This article presents a current injection power flow analysis and optimal generation dispatch method for bipolar DC microgrids. In bipolar DC systems, despite a certain local voltage being balanced by the converter control, voltage unbalance can occur at buses that are electrically far from the balanced voltage. In addition, from the aspect of system operation, the optimization of operation cost and voltage unbalance has not been fully investigated yet. Herein, for steady-state analysis, the current injection Newton-Raphson power flow for a bipolar DC microgrid is developed using static models of the network, voltage balancer, sources, and loads. Afterwards, the optimization problem is formulated based on voltage sensitivity, which can be obtained from the Jacobian matrix, to reduce the operation cost while resolving the voltage unbalance. The problem of quadratic programming can be solved sequentially to find the final optimal solution. The case study validates that the power flow method is sufficiently accurate compared to the simulation in PSCAD/EMTDC and that optimal generation can be achieved while reducing the operation cost and mitigating voltage unbalance.

中文翻译：

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双极直流微电网的电流注入功率流分析和最优发电调度

本文提出了双极直流微电网的电流注入潮流分析和最优发电调度方法。在双极DC系统中，尽管通过转换器控制平衡了某些局部电压，但在电气上与平衡电压相距较远的总线上仍可能发生电压不平衡。另外，从系统运行的角度来看，运行成本和电压不平衡的优化还没有得到充分的研究。在此，为了进行稳态分析，使用网络，电压平衡器，电源和负载的静态模型开发了双极DC微电网的电流注入Newton-Raphson功率流。然后，基于电压敏感度提出优化问题，可以从雅可比矩阵中获得电压敏感度，从而在降低电压不平衡的同时降低运营成本。可以依次解决二次规划问题，以找到最终的最优解。案例研究证明，与PSCAD / EMTDC中的仿真相比，潮流方法足够准确，并且可以在降低运行成本和减轻电压不平衡的同时实现最佳发电。