CN86103586A - Double tuned low energy consumption filter device and method - Google Patents

Abstract

A power high-order harmonic filtering device and method can be used to eliminate grid voltage waveform distortion caused by high-order harmonic current, and improve power supply quality and safety. Ordinary static filtering devices are single-tuned filters with step-adjustable quality factor with additional resistors, or single-tuned filters with non-adjustable quality factors without additional resistors. The device and method are characterized in that the filter is composed of a reactor with stepless and continuously adjustable quality factor and inductance, a low-inductance resistor and the like. The adjustment range is large, convenient, low energy consumption, and it is easy to realize the parallel operation of multiple filtering devices.

Description

Dual-tuning low-energy consumption filtering device and method

The present invention relates to an electric power high-order harmonic device and method.

Thyristor-powered rolling mills and steelmaking arc furnaces are among the primary sources of harmonics in power systems. The presence of high-order harmonic currents distorts the grid voltage waveform, shortening the service life of power electronics, disrupting electrical control systems, and causing high-frequency magnetic interference with communications, which can severely impact production safety. Consequently, power authorities both domestically and internationally have strict regulations on harmonic performance for their users.

Foreign filtering devices can now be divided into two categories: the first category: single-tuned filters with adjustable quality factors and additional series (or parallel) resistors; the second category: single-tuned filters with unadjustable quality factors and no additional resistors.

The disadvantages of the first type of filter are: large fundamental wave loss. For example, Wuhan Iron and Steel Project 07 uses this type of device. The loss of the 3rd and 5th order filters is too large, which makes it difficult to solve the problem of resistor heating. Multiple single-tuned filters with the same order are difficult to operate in parallel, resulting in a single power supply method, which is not conducive to economic operation; the quality factor is adjusted in steps and cannot achieve optimal adjustment.

The disadvantages of the second type of filter: it requires correct harmonic parameters and high manufacturing precision; it is more difficult to realize the parallel operation of multiple filters of the same order.

In addition, the resistors in the filtering devices imported from abroad (including the parallel resistors in the high-pass filter) use a complex mesh structure and are expensive.

Domestic filters are currently in the stage of researching and imitating the first type of filters.

The present invention features continuously adjustable inductance and quality factor of the tuning reactor in the filter device (called dual-adjustment), eliminating the need for additional series (or parallel) resistors. The low-inductance resistors in the high-pass filter are made of an iron-chromium alloy, resulting in low inductance, a power factor exceeding 0.99 for harmonics below the 19th order, and a high accuracy of less than 3%. These features provide the filter device with low losses.

The filter device's reactor consists of a short-circuit ring _D1 at the top, upper coil _L1 , lower coil _L2 , base _D2 support and adjustment nut screw, and insulating blocks. By rotating the nut on the support and adjustment screw, short-circuit ring _D1 can be moved up and down to achieve continuous adjustment of the quality factor within a range of 0-13%. Similarly, the distance between the two coil windings _L1 and _L2 can be moved up and down to achieve stepless and continuous adjustment of the inductance within a continuous adjustment range of ±5%.

The low-inductance resistor of the filtering device is characterized by low inductance, high power factor, and high resistance precision. The ends of the open box-shaped resistor are made of non-magnetic metal plates, and its base uses four insulators with a voltage resistance of more than 42KV. The operating ambient temperature is 45°C. The structural arrangement of the waveform resistor should make the current flow in a reciprocating direction on the plane to minimize electromagnetic induction. The resistor is assembled and fixed to the end plate with a screw nut insulated mica sheet and an end porcelain bottle. The vertical multi-layer structure is adopted. The distance between each layer of resistor sheets is determined according to the heat dissipation conditions and dynamic stability performance requirements. The low-inductance resistor has several taps on the upper and lower layers to facilitate resistance adjustment according to usage requirements.

The power factor of the low-inductance resistors can reach above 0.99 within the 19th harmonic, with a resistance accuracy of 3%. For 6-35 kV power supply systems, each filter branch is equipped with a switch relay protection device. The HP ₁₁ high-pass filter consists of a low-inductance resistor connected in parallel with a tuned reactor, which is then connected in series with a filter capacitor. The 3 (H ₃ ), 5 (H ₅ ), and 7 (H ₇ ) low-pass filters are constructed by connecting a capacitor in series with a tuned reactor with continuously adjustable quality factor and inductance, forming a single-tuned filter.

The applicable scope of the present invention is to suppress the high-order harmonics generated by various nonlinear loads and improve the power factor; the rated voltage is 6KV~35KV, and the rated installation capacity is below 40000KVAR.

The above characteristics give the filtering device the advantage of low loss.

The dual-tuning low-energy consumption filter device has the following advantages:

Easy to achieve optimal adjustment of quality factor;

It is easy to realize parallel operation of multiple single-tuned filters;

Because the fundamental wave loss of the dual-tuned tuned reactor is very low, and the use of this patented technology can improve the quality factor, the fundamental wave loss of the filter device is greatly reduced;

By eliminating the additional series (parallel) resistors in the single-tuned filter, the failure rate and operation and maintenance workload can be reduced, the operation reliability of the device can be improved, the floor space can be reduced, and investment can be saved.

It uses low inductance resistors with simple structure, small inductance, good heat dissipation conditions and low price.

The dual-mode, low-energy filter device is now in operation at Ma'anshan Iron and Steel Company's No. 51 Substation. It filters the high-order harmonics generated by the thyristor power supply units of three sets of main drive motors in the 850mm initial rolling mill, the 2300mm medium plate mill, and the six-stand continuous billet mill, improving the power factor. The total capacity of the thyristor-powered DC motors is 18,500 kW, and the filter unit has an installed capacity of 12,000 kVA. Four filter groups, _H3 , _H5 , _H7 , and _HP11 , were designed. Since its commissioning in October 1986, the system has performed well, achieving significant filtering results and fully meeting design requirements and relevant regulations of the power sector, resulting in significant economic benefits for Ma'anshan Iron and Steel.

The comprehensive voltage distortion coefficient of 110KV busbar is reduced from 1.59% to 1.09%;

The comprehensive voltage distortion coefficient of 10KV busbar was reduced from 7.78% to 1.69%.

The power factor improved from 0.6 to 0.99;

The electromagnetic noise of the power transformer and other electrical equipment connected to the rolling mill power supply bus is significantly reduced.

Ma Steel can obtain comprehensive economic benefits of nearly one million yuan each year, and the infrastructure investment can be recovered within one year.

Description of the drawings:

Figure 1: Reactor

D1: short-circuit ring;

Z: Support brass screw;

J: Metal Plate

L1: upper coil;

L2: lower coil;

D2: base;

Figure 2: Reactor A-A cross section

1: Copper nut 2: Copper washer

3: Insulation sleeve    4: Insulation block

Figure 3: Resistors

5: Aluminum plate bracket; 6: Resistor

7: Fastening screw; 8: Insulation support

9: Wiring splint

Figure 4: Resistor B-direction diagram

Figure 5: Resistor C-direction diagram

Figure 6: Resistor I-I plane

10: Screw rod; 11: Nut;

12: spring washer;    13: gasket;

14: Insulation sleeve; 15: Insulation cardboard;

16: insulator; 17: metal spacer;

18: resistor; 19: metal spacer;

20: mica insulation pad; 21: insulation sleeve;

Figure 7: Schematic diagram of the main electrical connections for the filter unit at Masteel's No. 51 substation

G: disconnector;    DL: circuit breaker;

C: capacitor; Rp: parallel low-inductance resistor;

L: Reactor with continuously and steplessly adjustable inductance and quality factor;

_XL : Reactor inductive reactance;

R _L : Reactor resistance;

H ₃ H ₅ H ₇ : 3rd, 5th, and 7th order single tuned filters respectively;

HP ₁₁ : High-pass filter for harmonics 11 and above

Claims (9)

1, electric power high-order harmonic filtering device is by resistor; tuning reactor; filtering capacitor and corresponding switch, protective relaying device are formed; the characteristics of this device and method are that the tuning reactor of filter is quality factor and inductance stepless continuous adjustable (dual modulated type), its adjustable range 0-13%, low inductance resistor; has low inductance; high accuracy, High Power Factor, at 19 subharmonic with the internal power factor all more than 0.99.Realize the parallel running of many table apparatus easily with this kind filter.The method of reasonable distribution harmonic current.

2, according to the tuning reactor of claim 1.Be characterized in that the top is short-circuited conducting sleeve D ₁, made by metallic conductor.Short-circuited conducting sleeve and metallic plate J welding, porose passing through in the metallic plate, the hole is fastening with standing screw Z connection insulation with nut 1, can make the position of short-circuited conducting sleeve do upper and lower adjustment by bolt and nut, realizes the adjustable of quality factor.

3, the short-circuited conducting sleeve according to authority 2 is characterized in metal ring, and it vertically is the width of aluminum metal ring, and its horizontal direction is the thickness of aluminum metal ring, and the standing screw of short-circuited conducting sleeve and reactor has the fixed connection more than four to adjust point along circumference.The cross section of short-circuited conducting sleeve metallic plate is calculated by reasonable current density and is chosen.

4, be characterized in that according to the filter reactor of claim 1 coil divides two groups up and down, adopt screw rod, nut connects, and distance that can up-down adjustment two coils is to realize the adjustable continuously of inductance.

5, according to the filter of claim 1, be characterized in that low inductance resistor is to adopt the ferrochrome material, the series connection that the waveform pellet resistance is formed, open type box-shaped resistor, power factor at 19 subharmonic with interior equal can reaching more than 0.99.

6, being characterized in that according to the low sense resistor of claim 5 base adopts four insulators, more than the withstand voltage 42KV, the environment for use temperature can reach ± and 45 ℃, resistance precision is in 3%.

7, according to the low sense resistor characteristics of claim 5 be the end fixed head with non-ferromagnetic thing metallic plate, vertically adopt sandwich construction, square between every layer of resistor disc is determined by the requirement of radiating condition and dynamic stability.Two-layer up and down resistor disc is established several taps, can regulate resistance according to the root instructions for use.

8,, be characterized in that electric power high order harmonic component 3,5,7,9,11,13,23,25, inferior difference are designed to HP by specific requirement according to the filter of claim 1 ₁₁Inferior above high pass filtering device is made of and H be in series with capacitor more in parallel with tuning reactor of low inductance resistor ₃H ₅, H ₇Connect by capacitor and quality factor and the adjustable tuning reactor of inductance Deng low pass filter and to constitute

When 9, being applied to 6～35KV system filter branch road according to the filter of claim 1, be characterized in adopting the continuously adjustable technology of quality factor inductance, can be conveniently used in two groups of above filter parallel runnings, and by the adjustable mode reasonable distribution harmonic current of quality factor.

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