| With the increasing proportion of energy fed elevator in the distribution network,its impact on the power quality of the distribution network can not be ignored.The energy fed elevator is a typical nonlinear load.The harmonic current generated in the working process is easy to match the impedance of the distribution network,which leads to the deterioration of broadband harmonic current and harms the normal operation of the distribution network load.The harmonic emission characteristics of the energy fed elevator will also be affected by the operation environment of the distribution network.Aiming at the problem that the current dynamic harmonic analysis model of elevator energy feedback system is too simplified,this paper deduces the dynamic harmonic emission characteristics under different working conditions based on the closed-loop control model of elevator energy feedback system,studies the interaction mechanism and characteristics between elevator energy feedback system and distribution network,and establishes a more accurate dynamic harmonic analysis model of elevator energy feedback system,At the same time,based on the correlation analysis of dynamic harmonic and power,the optimization strategy of energy fed elevator is designed.The work of this paper is of great significance for harmonic control of energy fed elevator load in distribution network.Firstly,based on the structure and running speed curve of elevator energy feedback system,the relationship between the output electromagnetic torque of traction motor and the load and running speed is obtained,and then the mechanism of elevator energy feedback is analyzed.On this basis,two typical topologies of energy fed inverter are introduced.By analyzing the advantages and disadvantages of the two topologies in power quality control,the energy fed elevator with integrated topology is finally adopted as the research object of this paper.Secondly,the dynamic harmonic analysis model of the energy feedback system with closed-loop control is constructed,and the harmonic emission mechanism and characteristics of the elevator under constant speed and non constant speed operation are theoretically deduced.Furthermore,the interaction mechanism between grid connected operation of energy fed elevator and distribution network is analyzed theoretically.Then,the simulation model of the elevator energy feedback system is built and the reliability of the model is verified.Combined with the measured data,the correlation between the dynamic harmonic emission and power of the elevator energy feedback system is analyzed.Based on the research results,the power is divided into different parts,and the harmonic current emission characteristics of the elevator in the stages of constant speed operation,acceleration operation and braking operation are analyzed respectively.At the same time,the simulation model of the interaction between the elevator energy feedback system and the distribution network is constructed,and the dynamic harmonic emission characteristics considering the influence of the distribution network are simulated and analyzed.Finally,based on the correlation between the dynamic harmonic emission characteristics and power of the elevator energy feedback system,the ontology governance strategy is applied.The strategy based on super capacitor energy storage is used to optimize the low order harmonic emission characteristics.The operation principle of the system and the design method of the controller are analyzed;LCL filter is used as the optimization strategy of high-order harmonic emission characteristics,and the parameters of LCL filter are designed according to the harmonic emission characteristics of elevator energy feedback system studied in this paper.The simulation model verifies the effectiveness and feasibility of the dynamic harmonic characteristics control strategy with super capacitor energy storage and LCL filter. |
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