Method of control of series compensation device

 

(57) Abstract:

Usage: in electrical engineering systems of power supply of consumers with sharply varying schedules. Essence: compare the frequency of the occurring and calculated resonance oscillations in a power supply system as a function of the amplitude of the resulting oscillations and difference frequencies compared change capacitance install longitudinal capacitive compensation, and when exceeding the estimated frequency of resonance oscillations increase the capacitance of the installation of series compensation, and when exceeding the frequency of the occurring vibrations reduce the capacitance of the device longitudinal compensation. 1 Il.

The invention relates to electrical engineering, in particular to the transmission and distribution of electricity, alternating current, and can be used in systems of power supply of consumers with sharply varying schedules.

Known adjustable mounting longitudinal capacitive compensation containing the partitioned condenser battery (KB), the capacitance of which varies depending on the voltage at its input, the current line and shift angle between them. Nedostatiuschie solution in which, depending on the sign and magnitude of the damping rate of the oscillations of the transition process shunted all KB installation of series compensation (CCP) or its separate sections. This solution allows you to selectively protect the KB from oscillatory phenomena.

A significant drawback of this solution is not taking into account the frequency of the resonance point frequency response (this order) power supply system that does not allow you to actively suppress emerged oscillatory phenomena and to effectively use the capacity of KB.

It is also known technical solution, which presents expressions for determination of singular points of this order of power supply system with the installation of series compensation, permitting comparison of the frequencies of the oscillations of the load current and possible subharmonic oscillations with the singular points of the frequency response. In essence it is closest to the proposed and adopted for the prototype.

A significant disadvantage of the prototype is the lack of active management of the modes of oscillation suppression.

The purpose of the invention is the stability of the electricity system and the efficiency of the condensate is ncacii by changing its resistance depending on the amplitude envelope of the resulting subharmonic oscillations, measure the frequency of the subharmonic oscillations occur, determine the estimated frequency and the steepness of the amplitude of the resonant oscillation by formulas

calc= , where

A = + + ,

B = , whereaboutangular frequency network;

to- capacitance install series compensation;

PC- capacitance installation of shunt compensation;

n- inductive load resistor;

with- inductive resistance in the food chain;

Fcalc= , where- the total inductive impedance;

R-total active resistance, determine the estimated difference emerged and resonant vibrations of providing the desired degree of resistance by the formula

calc= FBwhere is the required degree of stability, depending on the steepness of the amplitude of oscillations and the frequency difference between emerging and resonance oscillations,

FBthe amplitude of the arising of subharmonic oscillations, determine the new value of the estimated frequency of the resonant oscillations of providing the desired degree of resistance by the formula

calcl=calccalcdetermine resistancetolthat is relevant to the series compensation unit, equaltoland when exceeding the frequency of the resulting oscillation frequency of the resonant oscillations reducetoand when exceeding the estimated frequency of the oscillation frequency of the occurring oscillations increaseto.

In the known technical solutions according to the results of the analysis of the decay constant envelope subharmonic oscillations of the transition process changes the resistance of the KB series compensation by shunting its individual sections. Such regulationtowithout taking into account the frequency characteristics of the electricity system in some cases may not lead to suppression, but to increase the oscillatory process, because the regulation is essentially "blind" and with decreasingtocan sometimes not be removed but rather to approach the resonant points in this order power system. In these cases, in the future it is necessary to shunt the entire KB series compensation, causing additional disturbance in the system, the violation of its stable operation.

In this way, before you switch partitions KB determine in which direction the frequency fluctuations arisingINare resonance points this order - (calcand then Nero stability of power system . Thus the higher the amplitude of the resulting subharmonic oscillations FBand the steeper the amplitude of the resonance points this order Fcalcthe further apart in frequency response must be these points, i.e., the greater must be the value of calc. In the simplest case, this dependence can be taken linear (directly proportional), and in General is functional.

The implementation of the method of regulation of the code of criminal procedure is illustrated using the installation shown in the drawing.

Installation of series compensation consists of a series of n sections of the capacitor battery 11, 12, . . . , 1nn switching blocks 21, . . . , 2nunit 3 selection voltage on KB, bandpass filter 4, block 5 frequency oscillations, block 6 determine the amplitude, three analog-to-digital converters 7, 8, 9, computing device 10, the sensor 12 voltage, phase detector 13, block 14 for determining the resistance of the load, the control system 15.

The device operates as follows.

The deflection voltages KB allocated block 3 and is supplied to band-pass filter 4. The filter extracts envelope fluctuations naemul order is possible in this network with the CPC subharmonic resonance oscillations in KB, for example, from the third to the tenth. Next, the video signal from the bandpass filter 4 at the same time on the block for determining the oscillation frequency of 5 and an amplitude of oscillation 6, they are then converted from analog to digital form by analog-to-digital converters 7 and 8 and fed to the computing device 10.

At the same time removed the signals proportional to the current line from the current sensor 11 and the output voltage of the CPC sensor voltage 12 which are fed to a phase detector 13, which determines the phase angle between them. The signal from phase detector 13 along with the signals from the current sensors 11 and voltage 12 is supplied to the block definition of the resistors 14, working on the algorithm:

n=

Rn=

(1) If necessary, to the fourth input of the unit resistors 14 may be filed with the signal from the device of reactive power compensation (shown dotted).

Further, the signal from the unit 14 to determine the resistance of the load from an analog form is converted to digital form in analog-to-digital Converter 9, and is supplied to the computing device 10, which is a microcontroller in a single chip design, but can be performed on a separate e is em:

1. The resonance point frequency characteristics of the power supply system according to the expressions

P1= , where

A = + + ,

B = ,

(2) whereaboutangular frequency network;

to- capacitance installation of series compensation, the video signal from the system 15 controls the switching blocks of the CPC;

PC- capacitance device shunt compensation;

n- inductive load resistance, the video signal from the ADC 9;

with- inductive resistance in the food chain

Fcalc= , where- the total inductive impedance;

R- total active resistance.

2. The estimated difference emerged and resonant vibrations of providing the desired degree of resistance by the formula

calc= FBwhere is the required degree of stability, depending on the steepness of the amplitude of oscillations and the frequency difference between emerging and resonant oscillations;

FBthe amplitude of the arising of subharmonic oscillations.

3. The new value of the estimated frequency of the resonant oscillations of providing the desired degree of resistance by the formula

calcl=calccalc< / BR>
4. lebani, and the necessary changes in the capacitance of the code of criminal procedure, and then checks the required degree of stability of the power system in the proposed discrete change of the resistance of the KB and the new values of the frequencies calculated resonance points.

After performing these operations, the computing device 10 sends a signal to the input of the control system 15 of the switching blocks 2n, which generates a signal for switching the respective block 2i.

Switching unit 2icarries out the necessary changes in the capacitance of the capacitor battery of the CPC. Thus, the device provides a necessary and sufficient switching sections KB installation of series compensation to ensure the required degree of stability of the power system, when this is entered or removed from the food chain, not the entire KB, and only certain sections, which ensures efficient use of the overall capacity of the capacitors.

In the algorithm computing device 10 may be used and other expressions to determine the resonant frequencies of all points of the supply system with regard to inductive reactance of the source of disturbances, the economic components of the influence of the capacitance of the code of criminal procedure subtle, therefore, in this range of frequencies of perturbations it is advisable to implement a similar control of the capacitive resistance of the installation of shunt compensation.

The algorithms determine the necessary change in the capacitance of the capacitor battery installations longitudinal and transverse compensation in the form of a program recorded in a persistent storage device of the computing device 10. The application of this method allows for more precise regulation of the resistance of the KB series compensation and flexible use of modern element base, all blocks of the device can be implemented on standard chips.

METHOD of CONTROL of series COMPENSATION DEVICE, in which change their resistance depending on the amplitude envelope of the resulting subharmonic oscillations, characterized in that, in order to increase the stability of the power system and efficient use of capacitors to measure the frequency of the subharmonic oscillations occur, determine the estimated frequencycalcand the amplitude of the resonant oscillation by formulas

calc= ,

where A = + + ,

B = ,

whereoangular frequency;otulana installation of shunt compensation;

Xn- inductive load resistor;

Xwith- inductive resistance in the food chain;

Fcalc= ,

where X- the total inductive impedance;

R- total active resistance, determine the estimated difference emerged and resonant vibrations of providing the desired degree of stability, according to the formula

calcF ,

where the required degree of resistance that depends on the amplitude of oscillations and the frequency difference between emerging and resonant oscillations;

F - amplitude occurred subharmonic oscillations,

determine the new value of the estimated frequency of the resonant oscillations of providing the desired degree of stability, according to the formula

calc=calc+calc,

determine the resistance of X corresponding to the new value of the estimated frequency of the resonant oscillation, set the capacitance of the installation of series compensation equal to X , and when exceeding the frequency of the resulting oscillation frequency of the resonant oscillations reduce X , while exceeding the estimated frequency of the oscillation frequency of the occurring vibrations - increment X .

 

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