JPS5852417B2 - Heiretsuuntenni Okeru Hatsudenkino Kairetsuhoushiki - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for disconnecting generators in parallel operation.

Generally, generators that operate in parallel are equipped with an automatic voltage regulator (
(hereinafter referred to as an AVR), and this AVR further includes a cross-current compensator.

In this case, the cross current compensator is adjusted on the premise that each generator receives a load distribution of active power and reactive power proportional to its rated capacity.

For this reason, the following problem usually occurs when the generators operating in parallel are disconnected from the operating system, so-called decoupling.

In other words, when performing the above-mentioned disconnection, the governor is operated to transfer the active power, but the governor cannot transfer the reactive power. (hereinafter referred to as ACB) will have an adverse effect on the life of the contacts.

On the other hand, in order to eliminate this drawback, it is possible to transfer the active power by operating the governor, manually adjust the AVH voltage setting device to transfer the reactive power, and then perform the disconnection. This method has the drawback that it requires a very troublesome operation, it is difficult to automate the process of disassembling the array, and it is not possible to perform the disassembly quickly.

Therefore, it is an object of the present invention to provide an AC system that allows not only active current but also reactive current to be transferred to other generators in continuous operation with a simple operation when disconnecting generators in parallel operation.
This is to prevent damage to contacts such as H, and to automate the disconnection operation.

In order to achieve such an object, the present invention changes the degree of drooping characteristics during transition of reactive current,
This will be explained in detail below using examples.

Fig. 1 is a circuit diagram showing the circuit configuration of one of the generators operated in parallel, and in the figure, 1 is an AC generator, 2
is an AVR, 3 is a voltage detection transformer, 4 is a current transformer for cross current compensation, and 5 is a resistor for cross current compensation.

Fig. 2 shows a vector diagram of the detected voltage in the circuit configuration shown in Fig. 1. In the figure, vector 1 is the generator voltage detected by the voltage detection transformer 3, and vector This is the voltage detected and converted by the current device 4 and the cross current compensation resistor 5.

Vector 3 is a voltage obtained by combining vectors 1 and V2, and this voltage is input to AVR 2, and the voltage is controlled by AVR 2 based on this input.

For this reason, the generator 1 can maintain the drooping characteristics shown in FIG.

In addition, in FIG. 2, ψ indicates the load power factor angle.

Normally, the drooping characteristics of the generator 1 shown in FIG. 3 and the drooping characteristics of other generators are set to be equal.

In this embodiment, another resistor can be instantly connected to the input side of AVR2 shown in FIG. 1 using a switching mechanism, and the input can be changed to instantly change the drooping characteristic shown in FIG. 3. In this way, the reactive current is transferred.

FIG. 4 is a circuit diagram illustrating an embodiment of a generator disconnection method in parallel operation according to the present invention, which illustrates this point in detail.
In the figure, 6 is a resistor connected between the voltage detection transformer 3 and the cross current compensation resistor 5;
Contacts 7 are connected in parallel.

In this case, one end of the cross current compensation current transformer 4 (generator 1
side) is connected between the voltage detection transformer 3 and the resistor 6, and the connection configuration of the other parts is the same as that in FIG. 1, so a description thereof will be omitted.

In such a configuration, the operation when disconnecting the generator 1 will be described.

During parallel operation, the contact 7 is closed, the resistor 6 is in a short-circuited state, and there is a normal cross-current compensation state.

Here, when transferring the load to disconnect the generator 1, first operate the governor to transfer the active power.

Next, contact 7 is opened.

As a result, the resistor 6 is added to the cross current compensation resistor 5,
The resistance value of the cross current compensation resistor 5 instantly increases,
The vector 2 shown in FIG. 2 increases, and the input voltage of the AVR 2 increases instantaneously.

Therefore, as shown in FIG. 6, the voltage characteristic changes from the characteristic a shown by the solid line during parallel operation, and becomes the characteristic shown by the dashed-dotted line at the time of load shift.

In other words, in the voltage characteristic shown in Fig. 6, during parallel operation, the load current ratio is balanced in terms of voltage at points A and C, respectively, so that 0A = OC, but by shifting the load, The load current ratio on the uncoupled side is small,
The load current on the side that carries the load becomes a dog, and the point of the load current shifts significantly, resulting in a difference in the generated voltage and a cross current.
Balance is maintained by this cross current.

Therefore, by inserting the resistor 6, the generator 1 on the disconnected side
The voltage characteristics of the voltage characteristics are steep drooping characteristics as shown by the dashed line in Figure 6, and the load current ratio is OD on the disconnected side and OB on the loaded side, and the balance is maintained, and the cross current The incidence of this will be significantly reduced.

In this case, the greater the drooping characteristic and the smaller the value of OD, the more the degree of cross current generation will be reduced.

When the reactive current is transferred using the method described above, ACB
By turning off the generator 1, the generator 1 is disconnected from the BUS, and the contact 7 is restored to its original on state to enter the normal cross current compensation state, thereby completing the disconnection of the generator 1.

Therefore, as explained above, since AC"B can be cut off while reactive current is being transferred, damage to AC and B can be prevented, and since reactive current can be transferred by simply turning off contact 7, the disconnection operation can be automated. can be achieved.

Here, in this embodiment, the contact 7 is not limited to a mechanical one, but may be constructed from a switching mechanism such as a semiconductor element.

Furthermore, in this embodiment, even if the resistor 6 is made a variable resistor and this resistance is changed, the resistance value applied to the cross current compensation resistor can be adjusted by attaching a tap to the resistor 6 and switching this tap. can do.

As explained above, according to the method of disconnecting generators in parallel operation according to the present invention, the resistance value of the cross-current compensation resistor is substantially increased at the time of disconnection, and the input of the AVR included in the generator to be parallelized is Since the reactive current is transferred by instantly increasing the voltage higher than in the steady state, and then the line is disconnected, damage to the ACH etc. can be prevented, and the transfer operation can be performed by switching. Since this can be done by opening and closing the contacts, it is possible to automate the disconnection operation, which has a great effect.

[Brief explanation of drawings]

Figure 1 is a circuit diagram to explain the parallel disconnection method in general parallel operation, and Figures 2 and 3 are vector diagrams and characteristic diagrams to explain the parallel disconnection method explained in Figure 1. 4
Fig. 5 is a circuit diagram showing an embodiment of the parallel operation method according to the present invention, and Fig. 6 is a characteristic diagram for explaining the parallel operation method according to the present invention. . 1... AC generator, 2... Automatic voltage regulator, 3... Voltage detection transformer, 4...
・Current transformer for cross current compensation, 5...Resistor for cross current compensation, 6...Resistor, 7...Contact.

Claims (1)

[Claims] 1 A cross-current compensation resistor connected to a cross-current compensation current transformer and a resistor are installed between a voltage detection transformer that detects the output voltage of the alternator and an automatic voltage regulator that controls this alternator. In addition to connecting them in series, the circuit is equipped with a switching mechanism that short-circuits the resistors during parallel operation, and when disconnected, the short-circuiting of the resistors by the switching mechanism is released, effectively reducing the resistance value of the cross-current compensation resistor. The input voltage of the automatic voltage regulator is increased to increase the input voltage of the automatic voltage regulator, the degree of cross current compensation is increased compared to other generators operating in parallel, the reactive current is transferred, and then the above AC generator is disconnected from the parallel operation. A method for disconnecting generators in parallel operation, characterized in that: