对冷冻水泵组能耗提出一种次优化的全年能耗评价方法，并根据此评价方法使用一种经优化的随机走步法进行水泵型号优化设计; 通过实例计算分析了控制压差、额定流量对全年能耗特性的影响，并对不同变频控制方式进行了比较． 结果表明: 使用随机走步法进行次优化寻优在对传统优化方法的局部最优与收敛性问题上表现较好，由负荷率分布不同所造成的系统全年总能耗差异可达50%以上，在对系统进行能耗评估时必须考虑全年负荷率分布; 控制旁通回路压差较大、额定流量较小的系统，低能耗区域更宽，中能耗区域也相应较宽，各负荷率下能耗偏离系统的极限最低能耗较远，能耗评价较宽松; 在大部分情况下，随着额定总流量或控制压差的增加，使用同步变频控制变得有利．

Proposed in this paper is an evaluation method of energy consumption suboptimization with chilled water pump group, and according to this evaluation method, an optimized random step optimization method is used to optimize the design of the model in pumps group. Then, the influences of control pressure difference and rated flow on annual energy consumption characteristics are analyzed by an example, and different frequency conversion control modes are compared. The results show that (1) the optimized random step optimization method performs better in coping with locally-optimal and convergent problems than traditional optimization methods do; (2) the annual total energy consumption differences caused by different load rate distribution can reach more than 50%, so the annual load distribution must be taken into account in the energy consumption evaluation of system; (3) the system of bigger bypass pressure and lower rated flow has wider low and middle energy regions, its energy consumption under different load rate limits is far away from the lowest energy consumption and the corresponding energy consumption evaluation is more tolerant; and (4) in most cases, adopting synchronous frequency conversion control becomes advantageous with the increase of flow or control bypass pressure rating.