| Start of section
Production, amateur Radio amateurs Aircraft model, rocket-model Useful, entertaining |
Stealth Master
Electronics Physics Technologies Inventions |
Secrets of the cosmos
Secrets of the Earth Secrets of the Ocean Tricks Map of section |
  |
| Use of the site materials is allowed subject to the link (for websites - hyperlinks) | |||
Navigation: => |
Home / Patent catalog / Catalog section / Back / |
|
INVENTION
Patent of the Russian Federation RU2096907
MANAGEMENT METHOD ASYNCHRONOUS GENERATOR
The name of the inventor: Vavilov VN; Valshonok ES; Ivanov S.L.
The name of the patent owner: Closed Joint-Stock Company "MNTO INSET"
Address for correspondence:
Date of commencement of the patent: 1996.03.06
Usage: in the energy sector, for example, in small hydropower stations, wind farms and autonomous power stations of low power. Essence: in the method of controlling an asynchronous generator, the excitation of which is carried out from a reactive power source, the output voltage is multiphase rectified, the output voltage is measured, compared with the value of the reference voltage, the mismatch signal of these quantities is formed and converted into a sequence of control values of the load by the direct current of the pulses , The error signal is formed as a sequence of pulses of a duration equal to the time of exceeding the ripple of the rectified output voltage above the reference voltage and the pauses between these pulses equal to the time of exceeding the reference voltage over the pulsations of the rectified output voltage, while the control pulses are formed from these pulses by the pulse or pause duration, Exceeding a predetermined minimum threshold value of the pulse width of the error signal by this predetermined value. Simultaneously with the transformation of impulses of the error signal into control pulses, the values of the pulses duration of the error signal or pauses are compared with the set maximum permissible values of the pulse duration or the pause of the error pulse sequence, and if any of them is exceeded, the AC load and the reactive power source are disconnected. This makes it possible to increase the reliability of the asynchronous generator and the quality of stabilization of the generator output voltage.
DESCRIPTION OF THE INVENTION
The invention relates to the production and transformation of electric power, namely to methods for controlling asynchronous generators with a squirrel-cage rotor operating under conditions of varying local load, and can be used in power engineering, for example in small HPPs and wind power plants.
Known is a method for controlling an asynchronous generator (AG) with a squirrel-cage rotor excited from a reactive power source, which consists in connecting an additional regulated load (auto ballast) to the generator, with a change in which the output voltage of the generator stabilizes as a function of the deviation from the specified (nominal) value [1 ]
However, irrespective of the reactive power source used in said AG, this method does not allow to provide permanently operating monitoring of the operating parameters of the AG, which reduces its reliability and can lead to its failure.
The closest in technical essence and achieved result to the claimed method of controlling an asynchronous generator with loads in alternating and direct currents is known, including excitation of the generator from a source of reactive power, multiphase rectification of the output voltage, measurement of the value of the output voltage, comparing it with the value of the reference voltage, Mismatch of these quantities in the form of a sequence of pulses of duration corresponding to the output voltage of the AG, and converting it into a sequence of controllable values of the load with respect to the direct current of the pulses [2]
The disadvantage of this method, as well as the previous one, is the reduced reliability of the AH due to the lack of control over the deviation of the AG parameters from the allowable values, which excludes the possibility of performing pre-emergency and emergency situations of the AG and, consequently, can lead to its failure.
In addition, such a method does not provide the required quality of output voltage stabilization due to control system regulation for any short-term "fluctuation" outbursts or dips of the AG output voltage, which leads to excessive switching on or off of the DC load and a decrease in the dynamic noise immunity of the AG control system.
The technical result of the proposed invention is to increase the reliability of the AG and the quality of its output voltage stabilization by ensuring the detection of pre-emergency AH situations and increasing the dynamic noise immunity of its control system.
The technical result is achieved by the fact that in the method of controlling an asynchronous generator with loads in alternating and direct currents including excitation of the generator from a reactive power source, multiphase rectification of the output voltage, measuring the value of the output voltage, comparing it with the value of the reference voltage, generating a mismatch error signal of the indicated values and Converting it into a sequence controlling the magnitude of the load according to the direct current of the pulses, according to the invention, the error signal is formed as a sequence of pulses of a duration equal to the time of exceeding the ripple of the rectified output voltage above the reference voltage, and the pauses between the indicated pulses equal to the time of exceeding the reference voltage over the ripple of the rectified voltage, The control pulses are formed from said pulses by a pulse or pause duration exceeding a predetermined minimum threshold value of the pulse length of the error signal or its pause in the form of a delayed sequence of pulses relative to a sequence of impulse signals of the error signal to this predetermined value, simultaneously with the transformation of the impulse signals of the error signal into control pulses of the value The duration of the pulses and the pauses of the error signal are compared with the specified maximum permissible values, and if any of them exceeds the set value, the AC load and the reactive power source are disconnected.
Use as a signal of error of the signal in the form of a sequence of pulses of duration equal to the time of exceeding the ripple of the rectified output voltage over the reference one, and the pauses between these pulses equal to the time of exceeding the reference voltage over the ripples of the rectified one, and also comparing the pulse durations and their pauses with the specified maximum permissible values And turning off the AG in case of exceeding these values allows to provide a constant control over the duration of the pulses and pauses of the control pulses and to reveal not only the situation of the deviation of the output voltage from the permissible value, but also the time during which this change is observed, which allows revealing the preliminary situations and avoiding Accident AG, and, consequently, increase the reliability of AG in comparison with the prototype.
Conversion of impulse signals to the control signals in the above manner allows during the delay time of the control pulse of the error signal to determine the length of the pulse or the pause of the latter and, in the case of their decrease with respect to the specified minimum threshold value of the pulse length of the error signal or its pause, exclude its formation into a control pulse, , Which excludes the response of the control system to short-term emissions or dips in the output voltage of the AG and superfluous switching of the DC load, and increases the dynamic noise immunity of the AG control system and stabilizes the output voltage in comparison with the prototype.
Comparison of the proposed method with the prototype method shows that it differs from the latter in that the error signal is formed as a sequence of pulses of duration equal to the time of exceeding the ripple of the rectified output voltage above the reference voltage and the pauses between these pulses equal to the time of exceeding the reference voltage over the ripples of the rectified The control pulses are formed from said pulses by a pulse or pause duration exceeding a predetermined minimum threshold value of the pulse length of the error signal or its pause in the form of a delayed sequence of pulses relative to a sequence of impulse signals of the error signal to this predetermined value, and simultaneously with the transformation of the impulse signal pulses In the control pulses, the values of the pulse durations or pauses of the error signal are compared with their predetermined permissible values, and if any of them exceeds the set value, the AC load and the reactive power source are disconnected.
Thus, the invention corresponds to the criterion of "novelty".
Comparison of the invention with other technical solutions known in the art allows us to conclude that it follows from them in a non-obvious way and, therefore, corresponds to the criterion of "inventive level".
The possibility of implementing this invention in asynchronous generators used in power engineering, for example in small hydro power stations and wind farms, provides him with the criterion of "industrial applicability".
In Fig. 1 shows the device for implementing the proposed method: block diagram AG with control system; In Fig. 2 is a graphical representation of the impulses of the error signal U cp , where 
1 the pulse width of the error signal, 2 duration of a pause between the specified pulses; In Fig. 3 of the same, control pulses U y , where 3 - duration of the control pulse, 4 the duration of its pause, t 1 the delay time of the control pulses relative to the impulse signal pulses equal to the minimum threshold value of the pulse duration of the error signal or pause; In Fig. 4 is a graphical representation of the process of pulse formation of a mismatch signal and pauses when the rectified output voltage U out is changed relative to the reference voltage U op , while curve 1 rectified output voltage is relative to the threshold level, curve 2 is a form of the error signal at the output of the comparator; Curve 3 delayed by t 1 control pulses; In Fig. 5 is a graphic representation of the control process in various modes of the AH when the payload changes: a) in the medium load mode; B) in a mode close to overload; C) in a mode close to idling, where U cp12 is the error signal at the output of the integrator 12; In Fig. 6 is the external characteristic of the AG, where I 1 is the output current of the generator 1 when the external load is completely disconnected; While all power is "dumped" into ballast 7; I 3 output current of the generator 1 at the maximum external load and completely disconnected ballast load 7; I 2 intermediate value of the output current of the generator (normal operating mode I 1 <I 2 <I 3 ).
The proposed method is realized using the device shown in FIG. 1
 |
 |
 |
 |
 |
|
The device includes an AG 1, a reactive power source (PMM) 2 made, for example, as a phase capacitor system and an AC load 3 (payload) connected via circuit breakers 4 and 5, and a three-phase bridge rectifier 6 performing Function of the voltage sensor. With the bridge rectifier 6, the DC load R b 7 (auto ballast) is connected via the control switch 8. The control system AG 1 is connected to the switchboard 8. The control system 9 includes the reference voltage source AG 1. The control system 9 includes a reference voltage source 10 connected to One of the outputs of the comparator 11, the second input of which is connected to the rectifier 6. The output of the comparator 11 is connected to the input of the integrator 12 and the pulse width and pause analyzers 14 and 15, for example based on reset integrators and comparators (not shown in the drawing).
The output of the integrator 12 is connected to a Schmidt trigger 13 which is connected to the switch 8.
The outputs of the analyzers 14 and 15 are connected via the OR gate 17 to the input of the control unit 18 which is connected to the switches 4 and 5.
The control of the asynchronous generator is carried out as follows.
To the windings of the stator AG 1 through the switch 4 connects the IRM 2, and after the appearance of the output voltage (U out ) to the AG 1, a load AC is connected through the switch 5 to R n 3. The output AG 1 output three-phase voltage U outI is rectified by a three- phase bridge rectifier 6 and Receive a constant rectified voltage U out II with pulsations corresponding to three-phase bridge rectification. The rectified voltage U OUTII is compared with the reference voltage U op from the source 10. As a result of the comparison, a sequence of impulse signal pulses (see Figures 2, 3) is generated by the comparator 11 with a duration 1 , equal to the time of excess of the ripple of the rectified output voltage AG UoutII above the reference U op and with the duration of the pauses 2 times the excess of the reference voltage over the ripple of the rectified U output .
The sequence of impulse signal pulses generated in this way is converted into control pulses by means of an integrator 12 and a Schmidt trigger 13.
In this case, the control pulses are formed only from the pulses of the error signal with the pulse duration 1 or pause 2 , which exceeds the given value t 1, the minimum threshold value of the pulse duration or pause of the error signal. When 1 , 2 > t 1, the sequence of control pulses is formed as a delayed sequence of pulses relative to the pulses of the error signal by an amount t 1 (see Figure 3).
Simultaneously with the generation of control pulses, the pulse lengths of the error signal and their pauses are compared with the set maximum permissible values t 2 of the pulse duration or pause of the error signal pulse train in the analyzers 14 and 15, respectively.
If the setpoint t2 is exceeded, any of these values via the control unit 18 are disconnected by the switches 4 and 5 of the PMI 2 and the payload R 3 and therefore AG 1 (these cases are not shown in Figure 4).
The time value t 1 is selected within a few percent of the network voltage period.
The maximum permissible time t 2 is selected based on the allowable time during which the generator can operate with overload or overvoltage (seconds or tens of seconds).
During the adjustment of the control system 9, the external characteristic AG 1 is obtained (see Figure 6) and with its help determine the optimum values of the reactive excitation power (it is determined by the power factor cos 
Generator and load R н 3 and resistance of autoballast P б 7 [1]
The range of voltage regulation is determined by the requirements of power quality (for example, 232-198V), which corresponds to a change in the load current I n from zero to the maximum value, and, accordingly, the change in the average auto ballast current I b from maximum to zero (average current I b from maximum to zero (The average current I b , since the power consumed by the autoballast is determined by the width of the control pulses).
With decreasing or increasing the payload R n 3, the voltage U output I AG increases (relative to the nominal U nom ) or falls, which leads to an increase or decrease in the duration (width) t 1 of the control pulses.
With increasing AC load R n 3 and a decrease in Uout I, the pulse length of the error signal 1 decreases, and its pauses 2 is increased. If 1 <t 1 a 2 <t 1 (given the minimum threshold value of the specified pulse or its pause), then the DC load R b 7 is not connected, and additional power can be given to the payload R and 3. On the other hand, with a decrease in the AC load R n 3 and an increase in U out I, the pulse pause duration 2 decreases, and the pulse duration 1 - increases. If 2 <t 1 ( 1 > t 1 ), then switching off the resistance of auto ballast R 6 7 will only aggravate the increase of U outlets , and its non-switching allows to keep U outlets in the specified range. Simultaneous monitoring of the pulse lengths of the mismatch signal and their pauses beyond the preset maximum permissible values t 2 and subsequent deactivation of autoballast R b 7 and IRM allows to determine and exclude pre-emergency AH situations.
In Fig. 5 (a, b, c) are illustrated modes of operation AG (mode of medium load, overload and idling).
The medium load mode (Figure 5, a) corresponds to the above example. In the overload mode, the Schmidt trigger 13 senses the output to the integrator signal 12 as "0" (Fig.5b), so the control pulses will not flow to Rb 7, ie the resistance of the autoballast Rb7 will be disabled. In idle mode (Figure 5, c), the Schmidt trigger 13 senses the output of integrator 12 as "1". In this case there is a constant inclusion of ballast R 6 7.
Thus, the proposed invention due to the use of the signal as a signal in the form of a pulse train formed in this manner as well as due to the formation of control pulses from the pulse sequence of the error signal makes it possible to provide a constant control over the deviation of the AG parameters over admissible values, which allows to identify pre-emergency Situation and, consequently, increase the reliability of the AG in comparison with the prototype.
In addition, the proposed method excludes the response of the AG control system to short-term emissions or dips in the output voltage and, consequently, unnecessary DC switching of the load, which increases the dynamic noise immunity of the AG control system and stabilizes the output voltage in comparison with the prototype.
CLAIM
A method for controlling an asynchronous generator with AC and DC loads, including excitation of the generator from a reactive power source, multiphase rectification of the output voltage, measuring the value of this voltage, comparing it with the value of the reference voltage, generating a discrepancy signal for said quantities, and converting it into a sequence of load control quantities With a constant pulse current, characterized in that the error signal is formed as a sequence of pulses with a duration equal to the time of exceeding the ripple of the rectified output voltage above the reference voltage and the pauses between these pulses equal to the time of exceeding the reference voltage over the ripple of the rectified voltage, while the control pulses are formed from Of said pulses with a pulse duration or a pause exceeding a predetermined minimum threshold value of the pulse length of the error signal or its pause in the form of a delayed sequence of pulses relative to a sequence of impulse signals of the error signal to this predetermined value, simultaneously with converting the impulse signal pulses to driving pulses, pulse duration values or pauses The error signal is compared with the specified maximum permissible values and, if any of them exceeds the set value, the AC load and the reactive power source are disconnected.
print version
Date of publication 11.01.2007gg
Comments
When commenting on, remember that the content and tone of your message can hurt the feelings of real people, show respect and tolerance to your interlocutors even if you do not share their opinion, your behavior in the conditions of freedom of expression and anonymity provided by the Internet, changes Not only virtual, but also the real world. All comments are hidden from the index, spam is controlled.