电力变压器容量损耗测试仪的设计研究 ..doc

电力变压器容量损耗测试仪的设计研究 本文来自工控商务网：/ ? 摘 要: 设计了一种用于电力变压器空载及负载试验的容量损耗测试仪器。该仪器具有以下特点:仪器对三相电压电流同时采样;基于旋转式光电编码器和液晶显示屏的人机交互界面简洁而高效;可编程计数器阵列PCA“捕获”信号的过零点用于双向过零平均鉴相,得到准确的相位差和周期;基于实时参数自寻优的软件同步采样,有效地减小了周期截断误差,提高了测量准确度;数字化功率测量引入了传统的二表法和三表法,扩展了仪器的使用范围;实际容量根据负载损耗用软件查表的方法来判别;测量值已从试验温度折算到了参考温度(75 ℃)时的值。 ? ?关键词: 电力变压器;功率损耗测量;容量判别;智能同步采样;参考温度折算 ? ? On design of capacity and lossmeasuring instrument forpower transformer ? ? Abstract: A capacity and los s measuring instrument for no-load and load test of power t ransformeris developed . T he instrument simultaneously sample for three phase voltage and cur r ent .Rota ry photoelectric coding switch and LCD are used for human-comp ute r int eraction, it makes theinte rface compact and efficient . Utilizing the function of positive and negative edge trigger of the programmable counter ar r ay (PCA) unit in MPU, signal ze ro-cros s is captured for the phase detected based on dou ble way . T he software synchronism sampling method based on real-time pa rameter self-optimizing minishes pe riod t runca tion e r ror, and the meas urement accur acy is improved .The digitization power measure impor ts tr aditional two-unit and thr ee-unit methods and expands application range of the inst rument . T he capacity is discriminated by software table-look-up on the load los s . T he value of a quantity is conve rted to the value when r eference tempe rature(75 ℃)from test temper ature . ? ? Key words: power tr ansforme r; power los s measurment; capacity distinguis hing; intelligencesynchronous sampling; r eference temper atur e conver ting ? ?电力变压器的容量损耗测试对于变压器制造单位的出厂试验,以及电力部门有效降低线损、防止高耗变压器进入电网有着重要的意义。为此, 设计了一种用于电力变压器的空载及负载试验的容量损耗测试仪。该仪器所测的直接参数是三相电压、三相电流、三相功率及试验电源的频率。空载试验时根据所测数据计算出平均电压、平均电流、总功率、空载电流和校正后的空载损耗;负载试验时根据测量值计算出短路阻抗、短路损耗以及在额定电流下折算到75 ℃参考温度时的短路损耗;基于软件查表功能的设计,按照有关标准进行被测变压器的容量判别[1-2] 。该仪器集多种试验方式于一体,提供了二表法和三表法试验。为适合直接测量和通过互感器测量,仪器的电压测量范围为0～500 V(125 V 与500 V 量程自动转换);电流测量范围为0 ～60 A(6 A与60 A 两个量程)。在设计中结合先进芯片技术和软件智能同步采样测量策略,使仪器的电压电流和功率的测量精度大为提高。 ? 1