JP6834804B2 - Automatic voltage regulator for generator - Google Patents

Description

The present invention relates to an automatic voltage regulator for a generator.

Conventionally, for example, as disclosed in Japanese Patent Application Laid-Open No. 2000-262099, an automatic voltage adjusting device including a cross current compensating device for supplying electric power by parallel operation of a plurality of generators is known. By using the cross current compensator, it is possible to suppress the cross flow flowing between the generators operating in parallel.

Japanese Unexamined Patent Publication No. 2000-262099

The automatic voltage regulator used in the brushless synchronous generator is connected to an exciting current transformer to supply the exciting current. When the load power factor fluctuates, the exciting current generated by the exciting current transformer may decrease, and the automatic voltage adjustment function may not work sufficiently to solve the shortage of exciting current. Conventionally, in order to make up for such a shortage of exciting current, there is a problem that it is necessary to replace the existing current transformer for excitation with another current transformer for exciting that can generate a larger exciting current.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an automatic voltage adjusting device for a generator capable of increasing an exciting current.

The automatic voltage regulator for a generator according to the present invention supplies an exciting current generated from a secondary current of an exciting current transformer and an exciting transformer provided on the output side of the generator to the exciter of the generator. Then, the DC current is applied from the secondary current of the exciting current supply unit that adjusts the magnitude of the exciting current so that the generator voltage approaches a predetermined voltage and the cross current compensating current transformer connected to the generator. The exciting current increasing unit is provided with an exciting current increasing unit that is generated and supplies the DC current to the exciter, and the exciting current supply unit is based on the voltage of the exciting transformer and the secondary current of the cross current compensating transformer. A voltage detection unit that detects the generator voltage, a comparison unit that compares the generator voltage detected by the voltage detection unit with the predetermined voltage, and the exciting current from the current of the exciting current transformer. The exciting current increasing unit includes an exciting current generating unit that generates and adjusts the magnitude of the exciting current based on a signal from the comparing unit so that the generator voltage approaches the predetermined voltage. , The switch unit that cuts off the secondary current from the cross current compensation transformer by turning it on to pass the secondary current from the cross current compensation transformer, and the switch unit. And the AC / DC conversion unit that supplies the DC current to the exciter by converting the secondary current that has passed through the switch unit into the DC current, which is interposed between the and the output side of the excitation current generation unit. The voltage detection unit outputs a control signal indicating the result of comparing the generator voltage with a predetermined threshold value to the switch unit, and the switch unit turns on and off in response to the control signal. Is switched.

According to the present invention, by providing the exciting current increasing portion, the secondary current of the current transformer for cross current compensation can be used not only for cross current compensation but also for generating a direct current to be supplied to the exciter. it can. By adding this direct current, the exciting current supplied to the exciter can be increased.

It is a circuit block diagram which shows the automatic voltage regulator for a generator which concerns on embodiment of this invention, and the power generation system provided with this.

[Structure of the device of the embodiment]
FIG. 1 is a circuit block diagram showing an automatic voltage adjusting device 15 according to an embodiment of the present invention and a power generation system 1 including the automatic voltage adjusting device 15. The power generation system 1 is connected to the load 2. The power generation system 1 includes a brushless alternator 11, an exciting transformer 12 composed of a transformer and a reactor, an exciting current transformer 13, a cross current compensation current transformer 14, and an automatic voltage regulator 15. , Is equipped. The brushless alternator 11 is also hereinafter simply referred to as "generator 11". The automatic voltage adjusting device 15 is a device for adjusting the generator voltage, which is the voltage output by the generator 11.

The generator 11 includes a generator main body 11a and an exciter 11b. Although not shown, the power generation system 1 includes a plurality of generators 11. These plurality of generators 11 are operated in parallel. The cross current compensating current transformer 14 is provided to suppress the cross flow flowing between the generators 11 that operate in parallel. The cross current detected by the cross current compensating current transformer 14 is used as a signal for controlling the drop of the generator voltage.

The automatic voltage adjusting device 15 includes an exciting current supply unit 15a and an exciting current increasing unit 15b. _{The exciting current supply unit 15a supplies the exciting current I 1} generated from the secondary currents of the exciting current transformer 13 and the exciting transformer 12 to the exciter 11b. The exciting current supply unit 15a adjusts the magnitude of the _{exciting current I 1} so that the generator voltage approaches a predetermined target voltage.

Specifically, as shown in FIG. 1, the exciting current supply unit 15a includes a voltage detection unit 151, a voltage setting unit 152, a comparison unit 153, and an exciting current generation unit 154. The voltage detection unit 151 detects the generator voltage based on the voltage of the exciting transformer 12 and the secondary current of the cross current compensation current transformer 14. The target voltage of the generator voltage is preset in the voltage setting unit 152. The comparison unit 153 compares the generator voltage detected by the voltage detection unit 151 with the target voltage set by the voltage setting unit 152. The comparison unit 153 determines whether the generator voltage is higher or lower than the target voltage, and gives a control signal to the exciting current generation unit 154 based on the height.

The exciting current generation unit 154 generates an _{exciting current I 1} from the current of the exciting current transformer 13. The exciting current generation unit 154 adjusts the magnitude of the _{exciting current I 1} based on the signal from the comparison unit 153 so that the generator voltage approaches a predetermined target voltage. The exciting current generator 154 can synthesize and direct current the currents obtained by the exciting transformer, the reactor, and the exciting current transformer for use as _{the exciting current I 1.}

The voltage detection unit 151 also has a function of taking in the secondary current from the cross current compensation current transformer 14 and controlling the generator voltage drooping characteristic of the generator 11.

_{The exciting current increasing unit 15b generates a direct current I 2} from the secondary current of the cross current compensating current transformer 14, and supplies the direct current I ₂ to the exciter 11b. Specifically, as shown in FIG. 1, the exciting current increasing unit 15b includes a switch unit 155 and an AC / DC conversion unit 156.

When the switch unit 155 is turned on, the secondary current from the cross current compensation current transformer 14 is passed, and when it is turned off, the secondary current from the cross current compensation current transformer 14 is cut off. The switch unit 155 may be constructed by using various known switching means such as a semiconductor switching element, an electromagnetic relay, and a solid state relay. The AC / DC conversion unit 156 is interposed between the switch unit 155 and the output side of the exciting current generation unit 154. AC-DC converting unit 156, to convert the secondary current passing through the switch unit 155 to the DC current I _2, and supplies the direct current I ₂ to the exciter 11b.

The voltage detection unit 151 outputs a control signal indicating the result of comparing the generator voltage and the threshold value to the switch unit 155. The switch unit 155 switches on and off in response to the control signal from the voltage detection unit 151.

According to the above configuration, the exciting current increasing unit 15b can supply the direct current I ₂ generated from the secondary current of the cross current compensating current transformer 14 to the exciter 11b as needed. Therefore, the current supplied to the exciter 11b can be increased without replacing the exciting current transformer 13. Further, since the voltage detection unit 151 is also used for on / off control of the switch unit 155, it is possible to control the exciting current increasing unit 15b by utilizing the configuration of the exciting current supply unit 15a.

[Operation of the device of the embodiment]
In the embodiment, as an example, the exciting current increasing unit 15b is operated at the timing when the exciting current shortage described below occurs.

First, the problem of insufficient exciting current may be explained. Voltage fluctuation and voltage drop may occur when a power supply with a large load is turned on. As the generator voltage decreases, the current _{generated by the exciting transformer 12 in the exciting current I 1} decreases, and the current generated by the exciting current transformer 13 increases instead. _{The required exciting current I 1} is generated by combining the current of the exciting transformer 12 and the current of the exciting current transformer 13.

However, when the power factor of the load 2 is different from the initially assumed value, the combined current of the current generated by the exciting current transformer 13 and the current generated by the exciting transformer 12 changes, and the exciting current I ₁ is assumed. May be less than the value. An example of a case where the power factor of the load 2 is different from the initially assumed value is a case where a new device that was not provided at the time of installation of the power generation system 1 is connected to the power generation system 1. In that case, the exciting current I ₁ may be insufficient and the generator voltage may become stable without reaching the required voltage.

The automatic voltage adjusting device 15 according to the embodiment can make up for this shortage of exciting current. When the exciting current increasing unit 15b detects a voltage drop due to the above-mentioned insufficient exciting current, the exciting current increasing unit 15b starts supplying the _{direct current I 2 to the exciting machine 11b.}

First, the voltage detection unit 151 detects the time during which the generator voltage continues to fall below the first threshold value. The voltage detection unit 151 outputs an ON control signal to the switch unit 155 when the length of the detected time is equal to or longer than the first predetermined time. The "first threshold value" is a predetermined value, and may be the same value as the target voltage set by the voltage setting unit 152. The "first predetermined time" shall be set in advance to a length sufficient for determining whether or not the generator voltage has stabilized below the target voltage due to the above-mentioned insufficient exciting current.

When the switch unit 155 is turned on in response to the on control signal from the voltage detection unit 151, the secondary current passes through the switch unit 155 and flows to the AC / DC conversion unit 156. Since the secondary current of the cross current compensation current transformer 14 is alternating current, the AC / DC converter 156 converts the secondary current into a direct current I ₂ . Since the output end of the AC / DC conversion unit 156 is connected to the output end of the exciting current generation unit 154, the DC current I _{2 converted by the AC / DC conversion unit 156 is the exciting current I 1} generated by the excitation current generation unit 154. Is added to.

According to the above operation, it is possible to accurately detect a situation in which the generator voltage becomes stable without reaching the required voltage due to the shortage of the _{exciting current I 1.} Therefore, it is possible to accurately determine the timing for compensating for the shortage of the exciting current I _1.

Further, the exciting current increasing unit 15b stops the supply of the _{direct current I 2} when a sufficient voltage recovery is confirmed after the supply _{of the direct current I 2 to the exciter 11b is started by turning on the switch unit 155.} As an example of the method for confirming the voltage recovery, it may be considered that the voltage has recovered when the time during which the generator voltage continues to be the second threshold value or more becomes the second predetermined time or more. The "second threshold value" is a predetermined value, may be the same voltage as the above-mentioned first threshold value, or may be set to a value higher or lower than the first threshold value. The "second predetermined time" is a predetermined time, which may be the same length as the first predetermined time described above, or may be set to a time longer or shorter than the first predetermined time. As an example, the first threshold value and the second threshold value may be set to the same values as the target voltage, and the first predetermined time and the second predetermined time may be the same time as each other.

When the voltage recovery unit 151 confirms the voltage recovery, the voltage detection unit 151 outputs a signal for turning off the switch unit 155. As a result, the exciting current increasing unit 15b stops the output of the _{direct current I 2.} According to such an operation, it is possible to accurately detect that the generator voltage has been restored by compensating for the insufficient exciting current. Therefore, it is possible to accurately determine the timing at which the increase in the exciting current by the exciting current increasing unit 15b should be stopped.

The automatic voltage adjusting device 15 and the power generation system 1 according to the embodiment are suitably used for a power generation system installed in a narrow place such as a ship where there is no room for space. When the power generation system 1 is installed in a narrow installation place such as a ship, the capacities of the exciting transformer 12 and the exciting current transformer 13 are optimized according to the assumed load 2. By optimizing to the minimum required capacity, each device such as the exciting transformer 12 and the exciting current transformer 13 is designed to be as small as possible, so that space can be saved.

However, if the power factor of the load 2 is different from the value initially assumed at the time of design, the exciting current I ₁ obtained by combining the currents generated by the exciting current transformer 13 and the exciting transformer 12 may decrease. When such an exciting current shortage occurs, the automatic voltage adjustment cannot be appropriately performed only by the exciting current supply unit 15a. If the automatic voltage adjustment is not performed properly, the power generation system 1 may become larger by newly replacing the exciting current transformer 13, or complicated work such as parameter resetting may occur. was there.

In this regard, since the exciting current increasing unit 15b is provided in the embodiment, the exciting current is added by adding the _{direct current I 2 as necessary without changing the equipment, increasing the size of the system, and performing complicated work.} I ₁ can be increased.

1 Generator system, 2 Load, 11 Generator (brushless alternator), 11a Generator body, 11b Exciter, 12 Excitation transformer, 13 Excitation transformer, 14 Cross current compensation transformer, 15 Automatic voltage Adjuster, 15a exciting current supply unit, 15b exciting current increasing unit, 151 voltage detection unit, 152 voltage setting unit, 153 comparison unit, 154 exciting current generator unit, 155 switch unit, 156 AC / direct conversion unit, I ₁ exciting current, I ₂ DC current

Claims (1)

The exciting current generated from the secondary current of the exciting current transformer and the exciting transformer provided on the output side of the generator is supplied to the exciter of the generator so that the generator voltage approaches a predetermined voltage. With an exciting current supply unit that adjusts the magnitude of the exciting current,
An exciting current increasing unit that generates a direct current from the secondary current of the current transformer for cross current compensation connected to the generator and supplies the direct current to the exciter.
With
The exciting current supply unit
A voltage detector that detects the generator voltage based on the voltage of the exciting transformer and the secondary current of the cross current compensation current transformer.
A comparison unit that compares the generator voltage detected by the voltage detection unit with the predetermined voltage, and
An exciting current that generates the exciting current from the current of the exciting current transformer and adjusts the magnitude of the exciting current based on a signal from the comparison unit so that the generator voltage approaches the predetermined voltage. Generator and
Including
The exciting current increasing part is
A switch unit that allows the secondary current from the cross current compensation current transformer to pass when it is turned on and cuts off the secondary current from the cross current compensation current transformer when it is turned off.
AC / DC conversion that supplies the DC current to the exciter by interposing between the switch unit and the output side of the exciting current generation unit and converting the secondary current that has passed through the switch unit into the DC current. Department and
Including
The voltage detection unit outputs a control signal indicating the result of comparing the generator voltage with a predetermined threshold value to the switch unit.
The switch unit is responsive to on and off before switching the generator automatic voltage regulator to the control signal.

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