Internal energy metering error
Yesterday, a shift electrician at an automotive technology company in Jiangsu called me, reflecting two problems:
The sum of the energy readings in the multifunction meter on all 35kV switching cabinets in the 35kV substation does not correspond to the readings in the substation's 35kV meter.
The energy readings in the multi-function table on the low-voltage side feeder cabinet of the 10kV distribution room are very different from the sum of the power metering of all workshop power cabinets connected to the feeder.
The company, which has 12 10kV distribution stations connected to the 35kV substation, is being built by a third party on an energy performance management system.
I will make the following simple reply to the above questions:
Question I,
35kV power substation, 35kV power company meter connected to the high precision metering special transformer, and multi-functional meter connected to the transformer is a protective transformer, can not be used as a basis for the energy assessment of the energy parameters in this multi-function table.
I provide detailed information on the knowledge of special transformers for energy measurement and protection, at www.kinnen.cn. Or pay attention to WeChat Public Number: KinnenElectric, follow and get reading.
Question II,
The causes of this phenomenon are in the following cases:
1, feeder line is too long, branch more, line loss.
2, low-pressure transformer is not the same manufacturer, the same batch. The transformer characteristic error is large.
3, the company's factory workshops are nonlinear load-based, high harmonic generation. How to measure the power of nonlinear load closely and accurately, and carry out effective energy performance management. It is suggested that the energy meter to measure the base wave and harmonious wave power should be installed at the load terminal, and a filter can be installed for the load with a large nonlinear load.
I provide detailed information on the effect of high harmonics on energy metering, at www.kinnen.cn. Or pay attention to WeChat Public Number: KinnenElectric, follow and get reading.
江苏某汽车科技公司的值班电工打电话给我，反映了两个问题：
一、35kV变电总站内的所有35kV开关柜上的多功能表中电能读数之和，与变电站35kV计量表中的读数不符。
二、10kV配电房低压侧馈线柜上的多功能表中的电能读数，与连接在该馈线上的所有车间动力柜电能计量之和，出入很大。
该公司连接在35kV变电总站上的10kV配电站有12个，正在由第三方进行能源绩效管理系统的建设。
上述问题，本人作如下简单回复：
问题一、
35kV变电总站中，35kV电力公司计量表连接在精度很高的计量专用的互感器上，而多功能表所连接的互感器是保护用互感器，不能以此多功能表中的电能参数作为电能考核依据。
关于电能测量与保护专用互感器方面的知识，本人在www.kinnen.cn网站上作详细介绍。或者关注微信公众号：近能电力工程技术，关注后获得阅读。
问题二、
该现象产生的原因有以下几种情况：
1、馈线线路过长，分支多，线路损耗大。
2、低压互感器非同一厂家、同一批次。互感器特性误差大。
3、该公司各厂车间均为非线性负荷很大的负载为主，有高次谐波产生。如何接近准确地测量非线性负载的电能，进行有效的能源绩效管理。建议在负载终端装设分别计量基波电量和谐波电量的电能表，对非线性负荷较大的负载可装设仪用滤波器。
关于高次谐波对电能计量的影响，本人在www.kinnen.cn网站上作详细介绍。或者关注微信公众号：近能电力工程技术，关注后获得阅读。
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| Updated: 2020年2月25日 |
| 1448 views |
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