改进的显随机动态规划在梯级水库优化调度中的应用

Application of the Improved Explicit Stochastic Dynamic Programming Model in the Optimal Operation of Cascade Reservoirs

为了解决常规水库调度图难以获得最优调度方案、且梯级水库随机优化调度求解“维数灾”等问题,以东北第二松花江流域白山~丰满梯级水库水电站为例,分析梯级水库的实际径流特性,依据同流域的梯级水库天然径流具有较强的相关性的特点,提出了降维的马尔科夫链随机径流描述模型,解决梯级水库随机优化调度模型求解的维数灾问题;同时结合有、无时段径流预报的描述方法,使得径流描述更加贴近实际;根据所提出的径流描述模型,采用调度期内发电量期望值最大作为优化调度模型的目标函数,研究相邻时段无径流预报、相邻时段有径流预报、本时段无预报且后时段有预报、本时段有预报且后时段无预报等情况下的模型递推方程,首次创建了考虑有、无时段径流预报相结合的梯级水库优化调度模型;利用了惩罚系数和改变保证出力约束相结合的方法,求解得到各种出力保证率下的水库最优决策方案;在相同的出力保证率情况下,通过对白山、丰满梯级水库历史径流序列模拟优化调度结果的对比分析可知,所得到的优化调度规则比常规水库调度图和传统随机优化调度规则都获得了更多的发电效益,模型求解时间也比传统方法提高了数倍,充分说明了本文所创建模型的有效性和调度规则的优越性。

Considering that it is difficult to obtain the optimal operation scheme from the conventional reservoir operation diagram and that the stochastic optimal operation solution of cascade reservoirs causes“dimension disaster”,this paper takes Baishan and Fengman cascade reservoirs hydropower stations in the second Songhua River in northeast China as examples to analyze the actual runoff characteristics of cascade reservoirs,based on the characteristics that the natural runoff of cascade reservoirs in the same basin has strong correlation,a reduced-dimension Markov chain stochastic runoff description model is proposed to solve the dimension disaster problem of the stochastic optimal operation model of cascade reservoirs.At the same time,the description method of runoff forecast with and without time intervals is used to make the runoff description more practical.According to the proposed runoff description model,the maximum expected value of power generation during the operation period is used as the objective function of the optimal operation model,and the model recurrence equations under the conditions of no runoff forecast in the adjacent period,no runoff forecast in the adjacent period,no forecast in the current period and no forecast in the later period,no forecast in the current period and no forecast in the later period are studied.The optimal operation model of cascade reservoirs considering the combination of runoff forecast in the current period and no forecast in the later period is created for the first time.The method of combining the penalty coefficient and changing the guaranteed output constraint is used to solve the optimal decision scheme of the reservoir under various output guarantee rates.Under the same output guarantee rate,through a comparative analysis of the simulated optimal operation results of the historical runoff series of Baishan and Fengman cascade reservoirs,it can be seen that the optimal operation rules obtained in this paper obtain more power generation benefits than the conventional reservoir operation chart and the traditional stochastic optimal operation rules,and the model solving time is also several times more than that of the traditional method.It fully illustrates the effectiveness of the model and the superiority of the scheduling rules created in this paper.