Techniques for improving the quality of electricity on the basis of reactive power compensation Текст научной статьи по специальности «Электротехника, электронная техника, информационные технологии»

Techniques for improving the quality of electricity on the basis of reactive power compensation

Section 12. Electrical engineering

Fedotov Alexander Ivanovitch, Kazan State Power Engineering University Professor, department «Electrical Power Systems and Networks»

E-mail: [email protected] Akhmetshin Azat Rinatovich, Kazan State Power Engineering University, Associate professor, department «Electrical Power Systems and Networks»

E-mail: [email protected] Vagapov Georgii Valerianovich, Kazan State Power Engineering University Associate professor, department «Electrical equipment of companies,

organizations and institutions» E-mail: [email protected] Chernova Natalia Vladimirovna, Kazan State Power Engineering University, Associate professor, department «Electrical Power Systems and Networks»

E-mail: [email protected]

Techniques for improving the quality of electricity on the basis of reactive power compensation

Abstract: The article examines the economic feasibility of deep reactive power compensation. Influence of deep reactive power compensation on the voltage level. The analysis of the generalized network parameter to determine the voltage at substations for single-line and main electrical distribution networks. The numerical calculations show the need for a harmonized application of reactive power compensation and selection of booster transformers.

Keywords: reactive power compensation, power quality, capacity of power lines, power factor, power distribution networks

Determination of economical way of reactive power compensation

Because compensating devices are expensive equipment, it is necessary to assess the feasibility of deep reactive power compensation, i. e. in the range of reactive power factor change from its normative value to zero [1].

For this cover line 0, 4kv with load (P) n + jQn fig. 1, on which end has PFC (capacitor installation of Ku, fig. 1).

As the center of power (CPU) used tire low voltage transformer substation. The economic effect of the additional installation of KU was calculated under the following assumptions: the cost of the devices has been adopted on the basis of the PFC data hosted on the website: http://www.elprivod.ru/; the cost of losses of the electric power-1,5 rubbles/kWh; the number of hours of use maximum load was taken under [2] to

3200 h Linear resistance lines, fig. 1, set in accordance with the cross-section, which, in turn, was coordinated with a maximum permissible current.

Fig. 1 scheme for distribution network

In fig. 2 the results of calculations payback period of nominal parameters of PFC device. As you can see from the graphs, the minimum is achieved in most cases, values of tgç=0.1.

The full compensation of reactive power, when tgç = 0, slightly increases the payback period and may be useful

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to increase the voltage to the transformer. reactive power compensation, • is the distance from the

In General, estimates indicate that the decisive substation. The edge length you can take the 200 m, in

factor in determining the cost effectiveness of deep which case the rate of return does not exceed 6.5 years.

Fig. 2 based on the payback period from the depths of the PFC

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Techniques for improving the quality of electricity on the basis of reactive power compensation

Raising the voltage level on the basis of the total reactive power compensation

Consider the technical effect of reactive power compensation in full, namely to increase the voltage to the transformer. Determine how dependent voltage level substation, depending on the settings in the power supply, Fig. 3, and from the voltage values prior to the installation of PFC.

The voltage on the transformer substation (TS) with low sides to PFC devices shall be calculated by the formula:

U ' = U - P • Г£ + QH • *£ = U - P • (ft + tg^" • *£ ) (l)

u 0,4 U ЦП и, U ЦП и, ) (1)

U 0,4 U 0,4

Where U ЦП — voltage to the CPU; Рн и QH - active and reactive power of the load, rE, xE — Summary of active and reactive resistance up to 0.4 kV, including tire resistance line and transformer; the voltage at the low side tires of TP; tg^H - reactive power factor loads.

If the TP makes full compensation of reactive power, the reactive component of the load from the formula (l) is deleted and then the bus bar voltage low side TP U "0>4 (converted to high side) shall be calculated by the formula: u" = u -P -r U"

Connect the voltage at TP before and after total power factor correction:

U "0,4 = U цп

Рн U ЦП •U 'о,4 - (U м)2 - Рн • tgФн • X Е

U"0,4 Рн

Next, set the desired voltage level U "0>4 - is larger than the voltage U '0 4, i.e

U "0,4 = ku U 'BA,

where кц - coefficient characterizing the percentage voltage after PFC. Then define the conditions under which it can be achieved depending on factors such as tire with low voltage side of the transformer, the load factor, active power reactive power load and the total reactance of up to 0.4 kV bus, including resistance line and transformer. Denote:

Uß = Рн ■ Чфн ■ XS

And call it Uв generalized network parameter, which is a square 2.

We Get:

К U ;4 = U ЦП - (U ЦП-U 'J/ku+U UU 'J

Then

U ß = (ku2 -1)-(U 'J2-U ЦП -U ' 0Jku~ 1).

The results of the calculations are presented in fig. 4. On the basis of nomogram, fig.. 9, you can determine the level of the substation voltage reactive power compensation after total of generalized network parameters for any of the baseline. So, for example, if the source voltage

0.4 kV TSS side equal to 0.95 p. u. and U в =0,5 кВ2, then the voltage will increase after the full compensation of reactive power at 1%; If the same and U в =3,0 кВ2, the voltage will increase by 3%, fig. 9. The result is predictable: the longer the transmission line or the higher initial value load power PH or its tg^H, the greater the effect of the reactive power compensation.

а — Uun - 10, кВ

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Section 12. Electrical engineering

б - U

ЦП

10,5 кВ

в — U ЦП — 11 кВ

Fig. 4. The dependence of voltage U'0>4 on the value Uß.

Using common network settings is useful not only for the individual but also for main power fig. 5.

Fig. 5. The concept of RES 10 kV

To determine the voltage before and after PFC using the program to model the Simulink Model REFS provided in Fig. 6.

The model consists of a CPU, power transmission lines, load. The CPU is a three-phase AC voltage source frequency 50 Hz. transmission lines represented by

three phase series-connected active and reactive resistance. The load is represented by three phase parallel connected active and reactive load. The complete PFC is by eliminating the reactive load of unit loads. Simulation results are presented in fig. 7, schedule b.

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Techniques for improving the quality of electricity on the basis of reactive power compensation

In order to use the dependencies, and fig. 4 obtained u2 = P ■ tgф ■ х -I; i = 1,...,4;

for single lines, you should determine the value of the U 2 p = p + p + + p

^ нг ,...,4 ± i ± i +1 I4*

for each LAP, and fig. 5:

To determine the voltage level in the main RECS offered the following:

№ 1 TP voltage at full PFC is determined by the formula:

U 'H1 = UH1 ■ ku, ,

Where km coefficient characterizing the

percentage voltage after PFC to zero for no. 1 and the

formula for on the fig. 5. Voltage value for future TP is defined in the same manner and should take into account the factor that characterizes the required percentage of total voltage PFC the previous TP.

The results of calculations for the model fig. 7, where l1=2l =3l = l4= 10 km are shown in Fig. 7.

Fig. 7. The voltage levels on the TP RECS

a-voltage to PFC; b-tension after PFC based on calculations using the model fig. 6, g — voltage devices using WSP

From Fig. 7 it is seen that the values obtained for the voltage level using the proposed method and the results of simulation in the software product Simulink apart within 1% calculations show that for the longest electricity transmission, Fig. 5, where to install the WTD significant influence on their quantitative structure provides the level of PFC.

The technique of determining the voltage level on the sub-stations at full reactive power compensation on generalized network parameters and shows the need for a coordinated selection levels and the number and

parameters VDT. Calculations show the efficiency of the energy savings due to deep 0,1 tgç, that is, providing a reduction in the payback period of the installation of compensation of reactive power, in comparison with normative values tgç.

The developed method allows you to select options VDT longitudinal control voltage of 0.4-10 kV networks, taking into account the effect of the regulatory burden. Must take into account the nature and magnitude of the change in the load on the voltage level to select the type of guy and VDT TVMG TVK and to provide

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consumers with the desired voltage. № 2014/448 to perform public works in the field of

This article was prepared during the execution of scientific activities of the base part of the state task of

R & D “Methods to improve power supply reliability the Russian Ministry.

and power quality in distribution networks”, the job

References

1. Akhmetshin A. R. activities to increase the bandwidth of the transmission lines in distributive networks 10 kV/A. Fedotov, A. R. Akhmetshin//Izvestiya vuzov. Energy issues.-No. 5-6, 2011.-s. 79-85.

2. Handbook for designing of electrical networks ed. D. l. Fajbisovica.-3 ed., revised and additional charge.-m.: ENAS, 2009.-392 s.

3. GOST r 54149-2010 “electrical energy. Electromagnetic compatibility of technical equipment. Quality of electric energy supply systems General URL: http://protect.gost.ru/nom.aspx?mode=doc&id=132893&nomentype= 1&baseC=28&page=0&code=01. (Date of circulation: 21.09.13).

4. Akhmetshin A. R. activities to increase the bandwidth of the transmission lines in distributive networks 10 kV/A. Fedotov, A. R. Akhmetshin//Izvestiya vuzov. Energy issues.-No. 5-6, 2011.-s. 79-85.

5. Site of the company “ECL-electro”. URL: http://www.ske-electro.ru

6. Danilov i. e., Lototsky K. V. electric machines m. Kolos. 527 s. 1972.

Dubrovin Viktor Stepanovych, N. P. Ogaryov Mordovia State University, candidate of engineering sciences, associate professor of communication networks and relay systems department

E-mail: [email protected] Zyuzin Alexey Mikhailovich, Private educational institution of additional professional education «Saransk House of Science and Technology of the Russian Union of scientific and engineering associations» Director

E-mail: [email protected]

The use of controlled filter to reduce non-linear distortion in the quadrature generators of harmonic signals

Abstract: The article deals with the construction of the controlled oscillator of harmonic quadrature signals. Calculated ratios were tested on the PSIM-9 mathematical model. The generator has a high performance in dynamic modes. The harmonic content of the generated oscillations does not exceed 0,011%.

Keywords: block diagram, transfer function, quadrature signals, frequency characteristics.

Дубровин Виктор Степанович, Мордовский государственный университет им. Н. П. Огарёва, кандидат технических наук, доцент кафедры инфокоммуникационных технологий и систем связи

E-mail: [email protected] Зюзин Алексей Михайлович,

Частное образовательное учреждение дополнительного профессионального образования «Саранский Дом науки и техники Российского Союза научных и инженерных

общественных объединений» Директор E-mail: [email protected]

Применение управляемого фильтра для уменьшения нелинейных искажений в генераторах квадратурных гармонических сигналов

Аннотация: В статье рассматриваются вопросы построения управляемого генератора гармонических квадратурных сигналов. Расчетные соотношения проверены на математической модели в программе PSIM-9.

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