Filtering of DC active power filter for the hottes

Study on the filtering characteristics of DC active power filter for HVDC system

classification No. in Chinese figure: tm76 the study on the filtering characteristics of the DC active power filter for HVDC system Xiao Guo Chun, Li Kuang, Wang Zhao an (School of electrical engineering, Xian Jiaotong University, Xi'an 710049, China) abstract: according to the practical HVDC system, the dc active power filter is installed in both converters respectively. Shubhayan Sarkar, chemical analyst of adof s, said: "Backward integrated polymer producers will better control the fluctuation of raw material prices. Pting short distance transmission line equivalent circuit model, the filtering characteristic of the DC active power filter is analyzed and its corresponding experiment investment is presented in the paper. In order to evaluate the filtering characteristic of the DC active power filter, an active filtering attention Co efficient is also introduced. The theory analysis and experimental results show that the hybrid filters consisting of passive filter and active filter can further increase the filtering performance on the DC side in HVDC system. Key words: HVDC system active power filter DC filter 1 Introduction with the development of modern power system, the increase of transmission capacity and transmission distance, and the interconnection of regional networks, there have been dynamic problems such as system stability, low-frequency oscillation and subsynchronous oscillation, which have limited the application of AC transmission. DC transmission has the advantages of energy saving, low line cost and no system stability problems [1]. The use of DC transmission technology can improve the economic indicators, technical performance, operation reliability and scheduling flexibility of the power system. High voltage direct current transmission (HVDC) plays an important role in long-distance and high-capacity transmission. Especially under the current situation of West to East power transmission and nationwide connection, DC transmission has broad development prospects in China with its unique advantages [2]. However, in the HVDC transmission system, the converter station (including rectifier station and inverter station) will produce harmonics in the DC current and voltage of the DC transmission line. When the DC transmission system adopts overhead lines to transmit DC current with long distance and high power, the flow of these harmonics will interfere with the adjacent communication lines, and the main interference frequency range is 300~3000hz [3]. In order to filter the harmonics on the HVDC transmission line and avoid the interference to the communication lines along the line, the traditional method is to set a passive power filter on the DC side, but the passive power filter itself has limitations. When high-performance filtering is required on the DC side of DC transmission system, the cost of passive power filter will increase significantly, and at this time, the hybrid power filter composed of DC active power filter and passive power filter will have stronger competitiveness [4]. In order to promote the development of DC transmission technology in China and eliminate the interference of DC transmission lines to adjacent communication lines, it is of great practical significance to actively carry out the research on the theory and application of 16 and 20 length harmonic decorative boards of DC active power filters for HVDC transmission systems. Literature [5] has made theoretical and Experimental Research on the structure and basic principle of DC active power filter for HVDC transmission. This paper is the continuation of the above work. According to the actual HVDC transmission system, DC active power filter is set at the rectifier side and inverter side at the same time, and the equivalent circuit model of short-distance transmission line is adopted. In this case, the filtering characteristics of DC active power filter are analyzed in detail and the corresponding experimental research is carried out. At the same time, in order to evaluate the filtering performance of active power filter, the concept of attenuation multiple of active power filter is introduced. Theoretical analysis and experimental results show that the hybrid filter composed of passive filter and active power filter can greatly improve the filtering performance of the DC side of HVDC transmission system. The research results of this paper provide a theoretical basis for the practical application of active power filter in HVDC transmission system. 2 high voltage DC transmission system with DC active power filter generally speaking, the high voltage DC transmission system is mainly composed of converter, power filter and reactive power compensation device, smoothing reactor and DC line [1]. In order to suppress the harmonic component in the overhead line and control its interference to the communication line within the specified range, a DC power filter is set at the DC side. In order to study the control method of hybrid power filter composed of DC active power filter (dcapf) and passive power filter on the DC side and its filtering performance at the outlet and inlet of DC transmission bus, according to the actual situation of HVDC transmission project, The bipolar 12 pulse HVDC transmission systems (such as Gezhouba Shanghai, Tianshengqiao Guangzhou and Three Gorges Changzhou HVDC transmission projects) widely used in the world and China are simplified. The simplified HVDC side system is shown in Figure 1. This measurement will be fruitless. This is exactly half of the symmetry of the actual bipolar 12 pulse HVDC transmission system (positive or negative system), and the structure of the converter station (including rectifier station and inverter station) is also symmetrical, so the model fully conforms to the actual situation of the DC side of the bipolar 12 pulse HVDC transmission system. It should be noted that since the power flow direction of DC transmission can be controlled arbitrarily, the distinction between rectifier and inverter here is mainly to simplify the following description. Figure 1 Schematic diagram of DC side of DC transmission system with DC active power filter. In Figure 1, there are two converter stations, one as rectifier and the other as inverter; LS1 and Ls2 are smoothing reactors of the converter; C11, L11 and C21, l several positive signals have appeared in the economic operation of China's extruder industry 21, C12, L12 and C22, L22