含混合式抽蓄的梯级水电站短期临界调峰模式

Short-term critical peak-shaving mode of cascade hydropower plants with on-stream integral pumped storage hydropower plant

利用梯级水库电站建设混合式抽蓄电站,在提高新型电力系统清洁灵活性调峰能力的同时,也使得原梯级电站的运行方式变得更为复杂,亟需开展梯级电站与混合式抽蓄电站的联合调度模式研究。本文首先剖析了混合式抽蓄电站与梯级水电站日内联合调峰运行特点,建立了短期含混合式抽蓄的梯级水电站调峰优化模型;其次,发现了日内联合调峰的临界特性,并从临界调峰方式、临界调峰流量、临界调峰能力三方面定量刻画了该临界调峰特性,推导了梯级水电站临界调峰流量、混合式抽蓄电站临界抽发流量等计算公式,提出了混合式抽蓄电站与梯级水电站的临界调峰模式;最后,将上述理论成果应用至依托安康与旬阳梯级水库修建的安康混合式抽蓄电站。结果表明:安康水电站额定水头下临界调峰流量为892 m^(3)/s,小于892 m^(3)/s时,抽蓄电站日内满抽满发,以最大化调峰方式运行;大于892 m^(3)/s后,混合式抽蓄电站可转为与常规水电站同抽同发运行模式以及部分抽蓄机组转常规水电站机组运行模式等;长系列计算结果表明,与常规水电站同抽同发运行模式提高了抽蓄电站运行小时数,但降低了联合调度主体调峰能力,部分抽蓄机组转常规水电站机组运行模式耗用了安康水电站的可用发电水量,但提高了联合调度主体调峰能力,实际调度过程中应根据电网运行情况、电站运营主体等灵活选择抽蓄电站运行模式。

Relying on existing cascaded hydropower stations to construct an on-stream integral pumped storage hydropower plant(OIPSHP)not only enhances the clean and flexible peak-shaving capacity of new power system,but also complicates the operation mode of original cascaded hydropower stations.Hence,it is urgent to carry out research on the joint peak-shaving mode of cascaded hydropower stations and OIPSHPs.In this article,the operation characteristics of OIPSHP and cascaded hydropower stations are analyzed,and a short-term peak-shaving optimization model for cascaded hydropower stations with OIPSHP is established firstly.Secondly,the critical characteristics of day-scale joint peak-shaving mode are found,and general calculation formulas for the critical peak-shaving flow of cascaded hydropower stations and the critical extraction flow of OIPSHP are derived and the critical peak-shaving mode of OIPSHP are condensed.Finally,the theoretical results are applied to one practical case,AnKang OIPSHP depending on cascade AnKang and Xunyang reservoirs.It is found that the critical peak-shaving flow of the AnKang hydropower station is 892 m^(3)/s under rated head.If the outflow is less than 892 m^(3)/s,the OIPSHP will fully extract and inject to maximize peak shaving.Once the outflow exceeds 892 m^(3)/s,the OIPSHP can switch to operate in conjunction with a conventional hydropower station in a synchronized manner,as well as operate some pumped-storage units as conventional hydropower station units.Long-term dispatch results show that operating in sync with conventional hydropower stations increases the operation hours of OIPSHP but lowers the joint dispatching entity’s peak-shaving benefit.On the other hand,switching some OIPSHP units to operate as conventional hydropower station units consumes AnKang hydropower station’s generation water usage but improves the joint dispatching entity’s peak-shaving benefit.Therefore,flexible selection of OIPSHP operation modes should be implemented in actual dispatching processes based on the operation of power grids and the operation main body of hydropower stations and OIPSHP.