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 It is always difficult that a higher rank model system is controlled. Hence,a reducing model is often needed to equal to the original system in order to control timely. So, a controller is designed for this lower rank model so as to reach the same goal with the original system. Firstly, the internal balance transform is used to the original system and the rank of the reduced model is determined.Secondly ,finding the linear transform through solving a Riccati equation ,the final reduced model is obtained... It is always difficult that a higher rank model system is controlled. Hence,a reducing model is often needed to equal to the original system in order to control timely. So, a controller is designed for this lower rank model so as to reach the same goal with the original system. Firstly, the internal balance transform is used to the original system and the rank of the reduced model is determined.Secondly ,finding the linear transform through solving a Riccati equation ,the final reduced model is obtained by aggregation method. Thirdly, two classical model reduction methods are introduced so that comparing with the method of this paper.Finally,the simulation is made for the two practical examples. It is shown that the calculating result is satisfied, the method is reasonable and effective.  对于一个高阶的控制系统,为了实现对其适时控制,需要一个降阶模型与之对应,对此低阶模型设计控制器以达到对原系统控制的目的。首先,在内平衡变换的基础上,确定降阶模型的阶数;其次,通过解一个Riccati方程得到一个变换矩阵,进而得到降阶以后的模型;然后,介绍了两种经典的模型降阶方法,以作为与此方法的比较。最后,对两个实例进行了仿真计算。计算表明,此方法是有效和可行的。  Based on System Dynamic approach and Vensim software package,a model was developed to simulate field and mezzo scale water balance transform processing in paddy rice.The model was calibrated and validated with data from Tuanlin Experiment Station,Zhanghe Irrigation Scheme,and then it was applied to simulate the return flow at the field and mezzo scale.The variation laws of evaluation indices with scale and hydrological year were investigated,and then main elements which affect return flow were analysis.The... Based on System Dynamic approach and Vensim software package,a model was developed to simulate field and mezzo scale water balance transform processing in paddy rice.The model was calibrated and validated with data from Tuanlin Experiment Station,Zhanghe Irrigation Scheme,and then it was applied to simulate the return flow at the field and mezzo scale.The variation laws of evaluation indices with scale and hydrological year were investigated,and then main elements which affect return flow were analysis.The results show surface return flow decreased linearly with increase of effective height of the border;return flow of the border increased linearly with terrain length and decreased significantly with increase of terrain width;return flow of the border and field increased with increase of hydraulic conductivity;subsurface return flow increased with increase of topographic slope;surface return flow,return flow of border and field decreased with increase of the upland ratio.A narrow combination of field got higher reuse efficiency of return flow.Return flow coefficient of irrigation & rainfall was more suitable for return flow evaluation than return flow coefficient of irrigation.Return flow coefficient of mezzo scale was twice of the field scale.Reuse efficiency of return flow in mezzo scale was very low and it was higher in dry year than normal year.  以V ens im为工具,建立了稻田田间及中等尺度水量转化的系统动力学模型;通过漳河灌区团林试区实测资料检验,证实了模型的适用性及其精度。将模型用于田间及中等尺度回归水的模拟,探讨了回归水评价指标随田间及中等尺度的变化规律,对影响稻田回归水变化的因素进行了敏感性分析。结果表明:地表回归水量随田埂有效高度的增加线性减少;田埂回归水量随田块长度的增加线性增加,随田埂宽度的增加而明显减少;田埂回归水和田间回归水均随水力传导度的增加而增加;地下回归水随坡度的变陡而增大;地表回归水、田间回归水及田埂回归水均随旱作比例的增加而减少。田块狭长组合方式的回归水重复利用系数比宽窄组合方式大。回归水评价指标计算表明,灌溉降雨回归系数比灌溉回归系数能更好的反映田间出流及回归水的利用;中等尺度的灌溉回归系数和灌溉降雨回归系数分别是田间尺度的1倍左右;中等尺度上的重复利用系数不大,说明可以提供给下游使用的回归水量大;干旱年份的回归水重复利用系数比平水年的大。  The traction power supply system of electric railway has the disadvantages of heavy unbalanced three phase,large harmonics and reactive power,needing neutral section insulator in every supply sector,which conditions the improvement of high speed and over loading railway.A new cophase traction power supply system based on threephase to fourphase transformer proposed not only can resolve all the questions above,but also has the virtues of saving autotransformer,simple structure of balance transform set,easily... The traction power supply system of electric railway has the disadvantages of heavy unbalanced three phase,large harmonics and reactive power,needing neutral section insulator in every supply sector,which conditions the improvement of high speed and over loading railway.A new cophase traction power supply system based on threephase to fourphase transformer proposed not only can resolve all the questions above,but also has the virtues of saving autotransformer,simple structure of balance transform set,easily being controlled and better balance effect,equalized load of each bridge arm of converter,better effect of communication defence,superior general economic technology indicator,and secure working.The principle of balanced transformation is discussed.The detecting method of the compensating currents and control mode of the active power filter are proposed.By analyzing and simulating,the proposed balance mode,detecting and control methods are verified to be true,and the proposed cophase power supply system is proved to be feasible.  电气化铁道牵引供电系统三相严重不平衡,存在大量的谐波和无功;各供电区段需要用分相绝缘器分断,制约了高速、重载铁路的发展。该文提出的基于三相变四相变压器的新型同相牵引供电系统,不但可以解决以上问题,而且具有省自耦变压器,平衡变换装置结构简单、易控制、平衡效果好,变流器各桥臂负荷均衡,通信防护效果好,综合经济技术性能优越,工作可靠等优点;文中讨论了平衡变换原理,给出了补偿电流检测与有源滤波器控制方法。分析和仿真证明提出的平衡方式、检测与控制方法是正确的,同相供电系统方案是可行的。  
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