Xu Shuang Ankerui Electric Co., Ltd.    Jiading 201801 1 Introduction With the advancement of science and technology and the continuous improvement of urbanization, urban rail transit is closely related to people's daily life. The electrical equipment of the ground track transportation system is colorful and complex. Among them, electric locomotives, air-conditioning pumps and fans, elevators, equipment room network equipment, UPS , lighting control systems, fire fighting systems, monitoring systems and other power electronic equipment are distributed throughout the entire subway. . The harsh harmonic environment has caused a great threat to ensure the normal operation of the power system and equipment. This paper analyzes the causes of harmonic problems and proposes solutions that can meet the project implementation. 2. Problems with Rail Transit There are five major problems in the orbital power supply system : (1) The rail transit power supply system is a special single-phase power supply, which leads to a serious imbalance of the three phases; (2) The electric railway rail power supply system is powered by a high-power rectifier bridge to supply current to the locomotives. Current domestic electric locomotives use DC choppers as the traction locomotive DC power supply rectification system. Severe and rapid changes, resulting in a large number of 11th and 13th harmonic currents; (3) Followed by a large number of non-linear loads ( 3 times, 5 times, 7 times, etc.) for the inverter, UPS , and switching power supply for the station . With the need of energy saving, the proportion of variable frequency load increased year by year. As the frequency conversion load increases year by year, the harmonic currents generated by it increase accordingly. (4) electric locomotive frequent starting, acceleration, braking system so that rapid changes in reactive power, harmonic reactive power also increases the presence of loss of the system, so that the power factor and low volatile. (5) According to GB50157-2003 "Code for Design of Subways", parallel power capacitors should be used as reactive power compensation devices for power supply systems for subway powered lighting. Theoretically, the power capacitor appears capacitive both under the fundamental wave and under the harmonic wave. Therefore, it will react to both the harmonics from the high-voltage side of the distribution transformer and the harmonics from the low-voltage variable-frequency load. Play amplifying effect. Its amplification has been verified by the actual measurement results of several subway systems in China. 3 Harmonic Harm ( 1) Affecting the normal operation of power electrical equipment, in addition to causing additional losses, it can also cause severe overheating of transformers, which can cause overheating of capacitors, cables, etc., insulation aging, and shortened life span. In severe cases, it can lead to the destruction of transformers, cables, and capacitors. Breakdown and other failures; (2) It will cause partial parallel resonance and series resonance in the system, so that the harmonics will be amplified and the aforementioned hazards will be greatly increased, even causing serious accidents; (3) It will lead to relay protection within the power system and misoperation of the automatic device, such as the protection switch tripping, leading to partial line power failure; (4) Make the precision equipment such as computers in the power system unable to work properly; 4. Rail Transit System Harmonic Solution ANAPF active filter having a dynamic response speed is less than 20ms, filtered 2-21 harmonics, harmonic current can be real-time detection system, a control command issued harmonic current reversal equal, harmonic current balancing system, filtered System harmonic currents, remove system harmonic currents, remove harmonic losses, stabilize system voltages, balance three-phase voltages, and compensate for reactive power losses. 4. 1  Main technical features of ANAPF active filter DSP+FPGA full digital control method with extremely fast response time  ; Main circuit topology and advanced control algorithms, more precise and more stable operation; a machine can make both harmonic, but also up and reactive; modular design, easy commissioning; parallel convenient design, easy Capacity expansion; with perfect bridge arm over-current, protection function; easy to use, easy to operate and maintain. 4.2 Main Technical Parameters of ANAPF Active Filter Wiring Three-phase three-wire or three-phase four-wire Access voltage 3×380V ±10% Access frequency 50Hz ±2% Dynamic compensation response time Dynamic response < 4ms , full response time < 20ms ; On-off level 10kHz Harmonic compensation times 2-21 times Type of protection DC over-voltage IGBT over-current device temperature protection Overload protection Automatic current limit in the set value, no overload occurs cooling method Smart air cooling noise < 65db ( in the cabinet and operating in the rated state ) Working temperature -10 °C to +45 °C Working environment humidity < 85% RH non-condensing Installation occasion Indoor installation Altitude ≤1000m (for derating at higher altitudes) Incoming and outgoing ways Down in and out Protection level IP21 Intelligent communication interface RS485/MODBUS-RTU Remote monitoring Optional Weight (kg) Three-phase four-wire Three-phase three-wire 30A , 50A 75A , 100A 30A , 50A 75A , 100A 280 360 240 290 4.3 ANAPF Active Filter Quotation and Component List Model Number: ANAPF100-400/B Reference price: 120,000 yuan/set The main product details: No. Name Model number Quantity 1 APF electrical cabinet 800X600X2200 1 2 Converter APFCOV-CVT100 1 3 Controller APFMC-C100 1 4 Reactor APF-RE.(S)DG-100 1 5 Active current transformer LT208-S7 3 6 filter DL-1TH1 2 7 breaker CVS160FTM160D4P3D 1 8 Contactor LC1D150M7C 1 9 MCB NDM1-63C32 1 10 Intermediate relay MY4NAC 2 11 R type transformer R320-0.38/0.22 1 12 Harmonic Detector ACR350EGH 1 13 wire 16mm 2 Some 14 wire 4mm 2 Some 4.4   Application Case of ANAPF Active Filter in Rail Transit In an urban rail transit system , harmonic control of substation systems uses centralized compensation. The following figure shows an active filter device into longitudinal harmonic voltage, harmonic current control in FIG: Can be clear from the current waveform before and after the filter into the grid, the grid current harmonics are filtered out most of the waveform has a sine wave, the total current of 2343A to 2240A reduced, lowering the effective value current 4.3%; total The current distortion rate decreased from 25.2% to 3.3% , the compensation rate reached 89% , and the power factor increased from 0.95 to 0.99 . According to the allowable value of the harmonic current of the national standard grid, it can be clearly seen that the harmonic currents before the compensation obviously exceed the requirements of the national standard several times. After the compensation, all the harmonic currents can reach the national standard requirements. For rail transit power supply systems, safe operation is the first priority. After the active filter is put into operation, the harmonics of the distribution system are well suppressed, the power supply system reliability is improved, and the influence of harmonics on the power supply of the rail transit system is eliminated, which ensures the safe operation of the urban rail system. 5 Conclusion This paper analyzes the existence, harmonic characteristics and harm of harmonics in the urban rail transit system. The characteristics and technical parameters of the ANAPF low-voltage active filter are introduced, and the application cases of active filters in an urban rail transit system are compared. after analyzing the harmonic control before and after the active filter into by the active filter before and after comparison chart analysis investment in urban rail transit harmonic governance to improve power quality, improve the overall operating efficiency of rail transportation equipment and electrical systems Energy use efficiency. ã€references】 [1] One Guo Tongji University electrical engineering design and simulation of hybrid filters Urban Mass Transit System 2009:... 340--343 [2] Ankerui Electric Co., Ltd. Product Manual. 2013.01. About the Author: Xu Shuang, female, undergraduate, Ankerui Electric Co., Ltd., the main research direction for the smart grid power distribution, Email: Mobile QQ "AAPF Active Power Filter Device Design and Application Atlas" (atlas number: ACR13CDX701) is edited by Ankerui Electric Co., Ltd. This atlas combines the characteristics of ANAPF active power filter device products, based on electrical design specifications, research Eliminating the problem of high-order harmonics in the power supply and distribution system to achieve the goal of improving the quality of power supply and ensuring the safe operation of the power system. The Atlas is applicable to the design and modification of harmonic suppression and comprehensive management of electrical equipment in industrial, civil, and public buildings in new construction, reconstruction, expansion, and technological transformation projects. If you need atlas, please provide your organization's name, department, address, zip code, contact person, contact telephone number, email address, fax 021-69155331, mail or QQ to Ankeru Xu cream engineer, Ankerui Electric will give you a free gift. .
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