Xu Shuang

Ankerui Electric Co., Ltd.     Jiading 201801

【Abstract】 This paper analyzes the causes of harmonic generation in power systems , summarizes the measures for suppressing harmonics , analyzes the application of passive filter devices and active filter devices in harmonic suppression , and analyzes and summarizes the active filter devices. Direction of development.

【Keywords】:Harmonic    Passive filter    Active filter   ANAPF


【text】:

1 Introduction

In the power system, the normal voltage and current waveforms should be sine waves with a frequency of 50Hz, but the actual waveforms always have different degrees of distortion, which is caused by harmonics. With the rapid development of electric power technology, the harm caused by harmonics has become increasingly serious. Harmonic pollution has become one of the major obstacles to the development of electric power technology.   [ 1   ] .

There are roughly three sources of harmonics in the power system : (1) From generators. The generator is difficult to make absolute symmetry in the production of three-phase windings, the core is also difficult to be absolutely uniform, and for other reasons, the generator will also generate some harmonics, but in general it is rare; (2 ) From transmission and distribution systems. Power transmission and distribution systems are mainly harmonics generated by power transformers. Because transformers contain iron cores, iron cores have magnetic saturation, cores are saturated after saturation, and transformer cores often work in sections where the magnetic flux density is high and the magnetization curve is steeper. Harmonic waves are more likely to occur. According to statistics, harmonics generated by power transformers, the 3rd harmonic current of which can reach 15% of the rated current ; (3) from a variety of electrical equipment. Mainly include some power electronic rectification equipment, frequency conversion devices, electric arc furnace, calcium carbide furnace, gas discharge type electric light source and so on. According to statistics, the harmonics generated by the rectifiers account for nearly 40% of all harmonics of the power system , which is the largest source of harmonics.

Based on the characteristics of harmonic generation, this article summarizes the measures to suppress harmonics, and analyzes the application of passive filter devices and active filter devices in harmonic suppression. The main research direction of active filters and a new idea of ​​active filter design are analyzed.

2 Harmonic control

2.1 Harmonic Control Standards

The hazards and influences of harmonics have attracted great attention from countries in the world. In order to ensure the safety, stability, and economic operation of power grids and electrical equipment, many countries, international organizations, and some large power companies have now established corresponding harmonic standards.

GB/T14549-1993 "Power Quality: Harmonics in Public Grids" [2 - 3]

GB/T15543-2008 "Power quality: three-phase voltage allow unbalance"

GB/T12325-2008 Power Quality: Allowable Variation of Supply Voltage

GB/T12326-2008 "Power Quality: Voltage Fluctuations and Flicker Changes"

GB/T18481-2001 "Power Quality: Temporary Overvoltage and Transient Overvoltage"

GB/T15945-2008 Power Quality: Allowable Frequency Deviation of Power System

GB7625.1-1998 Harmonic current limits issued by low-voltage electrical and electronic products

GB/T15576-1995 "General technical conditions for low-voltage reactive power static compensation device"

The purpose of each harmonic standard is very similar and is based on the following three purposes:

(1) The distortion of the power system current and voltage waveforms is controlled to the level that the system and its connected equipment can tolerate.

(2) Provide power to the user in a voltage waveform that meets the user's needs.

(3) Does not interfere with the normal operation of other systems ( such as communication systems ) .

2.2 Harmonic Measures

The characteristics of harmonic generation for harmonic generation are mainly in the following three forms: (1) Active governance, starting from a harmonic source, so that harmonic sources do not produce harmonics or reduce the harmonics generated by harmonic sources; ( 2) Receiver governance. That is, starting from equipment or systems that are affected by harmonics, improve their anti-harmonic interference capabilities; (3) Passive control, ie, external filter devices, prevent harmonics generated by harmonic sources from being injected into the grid, or prevent harmonics of the power system Inflow to the load.

Currently widely used is the use of passive control measures, plus filter devices. At present, the main methods are passive filters and active filters to prevent harmonics generated by harmonic sources from being injected into the grid, or to prevent harmonics of the power system from flowing into the load.

Although passive filters have the advantages of low investment, high efficiency, simple structure, and easy maintenance, they are widely used in distribution networks at this stage. However, because the filter characteristics are greatly affected by system parameters, only a few harmonics can be eliminated. Waves, but for some of the sub-harmonics will have amplification, and even resonance technology and other technical defects, with the development of power electronics technology, people gradually turn the direction of filtering research into active filters.

Compared to passive filters, active filters have the following advantages:

(1) The filter performance is not affected by the system impedance.

(2) No series or parallel resonance will occur with the system impedance. Changes in the system structure will not affect the control effect.

(3) In principle, it is more superior than PPF , and one device can be used to complete the governance of each harmonic.

(4) It can realize dynamic governance and can quickly respond to changes in frequency and size of harmonics.

(5) Since the device itself can perform output limitation, it will not be overloaded even if the harmonic content increases.

(6) It has multiple compensation functions and can compensate reactive power and negative sequence.

(7) Harmonic compensation characteristics are not affected by changes in the grid frequency.

(8) Centralized control of multiple harmonic sources.

Ankerui ANAPF series active power filter device is a new type of power electronic device for dynamic suppression of harmonics and compensation of reactive power. It can compensate harmonics and varying reactive power with varying sizes and frequencies. Applications can overcome the shortcomings of traditional harmonic suppression and reactive power compensation methods such as LC filters (traditionally can only be fixed and compensated), realize dynamic tracking compensation, and can both compensate harmonics and compensate reactive power , and are harmonic control and The best choice for reactive power compensation is to ensure the stable operation of the power grid.

3 ANAPF Series Active Power Filters

As a key technology for improving the quality of power supply, active power filters have been widely used in various production sectors of the national economy in developed industrial countries such as Japan, the United States, and Germany, and the number of harmonic compensation has gradually increased, and the capacity of stand-alone devices has increased. It is also gradually increasing, and its application area is developing from compensating the user's own harmonics to improving the power quality of the entire power system.

3.1 How ANAPF Active Power Filters Work

ANAPF series active power filter devices are connected to the power grid in parallel to detect the harmonic and reactive components of the load in real time. PWM inverter technology is used to generate one and current harmonic and reactive components from the converter. Corresponding inverse components are injected into the power system in real time to realize harmonic control and reactive power compensation. (see picture 1)

Figure 1 ANAPF active power filter device schematic

3.2 Technical parameters of ANAPF active power filter device

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

Function settings

Only harmonics are compensated, only reactive power is compensated, both harmonics are compensated and reactive power is compensated; manual and automatic switching are performed.

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 use at higher altitudes)

Incoming and outgoing ways

Down in and out

Protection level

IP21

Intelligent communication interface

RS485/MODBUS-RTU

Remote monitoring

Optional

Overall size (mm)

(W×D×H)

30A

50A

75A

100A

600×500×1500

600×500×1500

600×500×1800

800×600×2200

Weight (kg)

Three-phase four-wire

Three-phase three-wire

30A, 50A

75A, 100A

30A, 50A

75A, 100A

280

360

240

290

3.3 ANAPF active power filter device function module

u controller module APFMC-C100

Mainly by: DSP (digital signal processor), FPGA logic device, 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 voltage and current signal acquisition And processing, instruction current calculation, switch circuit generation, PWM signal output, system external communication and system protection functions. The control system is the core of the active filter, which determines the main performance and indicators of the active power filter system.

u converter module APFCOV

Its core is the storage capacitor and IGBT module. The function of the converter is mainly to rectify the voltage of the grid through the IGBT power module to charge the energy storage capacitor, so that the bus voltage is maintained at a certain stable value. In this process, the converter works mainly in the rectification state, when the main circuit generates When compensating the current, the converter operates in the inverter state again. Considering that the product is operated in the power grid for a long time, the DC supporting capacitor adopts a thin film capacitor, and the power module adopts a German original product to ensure the quality of the entire machine. The choice of converter varies according to the size of the compensation current.

u Reactor Modules APF-RE.DG, APF-RE.SDG

The APF reactor acts as a filter to filter out unwanted harmonics from the grid generated by the APF. Reactors can be divided into single-phase and three-phase, currents from 15A to 200A and other specifications.

uMan -machine interface APF-HMI

When the APF cabinet is working, the system can monitor its network-side current, APF bridge arm current, and load-side current. The user can set the APF operation mode through the HMI. For the problems that occur during the operation, corresponding event records can be generated. HMI is a smart meter designed by our company for the power monitoring needs of power systems, industrial and mining companies, public utilities, and intelligent buildings. It uses a high-brightness TFT-LCD color display interface and implements parameter settings and controls through panel keys. Measurement of all power parameters, comprehensive energy metering and assessment management, and analysis of various power quality parameters.

u matching current sampling transformer AKH-0.66-K

3.4 Technical advantages

l DSP+FPGA digital control mode with extremely fast response time;

l advanced main circuit topology and control algorithm, higher accuracy, more stable operation;

l A machine with multiple functions, it can not only make up for harmonics, but also make up for reactive power.

l Modular design, easy for production debugging;

l Convenient parallel design to facilitate capacity expansion;

l has a perfect bridge arm over-current protection;

l Easy to use, easy to operate and maintain.

3.5 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 Application of ANAPF Active Power Filter

Active power filters can be widely used in the distribution networks of industrial, commercial and institutional groups, such as: power systems, electrolytic plating companies, water treatment equipment, petrochemical companies, large shopping malls and office buildings, precision electronics companies, airports/ports Power supply system, medical care, etc. Depending on the application object, the application of ANAPF series active power filter devices will ensure the reliability of power supply, reduce interference, improve product quality, increase equipment life, and reduce equipment damage.

4.1 Main application areas and occasions

1) Airport: main control room, computer room, broadcasting system, EIB light dimming system, etc.

2) Hospitals: ICU (intensive care unit), MRI (magnetic resonance imaging), operating room, medical imaging room, radiotherapy department, etc.

3) Theaters and gymnasiums: Solve the damage of EIB dimming equipment and other control equipment caused by harmonics.

4) Schools: Precision laboratories, computer rooms, network centers, etc.

5) Research institutes: precision instruments, computer rooms, high-precision equipment, and other areas.

6) Large shopping malls: Solve the harmonic problems caused by the large number of applications of energy-saving lamps.

7) Bank: computer center, sales department computer, security system, etc.

8) Taxation, industry and commerce: large-scale computer centers, etc.

9) Telecom Room: Mobile Base Station

10) Factory: PLC, computer control equipment, high-precision machine tool, PCS system, measurement/weighing system, etc. of the production line.

11) TV stations: image equipment, dimming equipment, computers, etc.

4.2 ANAPF Active Power Filter Application Example

u project background

A company is a monocrystalline silicon manufacturing company. Monocrystalline silicon construction projects have a huge market and a broad space for development. In recent years, various crystal materials, especially the high-tech value-added materials represented by monocrystalline silicon and the development of related high-tech industries, have become the pillars of the contemporary information technology industry, and have made the information industry the most growth in the global economic development. Fast pilot industry. Its production process is divided into multiple melting and heating or direct current heating. Due to the use of semi-conductor controllable rectification methods, a very large amount of current harmonics are generated in the process of its own work , causing harmonic pollution to the power grid. These harmonics make accuracy of precision instruments inaccurate or even malfunction. Destruction of the system's reactive power compensation , resulting in increased system power supply losses and damage compensation capacitors, etc., have a great impact on the complex growth process of the single crystal silicon and the precision machining process in the later period. Therefore, the quality of the power grid indirectly determines the single The quality of crystalline silicon finished materials, almost all monocrystalline silicon manufacturing lines are faced with harmonic problems

u governance plan

Power quality conditions, Shanghai Acrel Electric Company Limited proposed a solution harmonic control, and ultimately determine the pilot transformer at # 3, using ANAPF active power filter apparatus, the automatic tracking control harmonic currents generated by the load To ensure the safe and reliable operation of the entire system .

The following is the field comparison data before and after the input of the ANAPF active filter:

1) Comparison of three-phase voltage waveform before and after, see Figure 2 and Figure 3 .

2) Comparison of the harmonic content of three-phase voltage before and after, see Figure 4 and Figure 5 .

3) Before and after comparison of three-phase current waveforms, see Figure 6 and Figure 7 .

4) Comparison of the harmonic content of three-phase current before and after, see Figure 8 and Figure 9 .

From the data before and after the active filter input from the field test, the active filter into operation, significantly lower voltage and current harmonics, voltage harmonics from the original 4.7% to 2.4%, from the current harmonics The original 18.4% dropped to 5.0%, and the effective value of harmonic current dropped from 273A to 63A. The three-phase voltage and three-phase current waveforms were significantly improved, fundamentally eliminating the influence of harmonics and ensuring the production of monocrystalline silicon. In quality, the company decided to use ANAPF active filters in its later reconstruction projects.

5 Concluding remarks

Harmonic control is one of the core contents of power quality problems, and it is also an urgent need for the development of modern power production. APF after two, three decades of development has become an important power compensation system and a harmonic reactive power means [4--5]. In practical applications, the parallel APF is a relatively mature topology and is the preferred solution; the series APF circuit needs to flow all the normal load current during operation, and the loss is relatively large, and the APF is switched off after the fault is switched on and off. This kind of protection circuit is also more complicated; the current main problem of series-parallel APF is that the control is complicated and the cost is high.

From recent research and application, it can be seen that APF has the following development trends:

(1) By using PWM modulation and multiplexing techniques to increase the equivalent switching frequency of the switching device, effective compensation for higher harmonics can be achieved;

(2) Adopt a hybrid filter system composed of APF and PF to reduce the capacity of APF , reduce costs, and increase efficiency;

(3) With the rapid development of semiconductor device manufacturing, the advantages of low-cost hybrid filtering system will gradually disappear, and because of its powerful, cost-effective parallel APF will be very promising active filter device;

(4) With the improvement of the withstand voltage level of power electronic devices and the increasing emphasis on power quality, APF will also be widely used in the high pressure field of industrial systems.

With the development of China's electric power industry, the demand for power quality will continue to increase. There is a huge market potential for the use of APF for power quality control. Especially in the aspects of compensating harmonics, reactive power, neutral current, unbalanced current and so on, active filter technology will surely have a broader application prospect.

references

[1] Wang Zhaoan , Yang Jun , Liu Jianjun . Harmonic suppression and reactive power compensation [M]. Machinery Industry Press , 1993.

[ 2 ] Power Quality Harmonics in Utility Grid GB/T14549-93 [S]. 1993.

[ 3 ] Ministry of Electric Power , Rules for Power Supply Business [S]. 1996.

[ 4 ] Yin Hongcheng , He Wei . Analysis and application of hybrid active power filter [J]. Integrated Circuit Communications ,   2007,   25(1) : 16 - 19.

[5] Huxue Zhi, skin power. Summary of APF and Their Applications [J]. ELECTRONIC TECHNOLOGY,   2005,   (1) : 39 - 42.

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About the Author:

Shao Yiqian, 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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