SU1436181A1 - Method of distributing active power flows in closed non-homogeneous electric network - Google Patents

Abstract

This invention relates to the field of electrical engineering. The purpose of the invention is to reduce active power losses. To do this, measure the phase shifts of the voltage across the network branches, determine their tangents, multiply each of them by the sine value of the additional angle of mutual resistance of the corresponding network branch, summed algebraically, the values obtained taking into account the specified direction of bypass of the closed network. In the case of the difference from zero and the positive sign of the obtained sum, the active power loop flow is changed in the direction coinciding with the given direction, bypassing the closed network, and in the case of the negative sign, in the direction opposite to the specified walking direction. I il. cl

Description

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0:

thirty

The invention relates to electric power industry and to be used in closed non-uniform electric networks of high and ultra high voltage.

The purpose of the invention is to reduce active power losses.

In the drawing (Shown is a diagram of the device that implements the method.

Mathematically, the economic condition for a tKoro mode for an arbitrary closed loop is defined by the following formula:

U t iz: sinc.tgcC z tg o, (1)

: CT.HC-t.

de sinij

Hi

 T20

Rj j zi

- sine of the additional angle of mutual resistance of the i-th branch,

- accordingly active and,. full resistance of the i-th $ 2 branch;

C / J; - voltage phase shift i-th

branches.

All quantities included in expression 1), except for sya. for a given network setup, the constants are constant. I The magnitudes of phase shifts of stresses along branches m} fl. The closed branch is variable in expression and is determined by direct measurements — it is special devices for maintaining the current mode, such as active and reactive power along the network branches and voltage modules at the network nodes. In this case, it is possible to determine 40 phase shifts of voltages along the branches of the circuit through preliminary determination of the phase of the voltage at the nodes when they are taken from the nodes for the base (F), and then the phases of the voltage of all the remaining / J5 nodes of the circuit can be defined as :

 E; X-Q, R

. arctg

and

, (2).

and -MiQ ± 2L50

 and.

tf, Qj, P - voltage, reactive

and power is active, respectively. X, R - the value of resistance

55

network element index 1 and

2 - respectively the beginning. and the end of the network element

In addition, the phase shift of the voltage of any circuit branch can be determined from the known phase shifts of the other branches of the closed network according to the expression kk.

.one /. .: .. -21 SG, (3)

Cai: (

Q

five

0

. $

about es 40 / J5

50

55

THAT allows you to reduce the amount of required teleinformation about mode settings.

The further away from the economic mode the current mode is, the greater the difference of the functional in the left part of equation (1) from zero.

The sign of the obtained functional value indicates in which direction the contour power flow should be changed in accordance with the chosen direction of the bypass of the closed network, and the value is proportional to the required change.

Longitudinal compensation devices, reactors, booster transformers, and others whose parameters can be changed continuously or discretely can be used as an element of forced power distribution.

The parameters of the forced flow distribution device are changed so that the value of the functional standing on the left side of equation (1), corresponding to the new mode, i.e. after changing the parameter of the forced flow distribution device, it is set equal to or close to zero. At the same time, for each particular closed loop, the value of the calculated functional from measurements of the initial mode indicates how far from the economic mode the initial mode is, which allows the value of the change in the controlled parameter to be sampled (for the reactor, the resistance value, for the phase control device the necessary phase shift (angle) regulation), and the sign of the functional indicates in which direction it is necessary to change the parameter, decrease or increase .. As follows from equation (3) in a closed loop the phase voltage shift between any adjacent nodes can be determined by phase shifts along other branches of the circuit.

one

This capability allows for a reduction in the amount of telemetry information.

In addition, the proposed approach to the choice of control actions allows the equivalence of any section of a closed loop, so the branch can be understood to mean some equivalent part of the circuit in R and X (without load) connection between two adjacent nodes. The parameters R, X of the equivalent communication can be obtained from preliminary calculations, and the correction of the parameters of the equivalent communication is required only sporadically, a few significant changes in the scheme occur infrequently.

Measuring body 1 of each branch with its output is connected to the input of the divider 2 voltage corresponding to this branch, mode evaluation unit 3, and the outputs of all voltage dividers 2 are connected to the input of adder 4, the output of which is through diodes 5, threshold elements 6 and the delay line 7 is connected to the outputs of the mode evaluation unit 3, which are connected to the first and second inputs of the control output generating unit 8, the output of which is connected to the input of the executive unit 9..

The device works in the following way.

In each mode, the measured value of the phase shifts of the voltages along the branches of the closed network comes from the measuring bodies to the corresponding inputs of the voltage dividers 2 of the mode evaluation unit 3, and the output proportional to the product sinoi tg (S i corresponding branches which are fed to the input of the adder 4, the output of which forms a signal proportional to the value of al th

hebraic sum 21 sinoC-.tgc / - П,

.

the sign of which indicates in which direction it is necessary to change the contour flow, and the module indicates by what amount the change in the contour power flow should be made. The minimum of active power losses in a closed network corresponds to the regime, when the algebraic sum considered is zero. The generated signal from the output of the adder 4 through the diodes 5, by means of which the control signal is split across the channels (reduce, increase), is fed to the threshold elements 6, which constitute the dead zone. Thus, with a small signal from the output of the adder 4, i.e. the mode of active power loss in the scheme is close to the economic one; in the code of threshold elements, the zero state and, accordingly, the control output generating unit 8 does not generate a control signal.

When the signal from the output of the adder 4 is greater than the value set at the threshold elements 6 (in general, it can be different and depends on the control resolution), the signal passes to the output of the threshold element 6 corresponding to the signal sign and enters the delay line 7 and if during the time interval at the output of this threshold element 6 there is a non-zero signal, then it passes to the inputs of the control output generating unit 8, where, in accordance with the sign of the incoming signal, the proportional on its value, the magnitude of the control action, which from the output of the control action block 8 enters the actuator 9. The control process for the initial mode ends when a zero value is set at the output of the threshold elements 6 during a predetermined time interval on delay lines 7, which is selected on the basis of the detuning from irregular oscillations and the time of collection and calculation of the required telemetric processing.

Claims (1)

Invention Formula The method of distribution of active power flows in a closed non-uniform electric network of p branches, according to which the contour flow of active power is changed, which is due to the fact that, in order to reduce active-power losses, the tangents of the measured phase shifts are multiplied. on the sine value of the additional angle of mutual resistance of the corresponding branch of the network, algebraically summarize the obtained values five taking into account the specified direction of bypass of the closed network and in the case of a difference from the zero on the positive sign of the sum obtained, the active power loop flow is changed to the side, coinciding with the specified direction of the bypass of the closed network, and in the case of a negative sign - in the direction opposite to the specified direction of the bypass.