热源循环泵流量对热电联供系统优化运行影响

建立利用热网蓄热以促进风电消纳的热电联合优化运行模型,分析热源循环泵流量对热电联供系统运行经济性的影响。案例分析结果表明,循环泵日电费随相对流量减小而降低。相对流量87%~100%范围内,目标函数(热电机组的日运行费用、日市电费、日弃风罚款之和最小)不变。当相对流量降至86%后,目标函数不降反升,且增大幅度大于循环泵日电费降低幅度。受供水温度及供回水温差的限制,随着相对流量减小,日间热电机组制热功率受到限制。为了满足热电联合优化运行模型热平衡条件(总供热量等于总耗热量),夜间热电机组制热功率无法降低,热电机组发电功率居高不下,导致风电消纳受限,弃风电量增大。日弃风罚款随之增加,最终导致目标函数升高。相对流量为87%时,热电联供系统的日运行费用最低。

Influence of Heat Source Circulating Pump Flow Rate on Optimal Operation of Combined Heat and Power System

An optimal operation model of combined heat and power with heat storage in heating network to promote wind power consumption is established.The influence of heat source circulating pump flow rate on the operating economy of the combined heat and power system is analyzed.The case analysis results show that the daily electricity cost of the circulating pump decreases with the decrease of relative flow rate.Within the range of 87%to 100%of the relative flow rate,the objective function(the sum of the daily operating cost of the thermal power unit,the daily grid electricity cost and the daily penalty for wind power abandonment is the minimum)remains unchanged.When the relative flow rate drops to 86%,the objective function does not decrease but rises,and the increase range is greater than decrease range of the daily electricity cost of the circulating pump.Limited by the supply water temperature and the temperature difference between the supply and return water,the daytime heating power of the thermal power unit is limited as the relative flow rate decreases.In order to meet the thermal balance condition of the optimal operation model of combined heat and power(the total heat supply equals the total heat consumption),the heating power of the thermal power unit cannot be reduced at night,and the power generation power of the thermal power unit remains high,resulting in the limitation of wind power consumption and the increase of wind power abandonment.The daily penalty for wind power abandonment increases,which eventually leads to an increase in the objective function.When the relative flow rate is 87%,the combined heat and power system has the lowest daily operating cost.