考虑中间变压器饱和特性的电容式电压互感器宽频非线性模型  

Wideband and Nonlinear Model of Capacitive Voltage Transformer Considering the Saturation of Intermediate Transformer

作　　者：司马文霞[1] 王惠 杨鸣[1] 周原 彭代晓 舒想 SIMA Wenxia;WANG Hui;YANG Ming;ZHOU Yuan;PENG Daixiao;SHU Xiang(State Key Laboratory of Power Transmission Equipment&System Security and New Technology(Chongqing University),Shapingba District,Chongqing 400044,China;Electric Power Research Institute of Guangdong Power Grid Co.,Ltd.,Guangzhou 510080,Guangdong Province,China;China Three Gorges Mechanical and Electrical Engineering Co.,Ltd.,Chengdu 610041,Sichuan Province,China)

机构地区：[1]输配电装备及系统安全与新技术国家重点实验室(重庆大学),重庆市沙坪坝区400044 [2]广东电网有限责任公司电力科学研究院,广东省广州市510080 [3]三峡机电工程技术有限公司,四川省成都市610041

出　　处：《中国电机工程学报》2021年第14期5034-5043,共10页Proceedings of the CSEE

基　　金：国家自然科学基金(重点项目)(51837002);国家电网公司科技项目(5700-202132199A-0-0-00)。

摘　　要：电容式电压互感器(capacitive voltage transformer,CVT)为电力系统计量、保护和控制装置提供可靠的电压信号。然而其暂态响应误差大,可能引发距离保护超越和误动作等问题,需建立精确的CVT模型为电力系统分析与保护研究提供基础模型。然而现有具备宽频表征能力的CVT模型多为线性模型,难以兼顾中间变压器铁芯组件对其电压传输特性的影响,且建模过程存在无源修正和降阶等问题,导致模型在特定频段或中间变压器铁芯饱和时的响应误差激增,基于此的电力系统保护策略可能失效。该文提出将CVT端口散射参数在状态方程中进行离散化表征的方法,进而通过诺顿等价建立CVT宽频导纳子模型,表征整体CVT的宽频电压传输特性;基于电磁对偶原理建立CVT工频非线性子模型,表征中间变压器铁芯励磁特性的饱和差异性;对2个子模型进行导纳互差后再进行并联耦合,建立考虑中间变压器铁芯饱和特性的CVT宽频非线性模型。对典型35kV CVT进行参数辨识和模型构建,针对其非线性和频率特性表征能力,分别设计低频涌流、电压传递特性测试和雷电冲击电压试验。结果表明,与传统CVT模型相比,该文提出的CVT模型在中间变压器铁芯饱和时的低频涌流首峰幅值仿真误差从77.79%降低至1.71%,在5Hz~1MHz范围内电压传递特性仿真归一化均方误差为0.91%,雷电冲击电压首峰值仿真误差为3.11%。试验证明所提出的CVT模型能够表征CVT的频率特性和非线性特性,可为涉及CVT的电磁暂态仿真研究提供基础模型。Capacitive voltage transformer(CVT) provides reliable voltage signals for power system metering, protection and control devices. However, the transient response error of CVTs is so large that may cause problems such as distance protection overtaking and malfunction. It is necessary to establish an accurate CVT model as a fundamental model of analysis and protection research. The conventional CVT models with frequency characterization capabilities are mostly linear models, making it hard to consider nonlinearity influence of intermediate transformer iron-core-built components on voltage transmission. And there are other problems such as passive correction and order reduction when modeling, resulting in a sharp increase in the response error of the model in a specific frequency band or when the core of intermediate transformer is saturated. Therefore, power system protection strategies based on it may fail. This paper proposed a method to discretize CVT port scattering parameters in the state equation and established a CVT wideband admittance sub-model through Norton equivalent to characterize the frequency characteristics of CVT. Based on the principle of electromagnetic duality, a power-frequency nonlinear sub-model of CVT was established to characterize the nonlinearity of the excitation characteristics of the intermediate transformer. Then the two sub-model were coupled in parallel after admittance mutual difference, and a CVT wideband nonlinear coupling model considering the saturation of intermediate transformer was obtained. After parameters identification, the coupling model of a typical 35 kV CVT was established. Low-frequency inrush current, voltage transfer characteristic and lightning impulse voltage tests were designed to validate the nonlinearity and frequency characteristics of the coupling CVT model. Results indicate that when the core of intermediate transformer is saturated, the first peak amplitude of inrush current simulation error of the CVT model proposed in this paper was 1.71%, far lower tha

关 键 词：电容式电压互感器 非线性 频率特性 离散状态方程 导纳互差 

分 类 号：TM451.2[电气工程—电器]