事故掉电引发的停泵水锤是泵站调水工程安全运行最主要的威胁之一,而对于下游水位低于上游水位的长距离负扬程加压泵站调水工程而言,事故停泵易造成管道拉空,负水锤防护难度较大,因此,针对其停泵工况的水力控制研究十分重要。以某长距离负扬程泵站调水工程为例,模拟计算了事故停泵、阀门拒动这一控制性工况下的水力过渡过程,并对比分析了空气罐、空气阀与空气阀联合空气阀调压室3种水力控制方案的水锤防护效果。结果表明:对于长距离负扬程加压泵站调水系统而言,当采用空气罐的水力控制方式时,所需的空气罐体积较大,投资高昂;当单纯采用空气阀的水力控制方式时,难以有效解决管道局部高点处负压较大的问题,仍可能诱发弥合性水锤;当将部分空气阀附加一根短管组合成空气阀调压室后,能够有效控制管内负压。空气阀与空气阀调压室联合防护是一种十分经济且有效的水锤防护方案,可为这类负扬程加压调水工程的水力控制方式选取提供参考。

The pump-stopping water hammer caused by accidental power failure is one of the main threats to the safe operation of pump station project. For long-distance negative-lift pump station (LDNLPS) with downstream water level lower than upstream water level, accidental pump stop can easily cause pipeline emptying, which makes it challenging to protect against negative water hammer. It is crucial to investigate hydraulic control measures for pump stop conditions. Taking a LDNLPS as a case study, we simulated the hydraulic transients under accidental pump stop and valve rejection conditions. We compared and analyzed the water hammer protection effects of three hydraulic control schemes: air tank, air valve, and combination of air valve with air-valve surge chamber. The results indicate that using air tank requires large volume and high investment costs; air valve alone struggles to address the large negative pressure at local high points of the pipeline and may still induce bridging water hammer. Conversely, combining some air valves with short pipes to form air valve surge chamber effectively controls the negative pressure in the pipeline. In conclusion, the combination of air valve with air-valve surge chamber is economical and effective in protecting against water hammer, hence offering a viable solution for hydraulic control in similar LDNLPS projects.