Transmission Tower Vibration Analysis System Based on Internet of Things

Transcription

1 Transmsson Tower Vbraton Analyss System Based on Internet of Thngs Wang Zhangq, Wang Jan, and Zuo L Abstract A vbraton analyss system for transmsson tower based on the Internet of Thngs s descrbed n ths paper. Accordng to ng archtecture concept of the Internet of Thngs, the system conssts of three parts, whch can be dvded nto sensng network, data communcaton and system software. The sensng network ncludes vbraton acceleraton transducer and some other measurng sensors, WF technology s used for data communcaton n the sensng network. The software module s responsble for storage, analyss and processng of the detected data. The system software manly has the functons of the real-tme vbraton data collecton, data flterng and tme-frequency doman analyss. C/S and B/S archtectures are constructed for remote dsplay of vbraton data. Fnally, ths system s utlzed to perform vbraton analyss for a guyed tower and a steel tube tower, and the method to assess the health level of the tested model s dscussed. Index Terms The nternet of thngs, transmsson tower, vbraton montorng. I. INTRODUCTION The Internet of Thngs (or IoT for short) s a new generaton of technology, whch expands the Internet and constructs an nformaton exchangng network among thngs. IoT features the ablty of sensng, relable transmsson and ntellgent process [1]. The nformaton ntegrty wll be greatly enhanced by applyng IoT nto the Smart Grd []. IoT can acqure, transmt and process the nformaton etc. Some assocated specalsts have done certan expanson research based on the characterstcs of the new technology and apply t to the montorng of the transmsson lnes [3]. It s practcal and progressve to apply the technology of IoT nto the system of montorng and analyss of transmsson towers. Transmsson towers are the core of the power grd, t s necessary to keep the towers whch support the conductors off the ground workng safely and stably. When falure occurs to some components of tower, such as bolt loosens, angle ron falure etc., the stablty and the longevty of the structure wll decrease. In real stuatons, the falures may be dffcult to recognze through manual check because the tower s bg and the number of components s numerous. It s mpractcal to check all the bolts and jonts n the tower. Recently, some useful methods of checkng the healthy level of the tower are studed. The whole or partal vbraton features maybe a good reflecton of the structure system, Manuscrpt receved July 15, 015; revsed October 16, 015. The authors are wth the Department of Mechancal Engneerng, North Chna Electrc Power Unversty, Baodng Hebe Provnce, Chna (e-mal: wangzq093@163.com, ncepu_wj@163.com, @qq.com). whch means whether the tower s n good condton or not can be checked through montorng and analyzng the vbraton, whch can be collected va accelerometers. T. Yn etc. ntroduce a dynamc reducton-based structural damage detecton method for transmsson towers utlzng ambent vbraton data [4], [5]. Scott W. Doeblng etc. gve some advces of vbraton-based damage dentfcaton methods [6]. The Internet of thngs s a new technology whch smplfes and normalzes the archtecture of montorng and analyss system. Some technologes brought wthn the IoT make the constructon of the transmsson tower vbraton analyss system more modern. To construct the new generaton smart grd, combnng the IoT technology wth the transmsson tower vbraton analyss system s a promsng trend. The smart grd demands the transmsson towers falure malfuncton probablty comes down to a mnmum level. Ths paper focuses on the applcaton of montorng and analyss of transmsson towers usng IoT technology and the constructon of an expermental vbraton analyss system. Frstly some concepts of the Internet of Thngs are ntroduced, and then the ng archtecture of transmsson tower montorng system s proposed and establshed successfully. To check the feasblty of the system, some experments on a guyed tower and a steel tube tower are done and the results show that the montorng system can gan the dynamc characterstc far away from the ste effectvely. II. THE LAYING ARCHITECTURE OF THE ANALYSIS SYSTEM FOR TRANSMISSION TOWER VIBRATION BASED ON THE INTERNET OF THINGS The Internet of Thngs (IoT) whch was proposed by Kevn Ashton refers to unquely dentfable objects and ther vrtual representatons n an Internet-lke structure. In short, t s a knd of network whch can dentfy the thngs. IoT s smarter and t provdes users wth more convenent access to the thngs n the network and ths realzes the functon of remote montorng of transmsson towers. The archtecture of ng s helpful to dsplay IoT more clearly. IoT can be dvded nto three parts as sensng, network and applcaton [7]. The vbraton analyss system for transmsson tower s desgned based on the ng archtecture concept of the Internet of thngs, whch ncludes three parts,.e. sensng network, communcaton technology and software applcaton. And the archtecture s shown n Fg. 1. The sensng s manly n charge of measurng physcal sgnals and dong some smple processng. After do: /jmmm

2 some data processng, the raw data wll be transformed nto bnary codes whch can be transmtted easly. The data transmsson network s extended by the termnal equpment n the network [8]. The termnal equpment s decded by the need of communcaton dstance and data transfer rate. Dfferent termnal devce s constructed upon dfferent communcaton protocol. sensng sensors The archtecture of IoT for transmsson tower analyss sytem network termnal devces and protocol applcaton applcaton software Fg.1. The archtecture of IoT for transmsson tower analyss system. In the network, data s transferred from the sensng to the applcaton [9]. Network, actng as a brdge lnk, s the place where data s transferred from sendng to applcaton. The network s composed by cable network, wreless network, network management system and cloud computng. The correspondng network communcaton protocol can ensure the data transmsson. A transmsson tower whch s several klometers far away from the montorng center needs optcal fber communcaton when the data transfer rate s very hgh, whle f the rate s low, GPRS mode can be chosen. Some close communcaton demand may use Zgbee, WF etc. nstead. WF has a hgher communcaton rate and Zgbee has the advantages of low power consumpton. All the communcaton methods n the network can be summarzed as communcaton termnal devce and protocol. The applcaton software s on the applcaton, whch s the nterface between users and system. It can serve for the concrete applcaton and ntellgentze t n some extent [10]. The can enhance the experence of the users, whch realzes the nteracton between ndvduals and IoT. There are many factors should be consdered n ths and the most mportant one s that users can mplement what they need more convenently. The most mportant parts of the analyss system for the transmsson tower nclude three modules, whch are sensor network, communcaton technology and software applcaton. A. Sensng Network The man object of sensng network s to gather the requred data. To acheve ths goal, the hardware of ths network s equpped wth transducers and wred or wreless communcaton facltes. Data collecton equpment uses transducers to gan the requred data. And the schematc dagram of data acqurng equpment s shown n Fg.. In ths transmsson tower vbraton montorng system, some sensors are chosen for gatherng on-ste operaton data. The detals of the sensors, ncludng types, functons and parameters are depcted n Table I. Wnd Speed Temperature Electronc Tab Vbraton type Anemorumbometer AD590 temperature transducer HS1101 capactve humdty sensor DH5906 wreless vbraton acquston module RFID ant-metal tag MCU Communcaton Network Fg.. Schematc dagram of data acqurng equpment. TABLE I: SENSOR TYPES, FUNCTIONS AND PARAMETERS functon Measurng wnd speed and drecton Measure the temperature Measure humdty Measure vbraton the the Identfy the tower nformaton B. Communcaton Technology Man features of the sensors Power supply:0vac/50hz or 1VDC; Wnd speed measurement range:0~ 50m/s,0~1 levels; Wnd velocty measurement precesson: ± ( V)m/s(V-real wnd velocty); Wnd orentaton measurement range:0~360 ; Wnd orentaton measurement precson:±11.5 Power supply:3~30v; Output current:3μa(-50 )~43μA(+150 ); Senstvty:1μA/ Power supply:5vdc; Type output:0 ~ 0%RH as 1 ~ 1.6VDC Sample frequency:hz 5Hz 10Hz 0Hz 50Hz 100Hz 00Hz; A/D resoluton:16 bt A/D convertor; Systematc uncertanty: less than 3% (FULL); Wreless communcaton dstance: relable transmsson dstance s greater than 00m n the case of accessblty Frequency: MHz; Memory:96 Bts or extended to 51 Bts The montorng data of transmsson towers need to be transmtted to the montorng staton through communcaton technology, then the montorng staton conduct the condton assessment wth the predefned parameters. In ths system we chose WF wreless communcaton protocol to transmt data because the vbraton data rate s hgh. C. Software Applcaton The software applcaton s constructed by on-ste segment, control segment and applcaton segment, correspondng to the sensng, network and applcaton of the Internet of Thngs respectvely. The on-ste segment s used for collectng the data. The control segment mplements the data transmsson from tower to montorng center. The applcaton software analyzes the data and calls the expert system procedure to estmate whether the damage occurs. The archtecture dagram of the vbraton montor system 95

3 based on IoT s shown n Fg. 3. Fg. 3. Archtecture dagram of the vbraton montor system based on IoT. Database shown n Fg. 3 s constructed by SQL Server 005 whch provdes a full-scale database operaton. The software of data acquston and analyss s programmed by LabVIEW (Laboratory Vrtual Instrument Engneerng Workbench). On ths programmng platform, some practcal applcaton can be edted smply. III. TRANSMISSION TOWER VIBRATION MONITORING AND ANALYSIS SYSTEM Transmsson tower vbraton montorng and analyss system s constructed based on the concept of ng. It manly conssts of three modules, ncludng data acqurng module, data process and analyss module, remote dsplay module. A. Data Acqurng Module Data acqurng module s compled by graphcal program language LabVIEW. The data acqurng mode of one channel & N samplng s appled n ths data acqurng module. The acqured data s stored by storage program and named by the collecton tme. The acqured data s stored by storage program and named by the collecton tme. All of the data s stored n the hard dsk of the computer wth the form of.lvm. B. Data Process and Analyss Module 1) Flter process The purpose of flter s to remove nose from the sgnal. The collected sgnal may contan a seres of nose from electronc devce, hence flter s needed n order to gan avalable sgnal. In ths system, low-pass flter s adopted to gan the wanted transmsson tower vbraton sgnals. ) Tme frequency doman analyss After tme-frequency doman analyss of the acqured data, the vbraton characterstcs of the tower can be calculated. Frequency transformaton s one of the most popular methods of fault dagnoss. When some faults occur, the frequency form of the sgnal may change smultaneously. So some latent defects can be detected though the analyss of the vbraton frequency. In ths system, the classcal fast Fourer transformaton (FFT) s used to gan the frequency doman features of the towers. FFT s an algorthm to compute the dscrete Fourer transform and ts nverse. The man functon of FFT s that t can calculate one tme doman sgnal nto a frequency one. In the tme doman, transmsson tower vbraton s very complex and the sgnals usually perform a seres of rregular curves. Whle the vbraton feature n the frequency doman may reveals some potental faults n the structure. C. Remote Dsplay The remote dsplay functon affords the operators wth the nterface of montorng the on-ste condton remotely, whch plays an mportant role n the whole system. All the useful nformaton for the tower operaton status was dsplayed for the montors drectly. Ths functon makes the judgments of the on-ste status more reasonable. The remote connecton s desgned to construct the data connecton between the man montor and the on-ste devce. B/S and C/S dsplay modes are realzed here to enlarge the compatblty of the system. C/S mode, known as clent/server mode, s a computer network mode between clent and server, whch assgns the applcaton tasks to the clent and server respectvely. C/S mode can be realzed by Datasocket technology provded by LabVIEW. The schematc dagram s shown n Fg.4(a). B/S mode s a browser/server mode wth a core technology of web. TCP/IP and HTTP protocol s adopted to smplfy the access to the montor system. Users can vst the webste on a frequently-used browser wth permsson. The schematc dagram s shown n Fg. 4(b). Dsplay logc Server DataSocket server LabVIEW applcaton software n server (a) Schematc dagram of C/S mode Transacton logc clent LabVIEW applcaton software n clent Broswer Web server Database server response response Data processng logc (b) Schematc dagram of B/S mode Fg. 4. Schematc dagram of two modes. response Database IV. TRANSMISSION LINES VIBRATION MONITORING AND ANALYSIS EXPERIMENTS To verfy the montorng system, two towers are expermented whch are a steel tube tower and a guyed tower. Frstly, the factors whch nfluence the vbratonal characterstcs of the tested tower model wth methods of system dynamcs are proposed. And then the towers are tested n real envronment. The natural frequency of the towers can be acheved after data processng whch s done by the system software. Combned wth the theoretcal dervaton, the method of healthy dagnose s gven. A. Transmsson Tower Vbraton Model The forced vbraton equaton could be expressed n the 96

4 followng equaton: [ M]{ y } [ C]{ y } [ K]{ y} { Q( t)} (1) Where [M], [C] and [K] are the mass matrces, dampng matrces and stffness matrces, respectvely, {y }, {y } and {y} are acceleraton vector, velocty vector and dsplacement vector; and { Q ( t)} s the exctng force vector. The correspondng free vbraton equaton of non-dampng system s expressed as follows: [ M]{ y } [ K]{ y} {0} () n Fg. 7(a). After the mpulse loadng on the tower, t wll vbrate freely. The result of sampled data s shown n Fg. 7(b). The upper half shows the vbraton of the poston 1.5m upper from the ground whle the lower half s 3.0m from the ground. The vbraton feature of the steel tube tower s shown n Fg. 8. The characterstc equaton of the Eq. () s shown n Eq. (3). n K M ) 0 ( ) det( (3) And the former n order natural frequences, expressed as 1 n, can be obtaned from the Eq. (3). For the general engneerng problems, the dampng matrces could be processed nto the formaton of proportonal dampng as follows: n [ C] a[ M] b[ K] (4) where a and b are the constant of proportonalty. Substtutng Eq. (4) nto Eq. (1) and then usng the orthogonalty of the man modes, the dampng natural frequency of the system can be calculated as follows: where a b 1 ( 1,... n) (5) d Hence, the natural frequences of the system are determned by the system mass dstrbuton, system structure and elements connecton, whch can be descrbed by mass matrces, dampng matrces and stffness matrces. B. Transmsson Tower Vbraton Montorng and Analyss The transmsson tower analyss system developed s then put nto use to montor two towers operaton status. The tower vbraton data s collected by wreless vbraton transducer and then send to DWL-100AP. FFT transfers the tme doman sgnals nto the frequency doman ones and the characterstcs n the frequency doman show some ntrnsc features of the transmsson towers. The spot map of the guyed tower s shown n Fg. 5(a). The vbraton collecton modules are nstalled at the heght of 1.0m and 4.5m from the ground. The free vbraton data are shown n Fg. 5(b), and the upper half s the vbraton data at the heght of 1.0m whle the lower one s 4.5m. Frequency doman analyss s done wth the collected vbraton sgnal of the heght of 1.0m and the vbraton feature of the guyed tower s shown n Fg. 6. The experment s done for the vertcal flexble steel tube tower too. The radus of the steel tube tower s smaller wth the heght of the tower. Two wreless vbraton collecton modules are placed on the tower on the heght of 1.5m and 3.0m respectvely, and the physcal nstallaton can be show (a)the spot map of the guyed tower (b) Vbraton data of guyed tower Fg. 5. Experments of the guyed tower. The upper half shows the vbraton of the poston 1.0m upper from the ground. And the lower half shows the vbraton of the poston 4.5m upper from the ground. Fg. 6. The spectrum of the guyed tower vbraton. Form the frequency analyss, the analyss of the steel tube tower can gan some apparent vbraton features whle for the guyed tower, only the frst order frequency can be calculated from the analyss. The vbraton characterstc of the tower varous wth the constrant of the tower. In the experment, meely constant of ground was appled to the steel tube tower, and the other end of the tower s free. Mult-order frequency can be obtaned by frequency doman analyss of the acceleraton. Whle to the guyed tower, whose both ends are constranted, one order frequency value can be obtaned. The frequences of the towers reflect some potental problems of the operaton status. That means the towers are healthy when the detected natural frequences of the towers are close to the normal value. Oppostely, changngs of the natural frequency llustrate the changng of the system mass dstrbuton, system structure and elements connecton, 97

5 whch usually means the occurrence of falure. When faults occur, t s necessary to check the towers and repar the malfuncton. the developed system, experments on guyed tower, are mplemented by creatng the free vbraton after mpulse load. Through frequency doman analyss, the frst order natural frequency of the guyed tower model can be obtaned, and we can judge the health level of the tested model by comparng the real-tme montorng vbraton value wth the normal value. (a) The spot map of the steel tube tower (b) Vbraton data of steel tube tower Fg. 7. Experments of the steel tube tower. The upper half shows the vbraton of the poston 1.5m upper from the ground. And the lower half shows the vbraton of the poston 3.0m upper from the ground. REFERENCES [1] Q. B. Su, J. Lu, S. L, C. X. Fan, and J. J. Sun, Lterature revew of the Internet of Thngs: Concepton, archtecture and key technology, Journal of Bejng Unversty of Posts and Telecommuncatons, vol. 3, pp. 1-9, July 010. [] N. L, X. Chen, F. Wu, and X. Z. L, Informaton aggregaton technology for smart grd based on the nternet of thngs, Informaton and communcaton technology, pp. 1-8, 010. [3] C. X. Guo, Z. X. Gao, J. J. Zhang, and J. Q. B, Power transmsson and transformaton equpment condton montorng and mantenance asset management based on the Internet of Thngs, Journal of electrc power scence and technology, vol. 5, pp , Aprl 010. [4] T. Yn, H. F. Lam, H. M. Chow, and H. P. Zhu, Dynamc reducton-based structural damage detecton of transmsson tower utlzng ambent vbraton data, Engneerng Structures, vol. 31, pp , September 009. [5] H.-F. Lam and T. Yn, Dynamc reducton-based structural damage detecton of transmsson towers: Practcal ssues and expermental verfcaton, Engneerng Structures, vol. 33, pp , May 011. [6] S. W. Doeblng, C. R. Farrar, and M. B. Prme, A summary revew of vbraton-based damage dentfcaton methods, Shock and Vbraton Dgest, vol. 30, pp , February [7] Z. H. Nng, The key technology and applcaton study of the nternet of thngs, Computer Programmng Sklls & Mantenance, vol. 0, no. 16, pp , 011. [8] L. Chunl, "Intellgent transportaton based on the nternet of thngs," n Proc. nd IEEE Internatonal Conference on Consumer Electroncs, Communcatons and Networks (CECNet), 01, pp [9] X. Z. L and J. M. Lu, The technology and applcaton of the nternet of thngs for the Smart Grd, Telecommuncatons Network Technology, vol. 8, pp , 010. [10] Z. H. Hou, The unversal desgn of applcaton archtecture of the nternet of thngs, The Technology of the Internet of Thngs, vol. 1, no. 7, pp , 011. Fg. 8. The spectrum of the steel tube tower vbraton. Wang Zhangq was born n Shanx Provnce He receved hs Ph.D degree n 1997 from North Chna Electrc Power Unversty. Now he s a professor n Department of Mechancal Engneerng n NCEPU. Hs man research nterests nclude nonlnear dynamcs of transmsson towers. V. CONCLUSION In ths paper, the transmsson tower vbraton montorng technology based on the Internet of Thngs (IoT) s analyzed and studed. A set of vbraton montorng system for transmsson tower s desgned and mplemented n detal. The system manly contans three segments as network sensng, data communcaton and system software. The man procedure s compled on LabVIEW platform and t s able to acqure and analyze the data, remote dsplay etc. To verfy Wang Jan receved hs B.Sc. degree n 011 from North Chna Electrc Power Unversty. He receved hs M.Sc. degree n 013 from North Chna Electrc Power Unversty. Now he s a doctoral canddate n the Department of Mechancal Engneerng n North Chna Electrc Power Unversty. Hs man research nterests nclude dynamcs of transmsson towers and ts condton montorng. 98