RU2502177C1 - Method for matching symmetrical four-wire power transmission line to electrical load - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: matching of a symmetrical four-wire power transmission line to electrical load is achieved as a result of fulfilment of certain conditions consisting in comparison of actual and reference load resistances, voltages at the end of the line or currents supplied to load. Input data on voltages and current in the line can be obtained through interface units, or sensors made in the form of voltage and current transformers or in the form of voltage dividers and alternating current shunts, and spectrum analysers. As a result of input data processing in a processor, there formed are control signals for correcting elements, which can include undervoltage relays of power transformers, filters of higher harmonic components of currents and voltages of different modification or a symmetrical three-phase device generating current and voltage at basic frequency.

EFFECT: providing conditions for matching of four-wire high-voltage power transmission line with electrical load.

3 dwg

Description

The invention relates to electrical engineering and can be used in the design, installation, commissioning and operation of four-wire power lines (power lines) when transmitting electrical energy to the consumer.

The transmission of electric energy through extended power lines, as well as electric energy of increased frequency through relatively non-extended power lines is ensured by: single- and two-wire power lines with one pair of electromagnetic field waves (incident and reflected); in three-wire - in three pairs; four-wire - four, etc. [one]. As a result of matching the power lines with the electric load, the throughput of the power lines increases due to the exclusion of the reflected wave. In addition, the degree of distortion of the voltage and current curves decreases, the reliability of the operation of electrical equipment increases, the operation of relay protection, automation and communication is normalized, and the environmental situation in the area of operation of power lines is improved.

The condition of the coordinated mode of operation of a single-wire power transmission line [2] is known, on the basis of which the device [patent RU 2390924] operates, where a coordinated mode of operation of a single-wire extended power line is implemented. However, a four-wire power transmission line cannot be matched only by the condition of a coordinated mode [2] due to the specificity of the propagation of voltages and currents along four-wire power lines [3].

Known methods for matching communication lines with the load [4, patent RU 2381627]. However, the technical elements used here, such as a differential amplifier, are not designed to operate at high voltage, for example 1 kV, which means that the specifics of the implementation of the methods [4, patent RU 2381627] are quite peculiar and not applicable in long-distance high voltage power lines.

The objective of the invention is the formation of a method for matching a four-wire power transmission line with an electrical load.

The technical result consists in providing the conditions for matching a four-wire high-voltage power line with an electric load, the implementation of which will entail a reduction in electric energy losses, an increase in the transmission capacity of the line, and a decrease in the degree of distortion of voltage and current curves.

The technical result is achieved by the fact that the method of matching a symmetrical four-wire power line, which is part of a symmetrical electric power system with an electric load, consists in the fact that the initial information about the voltages and currents in the line through the interface devices enters the processor, according to the invention, the matching conditions are checked in the processor a four-wire power line with an electrical load for each line wire as a result of comparing the actual and this values of the load resistances, voltages at the end of the line or currents supplied to the load, and control signals are generated for the corrective organs, which can be used on-load tap-changers of power transformers, filters of higher harmonic components of currents and voltages of various modifications or a symmetric three-phase device generating current and voltage at the fundamental frequency.

The conditions for the implementation of a homogeneous symmetrical section for linear wires are conditionally A, B and C [1]:

where R _0An , R _0Bn , R _0Cn - linear resistance, respectively, of the linear wires A, B, C at the frequency of the nth harmonic component, Ohm / km; L _0An , L _0Bn , L _0Cn - linear inductances, respectively, of linear wires A, B, C at the frequency of the nth harmonic component, GN / km; C _0An , C _0Bn , C _0Cn - linear capacitance, respectively, of linear wires A, B, C at the frequency of the nth harmonic component, f / km; G _0ABn , G _0BCn , G _0CAn - linear active conductivity between the linear wires, respectively, A and B, B and C, C and A at the frequency of the nth harmonic component, S / km; M _0ABn , M _0BCn , M _0CAn - linear mutual inductances between the linear wires, respectively, A and B, B and C, C and A at the frequency of the nth harmonic component, GN / km; C _0ABn , C _0BCn , C _0CAn - linear capacitance between the linear wires, respectively, A and B, B and C, C and A at the frequency of the nth harmonic component, f / km; G _0A0n , G _0B0n , G _0C0n - linear conductivities, respectively, between a linear wire A and the earth’s surface, B and the earth’s surface, C and the earth’s surface at the frequency of the nth harmonic component, S / km; C _0A0n , C _0B0n , C _0C0n are linear capacities between the linear wire A and the earth’s surface, B and the earth’s surface, C and the earth’s surface at the frequency of the nth harmonic component, f / km.

The invention is illustrated by the diagrams: on (Fig. 1) shows an algorithm for ensuring and maintaining coordination of a four-wire uninsulated power transmission line with an electrical load, on (Fig. 2) a diagram of the algorithm of the processor, on (Fig. 3) the execution of logical operations in block A.

The conditions for matching a symmetrical four-wire power line with an electrical load [5-7]:

;

;

;

;

;

;

;

;

,

;

;

,

,

,

- комплексные значения действующих величин фазных напряжений в начале ЛЭП, В; γ_1n - постоянная распространения одной из пар волн электромагнитного поля по проводам ЛЭП; l - протяженность рассматриваемой четырехпроводной ЛЭП, км; İ_1An, İ_1Bn, İ_1Cn - комплексные значения действующих величин линейных токов в начале ЛЭП, А; İ2_Н.А, İ2_Н.В, İ2_Н.С - комплексные значения действующих величин линейных токов в конце ЛЭП, A;

,

,

- комплексные значения действующих величин фазных напряжений в конце ЛЭП, В.Where

,

,

- complex values of the current values of phase voltages at the beginning of power lines, V; γ _1n is the propagation constant of one of the pairs of waves of the electromagnetic field along the wires of the power lines; l is the length of the four-wire transmission line under consideration, km; İ _1An , İ _1Bn , İ _1Cn - complex values of the effective values of linear currents at the beginning of power lines, A; İ2 _NA, İ2 _N.V., İ2 _NS - integrated value of current quantities linear currents in the power transmission line end, A;

,

,

- complex values of the current values of phase voltages at the end of power lines, V.

The figures show:

1 - corrective body (KO1), such as on-load tap-changer of the transformer;

2 - a transformer (T1) supplying power lines with a voltage of 35 kV or less;

, каковыми являются датчики напряжения и тока, спектроанализаторы, установленные вначале ЛЭП напряжением 35 кВ или меньше;3 - interface devices

what are voltage and current sensors, spectrum analyzers installed at the beginning of power lines with voltage of 35 kV or less;

4 - analog-to-digital Converter (ADC);

5 - processor (P);

6 - digital-to-analog converter (DAC);

7 - showing or recording device (RO);

8 - power lines with voltage of 35 kV or less (power lines of 35 kV OR LESS);

9 - step-down transformer, voltage 10 kV / 0.4 kV (T2);

, каковыми являются датчики напряжения и тока, спектроанализаторы, установленные в конце ЛЭП напряжением 35 кВ или меньше;10 - interface devices

what are voltage and current sensors, spectrum analyzers installed at the end of power lines with a voltage of 35 kV or less;

11 (T3), 26 (T4), 25 (T5) - step-down transformers, voltage 220 V / 12 V;

12 - corrective body, such as on-load tap-changer of a step-down transformer with a voltage of 10 kV / 0.4 kV (KO2);

13 (VD1), 28 (VD2), 27 (VD3) - converter blocks, phase A;

14 - filter block of higher harmonic components of currents and voltages (Ф);

15 - generalized electrical load ( Z _LOAD );

16 - corrective body (KO3), such as a symmetric three-phase device that generates current and voltage at the frequency of the fundamental harmonic;

;17 - generalized load resistance

;

18 - generalized load resistance, taking into account the implementation of the coordination of power lines with a voltage of 35 kV or less than 8 (power lines of 35 kV OR LESS),

;19 - amplitude values of the load voltage

;

20 - amplitude values of the load current (İ2 _.A );

21 is a specialized program for predicting the magnitude of the main characteristics of electric energy in a three-wire power transmission line (LEP3 v.1.00);

22 - the current values, what should be characterized by the electric energy transmitted by the transmission line compatible with the electrical load (İ2 _NA);

;23 - voltage values, which should be characterized by electric energy transmitted through power lines, consistent with the electrical load

;

24 - logical block (A).

The essence of the proposed development is to implement, using technical means, the conditions for matching a four-wire high-voltage power line with an electric load [5-7], to form an algorithm to ensure and maintain a consistent operating mode for an extended four-wire power line.

Let it be necessary to match phase A with the electrical load. For phases B and C, the matching algorithm with the electrical load will be similar.

, а в иных случаях - 17

. В данном случае полное сопротивление 18

является эталонной величиной, к которой должно стремиться значение 17

в процессе исполнения предлагаемого алгоритма.Figure (1) shows an algorithm for ensuring and maintaining matching of a four-wire power transmission line with an electrical load. Here, a power transmission line of 35 kV or less than 8 (a power line of 35 kV OR LESS) was used as an object of approval. In addition, the use of the following electrical equipment was implemented: a transformer 2 (T1) transformer with a balancing device [8], supplying power lines with a voltage of 35 kV or less than 8 (power lines of 35 kV OR LESS); a transformer with a balancing device 9 (T2) and a transformer 11 (T3), 26 (T4), 25 (T5) - these are two different groups of step-down transformers having different nominal characteristics; converter units 13 (VD1), 28 (VD2), 27 (VD3) - current and voltage converters for computers, phase A, representing in this case a generalized electrical load 15 ( Z _HEAT ). Blocks 9 (T2), 11 (T3), 26 (T4), 25 (T5), 13 (VD1), 28 (VD2), 27 (VD3) and 15 ( Z _HEAT ) form a common block whose total resistance at achievement of the agreed mode of operation of power lines 8 (power lines 35 kV OR LESS) is determined by the value 18

, and in other cases - 17

. In this case, the impedance is 18

is the reference value that value 17 should aim for

in the process of executing the proposed algorithm.

или 18

. Эти сведения в процессор поступают от устройств сопряжения, каковыми являются датчики тока и напряжения 3

и 10

, где анализируемые характеристики электрической энергии доводятся до величин, воспринимаемых компьютерной техникой. Датчики 3

устанавливаются и используются для сбора сведений о напряжениях и токах в начале исследуемой протяженной четырехпроводной ЛЭП 8 (ЛЭП 35 кВ ИЛИ МЕНЬШЕ), а датчики 10

- в конце этой линии электропередачи 8 (ЛЭП 35 кВ ИЛИ МЕНЬШЕ). В качестве датчиков 3

и 10

могут быть использованы трансформаторы напряжения и тока, спектроанализаторы, а также делители напряжения и шунты переменного тока.The main unit of the algorithm for matching a four-wire power line 8 (power line 35 kV OR LESS) with an electrical load is processor 5 (P) (Fig. 1), where the analysis of information about the state of the generalized load resistance 17

or 18

. This information is supplied to the processor from the interface devices, which are current and voltage sensors 3

and 10

where the analyzed characteristics of electrical energy are brought to the values perceived by computer technology. Sensors 3

are installed and used to collect information about voltages and currents at the beginning of the studied extended four-wire power lines 8 (power lines 35 kV OR LESS), and sensors 10

- at the end of this power line is 8 (35 kV transmission line OR LESS). As sensors 3

and 10

voltage and current transformers, spectrum analyzers, as well as voltage dividers and AC shunts can be used.

и 10

аналоговые сигналы преобразовать в дискретные. Цифроаналоговый преобразователь 6 (ЦАП) позволяет сформированные в виде дискретных сигналов в процессоре 5 (П) команды корректирующим органам 1 (KO1), 12 (KO2), 14 (Ф) и 16 (КО3) преобразовать в аналоговые. В данном случае в качестве корректирующих органов 1 (KO1) и 12 (KO2) использованы устройства РПН силовых трансформаторов, в качестве блока корректирующего органа 14 (Ф) выступают различной модификации фильтрующие устройства высших гармонических составляющих токов и напряжений, а в качестве корректирующего органа 16 (КО3) - симметричное трехфазное устройство, генерирующее ток и напряжение на частоте основной гармоники, позволяющее изменять величину полного сопротивления обобщенной нагрузки 17

путем воздействия на технологический процесс. На (рис.1) это сопротивление обозначено символом 15 (Z _НАГР.). Результаты действия описываемого алгоритма выводятся на показывающий или самопишущий прибор 7 (РО).Analog-to-digital converter 4 (ADC) (Fig. 1) allows formed in sensors 3

and 10

convert analog signals to discrete. The digital-to-analog converter 6 (DAC) allows the corrective bodies 1 (KO1), 12 (KO2), 14 (Ф) and 16 (KO3) generated in the form of discrete signals in the processor 5 (P) to convert to analog. In this case, on-load tap-changers of power transformers were used as corrective bodies 1 (KO1) and 12 (KO2), filtering devices of higher harmonic components of currents and voltages of various modifications act as a block of corrective body 14 (Ф), and 16 ( KO3) - a symmetric three-phase device that generates current and voltage at the frequency of the fundamental harmonic, allowing you to change the value of the impedance of the generalized load 17

by influencing the process. In (Fig. 1) this resistance is indicated by the symbol 15 ( Z _HEAT. ). The results of the described algorithm are displayed on a indicating or recording device 7 (PO).

нагрузки, затем определяется величина 17

. Определенные таким образом величины 20 (İ2_.А), 19

, 17

подаются в следующий блок 24 (А).The algorithm diagram of the processor 5 (P) is presented in (Fig. 2). It is quite simple: from 4 (ADC) to the processor 5 (P), the amplitude values of current 20 (İ2 _.A ) and voltage 19

load, then a value of 17 is determined

. The quantities thus determined are 20 (İ2 _.A ), 19

, 17

served in the next block 24 (A).

формируются величины токов и напряжений в конце линии, какими должна характеризоваться электрическая энергия, передаваемая по ЛЭП 8 (ЛЭП 35 кВ ИЛИ МЕНЬШЕ), согласованной с электрической нагрузкой. Эти токи и напряжения определяются следующим образом [5-7]:Block 21 (LEP3 v.1.00) in (Fig. 2) illustrates the use in the proposed method of matching a four-wire power transmission line with an electric load of a specialized program for predicting the magnitude of the main characteristics of electric energy in a four-wire power transmission line [9], which is part of a symmetrical electric power system . Using the program, the effective values of the complex values of currents and voltages, the propagation constants of the waves of the electromagnetic field along the wires of the power transmission line, and the values of the intrinsic and mutual wave resistances are determined. In blocks 22 (İ2 _NA) and 23

values of currents and voltages are formed at the end of the line, which should characterize the electric energy transmitted through power lines 8 (power lines 35 kV OR LESS), consistent with the electrical load. These currents and voltages are determined as follows [5-7]:

;

;

;

;

;

;

;

;

,

;

;

,

,

,

- комплексные значения действующих величин фазных напряжений в начале ЛЭП, В; γ_1n - постоянная распространения одной из пар волн электромагнитного поля по проводам ЛЭП; l - протяженность рассматриваемой четырехпроводной ЛЭП, км; İ_1An, İ_1Bn, İ_1Cn -комплексные значения действующих величин линейных токов в начале ЛЭП, А.Where

,

,

- complex values of the current values of phase voltages at the beginning of power lines, V; γ _1n is the propagation constant of one of the pairs of waves of the electromagnetic field along the wires of the power lines; l is the length of the four-wire transmission line under consideration, km; İ _1An , İ _1Bn , İ _{1Cn -complex} values of the effective values of linear currents at the beginning of power lines, A.

The above conditions for matching a symmetric four-wire power line 8 (35 kV power transmission line OR LESS) with an electric load imply equalities (special case, l = 100 km):

;

;

,

,

and

;

;

.

.

The fulfilled conditions for the realization of a homogeneous symmetrical section for linear wires are conditionally A, B and C [1], given earlier in conjunction with the above conditions, with which we can state the fact that the values of phase and linear voltages and currents are equal, but differ from each other by a third of the period, that is, at an angle of 120º, will ensure the equality of the distribution coefficients. This confirms the fact of ensuring the transmission of electric energy through power line 8 (power lines 35 kV OR LESS), which is part of a symmetrical electric power system, with one pair of waves of an electromagnetic field.

, какое оно должно быть при согласовании четырехпроводной ЛЭП 8 (ЛЭП 35 кВ ИЛИ МЕНЬШЕ), входящей в состав симметричной электроэнергетической системы с этой нагрузкой. Полученные результаты отправляются в блок 24 (А).Next, the load impedance 18 is determined

what it should be when matching a four-wire power line 8 (power line 35 kV OR LESS), which is part of a symmetrical power system with this load. The results are sent to block 24 (A).

, 23

с сопротивлением нагрузки 17

и напряжением в конце линии 19

. Здесь же из сопоставления этих величин определяются ошибки по сопротивлению ∆Z1, ∆Z2, ∆Z3 и по напряжению ∆U1, ∆U2, ∆U3. Затем определяются ошибки по току ∆I01 - 05, ∆I07, ∆I08. При нулевых значениях ошибок по напряжению, ошибки по току ∆I06 и ∆I09 отсутствуют, поэтому в их определении нет необходимости. Информация о величинах ∆Z1, ∆Z2, ∆Z3 и ∆U1, ∆U2, ∆U3 поступает в один из девяти блоков с приоритетом 2. Последующее действие описываемого алгоритма заключается в определении ошибок либо по сопротивлению ∆Z04p, ∆Z06p, ∆Z07p, ∆Z08p, ∆Z09p, либо по напряжению ∆U01p, ∆U02p, ∆U03Kp, ∆U05p. Полученные таким образом значения ошибок по напряжению поступают в блок суммы ошибок по напряжению

, а величины ошибок по сопротивлению попадают в блок суммы ошибок по сопротивлению

. Сведения о результатах расчета ошибок поступают в один или несколько блоков корректирующих органов 1, 12, 16, 14 (KO1-3, Ф) (рис.1).In block 24 (A) (Fig. 3), logical operations are performed. Reference values are compared here. 18

, 23

with load resistance 17

and voltage at the end of line 19

. Here, from a comparison of these values, errors are determined by the resistance ∆Z1, ∆Z2, ∆Z3 and by the voltage ∆U1, ∆U2, ∆U3. Then, the current errors ΔI01 - 05, ΔI07, ΔI08 are determined. At zero values of voltage errors, there are no current errors ∆I06 and ∆I09, therefore, their determination is not necessary. Information on the quantities ΔZ1, ΔZ2, ΔZ3 and ΔU1, ΔU2, ΔU3 is received in one of nine blocks with priority 2. The subsequent action of the described algorithm consists in determining errors either from the resistance ΔZ04p, ΔZ06p, ΔZ07p, ∆Z08p, ∆Z09p, or voltage ∆U01p, ∆U02p, ∆U03Kp, ∆U05p. The voltage error values obtained in this way go to the voltage error sum block

, and the values of errors in resistance fall into the block of the sum of errors in resistance

. Information about the results of the calculation of errors is received in one or more blocks of corrective bodies 1, 12, 16, 14 (KO1-3, F) (Fig. 1).

следует собирать ошибки по току, а затем в результате сопоставления эталонного и действительного значений токов в конце линии сформировать сигнал для корректирующих органов 1, 12, 16, 14 (КО1-3, Ф) (рис.1).Here, as a criterion for the functioning of corrective organs, a mismatch of voltage at the end of the line or load resistance is selected. In principle, the current mismatch at the end of the line can also be chosen as such a criterion. For this, in the block

current errors should be collected, and then, as a result of comparing the reference and actual values of the currents at the end of the line, generate a signal for corrective organs 1, 12, 16, 14 (KO1-3, F) (Fig. 1).

и

ошибка по току не определяется. В этом случае предусмотрено определение дополнительной ошибки по напряжению ∆U_O в виде произведения разницы между 23

и 19

и коэффициента состояния Most. Затем сведения об этой дополнительной ошибке отправляются в блок

.In the process of implementing the proposed method of matching a four-wire power transmission line with an electrical load, it was found that with

and

current error is not detected. In this case, the definition of an additional voltage error ΔU _O is provided in the form of the product of the difference between 23

and 19

and condition coefficient Most. Then information about this additional error is sent to the block.

.

Block 24 (A) (Fig. 3) is implemented in the National Instruments Lab VIEW 2009 environment.

Information sources

1. Bolshanin G.A. Distribution of low-quality electric energy over sections of electric power systems. In 2 book Book 1 / G.A. Bolshanin. - Bratsk: BrSU, 2006. - 807s.

2. Bolshanin G.A. Correction of the quality of electric energy / G.A. Bolshanin. - Bratsk: GOU VPO "BrSU", 2007 - 120s.

3. Bolshanin G.A. Distribution of reduced quality electric energy over a homogeneous section of a four-wire power transmission line / G.A. Bolshanin, L.Yu. Bolsanin // Systems. Methods Technologies. - 2009. No. 3. - S.65-69.

4. Kerky D. Coordination of the output impedance using fully differential operational amplifiers / D. Kerky // Components and technologies. - 2010. - No. 5. - S.150-154.

5. Kozlov V.A. Conditions for matching a homogeneous three-wire high-voltage power line of 10 kV and above with a load / V.A. Kozlov, G.A. Bolshanin // Materials of the VII international scientific and practical conference. - Prague: Printing House "Education and Science", 2011. - P.86-90.

6. Kozlov V.A. The agreed mode of operation of a homogeneous three-wire power line / V.A. Kozlov, G.A. Bolshanin // Systems. Methods Technologies. - 2011. - No. 4. - S. 70-76.

7. Kozlov V.A. Coordinated operation mode of a homogeneous three-wire power transmission line of 220 kV and higher as a means of improving the electromagnetic environment / G. Bolshanin // Science today: theoretical aspects and application practice. 4.2: Sat scientific labor. - Tambov: Publishing House of TROO “Business-Science-Society”, 2011. - P.63-66.

8. Serdeshnov A. Balancing device for transformers. Means of voltage stabilization and loss reduction in 0.4 kV networks. / A. Serdeshnov, I. Protosovitsky, J. Leus, P. Shumra // News of electrical engineering. - 2005. - No. 1. - S.14-15.

9. Certificate of state registration of the computer program No. 20101111888 "Calculation of the parameters of a three-phase three-wire uninsulated power line (LEP3 v. 1.00)."

Claims (1)

The method of matching a symmetrical four-wire power line, which is part of a symmetric electric power system with an electric load, consists in the fact that the initial information about the voltages and currents in the line through the interface devices enters the processor, characterized in that the conditions for matching the four-wire power line with the processor are checked electric load for each wire of the line, as a result of comparing the actual and reference values of the load resistances, n voltage at the end of the line or currents entering the load, and control signals are generated for the corrective organs, which can be used on-load tap-changers of power transformers, filters of higher harmonic components of currents and voltages of various modifications or a symmetric three-phase device that generates current and voltage at a frequency fundamental harmonics.

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