1、附 录 附录 A 外文资料 Data Collection At present,the management of Chinas colleges and universitiesapartments are developing toward standardization and market development,accidents have occurred in electricity,while some colleges and universities have installed apartment energy metering control system,howev
2、er,these systems monitor the prevalence of low level,billing accuracy is low,electricity-sharing,the network number of the drawbacks of low extent.Therefore， improving the Energy Measurement monitoring device has become more urgent The issue of student hostels in colleges and universities to monitor
3、 energy metering system to study， design the student hostels in colleges and universities of the electricity data collector apartment. Data acquisition, also known as data acquisition, is the use of a device that collect data from outside the system and enter into an interface within the system.Data
4、 acquisition technology is widely cited in the various fields.Such as camera, microphone, all data collection tools.Data is being collected has been converted to electrical signals of various physical quantities such as temperature, water level, wind speed, pressure, etc., can be analog, it can be d
5、igital.Sample collection generally means that a certain time interval (called the sampling period) to repeat the same point of data collection.The data collected are mostly instantaneous value, but also a feature within a certain period of time value.Accurate data measurement is the basis for data c
6、ollection.Data measurement method of contact and non-contact detection elements varied.Regardless of which method and components are measured object does not affect the status and measurement environment as a precondition to ensure the accuracy of the data.Very broad meaning of data collection, incl
7、uding continuous physical hold the collection across the state.In computer-aided mapping, surveying and mapping, design, digital graphics or image data acquisition process may also be called, this time to be collected is the geometric volume (or include physical quantities, such as gray)data.1 In to
8、days fast-growing Internet industry, data collection has been widely used in the field of Internet and distributed data acquisition field has undergone important changes.First, the distributed control applications in intelligent data acquisition system at home and abroad have made great progress.Sec
9、ond, the bus-compatible data acquisition plug-in number is increasing, and personal computer-compatible data acquisition system the number is increasing.Various domestic and international data collection machine has come out, the data acquisition into a new era. Digital signal processor (DSP) to the
10、 high-speed data processing ability and strong peripherals interface, more and more widely used in power quality analysis field, in order to improve the real-time and reliability.The DSP and microcomputer as the center of the system, realize the power system signal collection and analysis. This pape
11、r based on the FFT algorithm with window interpolation electric system harmonic analysis, improves the accuracy of the power quality parameters. In electricity parameter acquisition circuit, by highaccuracy transformer and improve software synchronous communication sampling method to conduct electri
12、city parameters of the acquisition. The system consists of two main components, mainly complete data acquisition and logic control.To synchronous sampling and A/D converter circuit priority . The DSP development board(SY-5402EVM),complete data processing. THE signal after transformer, op-amp into A/
13、D converter, using DSP multi-channel buffer (McBSP) and serial port (A/D connected, data collection and operations. At the same time, adopt PLL circuit implementation synchronous sampling, can prevent well due to sampling synchronization and cause the measuring error. The overall system diagram of t
14、he A/D converter chooses the Analog to produce stats redetect (AD) company AD73360. The chip has six analogue input channel, each channel can output 16 the digital quantity. Six channel simultaneous sampling, and conversion, timeshare transmission, effectively reduce generated due to the sampling ti
15、me different phase error. SY - 5402EVM on-board DSP chip is TI companys 16 fixed-point digital signal processor TMS320VC5402. It has high costperformance and provide high-speed, bidirectional, multi-channel belt cushion, be used to serial port with system of other serial devices directly interface.
16、The realization method of ac sample： In the field of power quality analysis,The fast Fourier transform (FFT) algorithm analysis of electric system harmonic is commonly used.and the FFT algorithm to signal a strict requirements synchronous sampling. The synchronous sampling influence: its difficult t
17、o accomplish synchronous sampling and integer a period truncation in the actual measurement, so there was a affect the measurement accuracy of the frequency spectrum leakage problem. The signal has to deal with through sampling and A/D conversion get limited long digital sequence,the original signal
18、 multiplied by A rectangular window to truncated. Time-domain truncation will cause the detuning frequency domain, spectrum leakage occurs. In the synchronous sampling, because the actual signal every harmonic component cant exactly landed in frequency resolution point in, but fall between the frequ
19、ency resolution points. But FFT spectrum is discrete, only in all sampling points, while in other places of spectrum is not. Such through FFT and cannot directly get every harmonic component, but only the accurate value in neighboring frequency resolution point value to approximate instead of, can c
20、ause the fence effect error.The realization method of synchronous sampling signal： According to provide different ways of sampling signal, synchronous sampling method and divided into software synchronous sampling method and hardware synchronous sampling method is two kinds. Software is synchronous
21、sampling method by micro controller (MCU) or DSP provide synchronized sampling pulse, first measured the measured signal, the sampling interval period T T = T/N (N for week of sampling points), Thus the count value determined timer,Use timing interrupt way realization synchronous sampling. The advan
22、tage of this method is no hardware synchronous circuit, simple structure .This topic will be the eventual realization of access to embedded systems， the realization of the power measurement and monitoring,monitoring system to meet the electricity network,intelligencerequirement,it promote the develo
23、pment of remote monitoring services,bringing a certain degree of socio.economic effectiveness. On the fundamental reactive current and harmonic current detection, there are mainly 2 ways: First, the instantaneous reactive power theory based method, the second is based on adaptive cancellation techniques.In addition, there are other non-mainstream approach, such as fast Fourier transform method, wavelet transform. Instantaneous power theory based on the method of offensive principles ar
