﻿ 基于起调水位上限优化策略的水库弃水控制方法

# 基于起调水位上限优化策略的水库弃水控制方法Spillage Control Method Based on Optimization Strategy of Upper Limit Initial Water Level

Abstract: Spillage control is one of the important part of reservoir operation in flood season, and pre-discharging by reducing the initial water level is an effective method for spillage control. However, how to determine the initial water level of reservoir is a very important technical problem. A spillage control method based on optimization strategy of upper limit initial water level is proposed in the paper. Firstly, with the goal of minimizing spillage for cascade reservoirs, an optimal model is established, and solved by nonlinear global optimization method. Then, for an assumed flood combination scenario, the set of cascade spillage control scheduling schemes is obtained by inputting different initial water level strategies into the previous optimization model, and the optimal upper limit initial water level is achieved by comparing the amount of spillage between different schemes. Finally the upper limit initial water level control strategy table corresponding to different frequency flood scenarios is generated through the above idea. The case study results of the joint scheduling of the three reservoirs (Goupitan, Silin, Shatuo) in Wujiang River Basin show that the spillage water of cascade and each reservoir can be controlled at a lower level by the proposed method, when the cascade encounters the flood combination scenarios which are most likely to occur in history or the flood combination scenarios whose magnitude is very large and is extremely unfavorable to reservoir dispatching.

1. 引言

2. 基于起调水位上限优化策略的水库弃水控制方法

Figure 1. Process of spillage control method

2.1. 建立梯级弃水最小模型

$SW=\mathrm{min}\left(\underset{i=1}{\overset{M}{\sum }}\underset{t=1}{\overset{T}{\sum }}{Q}_{sp,i,t}\cdot \Delta t\right)$ (1)

① 水量平衡约束：水库在上下两个时段间入库流量、出库流量以及库容值变化的动态平衡。

${V}_{i,t+1}={V}_{i,t}+\left({Q}_{inall,i,t}-{Q}_{out,i,t}\right)\Delta t$ (2)

${Q}_{out,i,t}={Q}_{fd,i,t}+{Q}_{sp,i,t}$ (3)

${Q}_{inall,i,t}={Q}_{out,i-1,t}+{Q}_{in,i,t}$ (4)

② 始末水位约束：给定水库调度期始末控制水位。

$\begin{array}{l}{Z}_{up,i,1}={Z}_{beg,i}\\ {Z}_{up,i,T+1}={Z}_{end,i}\end{array}$ (5)

③ 库水位约束：保证水库安全合理运行的水位范围。

${\underset{_}{Z}}_{up,i}\le {Z}_{up,i,t}\le {\stackrel{¯}{Z}}_{up,i}$ (6)

④ 发电流量约束：取决于水电站机组最大过流能力和停机检修等。

${\underset{_}{Q}}_{fd,i}\le {Q}_{fd,i,t}\le {\stackrel{¯}{Q}}_{fd,i}$ (7)

⑤ 出库流量约束：上限为水库最大泄流能力，下限满足下游航运、供水、生态用水等综合利用需求。

${\underset{_}{Q}}_{out,i}\le {Q}_{out,i,t}\le {\stackrel{¯}{Q}}_{out,i}$ (8)

⑥ 出力约束：上限为水电站总装机的额定容量。

${N}_{i,t}\le {\stackrel{¯}{N}}_{i}$ (9)

2.2. 优选水库起调水位上限

2.3. 生成起调水位上限控制策略表

Table 1. Flood coding rules

Figure 2. Frequency analysis of flood combination

3. 应用实例

3.1. 工程背景

Figure 3. Basin’s map and distribution of spillage from 2011 to 2016

Table 2. Characteristics of hydropower plants

3.2. 来水条件和始末水位

Table 3. Amount of different design frequencies seven-day flood (billion m3)

Table 4. Account of flood combination in history

Figure 4. Seven-day flood of different design frequencies

3.3. 结果分析

3.3.1. 发电效益分析

Figure 5. Comparison of power generation and spillage water between two models

Table 5. The deviation of power generation and reduction of spillage water between two models

3.3.2. 优选起调水位上限

Figure 6. Amount of spillage corresponding to different initial water level strategies

3.3.3. 生成起调水位上限控制策略表

Figure 7. Results of different flood combinations

Table 6. The table of upper limit initial water level control strategy

Table 7. Dispatching results of different method

4. 结论

1) 本文通过调整构皮滩的起调水位策略，寻求将梯级弃水控制到最小程度的起调水位上限，研究结果发现随着构皮滩起调水位的降低，梯级最小弃水量逐渐减小，说明通过降低构皮滩起调水位控制梯级弃水的方式是合理的。

2) 本文通过不同洪水组合情景下的优化计算，得到构皮滩水库起调水位上限控制策略表，当梯级遭遇历史最容易出现的洪水组合或者量级很大对水库调度极为不利的洪水组合时，都可以通过本文方法将梯级和各个水库的弃水控制在较低水平。

3) 本文方法不仅可以实现控制梯级弃水的目的，还可以保证发电效益，对于(两年一遇，五年一遇，五年一遇)的洪水组合，发电量与梯级发电量最大模型相比十分接近，差距仅为1.29%。

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