我国中压配电网多采用中性点经消弧线圈接地方式。配电线路分支多，所处的地理环境复杂，因此配电网中弧光接地故障频发。弧光接地故障电流微弱，随机性较强，检测难度大。现有故障检测算法在应对此类故障时存在明显的不足。若故障长时间存在而未被及时隔离会引发火灾、损坏电力设备、造成人员触电伤亡等恶性事故。因此，研究快速、可靠的弧光接地故障识别和隔离方法，对配电网的安全运行具有重要的意义。论文针对中性点经消弧线圈接地配电网弧光接地故障检测问题开展研究，主要开展了如下工作：1）基于对数电弧模型建立了中性点经消弧线圈接地配电系统非线性弧光接地故障高精度模型，采用分段线性等效实现了电弧非线性伏安特性的精确表达；并基于分段线性等效实现了对非线性弧光接地故障状态方程的求解，给出了欠阻尼和过阻尼情况下故障零模电压、零模电流的解析表达式；仿真验证了分段线性等效建模和给出的解析表达式的正确性。2）基于现场实验数据和仿真数据从时频域、暂稳态角度归纳总结了弧光接地故障的典型特征，如：随机性、谐波特性、类伏安特性等；并针对对数电弧模型不能反映实际现场中电弧电压、电弧电流间的相角差问题，提出了一种能够获得更接近实际工况仿真数据的数据映射算法，并仿真验证了其正确性。3）发现了特征频带内零模电压与零模电流的伏安特性具有明显的旋转方向性；基于零模电压、零模电流间的初始极性和伏安特性动态轨迹设计了一种弧光接地故障检测算法；并利用现场录波数据和仿真数据验证了所提算法的正确性。研究表明：论文所提的分段线性等效能够精确地实现对电弧非线性的线性表达，并且可以写出零模电压、零模电流的解析表达式，所提出的基于伏安特性动态轨迹的故障检测算法具有较高的可靠性和灵敏性，可在故障后1/4周波内实现对故障的有效识别，有助于快速地发现并切除故障，保障配电网的安全运行。
In most of China's medium-voltage distribution system, the neutral point is grounded by Peterson coil. Distribution lines have many branches and their geographical environment is complex, so arc grounding fault occurs frequently in distribution system. The arc grounding fault has weak current and strong randomness, so it is difficult to detect the fault. The existing fault detection algorithms have obvious shortcomings in dealing with such fault. If the fault exists for a long time and is not isolated in time, it will lead to fire, damage to electrical equipment, causing casualties of electric shock and other malignant accidents. Therefore, it is of great significance for the safe operation of distribution system to study the fast and reliable method of identification and isolation of arc grounding fault. In this paper, the problem of arc grounding fault detection in distribution system with neutral grounding via Peterson coil is studied, and the following work is mainly carried out:1) Based on the log-arc model, the precise model of nonlinear arc grounding fault in distribution system with neutral grounding via Peterson coil is established. The nonlinear volt-ampere characteristics of arc is accurately expressed by piecewise linear equivalent. Based on the piecewise linear equivalent, the nonlinear fault equation is solved, and the analytical expressions of zero-mode voltage and zero-mode current in underdamped and overdamped states are given. Simulation results show that the piecewise linear equivalent modeling and analytical expression are correct.2) Based on the field experiment data and simulation data, the typical characteristics of arc grounding fault, such as random, harmonic and volt-ampere characteristics, are summarized from the perspective of time-frequency domain and transient-steady state. Aiming at the problem that the log-arc model cannot reflect the phase Angle difference between the arc voltage and the arc current in the actual field, a data mapping algorithm which can get more close to the simulation data of the actual working condition is proposed, and its correctness is verified by simulation.3) It is found that the volt-ampere characteristic between the zero-mode voltage and zero-mode current in the characteristic frequency band have significant rotation direction characteristic. Based on the initial polarity and the dynamic trajectory of volt-ampere characteristics between zero-mode voltage and zero-mode current, an arc grounding fault detection algorithm is designed. The correctness of the proposed algorithm is verified by the field recording data and simulation data.The research results show that: the piecewise linear equivalence proposed in this paper can accurately express the nonlinearity of arc, and the analytical expressions of zero-mode voltage and zero-mode current can be written based on the piecewise linear equivalence. The proposed fault detection algorithm based on dynamic trajectory of volt-ampere characteristic has high reliability and sensitivity, which can realize effective fault identification within 1/4 cycle wave after the fault, which is helpful to quickly find and cut the fault and ensure the safe operation of the distribution system
