配电网单相接地故障层次化零残流消弧关键技术研究

There are new challenges faced by traditional arc suppression technology as following: 1) paralleling control of distributed arc suppression devices in a substation; 2) coordination control of arc suppression devices between substations due to loop closing operation; 3) it is impossible to archive self-extinguishing of the arc because of a sharp increase in fundamental active and harmonic components of fault current which is caused by frog-haze condition, manufacturing and installing defects in power cables and their aging, unbalanced outputs of high-capacity electronic power devices which are connected to medium distribution lines directly, and arc flash faults. Therefore, hierarchical full compensation arc suppression method is proposed, it can realize full compensation of all components in the fault current by constructing “terminal- substation- master station” hierarchical control based on arc suppression coils and inverters. And then its key technologies would be discussed including its mechanism, modeling and stability. Firstly, multi-component coupling unified full compensation arc suppression mechanisms are analyzed based on the precise equivalent circuits. Secondly, considering characteristics of arc suppression coils, inverters and hierarchical control, dynamic phasor model of hierarchical full compensation arc suppression system is constructed. Thirdly, stability analysis of the complex and nonlinear full compensation arc suppression system would be carried out based on eigenvalue analysis method after reducing and linearizing the dynamic phasor model. The achievement of the project would deepen the arc suppression research system and optimize the resonant earth mode for distribution systems.

传统消弧技术面临新挑战：站内消弧装置分布式安装引起并列控制补偿消弧问题，不停电转移负荷时合环操作引起站间消弧装置协调控制补偿消弧问题，雾霾天气、电缆制造安装缺陷及老化、直接并入中压配电网电力电子装置不平衡输出、弧光接地等引起有功分量和谐波分量大幅增加而难以补偿等问题。为此，提出层次化零残流消弧新方法，其结合有源逆变器消弧装置和自动调谐式消弧线圈装置，形成“终端层—站域层—主站层”层次化控制，实现配电网单相接地电流各分量全补偿消弧。重点研究层次化零残流消弧机理、建模和稳定性分析等关键内容。建立层次化零残流消弧精确等值电路，研究多分量耦合统一消弧机理；计及有源逆变器消弧装置和消弧线圈装置等元件及其协同控制特性，建立层次化零残流消弧动态相量模型；实现动态相量模型的降阶与线性化，利用特征值分析法研究复杂非线性层次化零残流消弧稳定性。研究成果将深化配电网故障消弧研究体系，可优化谐振接地方式。

传统消弧技术面临新挑战：站内消弧装置分布式安装引起并列控制补偿消弧问题，不停电转移负荷时合环操作引起站间消弧装置协调控制补偿消弧问题，雾霾天气、电缆制造安装缺陷及老化、直接并入中压配电网电力电子装置不平衡输出、弧光接地等引起有功分量和谐波分量大幅增加而难以补偿等问题。为此，提出层次化零残流消弧新方法，其结合有源逆变器消弧装置和自动调谐式消弧线圈装置，形成“终端层—站域层—主站层”层次化控制，实现配电网单相接地电流各分量全补偿消弧。计及配电线路自身阻抗、故障点位置和故障过渡电阻因素影响，提出可通过对流经消弧线圈的电流进行折算消除传统电流消弧算法注入电流计算误差，折算因子为配电网正常运行时的相电压与故障时零序电压之比。为提高电压消弧方法的可靠性，利用单相接地故障下各相电流故障分量波形不相似原理，自适应选取时间窗，基于灰色关联度理论和Hausdorff算法，实现单相接地故障选相。提出了基于消弧装置调节和零序电流相似度测量的故障选线新方法。一旦发生单相接地故障，控制过补偿度在全补偿点附近进行连续多次调节，形成零序电流调节轨迹矩阵，应用灰色关联度可求取各零序电流调节轨迹之间的相似度，据此实现单相接地故障选线。为推进零残流消弧方法的实际应用，提出基于电压源逆变器的新型消弧模块接入调匝式消弧线圈并联阻尼电阻所在的二次绕组，或通过定制的单相升压变压器接入接地变压器，实现电流的有效注入，从而达到零残流消弧的目的。与此同时，还搭建了面向配电网单相接地故障消弧技术研究的物理模拟验证平台。研究成果将配电网单相接地故障消弧技术与单相接地故障选相、故障选线和区段定位进行了高度融合，提高了配电网消弧技术的可靠性和准确性，深化了配电网故障消弧研究体系，可优化现有的谐振接地方式，大幅提高配电网供电可靠性。