Research On Control Technologies For SAPF And The Engineering Application

As the rapid developing of power electronics technology, the power energy transformation and application become more and more convenient, however, the power quality problems get more seriously in the power system, particularly in harmonic pollution. It is well-known that APF (Active Power Filter) is the most effective method to solve harmonic pollution and improve the power quality. So the control and engineering technologies of Shunt APF (SAPF) are studied deeply in this paper, such research is of great importance to its early industrial application.In the second chapter of this paper, the work principle and mathematical model of SAPF are introduced. The harmonic current detection method and compensation current control technology that used in this paper are elaborated at the same time. In the third chapter, we analyzed the voltage control technology of SAPF and discussed its start and steady-state control methods of DC voltage.We got a new conclusion about how to set DC voltage ideal value through theoretical analysis and actual test. Then we proposed DC voltage deviation's square PI closed-loop control strategy based on the traditional DC voltage deviation PI control method.Such control strategy has rapid response and small static error features can supress output current effectively while SAPF is without load, what is more, it can put into practice simply and meet the control requirements while the load change suddenly.For the over-voltage problem of IGBT modules in main circuit occur many times, we researched the over-voltage mechanism in detail and showed the relevant waveforms.We reduce the main circuit equivalent stray inductance by effective measures and design over-voltage and thermal protection circuits, In this way, IGBT modules are protected comprehensively and the problem that power modules could be burned easily is solved.In order to verify the feasibility of above solution, a SAPF experimental prototype which is more than 200kVA is built. FF650R17IE4-type IPM is used as PWM converter in the main circuit. The control circuit comprises a dual-CPU (ADMC401 & LPC2378) system. In the fourth chapter of this paper, we describe the software and hardware design methods about the control system.In the part of hardware design, the main schematic about DSP control board, sampling board and interactive board of LPC2378 are given. In the part of software design, we optimized the program of ADMC401 by using assemble language and completed the program design of LPC2378 through C language.This paper is based on some prophase work. By developing amount of following study work, we got some achievement and improved the performance of SAPF both in software and hardware.Then we successfully developed a new SAPF prototype with greater capacity (compensation current can reach 400A) and better performance.Finally, this paper provided typical experimental data and waveforms which have verified the correctness and effectiveness of the system control strategy.