CAJ | 학술논문

上海地区有4回直流输电工程接入，逆变侧附近的变电站不断增多，变压器直流偏磁现象出现频繁。针对由多直流馈入而引起的交流变压器中性点直流电流增大的问题，建立了适用于这种情况的地区等值电网仿真模型。搭建了地上和地下2部分等值电网模型，地上部分为详细的4回直流输电系统模型以及上海地区交流网架的合理等值，地下部分为直流输电系统接地极电阻以及接地极到所研究交流变压器的地网电阻串并联拟合而成。利用三沪二回大负荷试验期间以及向上直流单极-大地方式运行期间实地测量的交流变中性点直流电流数据对该模型进行了校核，仿真结果证明本建模方法有效可行。最后基于此模型研究了多回直流处于不同运行方式对流入交流变直流电流的影响，为进一步研究多直流落点地区变压器中性点直流电流的抑制措施提供了参考。
상해지구유4회직류수전공정접입，역변측부근적변전참불단증다，변압기직류편자현상출현빈번。침대유다직류궤입이인기적교류변압기중성점직류전류증대적문제，건립료괄용우저충정황적지구등치전망방진모형。탑건료지상화지하2부분등치전망모형，지상부분위상세적4회직류수전계통모형이급상해지구교류망가적합리등치，지하부분위직류수전계통접지겁전조이급접지겁도소연구교류변압기적지망전조천병련의합이성。이용삼호이회대부하시험기간이급향상직류단겁-대지방식운행기간실지측량적교류변중성점직류전류수거대해모형진행료교핵，방진결과증명본건모방법유효가행。최후기우차모형연구료다회직류처우불동운행방식대류입교류변직류전류적영향，위진일보연구다직류낙점지구변압기중성점직류전류적억제조시제공료삼고。
There are four HVDC power transmission lines connected with Shanghai power grid, so the number of substations near to the inversion stations is unceasingly increased and it makes the DC magnetic bias phenomena in transformers frequently occurred. In allusion to the increasing of DC current in AC transformer neutrals caused by different operation modes of multi-infeed HVDC transmission system, a simulation model of equivalent network suited to such condition is built. The built equivalent model is divided into two parts, namely the above-ground part and the underground part, the above-ground part includes detailed models of four HVDC power transmission lines and the reasonable equivalence of the frame of Shanghai AC power grid, and the underground part is the series-parallel fitting of earth electrode resistances of HVDC transmission systems with the grounding grid resistance from the earth electrode to the transformer to be researched. The built model is validated by the measured current data of AC transformer neutrals during the monopole high power test of the second ±500 kV HVDC project from the Three Gorges to Shanghai and that during mono-polar ground return operation mode of ±800 kV DC transmission project from Xiangjiaba to Shanghai, and simulation results show that the proposed modeling method is effective and feasible. Using the built model, the impacts of multi-infeed HVDC transmission system under various operation modes on DC current flowing in AC transformer are researched, and the research results are available for reference to further research on the measures to suppress neutral DC current of transformers located at the region with receiving ends of multi-infeed HVDC transmission system.