【摘要】：隨著我國水電資源開發(fā)的深入,貫流式低水頭電站越來越多。一般低水頭電站具有庫容小、明渠河道徑流式的特點(diǎn)。水電機(jī)組經(jīng)常在電力系統(tǒng)中承擔(dān)調(diào)頻調(diào)峰、以及汛期防洪泄水等任務(wù)。當(dāng)貫流式機(jī)組工況發(fā)生較大變化時,機(jī)組流量相應(yīng)發(fā)生變化,會在上游及下游河道中形成較大水位波動。這樣一來,不僅會影響機(jī)組出力的穩(wěn)定性,還會對水電站水工建筑物以及航運(yùn)安全造成不利影響。因此,本文針對這一問題,通過分析計算貫流式水輪發(fā)電機(jī)組甩負(fù)荷過渡過程,研究水電站上下游水位波動規(guī)律。本文首先建立了明渠河道、過水管道、以及水輪發(fā)電機(jī)組各部分?jǐn)?shù)學(xué)模型;然后,根據(jù)明渠和管道中的水流流動特性,選取不同時間步長分別給出明渠非恒定流和壓力管道非恒定流的特征線法計算模型。其次,構(gòu)建了“引水明渠+壓力管道+機(jī)組+壓力管道+尾水明渠”水力系統(tǒng)計算模型,將水輪機(jī)模型靜態(tài)全特性曲線用正交網(wǎng)格離散后存儲于三維數(shù)組中,采用MATLAB語言編寫過渡過程計算程序。最后分別計算了不同明渠河道長度與斷面面積、不同導(dǎo)葉與槳葉關(guān)閉時間情況下,貫流式機(jī)組甩負(fù)荷過渡過程中的上下游明渠河道水位波動變化曲線。計算結(jié)果表明,貫流式機(jī)組管道進(jìn)口壓力在甩負(fù)荷初始時刻會出現(xiàn)負(fù)水擊現(xiàn)象;明渠面積越小,明渠的水位波動幅度越大;明渠長度越長,明渠的水位波動周期越大;在相同導(dǎo)葉關(guān)閉時間情況下,槳葉關(guān)閉時間越長,轉(zhuǎn)速上升率越小,明渠水位波動越小。特別在槳葉不動作時,轉(zhuǎn)速上升率、明渠水位波動、軸向反推力及水輪機(jī)進(jìn)口壓力波動明顯降低。
[Abstract]:With the development of hydropower resources in China, there are more and more low-head tubular hydropower stations. Generally, low-head hydropower stations have the characteristics of small storage capacity and open channel runoff. Hydropower units often undertake the tasks of frequency modulation and peak regulation, flood control and discharge in flood season. When the operating condition of the tubular unit changes greatly, the unit discharge will change accordingly, which will form a large water level fluctuation in the upstream and downstream river channels. In this way, it will not only affect the stability of generating units, but also adversely affect hydraulic structures and shipping safety of hydropower stations. Therefore, in order to solve this problem, this paper analyzes and calculates the transient process of load rejection of tubular turbine generator sets, and studies the fluctuation law of water level in upstream and downstream of hydropower stations. In this paper, the mathematical models of open channel, water pipeline and hydro-generator unit are established. Then, according to the flow characteristics of open channel and pipeline, different time steps are selected to calculate the unsteady flow in the open channel and the unsteady flow in the pressure pipeline by the characteristic line method, respectively. Secondly, the hydraulic system calculation model of "open channel of pressure pipeline unit in open channel" is constructed, and the static full characteristic curve of turbine model is discretized by orthogonal grid and stored in three dimensional array. MATLAB language is used to program the calculation program of transition process. Finally, the variation curves of water level fluctuation in the upstream and downstream open channel during load rejection transition of tubular units are calculated under the conditions of different open channel length and section area, different guide vane and blade closing time. The calculation results show that the inlet pressure of tubular unit will appear negative water hammer phenomenon at the initial time of load rejection, the smaller the open channel area, the greater the fluctuation amplitude of open channel water level, the longer the length of open channel, the greater the period of open channel water level fluctuation. Under the same guide vane closing time, the longer the blade closing time, the smaller the speed rise rate and the smaller the open channel water level fluctuation. Especially when the blade is not moving, the speed rise rate, the open channel water level fluctuation, the axial reverse thrust and the turbine inlet pressure fluctuation are obviously reduced.
【學(xué)位授予單位】：西安理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV734

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本文編號：2384060