JP4143269B2 - Variable speed system and overvoltage protection device protection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable speed system that employs an overvoltage protection device to protect a power conversion device that supplies an excitation current having a variable frequency from overvoltage, and a protection method of the overvoltage protection device, and particularly occurs when a system failure occurs. The present invention relates to a variable speed system for protecting an overvoltage protection device from an overvoltage and a protection method for the overvoltage protection device.
[0002]
[Prior art]
FIG. 4 is a system diagram showing a conventional variable speed system. FIG. 4 shows a generator motor used in a hydro / pumped power plant, among variable speed systems.
[0003]
As shown in FIG. 4, the generator motor 1 includes a stator 1 a and a rotor 1 b, and the stator 1 a is connected to the system 4 via a circuit breaker 5 and a phase switching disconnector 6. On the other hand, the rotor 1b of the generator motor 1 is supplied with an excitation current having a variable frequency from the power converter 2 via the secondary circuit 8, whereby the rotor 1b of the generator motor 1 rotates at a variable speed. That is, the generator motor 1 is an induction machine that can be operated at a variable speed by exciting a rotor (secondary winding) 1b with an excitation current of a variable frequency (hereinafter, used for variable speed pumped-storage power generation or the like). Inductors including wound-type AC excitation synchronous machines).
[0004]
Further, an overvoltage protection device 3 and an overvoltage protection control device 9 as a control means for controlling the overvoltage protection device 3 are connected to the secondary circuit 8 connecting the power conversion device 2 and the rotor 1 b of the generator motor 1. Has been. The circuit breaker 5 is provided to disconnect the generator motor 1 from the system 4 where the generator motor 1 inputs and outputs power by opening and closing, or in parallel to the system 4. 6 reverses the rotation direction of the generator motor 1.
[0005]
With these configurations, when a failure occurs in the system 4, the voltage of the stator 1a of the generator motor 1 changes and induces a voltage in the rotor 1b. Although the voltage induced in the rotor 1b is applied to the power converter 2 via the secondary circuit 8, the power converter 2 fails when the voltage induced in the rotor 1b is large and is overvoltage. There is a fear. For this reason, when an overvoltage occurs, this overvoltage is detected by the overvoltage protection control device 9, whereby the overvoltage protection control device 9 performs control for operating the overvoltage protection device 3 and applies the overvoltage applied to the power converter 2. Suppress.
[0006]
As described above, in the configuration of FIG. 4, even when a failure occurs in the system 4, the overvoltage protection device 3 can suppress the overvoltage, so that the generator motor 1 can be controlled to continue to operate. Here, the overvoltage protection device 3 is usually designed with some allowance for the element capacity necessary for overvoltage suppression in consideration of economy.
[0007]
[Problems to be solved by the invention]
However, when failures occur continuously in the system 4 within a short time such as several seconds, the elements in the overvoltage protection device 3 may exceed the thermal use limit, and the overvoltage protection device 3 may fail. is there.
[0008]
However, it is usually difficult to design with sufficient allowance for the element capacity in the overvoltage protection device 3 so that the failure that occurs continuously in the system 4 in such a short time can be protected from the overvoltage. This is because it is very rare that a fault continuously occurs in the system 4 in a short time, and even if such a fault of the system 4 is assumed, the overvoltage is suppressed in all possible situations. This is because it is very difficult to determine the capacitance of the element necessary for the operation.
[0009]
Although it is technically possible to design the element capacity of the overvoltage protection device 3 to be large enough to withstand several failures within a short time, in this case, the overvoltage protection device is very expensive. In addition, if more than the expected number of failures occur in the system 4, the elements of the overvoltage protection device 3 are similarly damaged over the use limit.
[0010]
The present invention has been made in consideration of the above circumstances, and does not increase the element capacity of the overvoltage protection device, and the variable speed without causing the overvoltage protection device to fail with respect to the overvoltage continuously generated within a predetermined time. It is an object of the present invention to provide a protection method for a system and its overvoltage protection device.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, in the variable speed system according to the first aspect of the present invention, an induction machine capable of rotating the rotor at a variable speed, and the induction machine in parallel with the system, or a solution from the system. A circuit breaker to be connected; a power converter that supplies an excitation current of variable frequency to the rotor of the induction machine; and an overvoltage protection device that protects the power converter from an overvoltage induced in the rotor; In a variable speed system comprising a control means for operating the overvoltage protection device by detecting the overvoltage, a circuit breaker control means for controlling opening and closing of the circuit breaker is added to the control means, and the control means is within a predetermined time. The circuit breaker is controlled to open when a predetermined number of overvoltages occur .
[0012]
According to the variable speed system of the first aspect of the present invention, the circuit breaker control means for controlling the opening / closing of the circuit breaker is added to the control means of the overvoltage protection device, and an overvoltage is generated a predetermined number of times within a predetermined time. By performing the control to open the circuit breaker at this time, the power conversion device and the overvoltage protection device can be protected from the overvoltage that may occur continuously.
[0019]
In a variable speed system according to a second aspect of the present invention, an induction machine capable of rotating a rotor at a variable speed, a circuit breaker for paralleling the induction machine in a system or disconnecting from the system, A power converter that supplies an excitation current of variable frequency to the rotor of the induction machine; an overvoltage protection device that protects the power converter from an overvoltage induced in the rotor; and an overvoltage that detects the overvoltage. In a variable speed system comprising an overvoltage protection control means for operating a protection device, an electric energy detection means for detecting an electric energy consumed by a secondary circuit connecting the rotor and the electric power converter, and the electric energy detection connected to the means, characterized in that the amount of power and a circuit breaker control means for controlling to open the breaker when it exceeds a predetermined value within a predetermined time.
[0020]
According to the variable speed system according to the invention of claim 2 , in order to detect the amount of electric power generated with the overvoltage induced in the rotor of the induction machine, and to open the circuit breaker based on the detection result, Even when an overvoltage occurs continuously within a short time, it is possible to prevent a failure of an element in the overvoltage protection device.
[0021]
In the method for protecting an overvoltage protection device for a variable speed system according to a third aspect of the invention, an induction machine capable of rotating a rotor at a variable speed, and the induction machine in parallel with the system, A circuit breaker to be arranged; a power converter that supplies an exciting current of variable frequency to the rotor of the induction machine; and an overvoltage protection device that protects the power converter from an overvoltage induced in the rotor. In the protection method of the overvoltage protection device of the variable speed system provided, when the number of times of detection of the overvoltage within a predetermined time is equal to or less than a predetermined number of times, the overvoltage protection device is activated and exceeds the predetermined number of times. When an overvoltage is detected, the circuit breaker is opened to disconnect the induction machine from the system.
[0022]
According to the method for protecting an overvoltage protection device for a variable speed system according to the third aspect of the present invention, when the number of overvoltage detections within a predetermined time is equal to or less than a predetermined number, the overvoltage protection device is activated and set in advance. When an overvoltage is detected exceeding the specified number of times, the circuit breaker is opened and the induction machine is disconnected from the system, so that the power converter and overvoltage protection device can be removed from the overvoltage caused by a system failure that may occur continuously. Can be protected.
[0025]
In the protection method for an overvoltage protection device for a variable speed system according to a fourth aspect of the invention, an induction machine capable of rotating a rotor at a variable speed, and the induction machine in parallel with the system, A circuit breaker to be arranged; a power converter that supplies an exciting current of variable frequency to the rotor of the induction machine; and an overvoltage protection device that protects the power converter from an overvoltage induced in the rotor. In the protection method of the overvoltage protection device of the variable speed system, the overvoltage protection device is activated when the amount of power supplied to the rotor within a predetermined time is equal to or less than a predetermined value, and the overvoltage protection device is operated within the predetermined time. When it is detected that the electric energy exceeding the predetermined value is supplied to the rotor, the circuit breaker is opened to disconnect the induction machine from the system.
[0026]
According to the method for protecting an overvoltage protection device for a variable speed system according to a fourth aspect of the invention, the overvoltage protection device is activated when the amount of power supplied to the rotor within a predetermined time is equal to or less than a predetermined value. When detecting that the amount of power exceeding a predetermined value is supplied to the rotor within a predetermined time, the power converter and overvoltage are opened by opening the circuit breaker and disconnecting the induction machine from the system. The protection device can be protected.
[0027]
According to a fifth aspect of the present invention, there is provided a method for protecting an overvoltage protection device for a variable speed system according to the third or fourth aspect, wherein a predetermined time has elapsed after the circuit breaker is opened. When the induction machine is rotating at a rotational speed within a variable speed operation range, the circuit breaker is closed again, and the induction machines are re-parallelized in a series.
[0028]
According to the overvoltage protection device protection method for a variable speed system according to the fifth aspect of the present invention, the induction machine rotates at a rotational speed within the variable speed operation range when a certain time has elapsed after the circuit breaker is opened. If this is the case, the circuit breaker is closed again and the induction machines are re-paralleled in a series, so that the operation can be continued without stopping the induction machine.
[0029]
Therefore, according to claims 3 to 5 , the circuit breaker is opened and the induction machine is disconnected from the system, or can be continuously operated within the variable speed operation range, so that it meets the needs of the system. The induction machine can be operated.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0031]
[First Embodiment]
FIG. 1 is a system diagram showing a first embodiment of a variable speed system according to the present invention. In addition, the same code | symbol is attached | subjected and demonstrated to the part same as the conventional structure. The same applies to other embodiments. FIG. 3 is a flowchart showing an operation sequence in each embodiment of the protection method of the overvoltage protection device of the variable speed system according to the present invention.
[0032]
In FIG. 1, an induction machine 7 is composed of a stator 7a and a rotor 7b, and an excitation current of variable frequency is supplied from the power converter 2 to the rotor 7b, whereby the rotor 7b of the induction machine 7 is It is configured to be able to rotate at a variable speed. The secondary circuit 8 that connects the power conversion device 2 and the rotor 7b of the induction machine 7 includes an overvoltage protection device 3 that protects the power conversion device 2 from an overvoltage induced in the rotor 7b of the induction machine 7. The overvoltage protection control device 9 is connected as a control means for controlling the overvoltage protection device 3. Here, the circuit breaker 5 provided between the system 4 and the induction machine 7 disconnects the induction machine 7 from the system 4 by opening and closing thereof, or is parallel to the system 4, and the phase switching disconnection The device 6 reverses the direction of rotation of the induction machine 7.
[0033]
In the present embodiment, the overvoltage protection control device 9 controls the overvoltage protection device 3 and also controls the opening / closing of the circuit breaker 5. That is, the overvoltage protection control device 9 has a configuration in which a circuit breaker control means for controlling the opening / closing of the circuit breaker 5 is added to the control means of the overvoltage protection device 3. Further, the induction machine 7 is provided with a rotation speed detector 10, and this rotation speed detector 10 detects the rotation speed of the rotor 7 b of the induction machine 7.
[0034]
Next, the effect | action of this embodiment is demonstrated based on FIG. 1 and FIG.
[0035]
In the system 4, when the system 4 continuously fails and the voltage acting on the stator 7a of the induction machine 7 changes greatly, an overvoltage is induced in the rotor 7b. The overvoltage protection control device 9 detects this overvoltage via the secondary circuit 8. When this overvoltage is detected for the first time, the overvoltage protection control device 9 operates the overvoltage protection device 3.
[0036]
Then, when the overvoltage protection control device 9 detects the second overvoltage within a few seconds (hereinafter referred to as a short time) that is a predetermined time from the detection of the first overvoltage, the overvoltage protection control device 9 opens the circuit breaker 5. Thus, the induction machine 7 is controlled to be disconnected from the system 4. In this way, even if the second system failure occurs within a short time, the overvoltage due to the system failure can be cut off, and the power conversion device 2 and the overvoltage protection device 3 can be prevented from malfunctioning.
[0037]
Here, the overvoltage protection control device 9 is provided with a timer (not shown), and this timer operates as a trigger when the first system failure is detected, so that the second overvoltage that occurs within a short time is detected. I can capture it reliably.
[0038]
In the present embodiment, the overvoltage protection control device 9 performs control to open the circuit breaker 5 due to the overvoltage associated with the second system failure. However, the capacity of the element (not shown) in the overvoltage protection device 3 The overvoltage protection control device 9 may perform control to open the circuit breaker 5 after detecting an overvoltage caused by a failure several times.
[0039]
Further, in the first embodiment described so far, the overvoltage protection control device 9 controls the overvoltage protection device 3 and the circuit breaker 5, but the control means of the overvoltage protection device 3 controls the opening and closing of the circuit breaker 5. Therefore, the circuit breaker control means for controlling the overvoltage protection device 3 and the circuit breaker control for controlling the opening and closing of the circuit breaker 5 are connected to the overvoltage protection control device 9. Even if the apparatus is provided separately, the same effect can be obtained.
[0040]
As a modification of the present embodiment, when a system failure occurs as shown in FIG. 3, the overvoltage protection control device 9 detects it and opens the circuit breaker 5 to disconnect the induction machine 7 from the system. You may control to.
[0041]
By doing in this way, the power converter device 2 and the overvoltage protection apparatus 3 can be protected from the overvoltage by the system failure which may generate | occur | produce continuously. Further, in this case, when the overvoltage protection control device 9 detects an overvoltage due to a system failure, the overvoltage protection device 3 is first activated, and then a predetermined time based on the element capacity (not shown) in the overvoltage protection device 3. When the overvoltage protection device 3 is operating even when the time elapses, that is, when the overvoltage continues for a predetermined time, it is also possible to perform control such that the circuit breaker 5 is opened. By doing in this way, even when a failure occurs continuously in the system 4, the power conversion device 2 and the overvoltage protection device 3 can be protected.
[0042]
As described above, according to the present embodiment and the modification, the overvoltage protection control device 9 controls the circuit breaker 5 to open before the overvoltage protection device 3 exceeds the use limit due to the overvoltage continuously generated within a short time. By doing so, since the overvoltage applied to the overvoltage protection device 3 can be cut off, the overvoltage protection device 3 can be protected from overvoltage caused by a continuous system failure that does not occur extremely.
[0043]
Accordingly, the overvoltage protection device 3 can be damaged without causing the overvoltage protection device 3 to have a capacity to withstand the overvoltage continuously generated within a predetermined time, and against the overvoltage continuously generated within the predetermined time. Disappear.
[0044]
[Second Embodiment]
FIG. 2 is a system diagram showing a second embodiment of the variable speed system according to the present invention.
[0045]
Also in the present embodiment, as in the first embodiment, the secondary circuit 8 is connected to the overvoltage protection device 3 and the overvoltage protection control device 9, but in addition to these, the secondary circuit 8 is connected to the wattmeter 11. Has been. The wattmeter 11 is connected to the circuit breaker control device 12 so that the signal detected by the wattmeter 11 is input to the circuit breaker control device 12. The circuit breaker control device 12 is connected to the circuit breaker 5 and is configured to control opening and closing of the circuit breaker 5.
[0046]
Next, the operation of this embodiment will be described.
[0047]
As shown in FIG. 3, in this embodiment, the circuit breaker 5 is opened when the amount of power consumed by the secondary circuit 8 exceeds a specified value within a short time. That is, an overvoltage is induced in the rotor 7b of the induction machine 7 due to a system failure that has occurred in the system 4, and the overvoltage protection control device 9 detects this and protects the power conversion device 2 from the overvoltage. The device 3 is activated. At this time, excessive power is generated in the secondary circuit 8 more than usual with the occurrence of overvoltage.
[0048]
And the circuit breaker control apparatus 12 calculates | requires the electric energy consumed by the secondary circuit 8 in a short time, such as time integrating the electric power detected by the wattmeter 11 connected to the secondary circuit 8, When the amount of power in this short time exceeds a certain value, this is detected, the circuit breaker 5 is opened, and the induction machine 7 is disconnected from the system.
[0049]
That is, the wattmeter 11 and the circuit breaker control device 12 have a function as a power amount detecting means for detecting that a certain amount of power has flowed in the secondary circuit 8 within a short time, and a detected power amount. When the threshold value is exceeded, it functions as a circuit breaker control means for opening the circuit breaker 5. In this case, the threshold value of the electric energy that is a reference for opening the circuit breaker 5 may be determined based on the capacity of an element (not shown) provided in the overvoltage protection device 3.
[0050]
In this way, the present embodiment detects that the prescribed amount of power has been consumed within a short time in the secondary circuit 8 and opens the circuit breaker 5, thus protecting the power conversion device 2 and the overvoltage protection device 3. Can do.
[0051]
That is, normally, the overvoltage protection device 3 is configured to convert the overvoltage induced in the rotor 7b of the induction machine 7 into heat as power consumption of an element (not shown) so as to cancel the overvoltage. If an overvoltage is generated continuously, the amount of heat generated by the element increases and a failure occurs. In this embodiment, the power generated in the secondary circuit 8 due to the overvoltage induced in the rotor 7 b of the induction machine 7. When the amount of power is detected and the circuit breaker 5 is opened when the amount of power exceeds a threshold value, a failure of an element (not shown) in the overvoltage protection device 3 occurs even when an overvoltage occurs continuously within a short time. Can be prevented.
[0052]
Here, in the present embodiment, the wattmeter 11 is provided in the secondary circuit 8 and the circuit breaker control device 12 calculates the power amount within a short time based on the detected amount. Instead, a watt-hour meter with a timer as a watt-hour detection means may be installed in the secondary circuit 8, and in this case, the circuit breaker controller 12 detects the power amount within a short time detected by the watt-hour meter with a timer. What is necessary is just to set it as the structure which controls opening and closing of the circuit breaker 5 by the value of.
[0053]
Further, in this embodiment, the overvoltage protection control device 9 is used only for operation control of the overvoltage protection device 3, and the circuit breaker control device 12 is configured to perform opening / closing control of the circuit breaker 5. The function of the device 12 may be provided in the overvoltage protection control device 9 to control the opening / closing of the circuit breaker 5 from the overvoltage protection control device 9. In this case, the detected value of the wattmeter 11 connected to the secondary circuit 8 or the watt-hour meter with timer is input to the overvoltage protection control device 9.
[0054]
In addition, after opening the circuit breaker 5 as in the embodiment described later, the induction machine 7 which is the main machine is stopped, or the circuit breaker 5 is closed after the overvoltage protection device 3 becomes usable again. Control to continue operation in parallel can be performed.
[0055]
[Third Embodiment]
As shown in FIG. 3, the third embodiment stops the induction machine 7 after opening the circuit breaker 5 in order to protect the overvoltage protection device 3 in the first and second embodiments.
[0056]
[Fourth Embodiment]
In the fourth embodiment, as shown in FIG. 3, in the first and second embodiments, after the circuit breaker 5 is opened to protect the overvoltage protection device 3, the overvoltage protection device 3 is in a usable state. Wait for. When the rotational speed of the induction machine 7 detected by the rotational speed detector 10 is within the variable speed operation range when the reusable state is entered, the circuit breaker 5 is closed and re-paralleled with the system 4 to operate. Can be continued.
[0057]
Moreover, if the rotational speed of the induction machine 7 is outside the variable speed operation range when it becomes a reusable state, the induction machine 7 is stopped as in the third embodiment.
[0058]
Therefore, in the third and fourth embodiments, when the circuit breaker 5 is opened to protect the overvoltage protection device 3 from a continuous system failure, the induction machine 7 which is the main machine can be stopped, and the overvoltage protection device 3 If the induction machine 7 is at a rotational speed within the variable speed operation range after waiting for the motor to become usable again, the circuit breaker 5 is closed and re-paralleled to continue operation without stopping the main engine. it can.
[0059]
As described above, according to the third and fourth embodiments, after the circuit breaker 5 is opened, the induction machine 7 as the main machine can be stopped or continuously operated within the variable speed operation range. Therefore, by controlling in combination with the control methods of the first and second embodiments, the operation of the induction machine 7 that meets the needs of the system can be realized.
[0060]
The present invention is not limited to the above embodiments, and various modifications can be made. For example, in each of the above embodiments, an induction machine is used as the main machine, but other generator motors or flywheel generators may be used.
[0061]
【The invention's effect】
As described above, according to the present invention, the overvoltage protection device is provided with a capacity sufficient to withstand a case in which a system failure does not occur in an extreme case in which the failure occurs continuously twice or more within a predetermined time. Therefore, it is possible to perform control for protecting the overvoltage protection device from overvoltage continuously generated within a predetermined time.
[0062]
In addition, after protecting the overvoltage protection device from overvoltage that occurs continuously within a predetermined time, the induction machine may be stopped depending on the system needs, or if the induction machine is in the variable speed operation range, it may be operated continuously. it can.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a first embodiment of a variable speed system according to the present invention.
FIG. 2 is a system diagram showing a second embodiment of the variable speed system according to the present invention.
FIG. 3 is a flowchart showing an operation sequence in each embodiment of the protection method of the overvoltage protection device of the variable speed system according to the present invention.
FIG. 4 is a system diagram showing a conventional variable speed system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Generator motor 2 Power converter 3 Overvoltage protection device 4 System 5 Circuit breaker 6 Phase switching disconnector 7 Induction machine 8 Secondary circuit 9 Overvoltage protection control device 10 Rotation speed detector 11 Wattmeter 12 Circuit breaker control device

Claims (5)

An induction machine capable of rotating the rotor at a variable speed, a circuit breaker that parallels the induction machine in the system or disconnects from the system, and an excitation current of variable frequency to the rotor of the induction machine. A variable speed system comprising: a power conversion device to be supplied; an overvoltage protection device for protecting the power conversion device from an overvoltage induced in the rotor; and a control unit that detects the overvoltage and operates the overvoltage protection device. In
Adding a circuit breaker control means for controlling opening and closing of the circuit breaker to the control means ;
The variable speed system is characterized in that the control means performs control to open the circuit breaker when a predetermined number of overvoltages are generated within a predetermined time . An induction machine capable of rotating the rotor at a variable speed, a circuit breaker that parallels the induction machine in the system or disconnects from the system, and an excitation current of variable frequency to the rotor of the induction machine. A power conversion device to be supplied, an overvoltage protection device for protecting the power conversion device from an overvoltage induced in the rotor, and an overvoltage protection control unit that detects the overvoltage and operates the overvoltage protection device. In a transmission system, an electric energy detection means for detecting an electric energy consumed by a secondary circuit connecting the rotor and the power converter ;
This is connected to the power amount detecting means, a variable speed system in which the electric energy is characterized in that it comprises a circuit breaker control means for controlling to open the breaker when it exceeds a predetermined value within a predetermined time. An induction machine capable of rotating the rotor at a variable speed, a circuit breaker that parallels the induction machine in the system or disconnects from the system, and an excitation current of variable frequency to the rotor of the induction machine. In a protection method for an overvoltage protection device of a variable speed system comprising: a power conversion device to be supplied; and an overvoltage protection device for protecting the power conversion device from an overvoltage induced in the rotor.
When the number of times of detection of the overvoltage within a predetermined time is equal to or less than a predetermined number of times, the overvoltage protection device is activated, and when the overvoltage is detected exceeding the predetermined number of times, the circuit breaker is opened. A method for protecting an overvoltage protection device for a variable speed system, wherein the induction machine is disconnected from a system. An induction machine capable of rotating the rotor at a variable speed, a circuit breaker that parallels the induction machine in the system or disconnects from the system, and an excitation current of variable frequency to the rotor of the induction machine. In a protection method for an overvoltage protection device of a variable speed system comprising: a power conversion device to be supplied; and an overvoltage protection device for protecting the power conversion device from an overvoltage induced in the rotor.
The overvoltage protection device is activated when the amount of power supplied to the rotor within a predetermined time is less than or equal to a predetermined value, and the power exceeding the predetermined value for the rotor within the predetermined time A protection method for an overvoltage protection device of a variable speed system, wherein when detecting that a quantity is supplied, the circuit breaker is opened to disconnect the induction machine from the system. 5. The protection method for an overvoltage protection device for a variable speed system according to claim 3 or 4, wherein the induction machine rotates at a rotational speed within a variable speed operation range when a certain time has elapsed after the circuit breaker is opened. In this case, the circuit breaker is closed again, and the induction machine is re-parallelized in a series.

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