Design of Energy Consumption Collection Device in Data Center

Keyword data center multi-loop monitoring

Abstract This paper introduces a data center precision power distribution ark with multi-loop collection equipment design method of energy consumption. It explains the design principle, hardware structure and software design method, which in turn means the device could satisfy the design precision power supply of power load ark loop of integrated measurement and installation requirements, data center for energy consumption management to provide reliable basis for measurement.

Keywords Data center, multi-loop monitoring

1 Introduction

With the rapid development of the data center, the energy consumption of the data center is becoming more and more prominent. The energy management and power supply and distribution design of the data center have become a hot issue. The efficient and reliable data center power distribution system solution is to improve the data center. An efficient way to use electrical energy and reduce equipment energy consumption. To achieve energy saving in the data center, we first need to accurately monitor each electrical load, and there are many load circuits in the data center. Traditional measuring instruments cannot meet the requirements of cost, volume, installation, construction, etc., so we need Adopt multi-loop monitoring device suitable for centralized monitoring requirements of data center.

This article introduces a design method of a measuring device suitable for the use requirements of precision power distribution cabinets in data centers. The device is suitable for single input, single segment output, and single point detection; dual input, single segment output, single Point detection; dual-input, single-segment output, dual-point detection system power input mode. Can accurately measure various parameters of the power distribution system, including bus voltage, frequency and current of the three-phase incoming line, split-phase and total active power, reactive power, power factor, active energy, reactive power Electrical energy. And accurately measure the electrical parameters such as current, active power, reactive power, power factor, active energy, reactive energy, and on-off status of the branch of 36 outgoing (single-phase) branches, and can realize the computer room through remote communication Centralized monitoring of data.

2 Design ideas

In order to realize the function of integrating the measurement equivalent to 14 three-phase multi-function power meters with a single device , it is necessary to adopt unconventional hardware design ideas. We know that the most common implementation methods of three-phase multi-function power meters currently include three-phase power chip + CPU, high-precision ADC chip + CPU, three-phase SOC chip and single chip (CPU with ADC inside). And a single device to realize the functions of 14 three-phase multi-function meters, multiple combinations using any of the above methods is not very suitable, considering the cost of hardware and the difficulty of software implementation, we chose to use multiple electronic switches + Single chip (CPU with ADC inside) design method.

3 Overall hardware system design

Considering that the occasion used by the device is a data center precision power distribution cabinet, and it is necessary to measure various electrical parameters of 2 three-phase incoming lines and 36 outgoing lines, and the incoming circuit is generally relatively large because of the current. Reaching several hundred amps, the current of the outlet loop is relatively small, generally below 63 amps, so the current input part of the device adopts 5A current input, built-in small 5A current transformer, the outlet part adopts 20mA current input, external 100A / 20mA Transformer. Since the device is installed inside the cabinet, the device itself does not have a display. If the display is required, the touch screen is used, and the data is transmitted to the touch screen for display through RS485 communication connection. The overall hardware system is shown in Figure 1. Mainly divided into signal processing part, power supply part, communication part, setting part, data storage part and CPU part.

figure 1

3.1 Signal processing

The most critical part of the signal processing part is the signal processing of the AC sampling and the switching of the electronic switch. Because this design uses the method of AC sampling, the ADC sampling can only target positive signals, and the AC signal is a sine wave signal, the signal has positive and negative, so the signal needs to be raised to ensure that the lowest point of the signal is also Can be sampled by ADC. What is adopted here is TL431 to raise the signal, can also be sampled by ADC when raising the current signal to the lowest point. as shown in picture 2. There are 42 current signals in total, which are divided into 7 groups in this design. Each group has 6 current signals. Each group of current signals is selected by an electronic switch CD4051. At the same time, there are 7 current signals flowing into the ADC of the CPU for AD conversion.

figure 2

image 3

3.2 Power supply

The device uses a switching power supply module. The input voltage of the power module is AC85V ~ 265V, the input frequency is 45Hz ~ 60Hz, and it has multi-channel isolated voltage output to meet the requirements of different functions for different power supply voltages. The output voltage is stable, the failure rate is small, the output ripple is <1%, and the conversion efficiency is ≥75%. With overvoltage and overcurrent protection. The module has high stability, reliability and anti-interference ability after being used in actual field.

The device can be equipped with dual-channel power supply mode, dual-channel AC, dual-channel DC or one-channel AC + one-channel DC power supply mode, so that the device can still work normally when the precision distribution cabinet is cut over or overhauled.

3.3 Communication

The communication interface module adopts general RS-485 and Modbus RTU communication protocols, and can realize functions such as telemetry, remote control, and remote communication. In this design, because the device has no display, after being installed in the cabinet, the local display needs to communicate data to the touch screen through communication, and it needs to occupy a communication port. Therefore, the device is designed as a dual communication mode, which can be used with 2 systems communication.

3.4 Settings

Because the device does not have a display, the setting of some parameters is not very convenient. Here, the dial switch is used to set the parameters such as communication address and baud rate.

3.5 Data storage

This design uses FM31256 ferroelectric memory with a clock. On the basis of data storage, a real-time clock is integrated to record various faults or states.

3.6 CPU

Combining the hardware method and software processing method of this design, the CPU in this design uses ST's latest ARM-based 32-bit processor STM32F103VBT6 based on the Cortex-M3 architecture. The clock frequency can be up to 72MHz. 20K RAM, 12-bit AD, 4 16-bit timers, 3 USART communication ports and other resources have extremely high cost performance and can meet the application of this design.

4 Software design

The program design flow is shown in Figure 4. The design focus of this software is on signal sampling. Because the multi-channel signal is switched by an electronic switch, each current signal must be sampled once in each sampling period, so the AD sampling rate must be increased. Example: The period of each signal is 20ms, 32 points are collected in each period, and all current loops are divided into 7 groups, each group has 6, then at the same time, the CPU will sample 7 of them . And the CPU needs to switch 6 times to achieve the sampling of all 42 currents. Therefore, the AD sampling frequency of the CPU must be increased by 6 times on the basis of 32 points per cycle to ensure that 42 current signals are collected in one cycle. And the CPU should also control the timing of the electronic switch switching, otherwise the signal residue in the electronic switch is easy to appear, causing the CPU to collect the signal of the previous channel when collecting the signal of this channel.

Figure 4

Another important point of the software is the calculation of the signal. Because the amount of data calculation is very large, it is equivalent to complete the calculation of the current, active power, reactive power, power factor, active energy and reactive power of 42 single-phase loops within 20ms. Electric energy, and also need to deal with various other events at any time, such as communications. Therefore, the software algorithm and CPU operation rate are very important. In this design, the clock frequency of the CPU is 72MHz, which ensures the data processing in each signal cycle. After testing, the time spent in the entire measurement cycle is about 13ms, which is fully satisfied to complete all computing tasks within 20ms.

5 Measurement accuracy

According to YD / T-2011 "Technical Requirements and Inspection Methods for Network Cabinets for Data Equipment" 5.6.2, the measurement accuracy of the detection device configured in the cabinet is required to be level 2 or higher (that is, the error is within ± 2%). The measurement accuracy of the device designed according to this scheme was tested, and the results are shown in Table 1 to Table 7. As can be seen from the data in the table below, its measurement accuracy far exceeds the level 2 requirements and fully meets the requirements of the standard. It is a multi-loop acquisition device with high accuracy. The design measurement accuracy of this device is voltage and current 1%; electrical energy 1%.

Table 1 Incoming measurement accuracy test data Table 2 Outgoing measurement accuracy test data Table 3 Outgoing measurement accuracy test data

Table 4 Outlet measurement accuracy test data Table 5 Outlet measurement accuracy test data

Table 6: Outgoing measurement accuracy test data Table 7: Outgoing measurement accuracy test data

6 device applications

The AMC16MA series of data center multi-circuit monitoring devices designed in the above manner have been widely used in data center precision power distribution cabinets, combined with the configured touch screen to realize a complete precision power distribution cabinet monitoring system, and to achieve refined management of server terminal equipment The monitoring system can realize the following functions, and the display interface is shown in Figure 5:

Picture 5

5.1 Line monitoring:

1) Three-phase voltage, three-phase current, system frequency;

2) Each phase and total active power, reactive power, apparent power, power factor;

3) Active energy and reactive energy of each phase and total;

4) Voltage unbalance and current unbalance;

5) Inlet switch monitoring.

6) Optional monitoring of harmonic current;

5.2 Outgoing monitoring:

1) Rated current setting, current value of each phase;

2) Load percentage;

3) Switching state monitoring;

4) Active power, reactive power, apparent power, power factor of each phase;

5) Active energy and reactive energy of each phase;

6) The phase of each loop of the outgoing loop can be arbitrarily configured.

5.3 Alarm function:

1) Incoming line over-current 2 section threshold crossing alarm, the alarm value can be set arbitrarily;

2) Incoming line under-current 2 section threshold exceeding alarm, the alarm value can be set arbitrarily;

3) Incoming over-voltage, under-voltage, phase-loss, over-frequency, and low-frequency over-limit alarms;

4) Sound and light alarm function.

5.4 Communication:

1) The collected data can be uploaded through the touch screen;

5.5 Event record:

1) Various electrical parameters exceeding limit alarm records (current alarm and alarm records each 128)

2) 128 switching event records.

6 Summary

The multi-loop monitoring device designed according to the ideas in this article is a product dedicated to the precision power distribution cabinet of the data center, which can meet the needs of the precision power cabinet for multi-circuit power distribution. The hardware design of the product is simple, and it achieves a high cost performance in terms of performance and cost. It is an ideal monitoring device in data center power management.

The article comes from: "Electrical Application" No. 19, 2012.

references

【1】     Shanghai Ankerui Electric Co., Ltd., smart grid user-end power monitoring / energy management / electrical safety system solution [M], 2012.03

【2】     ST, STM32F103 data sheet [EB / OL], 2008.05

【3】     Yao Bo, Tu Shiliang,    Design of multi-loop monitoring unit based on ADE7758 + MC9S08AW32 scheme [J], Electrical Measurement and Instrumentation 2007 Vol. 44 No. 4

【4】         Jing Shenfeng, Yao Bo, Tang Jianjun,    Design and Application of Digital Measuring Relay Based on STM32F103R8T6 [J], Low Voltage Electricity, 2010 (21)

【5】    Xu Bin, Gu Xiongwen, Liu Yan Data Center Power Management Solution [J], Intelligent Building Electrical Technology 2012, 6 (1)

【6】    YD / T-2011 Technical requirements and inspection methods of network cabinets for data equipment

Yu Jing, female, undergraduate, engineer of Wuhan Ankerui Electric Co., Ltd., the main research direction is intelligent power monitoring and power management system

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