许多高耗能企业拥有自备发电厂。通过对自备电厂自调度实现发、用电白平衡对企业用电的经济性与区域电网的安全性都具有重要意义。由于发电机组的爬坡能力受限,不可能每个时间段起点突变,所以目前广泛采用的离散时间模型可能导致调度计划无法操作实现。为此,针对高耗能企业建立含积分约束的关口平衡模型。通过分析任意调度时段起点与终点时刻机组输出功率、机组爬坡率和该时段期望能量输出之间的关系,将含积分约束的关口平衡模型转化为一个混合整数规划模型。进而,基于最优控制理论中的极小值原理,给出一种安全经济的机组输出功率控制方式。以某具有自备电厂的大型钢铁企业发用电平衡为例进行数值求解,结果验证了模型及其控制方式的有效性。
Many energy-intensive enterprises own power plants themselves. Achieving balance of electrical energy consumption and supply through self-scheduling is very important to security and reliability of the power grid and often gets incentives from the power utility. Due the ramping limit of generating units and infeasible step-up change, a generation level schedule based on discrete-time model may not be realizable although ramp-rate constraints are satisfied in scheduling. This paper formulates a new model for balance analysis with integral constraints. Based on the detailed analysis of the admissible region of initial or terminal generation level and its relationship to scheduled energy delivery and ramp-rate constraints, the new model for balance analysis with integral constraints is converted into a mixed integral programming model. Based on the minimum principle in optimal control theory, a control method of unit power output is developed considering unit economics and security. Numerical testing is performed with the actual data of a large iron and steel enterprise and the results show that the model and the control method are effective.