Electronic transformer / photoelectric transformer and NKE-92 merging unit
NKE digital substation process level system which conforms to IEC 60044-7 (GB/T 20840.7) and IEC 60044-8 (GB/T 20840.8) model of electronic transformer standard, voltage transformer, current transformer rated output, rated output 1V or 150mV. Signal is sampled by the NKE-92 simulation of merging unit installed nearby small voltage electronic transformer output, into a digital signal (a rated output of 11585 or 463), and give the two equipment protection, control, measurement and so on interlayer via remote road 4 high-speed optical fiber Ethernet interface.
Electronic current transformer using Rogowski coil principle, electronic voltage transformer using the resistance capacitance voltage divider principle, and compared them with electromagnetic transformer has the following advantages:
(1) because it does not contain iron, eliminate magnetic saturation and ferromagnetic resonance phenomenon fundamentally, is conducive to improve the measurement precision and the reliability of protection;
(2) do not produce the high voltage current transformer two open, do not produce high current two short circuit voltage transformer, improve the operation and operating safety;
(3) two times the direct output of 0-5V small signal voltage, convenient and interface of merging unit, without the need for a two conversion (5A or 100V will be converted to 0-5V small voltage signal), to reduce the error source;
(4) wide range of frequency response, large dynamic range, good linearity;
(5) has the advantages of small volume, light weight, simple insulation;
(6) the minimum power consumption, obvious energy saving effect, meet the low carbon, environmental protection requirements.
NKE-92 each merging unit interval configuration a, uninterrupted time hair to receive the host PPS optical synchronous time scales; and a benchmark for the interval of electronic transformer output synchronous AD sampling, the sampling frequency is up to 12800Hz. Compared with the direct cable NKE-92 merging unit and the transformer output or hard wiring point-to-point serial optical fiber output, has many advantages, for example:
(1) the merging unit and the interval between two equipment communication layer
The transmission medium for long distance optical cable, cable laying no two, eliminates the DC component of the problems caused by it, improve the reliability of the protection;
(2) the cable so that the effective isolation between the one or two systems, the elimination of electrical fast transient burst and high frequency attenuation of shock wave, surge and other electromagnetic disturbance, improve the safety and reliability of equipment two;
(3) the analog quantity into digital quantity after the cable transmission, affect the accuracy will not change because of the environmental conditions;
(4) no cable laying, save copper metal consumption, reduce material cost;
(5) to PPS synchronous time sampling as a benchmark for synchronous AD, so as to ensure that the voltage and current signal station all the intervals of the synchronous sampling, realize the synchronous acquisition station unified real-time data, provides the technical foundation for wide area measurement and wide area protection;
(6) using high-speed optical fiber Ethernet interface to transfer data with IEC 61850 (DL/T860) standards, and ensure the sampling rate is extremely high, shorten transmission delay, greatly improves the real time data;
(7) has 4 high-speed optical fiber Ethernet interface, without the use of switches can guarantee in the protection, measurement, measurement, recording two times between the equipment to realize the sampling data sharing network;
(8) the merging unit is installed on the side nearest transformer, but also independent of each other, the maintenance of merging unit does not affect the operation of the equipment maintenance time;
(9) can sample the electromagnetic transducer output signal, meet the old station renovation needs
Electronic photoelectric type voltage current transformer
电子互感器/光电互感器和NKE-92合并单元
NKE数字化变电站过程层系统采用符合IEC 60044-7（GB/T 20840.7）和IEC 60044-8（GB/T 20840.8）标准的新型电子式互感器，电压互感器额定输出 ，电流互感器额定输出1V或150mV。电子互感器输出的小电压模拟信号由就近安装的NKE-92合并单元进行采样，转化为数字量信号（额定输出11585或463），并通过4路高速光纤以太网接口远传给保护、测控、计量等间隔层的二次设备。
电子式电流互感器采用Rogowski线圈原理，电子式电压互感器采用阻容分压原理，他们与电磁式互感器相比具有如下优势：
（1）由于不含铁心，从根本上消除了磁饱和与铁磁谐振现象，有利于提高测量精度和保护可靠性；
（2）电流互感器二次开路时不产生高电压，电压互感器二次短路时不产生大电流，提高运行与操作安全；
（3）二次直接输出0-5V小电压信号，方便与合并单元接口，无需进行二次转换（将5A或100V转换为0-5V小电压信号），减少误差源；
（4）频率响应范围宽，动态范围大，线性度好；
（5）体积小，重量轻，绝缘简单；
（6）功耗极小，节能效果显著，满足低碳、环保的要求。
NKE-92合并单元每个间隔配置一台，不间断接收对时主机发来的PPS光同步时标；并以此为基准对本间隔电子互感器的输出进行同步AD采样，采样频率最高可达12800Hz。NKE-92合并单元与互感器直接电缆硬接线输出或点对点光纤串行输出相比，具有很多优点，例如：
（1）合并单元与间隔层二次设备之间通信
传输介质为光缆，没有二次电缆的长距离敷设，消除了由此引起的直流分量问题，提高保护可靠性；
（2）光缆使一、二次系统之间有效隔离，消除电快速瞬变脉冲群、高频衰减震荡波、浪涌等电磁骚扰，提高二次设备安全可靠性；
（3）模拟量转化为数字量后在光缆中传输，不会因环境条件的变化影响精度；
（4）没有电缆的敷设，节省铜金属用量，降低材料成本；
（5）以PPS同步时标为基准进行同步AD采样，从而保证全站所有间隔的电压电流信号同步采样，实现全站统一断面实时数据的同步采集，为广域测量和广域保护提供了技术基础；
（6）采用高速光纤以太网接口传输数据，符合IEC 61850（DL/T860）标准，保证了极高的采样率，缩短传输延时，极大地提高了数据实时性；
（7）具备4路高速光纤以太网接口，不必使用交换机就能保证在保护、测量、计量、录波等二次设备间实现采样数据的网络共享；
（8）合并单元就近安装于互感器旁，但又相互独立，合并单元检修维护不影响一次设备运行；
（9）可以采样电磁式互感器输出信号，满足老站改造的需求
ELECTRIC
