| The harbor shore power stations can rely on harbor ship with high precise and reliable power supply, stop the ship diesel power station and achieve energy saving purposes. It is a revolutionary progress in port power supply field. But there are many technical issues to be sloved in process of engineering application. The research on MVA-class converter is of great importance to shore power stations, and the main research contents of this thesis are as follows:(1) The application situation and the development trend of the harbor shore power station were researched. The theory and technique foundation had been deeply researched based on the circuit topology, control technology, parallel technology and thermal design technology of the MVA-class converter. The paper explained the research background of the project and the tasks undertaken by author.(2) According to the analysis of the main circuit topology structure, the converter was divided to grid-connected PWM rectifier and passive power PWM inverter. The mathematical models of PWM rectifier based on double rotating coordinate system and instantaneous power model were established, and the mathematical models based on abc coordinate, αβ coordinate transformation, dqo coordinate transformation of the inverter were built too. Moreover the decoupled mathematical model of the converter was given.It was the foundation of control system analysis and algorithm research.(3) According to the high performance demand of the current sampling, the paper presented a sampling scheme based on wavelet and neural network theory. The method was composed of the function approximation capability of the neural network and local and multi-resolution characteristics of wavelet transform. For this reason the network had more flexible and efficient function approximation capability.The simulation and experiment verified the scheme could work well. According to the characteristic of three-phase high-factor rectifier based on αβ rotating frame, the paper presented a control scheme of rectifier current output waveform control based on neural network internal model theory. The control scheme took a neural network estimate model as the internal model of three-phase inverter to estimate the actual output waveform. The performance of highly accurate steady output, fast response and less distorted waveform were gained.(4) According to the parallel operation of MVA-class converter, the paper employed different power expansion methods to different power requirements. Research on the influence factors of IGBT devices connected in parallel, the paper put forward to a method to expand the converter capacity to500kVA with IGBT device parallel. On the base of analyzing the circulating current of the system level parallel operation, a new method was designed by using reactive power to regulate the inverter amplitude difference and by using two level asynchronous control to adjust the phase difference. The system level parallel could expand inverter capacity to1000kVA. According to the study of power level parallel principle, it was pointed out that the circulating current came from the different switch time of the power modules. A method using external inductor to restrain circulating current was presented to capacity to expand the converter capacity to3000kVA which could satisfy the engineering applications.(5) According to the heat dissipation command of MVA-class converter, the paper put forward solution of using optimal control technique to minimize the heat generation and improve the heat dissipation efficiency. A novel heat dissipation calculation method of MVA-class converter was presented. Based on the Research of space vector PWM modulation, the paper put forward an optimal space vector modulation method of flexible application of zero vector to reduce the switching frequency, thereby could effectively reduce heat generation. The single/alternative zero vector modulation methods of phase voltage modulation wave were manifested, then the double Fourier transform was employed to get their mathematics model in frequency domain. By the quantitative mathematical analysis of the harmonic characteristics, the paper got the conclusion that harmonic content of alternative zero vector modulation method was smaller than which of single zero vector modulation method. A practical formula to calculate the heat resistance of heat dissipation system was given, and the temperature calculation formulas of the IGBT module and heat dissipation system was derived. A heat dissipation system of the converter using forced air-cool was designed. The measured losses and temperatures were given, the calculation result and the experiment result verified the validity and practicability of the presented design method of heat dissipation system.(6) According to the demand of a port, a2000kVA shore power station was developed. Based on the multi module parallel combination, the main circuit diagram of shore power station and the high speed CAN communication method of the main controller and the slave modules were presented. Focusing on the grid-connected side and the load side filter system, the parameter calculation method was given too. Anti interference design of MVA class shore power was difficult, especially the communication part, optical fiber communication module was employed in the paper. The IGBT power module was easily effected and damaged by interference coming from the busbar, a low-inductance and low-effect design method of the busbar was proposed. As a result, a new structure of the busbar was obtained. Practical operation results showed that technical paper of the shore power station were good and could fully meet the demand.The series of harbor shore power stations had been successfully developed. The power stations completely meet the anticipated design requirements. At present the products had been put into market applications. The study on core technologies of the MVA-class converter enriched the design theory and technology system of harbor shore power stations. It provided important reference values to develop other MVA-class converter products. |
PDF Full Text Request