1 Overview With the power electronic converter device increasingly widespread, more power has been fully utilized. But widespread use of nonlinear power plant equipment generates a large number of current harmonic distortion, distortion of the current flowing in the power grid harmonic voltage leads; harmonic pollution increasingly threatens the power system security, stability, economic operation, to the same network of linear load and other users with a great impact. Harmonic has been with electromagnetic interference, lower power factor of the power system three tied for pollution. Therefore, understanding the principles of harmonic generation, supply and distribution system research to eliminate the higher harmonics improve power quality issues and ensure safe and economic operation of power systems has been very positive. Harmonics harmonic measurement is an important branch of the harmonic suppression, to solve the problem of harmonic generation plays 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 harmonic generation source in the following table: Name Trade inverter device 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 ) traffic Single (more) crystal silicon production equipment, intermediate frequency furnace manufacturing electric arc furnace, AC arc welding machine, induction heating means mechanical, energy, chemical industry 1.1 harmonic harm? so that the power element additional losses increase, easily lead to a fire. Harmonics utility grid elements 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. Harmonic will affect the normal operation of electrical equipment, the motor produces mechanical vibrations and noise, severe localized overheating of the transformer, the capacitors, cables and other equipment overheating, insulation aging, shortened life expectancy, resulting in damage. ? Cause network resonance. This could 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. ? Cause relay malfunction, electrical measurement error is too large. Harmonics can lead to protection, especially computer integrated protection device and automatic device malfunction, resulting in unnecessary power outages and lost production; harmonic measurement of electrical measuring instruments will make inaccurate, resulting in measurement error, to power management department or power users economic losses. ? Make industrial system crash. Near the harmonic source or higher harmonics communications and information processing equipment will cause interference, ranging from noise, lower communication quality, the computer does not work; while in loss of information, make industrial system crash. National Standard GB 1.2 Harmonic based / T14549-1993 "Power Quality: utility grid harmonic" GB / T15543-2008 "PQ: 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 transient over-voltage "GB / T15945-2008" power quality: power system frequency tolerance "GB7625.1-1998" harmonic current limits "GB / T15576-1995" static low voltage reactive power compensation device General technical conditions "low-voltage electrical and electronic products issued 2 APF unit 2.1 Model Description 2.2 works ANAPF series active power filter means connected to the grid in parallel, by the harmonic and reactive components of the real-time detection of the load, using PWM converter technology, which generates a harmonic component and the reactive component of the current corresponds to the anti-from converter the components and real power injection systems, in order to achieve harmonic control and reactive power compensation. Principle as follows: 2.3 The main technical features of DSP + FPGA digital control, it has a 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; facilitate parallel design, 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 generally standard cabinet structure, the installation should avoid inverted or flat, size is 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 advice and low-voltage switchgear are arranged side by side away from the wall, front operation, two-sided maintenance, on the back of the maintenance channel is not less than 800mm. 2) wall mounted: ANAPF also be arranged against the wall, front operation, maintenance front. 3) the electrical system designers should consider wiring and layout attention will ANAPF compensation in the access point as close as possible compensated, and in the upper reaches of sampling CT, or at the end of the reserved space for the design, installation, downstream of the CT sampled at not contain capacitive load. Schematic layout as follows: 4) ANAPF under all normal circumstances do not live metal casing should be strictly make the appropriate protective zero or protective earth according to the design requirements of the standard ground (TN-S, TN-CS, TT and so on). P1-side installation 2.6.2 Transformer 1) Transformer point grid, P2 end point loads. 2) Wiring transformer and ANAPF shown below: 3) Note that 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 wire cross-sectional area of ??2.7 CT sample main application and occasion 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, Radiation Oncology, and so on. Theater, stadium: Solving EIB dimming equipment and other control equipment damage due to the harmonics caused. School: Precision laboratory, computer room, network center. Institute: precision instruments, computer room, and other high-precision equipment are concentrated. Shopping malls: solving problems caused by harmonics caused by large-scale application of energy-saving lamps. Bank: computer center, business department computer security systems. Taxation, industry and commerce: 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 introduced 3.1 controller module APF APF device controller consists of: DSP (digital signal processor), FPGA logic, AD signal sampling circuit, DI / DO input and output control circuit, PWM waveform control circuit, RS485 communication circuit and other components, mainly used to complete the acquisition and processing of voltage and current signals to calculate the instruction current generates switching circuit, the output PWM signal, the system of external communications and system protection. Control system is the core of the active filter, which determines the main performance and indicators of active power filter system. Naming convention Dimensions (Unit: mm) core technology parameters 3.2 converter module active power filter APF converter is the storage capacitor and the IGBT module. The main role of the converter after the grid voltage IGBT power module by rectifying the energy storage capacitor charged and the bus voltage is maintained at a stable value, in this process, the converter main rectifier state, when the main circuit generates When the compensation current, the converter and the inverter working status. Considering the product is in a long-running power grid, so the DC link capacitor thin film capacitors, power modules using the German original products to ensure overall quality. Converter is selected according to the size of the compensation current varies. Naming convention Dimensions (Unit: mm) 3.3 Reactor module APF reactor from the filtering effect, filter unwanted harmonics grid APF issued. Reactors can be divided into single-phase and three-phase current from 15A to 200A naming rules and other specifications Dimensions (Unit: mm) Features high-quality low-loss silicon steel core; a coil wound using copper or aluminum foil; insulating use H level, longer life, higher safety factor; wide power range: single from 15A to 100A.