發(fā)布時間：2019-01-09 14:51

【摘要】：隨著階梯水價政策的實施,一個以水表計量性能提升、無線網(wǎng)絡(luò)接入和融入互聯(lián)網(wǎng)應(yīng)用為標(biāo)志的“互聯(lián)網(wǎng)+智能水表2.0”時代已經(jīng)到來。超聲波水表無機(jī)械運(yùn)動部件、壓力損失小、始動流量低、誤差特性曲線可修正,而且可實現(xiàn)數(shù)據(jù)遠(yuǎn)傳,具備下一代智能水表的基本特征和功能。研究超聲波水表,不僅可以推動階梯水價制度的建立,而且可以實現(xiàn)智能水表的轉(zhuǎn)型升級,對我國水表產(chǎn)業(yè)的發(fā)展具有重要意義。針對時差法接收到超聲波信號的時刻難以精確捕獲,小流速的流量計量精度低等問題,本文設(shè)計了一種相差法超聲波水表,可以實現(xiàn)家庭用水的精確計量。根據(jù)超聲波在水中的傳播速度和溫度的對應(yīng)關(guān)系實現(xiàn)水溫的檢測。然后針對相差法測得的流量值隨溫度呈非線性變化的問題,提出了基于最小二乘曲面擬合的溫度補(bǔ)償算法。主要研究內(nèi)容如下:1.在分析和比較幾種常用的超聲波流量檢測方法的基礎(chǔ)上,采用相差法檢測流量。通過對相位比較結(jié)果累加積分,不僅可以實現(xiàn)微小流量的檢測,還可以減小干擾信號的影響。針對流速檢測過程中采集到的數(shù)據(jù)波動大的問題,采用限幅濾波、算術(shù)平均值濾波和滑動平均值濾波相結(jié)合的復(fù)合濾波算法來對采集的數(shù)據(jù)進(jìn)行處理,改善了流速檢測結(jié)果的穩(wěn)定性。2.針對流量值隨溫度呈非線性變化這一問題,進(jìn)一步研究對檢測流量進(jìn)行溫度補(bǔ)償?shù)姆椒�。采用檢測超聲波在水中的傳播速度推算出溫度、而非常規(guī)的溫度傳感器檢測溫度的方法。實驗表明,溫度檢測檢測誤差在±2℃以內(nèi),并且降低了儀表的成本。3.提出了基于最小二乘曲面擬合的溫度補(bǔ)償算法,根據(jù)溫度和流量擬合得到的曲面對流量進(jìn)行預(yù)測和補(bǔ)償。在實現(xiàn)溫度補(bǔ)償后,針對超聲波水表自身計量特性的差異,進(jìn)一步提出多溫度點流量計量誤差二次補(bǔ)償算法,根據(jù)相鄰溫度點的流量計量誤差和權(quán)值計算當(dāng)前溫度和瞬時流量下的流量計量誤差,然后對誤差進(jìn)行補(bǔ)償,可以實現(xiàn)流量檢測的全局優(yōu)化。實驗表明,流量計量誤差在±2.0%以內(nèi)。經(jīng)過實驗驗證,本文設(shè)計的超聲波水表可以實現(xiàn)家庭用水的流量精確檢測,達(dá)到高精度、低功耗、低成本的目的。
[Abstract]:With the implementation of ladder water price policy, an era of "Internet Intelligent Water Meter 2.0", marked by the improvement of metering performance, wireless network access and integration into Internet applications, has arrived. Ultrasonic water meter has no mechanical moving parts, small pressure loss, low starting flow rate, correction of error characteristic curve, and can realize remote data transmission. It has the basic characteristics and functions of the next generation intelligent water meter. The study of ultrasonic water meter can not only promote the establishment of stepped water price system, but also realize the transformation and upgrading of intelligent water meter, which is of great significance to the development of water meter industry in China. In order to solve the problem that the time of receiving ultrasonic signal by moveout method is difficult to capture accurately and the measurement accuracy of flow rate of small velocity is low, a ultrasonic water meter with phase difference method is designed in this paper, which can be used to measure household water accurately. The detection of water temperature is realized according to the relationship between the velocity and temperature of ultrasonic wave propagation in water. Then a temperature compensation algorithm based on least square surface fitting is proposed to solve the problem that the flow rate measured by phase difference method is nonlinear with temperature. The main contents are as follows: 1. Based on the analysis and comparison of several ultrasonic flow detection methods, the phase difference method is used to detect the flow. By summing up the results of phase comparison, not only the detection of micro flow can be realized, but also the influence of interference signal can be reduced. Aiming at the problem of large fluctuation of data collected in the process of velocity detection, a composite filtering algorithm, which combines amplitude limiting filter, arithmetic average filter and sliding average filter, is used to process the collected data. Improved the stability of velocity detection results. 2. In order to solve the problem that the flow rate is nonlinear with the temperature, the method of temperature compensation for the detection flow rate is further studied. The temperature is calculated by measuring the velocity of ultrasonic wave in water, but not by conventional temperature sensor. The experimental results show that the temperature measurement error is within 鹵2 鈩，

本文編號：2405769