SU964961A1 - Device for control of direct frequncy converter - Google Patents

Description

(54) DEVICE FOR CONTROLLING THE DIRECT FREQUENCY CONVERTER

one

The invention relates to electrical engineering and is intended to control direct frequency converters operating on a high-power network.

It is an asynchronous device for controlling direct frequency converters, in which the output current follows the shape of the control current under the influence of any destabilizing factors, which is achieved by introducing a closed loop through the output current of the Converter 1.

The disadvantage of such a device is the difficulty of starting and separate control,. since when the valve set is turned on, the first control impulse is set with an arbitrary control angle, which can lead to disruption of tracking. Another disadvantage of the device is the complexity and low reliability of the operation of the control pulse distributors.

The closest in technical essence to the invention is a synchronous vertical type device with a pulse feedback circuit, comprising:

a control voltage and a reference voltage generator, connected via a first adder, to a comparator, a second adder, whose inputs are connected to a control voltage generator and an output voltage sensor, via an integrator to the second input of a comparator. The accumulator element of the integrator is shunted with a key, the control circuit of which is connected with the output of the comparator, to which the distributor is connected. The operation of the device provides high quality output voltage and. current due to feedback corrective action 2.

A disadvantage of the known device is the fact that feedback to the voltage is only possible in it. At the same time, direct frequency converters operating on a high-power network need to adjust the output current.

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The purpose of the invention is to extend the functionality.

The goal is achieved by the fact that a device for controlling a direct frequency converter containing a voltage generator connected through a first adder to a comparator, a second adder connected through an integrator whose storage element is bridged with a key, to a second comparator input whose output is connected to a distributor and the control circuit of the key, equipped with an output voltage sensor, output current sensor, control voltage generator, phase detector, second integrator, control delayed circuit and selective amplifier, the output voltage sensor through the phase detector, the second integrator and the controlled delay circuit connected to the control voltage generator and the output current sensor connected to the second input of the phase detector and connected directly to the inputs of the second adder and through a selective amplifier.

FIG. 1 shows a block diagram of the device; in fig. 2 - time diagrams that show his work.

The voltage sensor of the output network 1 is connected to the first input of the phase detector 2, the outputs of which through the second integrator 3, the controlled delay circuit 4 and the generator of the control voltage 5 together with the generator of the reference voltage 6 are connected to the inputs of the first adder 7, the output of which the comparator 8 is connected to the distributor 9. The output current sensor 10 is connected to the second input of the phase detector 2 and is connected to the inputs of the selective amplifier II and the second adder 12, the second input of which is connected to the output of the selective amplifier 11, and output through the integrator 13 to the input of the comparator 8. Cumulative {integrator element 13 zaschun .tirovai key 14, the control circuit is coupled to the output of comparator 8.

FIG. 2 the following notation is adopted: 15 - time diagram of the output network voltage; 16 is the time diagram of the control voltage; 17 is a time diagram of the first harmonic of the output current; 18 is a time diagram of the main harmonic of the output current.

The principle of operation of the device is as follows.

The power circuit is directly connected to the frequency converter with the output network through a choke, so the converter operates on a load with inductive response and the output voltage is ahead of the output current. To transfer active power to the network, the output current of the direct converter, the frequency must be in phase with the output voltage

networks (figure 15). The phase mismatch of the output current of the converter of the output network voltage is detected by the phase detector 2, the output voltage

which is integrated by the second integrator 3. If the phase mismatch is non-zero, the voltage at the integrator's output changes, and the delay generated by circuit 4 changes, and

the shift of the beginning of the formation of a control voltage by the generator 5 relative to the phase of the output network. As a result of the adjustment, a shift is obtained corresponding to a zero phase mismatch, while

The voltage of the second integrator 3 does not change and the device continues to operate with a modified phase shift of the control voltage (Figure 16). Thus, the control device supports

outputting maximum active power to the output network.

At the output of the adder 12, the difference between the main harmonic of the output current extracted by the selective amplifier is fixed.

11, and its current value, i.e. the deviation of the output current from the sinusoidal shape is fixed. The integrator 13 integrates this difference, which acts as a feedback signal to the comparator 8, which produces control pulses. Thus, if the average interval value of the output current differs from the value specified by the sinusoidal form of the voltage of the selective amplifier 11, this mismatch goes to the comparator 8 and corrects

values of the control angles in such a way that the mismatch decreases. Periodic error reset from the integrator 13 when the control pulse is generated by the comparator 8 leads to an increase in speed

feedback circuits, as well as the possibility of an error accumulation, which may cause a disruption in the operation of the device.

Thus, the proposed device retains the advantages of the prototype: correction

the harmonic composition of the output parameters of the converter, the speed of feedback feedback, reducing the possibility of disrupting the operation of the device due to the accumulation of errors on the integrator. In this case, the device provides the possibility of introducing feedback on the output current, which makes it possible to use the device to control direct frequency converters operating on a high-power network. The device provides transmission to the output network of the maximum active power. These advantages contribute to the improvement of technical and economic indicators of direct conversion of: spruce frequency, transmitting energy from the network of high frequency to the industrial network, for example, used; : in energy transfer systems of MHD generators.

Claims (2)

1. USSR author's certificate N 592003, cl. H 02 R 13/30, 1976. 2. Author's certificate of the USSR N537431, cl. H 02 R 13/16, 1975.