新能源电站Z型接地变回路选择及优化
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摘要
新能源电站汇集线系统常采用Z型接地变经电阻接地,但工程中接地变容量及接地电阻选择存在一定分歧:某些工程提出单相故障电流只流过接地变一相,应考虑增大3倍计算三相变容量,按现有规范选择容量过小;某些工程提出应考虑接地变零序阻抗的影响,否则接地电流大小达不到设计目的。文中对这些分歧作了分析,另外文中对接地变容量提出了一种优化计算方案。
Many new energy station collection line system are grounded by Z-type grounding transformer, but there are some differences in the selection of transformer capacity and grounding resistance in projects: some projects propose that single-phase fault current flows through the single-phase of grounding transformer,the three phase transformer capacity should be three times bigger,the transformer capacity would be too small if selected according to the relevant specifications; Some projects propose to consider the influence of the grounding transformer zerosequence impedance, otherwise the grounding current cannot reach the design purpose. In the paper, these differences are analyzed. In addition, an optimized calculation scheme for grounding transformer capacity is proposed.
Many new energy station collection line system are grounded by Z-type grounding transformer, but there are some differences in the selection of transformer capacity and grounding resistance in projects: some projects propose that single-phase fault current flows through the single-phase of grounding transformer,the three phase transformer capacity should be three times bigger,the transformer capacity would be too small if selected according to the relevant specifications; Some projects propose to consider the influence of the grounding transformer zerosequence impedance, otherwise the grounding current cannot reach the design purpose. In the paper, these differences are analyzed. In addition, an optimized calculation scheme for grounding transformer capacity is proposed.
引文
[1]DL/T 5153-2014,火力发电厂厂用电设计技术规程[S].
[2]DL/T 5222-2005,导体和电器选择设计技术规定[S].
[2]DL/T 5222-2005,导体和电器选择设计技术规定[S].