功率系统实验仿真,结果表明该逆变器系统具有优良的性能,可有效的降低受电端电网的谐波畸变率,畸变率完全符合国际谐波限制标准。

HVDC transmission technique which feathers low loss, smaller ripple, better flexibility, higher stability and realization of inter-connection of network at different frequencies, has been widely used in long distance overhead and cable transmission. Reducing the total harmonic distortion is the basic requirement of HVDC transmission. This paper proposes the thought of Selective Harmonic Elimination which is to compute the switching angles in a converter so as to produce the required fundamental voltage while at the same time not generate the selective harmonics, deduce the mathematic model of SHE-PWM via its principle analysis, which is a nonlinear transcendent equations. Moreover, a numerical iteration algorithm namely Newton-Raphson is introduced to solve the nonlinear transcendent equations. The basic thought of Newton-Raphson iteration algorithm is to transfer the nonlinear equations to linear equations which can be solved by Gauss algorithm and then approximate to the real solution of the nonlinear transcendent equations in step. This solving algorithm for the nonlinear transcendent equations can converge to the real solution with arbitrary precise in theory, which can be eligible to the requirement of practice. A simulation is investigated with MATLAB/SIMULINK based on the proposed topology configuration applicable to HVDC transmission system, the results confirm that the inverter system takes on excellent performance, the THD completely conform to the international standard of harmonic constraint, and the experiment also match the results.