受端混联型LCC⁃VSC直流侧谐波计算方法研究

Study on Harmonic Calculation Method of DC Side of Receiving End Hybrid LCC-VSC

受端混联型LCC-VSC混合直流输电技术不仅具备LCC和VSC的优势,而且在受端采用高压阀组LCC与低压阀组三端并联VSC相串联的结构,传输容量更大,制造难度低,造价低,是新型电力系统的重要组成部分,具有广阔的应用前景。然而,直流侧谐波特性对整个受端混联型LCC-VSC系统的控制保护有比较大的影响,目前很少有文献对该系统直流侧谐波特性展开研究和讨论。因此,分别建立LCC、直流滤波器和VSC谐波等效模型,根据受端混联型LCC-VSC拓扑结构提出其直流侧谐波计算等效模型,计算误差不超过10%。最后,利用某混合直流输电实例验证所提直流侧谐波计算方法的有效性和准确性。

The receiving end hybrid line commutated concerter based voltage source converter(LCC-VSC)not only has the advantages of LCC and VSC,but also adopts the structure of high-voltage valve group LCC and lowvoltage valve group three-end parallel VSC in series at the receiving end.Therefore,the receiving end hybrid LCCVSC has greater transmission capacity,low manufacturing difficulty and low cost.With these advantages,it is a very promising techonlogy of the future power system and has great application prospects.However,the DC side harmonic characteristics have a great impact on the control and protection strategy of the whole receiving end hybrid LCC-VSC system.Unfortunately,this problem is not studied fully.Therefore,the harmonic equivalent models of LCC,DC filter and VSC were established.Moreover,the DC side harmonic calculation equivalent model was proposed on basis of the receiving end hybrid LCC-VSC topology and the harmonic equivalent models.Theoretical analysis and simulations of a receiving end hybrid LCC-VSC project shows that the calculation error of the proposed model is no more than 10%.