With the application of power electronic converter device increasingly widespread, more power has been fully utilized. But widespread use of nonlinear power plant equipment generates a lot of current harmonic distortion, distortion of the current flowing in the power grid harmonic voltage leads; harmonic pollution is increasingly a threat to the power system security, stability, economic operation, linear load to the same network and other users a great impact. Harmonic has been with electromagnetic interference, the power factor of the power system to reduce tied for three hazard. Therefore, to understand the principles of harmonic generation, supply and distribution system research to eliminate the higher harmonics to improve the quality of power supply problems and ensuring safe operation of the power system has a very positive meaning. Harmonic harmonic measurement is an important branch of the problem, to suppress harmonics, harmonic generation problem has an important role in guiding. Therefore, measurement and analysis of harmonic power system analysis and control of an important work, is an important prerequisite for protection, fault measurement work carried out. The main source of harmonic generation in the following table: Name Trade frequency devices business, municipal, civil, utilities, industrial and mining enterprises UPS, switching power supply, power inverter utilities, commercial, electronic, telecommunications and other subway, light rail, charging station (pile ) Transportation single (multi) crystalline silicon production equipment, intermediate frequency furnace manufacturing electric arc furnaces, welding machines, induction heating equipment machinery, energy, chemical hazards harmonics 1.1? so that the power element additional losses increase, easily lead to a fire. Make utility grid harmonic components generate additional losses, reducing the efficiency of power generation, transmission and electrical equipment. A large number of third-harmonic flow through the neutral line will overheat and even cause a fire. ? Affect the normal operation of electrical equipment. Harmonics will affect the normal operation of electrical equipment, motor produces mechanical vibrations and noise, severe localized overheating of the transformer, capacitor, cables and other equipment overheating, insulation aging, shortened life expectancy, resulting in damage. ? Cause grid resonance. This may cause harmonic resonance current amplification times or even dozens of times, on system, particularly the formation of a great threat to the capacitors and reactors connected in series, often the capacitor and reactor burned. ? Make relay malfunction, electrical measurement error is too large. Harmonics can cause protection, especially computer integrated protection and automatic device malfunction, resulting in unnecessary power interruption and loss of production; harmonic metering also make electrical measurements inaccurate, resulting in measurement error, to power management department or power users bring economic losses. ? Make industrial system crash. Near the harmonic source or higher harmonics communications and information processing equipment will cause interference, ranging from noise, reduce the communication quality, the computer does not work; it leads to weight loss of information, so that the industrial system crash. National Standard GB 1.2 Harmonic based / T14549-1993 "Power Quality: utility grid harmonic" GB / T15543-2008 "power quality: three-phase voltage unbalance factor" GB / T12325-2008 "Power Quality: supply voltage tolerance "GB / T12326-2008" power quality: voltage fluctuation and flicker "GB / T18481-2001" Power Quality: temporary over-voltage and over-voltage transients "GB / T15945-2008" Power Quality: power system frequency tolerance "GB7625.1-1998" harmonic current limits "GB / T15576-1995" Low voltage reactive power compensation device static overall technical conditions "low-voltage electrical and electronic products issued two active power filter device 2.1 Model Description 2.2 works ANAPF series active power filter device, connected to the grid in parallel, by the harmonic and reactive components of real-time detection of the load, using PWM converter technology, and harmonic components and generates a reactive component of the current from the corresponding anti-converter in to inject real-time power system components and to achieve harmonic control and reactive power compensation. Principle in the following figure: 2.3 The main technical features of DSP + FPGA digital control, with a very fast response time; the main circuit topology and advanced control algorithms, more accurate and more stable operation; a machine can, can make harmonic , but also complement and reactive; modular design, easy commissioning; convenient parallel design for easy expansion; with perfect arm overcurrent protection function; easy to use, easy to operate and maintain. 2.4 Technical Data 2.5 Filtering Selection block diagram 2.6 Technical Requirements 2.6.1 installation layout requirements ANAPF general standard cabinet structure, the installation should avoid inverted or flat, dimensions determined by the selected harmonic compensation current value, the general layout of the form harmonic current compensation is determined by the position. Its layout requirements are as follows 1) from the wall Installation: Under normal circumstances, the low-voltage switchgear proposal from the wall are arranged side by side, front operation, maintenance-sided, on the back of the maintenance channel is not less than 800mm. 2) wall installation: ANAPF also be arranged against the wall, positive operation, maintenance front. 3) Electrical wiring system designers should consider and pay attention to the layout in compensation ANAPF access point as close as possible to compensate object, and in the upstream sampling CT or to reserve space at the end for the design, installation, downstream sampling at CT can not contain capacitive load. Schematic layout shown below: 4) ANAPF under all normal circumstances uncharged metal housing make the appropriate protection should be strictly zero or protective earth connection according to the design requirements of the standard ground (TN-S, TN-CS, TT, etc.). P1-side installation of a transformer 2.6.2) transformer grid point, P2 end point load. 2) transformers and wiring ANAPF shown below: 3) Note the transformer into the outlet to be consistent and in the right direction. 4) Install the cable specifications in the following table: Installation cable with cross-sectional area 2.7 CT sample line application and where the main airport: the main control room, computer room, broadcasting systems, EIB light dimming system. Hospital: ICU (intensive care unit), MRI (magnetic resonance imaging), operating room, medical imaging room, radiotherapy Branch. Theater, Stadium: Solving EIB dimming equipment and other control equipment damage caused due to harmonics. School: Precision laboratory, computer room, network center. Institute: precision instruments, computer room, focus area, such as high-precision equipment. Shopping malls: solve problems caused by harmonics caused by large-scale application of energy-saving lamps. Bank: computer center, business department computers, security systems. Tax, business: large computer centers. Telecommunications room: mobile base stations. Factory: production line PLC, computer-controlled equipment, high-precision machine tools, PCS systems, measuring / weighing systems. TV: imaging equipment, dimming equipment, computers and so on. 3 APF function module introduces 3.1 controller module APF APF device controller consists of: DSP (digital signal processors), FPGA logic devices, AD signal sampling circuit, DI / DO input and output control circuit, PWM waveform control circuit, RS485 communication circuits and other components, is mainly used to complete the acquisition and processing of voltage and current signals to calculate the instruction current generation switching circuit, the output of the PWM signal, the system of external communications and system protection functions. Control system is the core of the active filter, which determines the main performance and indicators of active power filter system. Naming Dimensions (Unit: mm) core technical parameters 3.2 converter module APF APF unit converter is the energy storage capacitor and IGBT modules. The main role of the converter after the grid voltage by IGBT power module rectifier for the energy storage capacitor is charged, so that the bus voltage is maintained at a stable value, in this process the converter main work in the rectifier state, when the main circuit generates When the compensation current, the converter has to work in the inverter status. Considering the product is in power running time, so direct support capacitive thin-film capacitors, power module using the German original products, in order to ensure overall quality. Converter is selected according to the size of the compensation current vary. Naming Dimensions (Unit: mm) 3.3 Reactor module APF reactors from the filtering effect, filter out unwanted harmonics grid APF issued. Reactors can be divided into single-phase and three-phase current from 15A to 200A, and other specifications naming Dimensions (Unit: mm) Features high-quality low-loss silicon steel core; coil using copper or aluminum foil around the system; Insulation H level, longer life, higher safety factor; wide power range: single from 15A to 100A.