RU2365968C1 - Alternating voltage stabiliser - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, and more specifically to ac voltage stabilisers, meant for use in electrical power supply systems. The alternating voltage stabiliser contains an autotransformer, commutator, automatic switch, power supply device for the control device, terminals for connection to mains and a load, load current sensor, device for displaying information on the state of the stabiliser, device for connecting the load, a device for controlling the stabiliser, containing a microcontroller, output voltage sensor, load current sensor and a clock pulse sensor, as well as protective earthing terminals. To determine input voltage and control of operation of the alternating voltage stabiliser, readings of the output voltage sensor are used in the absence of the input voltage sensor. To determine input voltage and control the stabiliser in on mode the relationship between impedances is used, when the impedance between input and output voltage contacts is many times less than impedance between the commutator and the common contact. The input voltage is within a small percentage equal to output voltage, measured by the output voltage sensor. To determine input voltage and control the stabiliser in on mode of the microcontroller, readings of the output voltage sensor are used to determine whether input voltage readings are within the permissible range and an instruction is given for switching on the stabiliser with the corresponding number of the switch contact or, if the input voltage readings lie outside the permissible range, an instruction is given for indication of the accident mode. To determine input voltage and control operation of the stabiliser in nominal operation mode, the microcontroller calculates the value of input voltage based on the reading of the output voltage sensor and the number of the closed switch contact. To determine input voltage and control operation in emergency mode, the microcontroller, based on the reading of the output voltage sensor and number of one of the two extreme contacts of the closed switch, calculates the critical value of input voltage which is outside the permissible range and gives an instruction for switching off the stabiliser and an instruction for indication of the accident mode. In accident mode, like in the on mode, based on the reading of the output voltage sensor, the microcontroller determines the input voltage reading, and if it lies within the permissible range, it gives an instruction for switching on the stabiliser with the corresponding number of the switch contact. The proposed regulator simplifies design of the stabiliser, increases reliability and reduces cost.

EFFECT: use of the control device increases reliability due to considerable reduction of the number of discrete electronic components and processing a considerable number of emergencies, as well as increased accuracy of measurement and amount of displayed information, and reduced cost.

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Description

The invention relates to electrical engineering, namely to AC voltage stabilizers, is intended for use in power supply systems to stabilize a single-phase voltage of an alternating current electric power source.

As a prototype of the claimed invention, an AC voltage stabilizer was taken - utility model patent No. 50691, application No. 2005123427, priority July 25, 2005, containing an autotransformer, a switch, a stabilizer control device, a power supply device for the stabilizer control device located in the housing, and also terminals for connection to mains and load, circuit breaker and protective earth terminal.

The control device of this stabilizer contains a microcontroller, the inputs of which are connected to the input voltage sensor, the output voltage sensor, the load current sensor and the clock sensor, and the outputs of the microcontroller are connected to the control inputs of the switch and the device for displaying information about the status of the stabilizer. This stabilizer is taken as a prototype.

The disadvantage of this stabilizer is: the complex structure of the stabilizer, high cost and unreliable operation.

The purpose of the claimed invention is to achieve a technical result leading to - simplification of the design of the stabilizer, improving the reliability of its operation and reducing cost compared to the prototype.

The technical result is achieved due to the fact that the AC voltage stabilizer (hereinafter referred to as the stabilizer) comprising an autotransformer, a switch, a circuit breaker, a control device power supply device, power and load connection terminals, a load current sensor, a stabilizer status information display device, a load connection device consisting of an amplifier and a magnetic starter, a stabilizer control device comprising a microcontroller, an output voltage sensor, a load current sensor and a clock sensor, a housing in which all of these elements are located, as well as protective ground terminals, to determine the input voltage and control the operation of the AC voltage stabilizer, the readings of the output voltage sensor are used in the absence of an input voltage sensor.

In the stabilizer, to determine the input voltage and control the stabilizer in the on mode, the dependence between the impedances is used, when the impedance between the contacts of the input and output voltage is many times smaller than the impedance between the switch and the common contact, while the input voltage is very accurately equal to the output voltage measured by the output voltage sensor ,

In the stabilizer, to determine the input voltage and control the stabilizer in the on mode, the microcontroller, using the program specially laid out in it, determines from the readings of the output voltage sensor whether the readings of the input voltage are within acceptable limits and sends a command to turn on the stabilizer with the corresponding switch key number when the testimony of the input voltage exceeds the permissible limits, it issues a command to the indicator about the nature of the accident.

In the stabilizer, to determine the input voltage and control the stabilizer in normal operation, the microcontroller, using the program specially laid down in it, calculates the input voltage value according to the output voltage sensor and the contact number of the included switch key.

In the stabilizer, to determine the input voltage and control the stabilizer in emergency mode, the microcontroller, using the program specially laid down in it, calculates a critical value of the input voltage that is outside the permissible limits by the readings of the output voltage sensor and the number of one of the two extreme contacts of the switched switch key and gives a command to turn off the stabilizer and a command to the indicator about the nature of the accident.

In the AC voltage stabilizer, which is in emergency mode, as well as in the on mode, the microcontroller, using the program specially laid down in it, determines the input voltage reading from the output voltage sensor and, if it is within acceptable limits, sends a command to turn on the stabilizer with the appropriate switch key contact number.

Figure 1 shows a functional diagram of an AC voltage stabilizer.

Figure 2 shows a simplified connection diagram of an autotransformer and an AC voltage stabilizer switch.

The stabilizer 1 contains an autotransformer 13, a stabilizer control device 2, a switch 14, a stabilizer control device power supply device 6, power and load connection terminals 8, a circuit breaker 9, a protective earth terminal 16, a load current sensor 15, an indication device 7 and a load connection device 12 consisting of an amplifier 10 and a magnetic starter 11. The control device 2 contains a microcontroller 3, an output voltage sensor 5, a clock sensor 4. These elements are placed in the housing 1.

The stabilizer has three operating modes.

1. The inclusion mode.

2. The mode of regular work.

3. The emergency mode.

Power on mode

After turning on the circuit breaker 9, the mains voltage from the terminals 8 is supplied to the autotransformer 13, the power supply device of the stabilizer control device 6, the switch 14, the load current sensor 15, the output voltage sensor 5 and the clock sensor 4. Thyristor keys 17 of the switch 14 (see figure 2 ) have a capacitance of Z ₀ = 1 / ωС, where C = 0.1 μF, and the total resistance: Z1≈Z ₀ / k, where k is the number of keys. The output voltage sensor has a resistance of R≈300 kΩ or more. Thus, the microcontroller calculates the input voltage Uin. Value, using the value of the output voltage Uout., Measured by the output voltage sensor, to calculate. Given the fact that when the load is off, (magnetic starter 11 is off), the input voltage is:

where uout. - the value of the output voltage;

Z1 - impedance between the connection pin Uvx. (mains 220 to 50 Hz) and a connection pin Uout. The value of Z1 is determined by the leakage currents of the switch and the impedance of the autotransformer windings connected between the network connection contact and the switch;

Z2 - impedance between the switch and pin N - common wire.

Given that Z2 is much larger than Z1 (not less than 100 times) with the load off, formula (1) takes the form:

If the magnitude of the input voltage is within acceptable limits, the control device performs the initial switching on using the load connection device 12 and the switching elements of the selected autotransformer branch in such a way that the output voltage at the load corresponds to the rated voltage.

Normal mode

All subsequent switching of the autotransformer taps is performed when the output voltage exceeds the specified limits, which determine the accuracy of stabilization of the output voltage, while the moments of these switches are no longer associated with the magnitude and shape of the input voltage.

Emergency mode

A) Initial inclusion mode. If the value of the input voltage is outside the permissible limits, the control device does not turn on the circuit breaker 6 and the switching elements of the switch and indicates on the display device the current state of the stabilizer - "network failure".

C) If the input voltage exceeds the operating range, which slightly exceeds the nominal range, the controller control device disconnects the load by turning off the magnetic starter 11 in the load connection device 12, then the switch disconnects all autotransformer taps involved in the regulation, supplying the output voltage to terminals terminated. The stabilizer goes into on mode, after normalizing the input voltage, that is, when the input voltage reaches the operating range, the control device resumes stabilizing the output voltage. In addition, the regulator control device monitors a number of emergency situations, when they occur, the output voltage to the load connection terminals is cut off. The microcontroller outputs information about emergency situations to the device displaying information about the status of the regulator.

After the initial start-up, the stabilizer goes into normal operation under the control of a microcontroller, which implements the following functions:

- measurement of the effective values of the output voltage and load current;

- calculation of the effective value of the input voltage from the value of the output voltage, taking into account the number of the tap and the load current;

- collection and analysis of signals received at the inputs of the microcontroller;

- the issuance of information to the display device about the current state of the stabilizer;

- load shedding in case of emergency with the appropriate indication;

- stabilization of the output voltage by switching the taps of the autotransformer;

- calculation of the moment of switching switching elements;

- other functions, such as measuring the temperature of power elements, turning on the fan, monitoring the health of switching elements, etc.

All of the above functions are implemented through the appropriate software, which is recorded in the program memory of the microcontroller during its programming. Switching is performed after the microcontroller determines with the help of a current synchronization sensor 4 the moment the load current passes through zero. The stabilization accuracy is determined by the voltage between adjacent taps of the autotransformer, and switching at zero load current eliminates network voltage distortion.

The results of measurements of input and output voltages, power, consumed load, and other auxiliary parameters, the microcontroller outputs to the display device 7 information about the status of the controller. A high voltage regulation speed is achieved by a high measurement speed using the parameters of measurement discretization, output voltage and load current for one period of the mains voltage, and the autotransformer is switched to other taps by switch keys when the phase of the load current passes through zero, which eliminates network voltage distortion.

The industrial applicability of the claimed invention of an AC voltage stabilizer is confirmed by the possibility of practical implementation by known means using known technical solutions.

Claims (1)

An AC voltage stabilizer comprising an autotransformer, a switch, a circuit breaker, a control device power supply device, mains and load connection terminals, a load current sensor, a stabilizer state information display device, a load connection device consisting of an amplifier and a magnetic starter, a stabilizer control device comprising microcontroller, output voltage sensor, load current sensor and clock sensor, housing in which all of the above are located elements and protective earth terminals, characterized in that the output voltage sensor is used to control the operation of the AC voltage stabilizer in the absence of an input voltage sensor, the microcontroller is used to determine the input voltage and control the AC voltage stabilizer in the on mode, using the program specially laid down in it, according to the readings of the output voltage sensor determines whether the readings of the input voltage are within acceptable limits and gives a command to switching on the stabilizer with the corresponding contact number of the switch key or when the input voltage reading is outside the permissible limits gives a command to the indicator about the accident, to determine the input voltage and control the operation of the AC voltage stabilizer in the normal mode of operation, the microcontroller using the program specially built into it, according to the sensor of the output voltage and the contact number of the included switch key calculates the value of the input voltage to determine the input voltage operation and control of the operation of the AC voltage stabilizer in emergency mode, the microcontroller, using the program specially laid out in it, calculates a critical value of the input voltage that is outside the permissible limits by the output voltage sensor and the number of one of the two extreme contacts of the switched switch key and sends a command to turn off the stabilizer and a command to the indicator about the accident, in the stabilizer in emergency mode, as well as in the on mode, the microcontroller using a specialist The program, laid down in it, determines the indication of the input voltage according to the output voltage sensor, and if it falls within acceptable limits, it gives a command to turn on the stabilizer with the corresponding contact number of the switch key.

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