外文翻譯---大型公共建筑消防應(yīng)急照明電源設(shè)計(jì)技術(shù)經(jīng)濟(jì)指標(biāo)的研究（英文）

1、 Research on Intelligent on-line Insulation Monitoring Device of Ship’s AC Power Grid CHENG Xiang-xin Maritime College of Shan Dong Jiaotong University Weihai, China chengxiangxin@sohu.com WU Shuo Maritime College of Sh

2、an Dong Jiaotong University Weihai, China wushuo84@163.com ABSTRACT—The insulation monitoring of ship power system is an important measure to remove faults and hidden troubles. Its condition concerns the security of powe

3、r system and operation safety of ships. Conventional ship power system insulation monitoring is hard to accurately monitor the insulation resistance decreasing or precisely locate the grounding branch. It takes much time

4、 and energy to rule out the insulation failure. This paper introduces the intelligent on-line insulation monitoring device. Based on zero-sequence current detecting method, dual-frequency injection method and SCM control

5、, it can accurately and efficiently monitor the ship power grid and guarantee the operation safety of ships. Keywords-Ship power grid; Short circuit; Insulation resistance; Insulation monitoring ? INTRODUCTION With

6、 the development of shipbuilding technology and the increasing tonnage of ship, the modern ship power system capacity has been continually growing. Accordingly, its distribution network structure has become more com

7、plex and the power grids have become more complex and intensive. Under the harsh condition of high temperature, vibration, shock, oil mist, humidity, salt spray, fungus [1], the ship power grid has brought a lot of influ

8、ences to the ship’s electrical insulation properties, which results in high incidence of power system insulation failure, thus frequently leads to terrible accidents, as minor as electrical equipment malfunction or damag

9、e, as major as fire, collision and sinking disaster. Limited by technical means, it has been difficult to monitor the state of complex branch insulation. Once the monitor failure happens, there is no other way to find ou

10、t insulation failure points except manual operation, which not only affects operation by supply interruptions, but also hurts crew physical and mental health because of high labor intensity. Thus, the ship’s power system

11、 insulation real-time monitoring has the extremely vital significance to the security and continuity of power supply system. Ⅱ BRIEF INTRODUCTIONS OF THE SHIP POWER GRID There are two types of ship power grid, AC power

12、grid and DC power grid. The DC power grid is seldom used, thus will not be analyzed in this paper. Three-phase AC mainly used in the power system on ship has the following three forms: (1)AC three-phase three-wire insula

13、ted system (three-phase three-wire system); (2)AC three-phase four-wire system with neutral earthed (three-phase four-wire system); (3)three-wire system with neutral grounding (using the hull as the neutral wire loop). W

14、hat the ship power system regularly uses is AC three-phase insulated system [2]. One of the great advantages of this system is that when short circuit current to earth occurs on one phase it will not cause power outage,

15、 thus ensures the continuity and reliability of ship power supply. Ⅲ INTELLIGENT INSULATION MONITORING DEVICE An advanced intelligent on-line insulation monitoring and warning device that can monitor the insulation

16、and locate the faulty branch is installed in a ship power system. Its high measurement accuracy, accurate positioning and high automation determines its domestic leading level. The main characteristics are as follow: 20

17、10 International Conference on Intelligent System Design and Engineering Application978-0-7695-4212-6/10 $26.00 © 2010 IEEE DOI 10.1109/ISDEA.2010.175 219unknown variables of resistance R and capacitance C, two equa

18、tions must be provided to obtain the values of R and C. Dual-frequency injection method can measure the values of voltage Uab and current i0 by injecting two different-frequency signals into power grid, and then two equa

19、tions can be obtained to solve the value of R and C. According to Fig. 1 (b) the equations can be listed as the following: i1 = Uab1/ R +j·2π·f1·C·Uab1 (1) i2 = Uab2/ R +j·2π·f2·C

20、·Uab2 (2) In the formula: R: Branch insulation resistance value C: Equivalent distributed capacitance value of the branch f1, f2: Frequency value of the two low-frequency signals i1: Resulting earth leakage

21、 current by the alone action of signal source with the frequency value f1 i2: Resulting earth leakage current by the alone action of signal source with the frequency value f2 Uab1: Resulting voltage-drop of the insulat

22、ion resistance by the alone action of signal source with the frequency value f1; Uab2: Resulting voltage-drop of the insulation resistance by the alone action of signal source with the frequency value f2. Insulation re

23、sistance values can be obtained by (1) and (2): (k =f2/f1) In the formula: Uab1m: Amplitude of Uab1 Uab2m: Amplitude of Uab2 I1m: Amplitude of i1 I2m: Amplitude of i2 According to measuring the voltage values of Uab1,

24、Uab2 and the earth leakage current of every loaded branch i1, i2, which are all corresponding to the frequencies injected into the power grid f1, f2, the insulation resistance of every loaded branch against earth can be

25、obtained through (3) thus the insulation fault branch can be distinguished. Digital filtering method is also used to eliminate the effect of power frequency in Uab1, Uab2 and i1, i2. Ⅴ SYSTEM CONFIGURATIONS [4] According

26、 to the principle mentioned above, the hardware block-diagram of monitoring device is designed, (see Fig. 2). When the zero- sequence current detecting method is used, Multiplexer controlled by single chip micyoco (SCM)

27、 system collects the power frequency leakage current data of every branch, after comparison with the preset value, the fault branch is distinguished. When the Dual-frequency injection method is used, SCM system gives ins

28、truction to the sine wave coder; the sine wave coder will generate a low-frequency sine wave signal f1. By D/A converting, power amplifying and transformer’s isolated boosting, the signal is injected into the power grid.

29、 Both multiplexer and A / D converter are controlled by SCM system. First the power grid voltage to earth transformed by voltage measurement unit is collected, the leakage current (after amplifying) of every branch also

30、 is collected one by one, and then the leakage current if1of every branch corresponding to the low frequency f1 and voltage Uf1 is obtained by digital filtering. In the same 21 22 2 2 21 2 2 11 ab m ab mm ab m m ab mU U

31、 K RK I U I U? ? ? =? ? ? ?（3） AmplifierMultiplexer AmplifierVoltage measuringPower gridSCM system Multiplexer A/D converterSine-wave coder Option switchD/A converter Transformer isolatingPower amplifierPower gridBranch

32、sensor of power gridAmplifierMultiplexer AmplifierVoltage measuringPower gridSCM system Multiplexer A/D converterSine-wave coder Option switchD/A converter Transformer isolatingPower amplifierPower gridBranch sensor of p