Standardized on-board active filter
This article describes the harm of harmonics and the governance of Yang Junjun. Pot Filler,Kitchen Faucet Pot Filler,Wall Mounted Folding Faucet,Wall Mounted Kitchen Faucet kaiping aida sanitary ware technology co.,ltd , https://www.aidafaucet.com
Ankerui Electric Co., Ltd.
1 Introduction
In recent years, power electronics technology has been continuously innovated and developed. Power electronics technology has been widely used in people's life, study, and work. Commonly used charging devices, computers, and UPS are all products of power electronics technology development. The invention and use of these devices have brought great convenience to the society, but with the large number of applications of these devices, the power quality problem is also very prominent. As the primary factor that currently harms power quality, harmonics have been highly valued by both power supply and supply. There are already many power quality solutions in the society, and a large-scale industry has formed, and Acrylic Electric is the leader.
2 Harmonic generation and treatment
What is harmonic? Harmonic is the electric quantity contained in the current which is an integral multiple of the fundamental wave. We often say the Nth harmonic, their frequency is N times the fundamental wave; in a broad sense, any power frequency Components with different frequencies can be called harmonics, which is why there are sometimes "interharmonics" (not integer multiples of power frequency).
2.1 Generation of harmonics
In a line containing only linear elements (resistors, etc.), the current flowing is proportional to the applied voltage, and the current waveform is a sine wave. The root cause of harmonic generation is the distortion of the waveform caused by the non-linear characteristics of certain devices and loads in the power system, that is, the applied voltage is not proportional to the generated current. When the power system supplies power to equipment containing nonlinear components, these devices not only transform and absorb the power of the system, but also convert some of the fundamental waves into harmonics, which are sent back into the system and pollute the power grid. The lighting and lighting that often occur in life, the brightness of the TV screen, etc. are all related to harmonics.
2.2 Harmonic hazards
In the transmission and distribution network, harmonics will reduce the capacity of the transformer and reduce the current carrying capacity of the cable. In severe cases, it will cause sudden power interruption and cause major social and economic losses. In the production enterprise, harmonics will interfere with the communication signal, and Causes component malfunction, reduces equipment stability, increases the defective product rate, accelerates equipment aging and shortens service life, and may damage equipment or even cause fire in severe cases.
2.3 Equipment for generating harmonics
The devices that generate harmonics are generally non-linear devices and are mainly classified into the following categories:
1. Core equipment with ferromagnetic saturation characteristics, such as transformers, reactors, etc.;
2. Equipment with a strong nonlinear characteristic of the arc as a working medium, such as a gas discharge lamp, an AC arc welder, a steelmaking electric arc furnace, etc.;
3. Equipment based on power electronic components, such as switching power supplies, converters, voltage regulators, etc.
Some common harmonic-generating loads and their harmonics can be found in Table 1.
Table 1 Harmonic content of common harmonic loads
Load type
Typical harmonic content (%)
Load type
Typical harmonic content (%)
Frequency converter
33~50
Medium frequency induction heating power supply
30~35
elevator
15~30
Six-pulse rectifier
28~38
LED light
15~20
Twelve-pulse rectifier
10~12
Energy saving lamp
15~30
Electric welder
25~58
Electronic ballast
15~18
Inverter air conditioner
6 to 34
Switching power supply
20~30
ups
10~25
2.4 Harmonic Treatment Scheme
At present, there are three main measures for harmonic control: receiving end-of-pipe treatment, that is, starting from equipment or systems affected by harmonics, improving their anti-harmonic interference capability; active management, that is, starting from the harmonic source itself, making harmonics The source does not generate or reduce harmonics; passive management, that is, an external filtering device prevents harmonics from being injected into the grid. Passive governance is currently the most widely used harmonic management solution.
There are two kinds of additional filtering devices, namely passive filtering device and active filtering device, which have their own advantages and disadvantages. The passive filter device has a simple structure, convenient installation and small initial investment, but can only filter a fixed number of harmonics and easily resonate with the power grid; the active filter device has a complicated structure and a high cost, but the compensation effect is good, and the maintenance is convenient in the later stage. , low maintenance costs. Therefore, the installation of active filter devices is currently widely used harmonic control methods.
3 On-board active filter device product introduction
The ANAPF on-board active filter device is a new type of power compensation device developed by our company. It adopts modern power electronics technology and is based on high-speed digital control technology. It consists of two main parts: the command current operation circuit and the compensation current generation circuit. Compared with the traditional passive filter (equivalent to providing a very low impedance path close to zero for the harmonic current to avoid the harmonic current injection system), the active filter device realizes the harmonics through the IGBT inverter module. Dynamic filtering.
3.1 ANAPF on-board active filter device works
The ANAPF on-board active filter device can detect the load current in real time through an external current transformer, and extract and calculate the harmonic component of the load current through internal DSP calculation, and then send it to the internal IGBT through the PWM signal to control the inverter. A harmonic current of equal magnitude to the load harmonic current is generated, and the harmonic current of the opposite direction is injected into the power grid to cancel the corresponding harmonic current for filtering purposes. The working principle diagram and compensation diagram are shown in Figure 1. .png)
.png)
Figure 1 ANAPF working principle and corresponding waveform
3.2 ANAPF on-board active filter device structure introduction and advantage analysis
ANAPF on-board active filter device is smaller, lighter, easier to install and more beautiful than the company's previous vertical cabinet products, which has higher requirements on the structure and internal integration of the product. . The ANAPF active filter device produced by our company is divided into two installation modes. The main parameters are as follows: The appearance of the wall-mounted onboard module is shown in Figure 2: .png)
Dimensions 485 × 275 × 610 (width * depth * height)
Rated current: 50A (can be increased as needed)
Rated voltage: AC380V
Wiring method: three-phase three-wire or three-phase four-wire
Entry method: up and down
Rated frequency: 50Hz
Module housing color: RAL7035
Protection level: IP20
Quality: 50KG
Figure 2 Wall-mounted onboard appearance
The appearance of the drawer type onboard module is shown in Figure 3: .png)
Dimensions 485 × 610 × 275 (width * depth * height)
Rated current: 50A (can be increased as needed)
Rated voltage: AC380V
Wiring method: three-phase three-wire or three-phase four-wire
Incoming mode: after entering and exiting
Rated frequency: 50Hz
Module housing color: RAL9004
Protection level: IP20
Quality: 50KG
Figure 3 drawer onboard appearance
The wall-hanging structure is suitable for occasions with small load capacity or compact site. It is generally recommended to be used in a single independent operation; the drawer type structure is often installed in parallel with multiple modules in the drawer cabinet, which can be compensated according to actual capacity requirements. Increase or decrease the number of modules in the cabinet, suitable for large load capacity occasions. At present, our company's conventional products have a maximum of six module combinations, and are researching and developing more modules and larger capacity. The drawer cabinet installation effect diagram is shown in Figure 4.
This method has the following advantages over the traditional full cabinet:
(1) Each module has a capacity of 50A (can float within the appropriate range), and there are more capacity options under the same cabinet layout, and the number of modules can be increased to more than 6 according to the actual needs of customers (the cabinet size needs to be widened) , the effect can refer to Figure 5);
(2) The capacity of the APF device can be increased or decreased according to the change of load usage (adding or subtracting the number of modules, and setting the corresponding parameters for the man-machine interface);
(3) Each module is separately installed with a heat dissipation unit, and a cooling fan can be installed on the cabinet, the heat dissipation effect is good, and the failure rate is low;
(4) Although there are communication connections between multiple modules, the failure of each station does not affect the other modules to continue working (the compensation capacity will be reduced accordingly);
(5) It is convenient to maintain in the later stage, and the faulty module can be repaired and replaced separately; the ANAPF active filter device can work continuously during maintenance.
(6) The structure is exquisite and flexible in design. It can be purchased separately as a component (module) and embedded in a third-party cabinet; the appearance and size of the cabinet type basically do not affect the internal installation and overall use effect.
(7) The production cycle is short, and even unconventional products can be guaranteed to be put into use in time to ensure the economic benefits of customers. .png)
.png)
Figure 4 Schematic diagram of modular modular installation Figure 5 Schematic diagram of assembly effect of two columns of modules
3.3 ANAPF on-board active filter device compensation effect
The following is a product application effect diagram of a load, the harmonic content is about 26%, the analysis of the power quality analyzer PW3198 can help us to see the compensation effect very intuitively. .png)
.png)
Harmonic distortion rate of the grid side before compensation. Harmonic distortion rate of the grid side before compensation
After compensation, the harmonic current content is only 4%, which is lower than the national standard requirement of 0.38KV grid. For example, the C phase is taken as an example. The corresponding harmonic content list is as follows: .png)
.png)
The content of each harmonic of phase C before compensation, the harmonic content of phase C after compensation
From the waveform, the effect can be seen more intuitively: the current waveform before compensation is M-shaped, and has become a sine wave after compensation, and the effect is good. .png)
.png)
Voltage and current waveform before compensation Compensation voltage and current waveform before compensation
3.4 Model selection of ANAPF on-board active filter
This product is a shunt active power filter, named as: .png)
The magnitude of the harmonic compensation current can be arranged by a professional pre-sales engineer to assist in the measurement or by self-estimation according to the transformer capacity and industry type. The calculation method is shown in formula (1). .png)
.......................................... Formula 1)
among them .png)
For the transformer load factor, that is, the ratio of the load to the rated capacity of the transformer, usually takes 0.6~0.8; .png)
For the current total harmonic distortion rate, the industry is slightly different, the specific values ​​are shown in Table 1 above; .png)
Is the rated capacity of the transformer, in KVA; .png)
For low voltage system voltage, generally take 0.38~0.4.
4 Conclusion
ANAPF on-board active filter device further reduces the size and weight on the basis of the original vertical cabinet, drawer and wall-mounted products. Due to its high integrated module design, post-maintenance becomes easier, more convenient and more effective. Also more significant. It can not only control harmonics, but also compensate for reactive power: effectively control harmonics, improve power quality, greatly reduce equipment failure rate, thereby improving electrical equipment utilization rate and product qualification rate, ensuring safe operation of power grids. It can reduce the user's power loss; and effectively compensate the reactive power, so that the power factor is as high as 0.98 or more, which avoids the user being fined due to insufficient power factor, and also brings considerable economic benefits to the user. It can be seen that the selection of ANAPF on-board products has great benefits for power grid facilities and user equipment. It can be said that the two parties have achieved a win-win situation.
[References]
Ankerui Power Quality Monitoring and Governance Selection Manual. 2015.08 Edition Ankerui Electric Co., Ltd. Product Manual. 2013.01. Edition Author: Yang Junjun, female, undergraduate. Position: Now working at Ankelui Electric Co., Ltd. Tel, mobile, QQ
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