JPS596574B2 - automatic synchronizer - Google Patents

Description

[Detailed description of the invention] This invention relates to an improvement in an automatic synchronizer.

A conventionally known automatic synchronization device of this type is shown in FIG.

In the figure, 1 is the voltage transformer input signal circuit on the busbar side, 2
3 is a potential transformer PT input signal circuit on the generator side; 3 is a voltage difference detection circuit between potential transformer PT input signal circuits 1 and 2;
4 is a voltage difference tolerance value setting circuit that sets the allowable voltage difference during synchronization verification; 5 is a sine wave bead generation circuit that obtains a bead signal by matching the input voltage signals from the instrument transformer input signal circuits 1 and 2; , 6 is a frequency difference detection circuit that detects a frequency difference from a bead signal during synchronization verification, 7 is an allowable frequency difference setting circuit that sets an allowable frequency difference value, and 8 is a progressive angle detection circuit that detects a progressive angle before the synchronization point. 10 is a closing condition determination circuit 11 is a relay amplification circuit; and 12 is a circuit for closing the circuit breaker.

Next, the operation will be explained.

When synchronizing both devices connected in parallel, it is necessary to match the voltage, frequency, and phase.

The bus voltage of the voltage transformer input signal circuit 1 on the bus side and the generator voltage of the voltage transformer input signal circuit 2 on the generator side are:
The voltage difference between the two derived by the voltage difference detection circuit 3,
It compares the voltage difference with the tolerance set by the voltage difference tolerance setting circuit 4, and if the difference between both voltages is within the set value, outputs a condition OK signal to the closing condition determination circuit 10. At the same time, the bus voltage and generator voltage are converted into a sine wave bead signal by the sine wave bead generation circuit 5, the frequency difference is detected by the period of the bead by the allowable frequency difference detection circuit 6, and the frequency difference is detected from the allowable frequency difference value setting circuit □. It is compared with the set value and if it is within the set value, a signal indicating that the condition is OK is output to the closing condition determination circuit 10. In addition, the sine wave bead signal is compared with a progressive angle setting value that causes a time advance to match the closing time of the breaker in the progressive angle detection circuit 8, and if the signals match, a signal of 0K is sent to the closing condition discriminating circuit 10. is output. At this time, if the conditions of the voltage difference detection circuit 3 and the permissible frequency difference detection circuit 6 are met, a signal is output to the relay amplification circuit 11, and further output to the circuit breaker closing circuit 12 to synchronize the circuit 3 and the allowable frequency difference detection circuit 6. In this case, the generation process of the gradual angle will be specifically explained based on FIG. 2. FIG. 2 a shows the sine wave bead signal waveform from the sine wave bead generation circuit 5, and the period T is .

(△f is the frequency difference) Figure 2b is a signal waveform diagram obtained by differentiating the sine wave bead signal, Figure 2c is a waveform diagram combining the signal waveforms of Figures 2a and b, and VB2 is the progressive angle. The progressive angle θ is determined by the signal from the setting circuit 9. Here, when connecting the alternator in parallel to the bus bar, the circuit breaker usually has a dead time of about 0.1 to 0.6 seconds from the energization of the closing wire until the contact closes, so this dead time is equivalent to that at the synchronous point. It is necessary to issue a command to close the VC breaker as early as possible.

Now the frequency difference △f (c/s), the dead time of the circuit breaker is TD
(s), this leading angle θA(0) is θA=3
66)×△f><(TD) and must be proportional to the frequency difference.

This characteristic is called the gradual characteristic, and since the variation of this characteristic most governs the magnitude of the shock and inrush current in parallel operation, it is especially desirable for the closing device to have accurate gradual characteristics over a wide range of frequency differences. It will be done. Traditionally, this progressive characteristic is defined by the busbar,
The sine wave bead voltage obtained from the voltages of the corresponding phases of both generators is regarded as a quantity proportional to the phase difference between the two voltages,
On the other hand, a method of measuring the gradual angle by comparing this voltage with a voltage corresponding to the frequency difference obtained by differentiating this voltage has been widely adopted. Therefore, if a voltage difference or waveform distortion occurs in the operating force, the bead voltage changes and an error occurs in the gradual advance angle. Since the conventional automatic synchronization device is configured as described above, the following drawbacks arise.

(1) As the phase difference increases, the voltage is not properly proportional to the phase difference, and an error occurs when attempting to set the progressive angle over a wide frequency range.

(2) If a voltage difference or waveform distortion (furthermore, a large frequency difference) occurs in the operation input, the shape of the bead voltage near the synchronization point will collapse, causing an error in the progressive angle.

(3) When the frequency difference is made small, it takes time to output the closing signal. This invention was made in view of the above-mentioned drawbacks of the conventional art, and attempts to eliminate the above-mentioned drawbacks by converting the multiphase AC voltages of both parallelly connected devices into K sawtooth waves for each phase. .

An embodiment of the present invention will be described below based on the drawings. In Fig. 3, 2 is a voltage transformer PT 3-phase input signal circuit on the generator side, and 13-A, l3-B, l3-c are on the bus side. A phase difference detection circuit for each phase detects a phase difference between one phase of the PT input circuit and each phase of the PT input circuit on the generator side, 14 is each phase of the phase difference detection circuits 13a, 13-B, l3-c. A synchronization point detection circuit 15 detects the point at which the phase difference becomes zero, and a sawtooth 15 switches the pulse width proportional to the phase difference angle of each phase every 120 degrees in the synchronization point detection circuit 14 to obtain a sawtooth bead signal. This is a wave bead generation circuit.

Note that the other configurations are the same as those of the prior art, so explanations will be omitted. In the figure, the voltage difference detection circuit 3 compares the bus voltage of the PT input signal circuit 1 on the bus side and the same-phase generator voltage of the PT 3-phase input signal circuit 2 on the generator side, and If the voltage difference is within the tolerance set by the voltage difference tolerance setting circuit 4, a signal is output to the closing condition determining circuit 10 as a condition 0K. At the same time, the bus voltage of the PT input signal circuit 1 on the bus side and the generator voltage of the PT 3-phase input signal circuit 2 on the generator side The phase difference between the two voltages is detected in the circuit 13-c, and these 13-A, l3-B,
The synchronization point detection circuit 14 detects the point where the phase difference in each phase of l3-c becomes zero. Furthermore, the phase difference between the two voltages is determined by the sawtooth bead voltage generation circuit 15, which sets the pulse width proportional to the phase difference angle of each phase to zero when the phase difference is 0 degree, and A sawtooth bead signal is obtained by switching to a signal in which the phase difference decreases every 120 degrees so that the phase difference becomes maximum when the phase difference is 120 degrees. (Fig. 4a) The frequency difference of the sawtooth wave bead signal is detected by the frequency difference detection circuit 6 based on the period of the bead, and compared with the set value from the allowable frequency difference value setting circuit 7. If it is within the set value, the signal is closed. A signal is output to the condition determination circuit 10 as the condition 0K.

In addition, the sawtooth wave bead signal is compared with the value (Bf in FIG. 4, VB2) of the progressive angle setting circuit 9, which provides a time advance in accordance with the ramp-in time of the cutter, in the progressive angle detection circuit 8, and the signal is Since they match, V) (θ in FIG. 4c) is output to the closing condition discriminating circuit 10. Figure 4c is a composite of the waveforms a and b. If the conditions of the progressive angle detection circuit 8 of the voltage difference detection circuit 3 and the frequency difference detection circuit 6 are met, and furthermore, the voltage phase at this time is the same phase as the bus voltage and the generator voltage, the relay amplification circuit 11 The signal is then output to the circuit breaker closing circuit 12 for synchronous closing. The closing condition determination circuit 10 does not output if the voltage phase of the other two generator voltages is different from the bus voltage, but the operation of the circuit is checked. If there is a change in the voltage waveforms of both connected devices, the change is detected every 12♂ without the need to wait for one cycle, and the command to close the breaker can be easily changed.

Accuracy can be improved by shortening the thumbwheel control period. Furthermore, by converting the 3-phase AC city voltage of both voltages connected in parallel into pulses and expressing the phase difference between both voltages by the pulse width, inaccuracies in periodic points due to harmonic distortion of both voltage waveforms can be reduced. It can be resolved.

In the above description, a three-phase AC voltage was used as the AC voltage, but a single-phase AC voltage may be used.

In that case, a change in phase can be confirmed every 18(5). As described above, according to the present invention, the voltage of each phase of one of the two AC voltages connected in parallel is compared with the voltage of the other reference phase, and the comparison results of the two phases are expressed in the sawtooth shape. Since the linear part of the sawtooth state does not change even if the frequency difference between the two changes, the gradual angle can be easily set over a wide range. In addition, since the phase difference is detected for each carrier, the synchronization point can be confirmed every 12 (5') in a short period of time without having to check the periodic point every 36♂ of each phase. Even if a change occurs in the waveforms of both AC voltages connected in parallel, it can be quickly dealt with.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional automatic synchronizing device, FIG. 2 is a waveform diagram showing progressive angle detection operation waveforms of the conventional automatic synchronizing device, and FIG. 3 is a diagram showing an automatic synchronizing device according to an embodiment of the present invention. The block diagram, FIG. 4, is a waveform diagram showing the progressive angle detection operation waveforms of the automatic synchronizer according to the present invention. In the figure, 1 is a bus line PT input signal circuit, 2 is a power generation PT input signal circuit, 3 is a voltage difference detection circuit, 4 is a voltage difference tolerance setting circuit, 5 is a sine wave bead generation circuit, 6 is a frequency difference detection circuit,
7 is an allowable frequency difference setting circuit, 8 is a gradual angle detection circuit, 9 is a gradual angle setting circuit, 10 is a closing condition discrimination circuit, 11 is a relay amplification circuit, 12 is a breaker closing circuit, 13-a is a Phase phase difference detection circuit, 13-b is b phase phase difference detection circuit, 13
-c is a c-phase phase difference detection circuit, 14 is a synchronization point detection circuit, 1
5 is a sawtooth bead generation circuit.

Claims (1)

[Claims] 1. A phase difference detection circuit that derives a phase difference by comparing the reference voltage of one of the two AC voltages connected in parallel with the voltage of each phase of the other, and this phase difference detection A sawtooth wave beat generation circuit that generates a sawtooth wave with an output corresponding to the phase difference of each phase from the circuit and a state in which the phase difference is decreasing, and a time advance that corresponds to the closing time of the cutter. and a gradual angle setting circuit for setting each sawtooth wave from the sawtooth wave beat generation circuit and the gradual angle setting circuit when the voltage difference and frequency difference between the two polyphase AC voltages are satisfied. An automatic synchronization device that sends out a closing command signal for the above-mentioned breaker when the set value matches the set value. 2 In a sawtooth wave beat generation circuit, when the sawtooth wave of one phase becomes zero, a continuous sawtooth wave is derived by deriving the sawtooth wave of another phase whose phase difference is decreasing. An automatic synchronization device according to claim 1, characterized in that: 3 The phase difference detection circuit is used to compare the reference voltage of one of the two multi-phase AC voltages connected in parallel with the voltage of each phase of the other in pulses, and calculate the phase difference according to the phase difference. 3. The automatic synchronization device according to claim 1, wherein the automatic synchronization device is derived based on a pulse width.