JP2005261008A - Permanent magnet generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect the element of an inverter by preventing an overvoltage when a generator speed becomes an overspeed. <P>SOLUTION: If the rotation of a water wheel 2 is transmitted to a permanent magnet generator 1, a power generation will be performed. The generated power is converted into a commercial frequency by an inverter 5, and then supplied to a distribution line 7. If an overspeed relay 10 detects that the rotational speed of the permanent magnet generator 1 becomes the overspeed, the power relay 11 operates and a clutch mechanism 12 will become in an open state. Thus, the rotary force of the water wheel 2 is not transmitted to the permanent magnet generator 1, the generated power of the permanent magnet generator 1 does not become the overvoltage, and the overvoltage is not applied to the power conversion element of the inverter 5, and the element can be protected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a permanent magnet power generator, and is devised to protect an inverter device from an overvoltage generated when a permanent magnet generator (PMG) is overspeeded.

  In a hydraulic power generation system in which an excitation control device and a speed control device are omitted and a permanent magnet generator is applied as a generator, the frequency of the voltage generated by the permanent magnet generator may not be a commercial frequency. In order to convert the power into the commercial frequency, the power generated by the permanent magnet generator is converted into the power at the commercial frequency by the inverter device, and then is sent to the commercial power system.

  Such a conventional hydroelectric power generation system will be described with reference to FIG. Although the actual circuit is a three-phase three-wire circuit, FIG. 2 shows a single-wire connection diagram.

  As shown in FIG. 2, the rotor of the permanent magnet generator 1 is connected to the water turbine 2 via the main shaft 3. That is, the rotational force generated by the water turbine 2 is transmitted to the generator shaft of the permanent magnet generator 1 via the main shaft 3. Since the permanent magnet generator 1 does not have an excitation control device, and the water turbine 2 does not have a speed control device, the output voltage and output frequency of the permanent magnet generator 1 change according to the rotational speed of the water turbine 2. The rotational speed of the permanent magnet generator 1 (water turbine 2) is detected by a rotational speed detector 4.

  The inverter device 5 includes a converter 5a, an inverter 5b, a gate circuit 5c, and the like. The converter 5a and the inverter 5b are configured by power elements (power conversion elements) such as thyristors and GTOs. Although not shown, the inverter device 5 is provided with a relay for device protection, a transformer for instrument, and various protection devices.

  Here, the apparatus comprised with the member shown with the code | symbol 1-6 is called the "permanent magnet power generator."

  The AC power generated by the permanent magnet generator 1 is once converted to DC power by the converter 5a, and further converted to AC power of commercial frequency by the inverter 5b. The AC power having the commercial frequency is supplied to the distribution line (commercial power system) 7 through the power supply line 6.

  In addition, although illustration is abbreviate | omitted, the feeder 6 is equipped with the relay for apparatus protection, the transformer for instruments, the switchgear, and various protective devices. There are also various devices that take in the generated power as in-house power.

Japanese Patent Laid-Open No. 13-057735

  In a hydroelectric power generation system without a speed control device as shown in FIG. 2, the rotational speed of the main engine (permanent magnet generator 1) becomes faster than the rated speed when the load is interrupted, and in some cases, the unrestrained speed may be reached. is there.

Since the permanent magnet generator 1 has a permanent magnet in the rotor and magnetic flux is always generated from the rotor, a voltage is generated in the armature winding when the rotor rotates. In the case of a generator such as the permanent magnet generator 1 in which a voltage is generated in the armature winding as long as it is rotated, the voltage generated in the rotor and the voltage generated in the armature winding are substantially proportional.
Further, in a hydroelectric power generation system without an excitation control device, when the generator voltage fluctuates, the voltage cannot be restored.

  Therefore, in a hydroelectric power generation system that employs the permanent magnet generator 1 and does not have a speed control device and an excitation control device, as shown in FIG. 2, when load interruption occurs during operation with a load, the rotational speed increases. Along with this, the generator circuit voltage rises, so the main circuit voltage also rises.

  For this reason, if the main circuit voltage rises beyond the withstand voltage of the elements of the converter 5a and the inverter 5b provided in the inverter device 5 applied to the main circuit, the elements of the converter 5a and the inverter 5b may be destroyed. If element destruction occurs, it becomes impossible to supply power to the commercial power system.

  In view of the above-described prior art, the present invention can cut off the mechanical input to the generator when the rotational speed of the permanent magnet generator becomes overspeed and becomes an overvoltage state for the elements of the inverter device. An object of the present invention is to provide a permanent magnet power generator capable of protecting the elements of the device.

The present invention that solves the above-mentioned problems is a permanent power supply that connects a turbine and a permanent magnet generator with a main shaft, converts the electric power generated by the permanent magnet generator into a commercial frequency by an inverter device, and then supplies the commercial power to the commercial power system. In the magnet power generator,
Overspeed detecting means for detecting the rotational speed of the permanent magnet generator and outputting an overspeed generation signal when the rotational speed becomes greater than a predetermined set rotational speed;
When an overspeed generation signal is output from the overspeed detection means, the relay is activated, and at other times the relay is inactivated,
The main shaft is interposed, and when the relay is in an inactive state, it is in a connected state and transmits the rotational force of the turbine to the permanent magnet generator. And a clutch mechanism for interrupting transmission of the rotational force to the permanent magnet generator.

  In the present invention, when the permanent magnet generator is in an overspeed state, the clutch mechanism is opened, the transmission of the rotational force from the turbine to the permanent magnet generator is interrupted, and the increase in the rotation speed of the permanent magnet generator is suppressed. Prevent the occurrence of overvoltage. For this reason, an overvoltage does not act on the element of an inverter, and an element can be protected from an overvoltage.

  The best mode for carrying out the present invention will be described below in detail with reference to examples.

  FIG. 1 is a circuit diagram showing a permanent magnet power generator according to an embodiment of the present invention. Although the actual circuit is a three-phase three-wire circuit, FIG. 1 shows a single-wire connection diagram.

  As shown in FIG. 1, the rotor (generator shaft) of the permanent magnet generator 1 is connected to a turbine 2 via a main shaft 3. That is, the rotational force generated by the water turbine 2 is transmitted to the generator shaft of the permanent magnet generator 1 via the main shaft 3. Since the permanent magnet generator 1 does not have an excitation control device, and the water turbine 2 does not have a speed control device, the output voltage and output frequency of the permanent magnet generator 1 change according to the rotational speed of the water turbine 2. The rotational speed of the permanent magnet generator 1 (water turbine 2) is detected by a rotational speed detector 4.

  The inverter device 5 includes a converter 5a, an inverter 5b, a gate circuit 5c, and the like. The converter 5a and the inverter 5b are configured by power elements (power conversion elements) such as thyristors and GTOs. Although not shown, the inverter device 5 is provided with a relay for device protection, a transformer for instrument, and various protection devices.

  Here, the apparatus comprised with the member shown with the code | symbol 1-6 is called the "permanent magnet power generator."

  The AC power generated by the permanent magnet generator 1 is once converted to DC power by the converter 5a, and further converted to AC power of commercial frequency by the inverter 5b. The AC power having the commercial frequency is supplied to the distribution line (commercial power system) 7 through the power supply line 6.

  In addition, although illustration is abbreviate | omitted, the feeder 6 is equipped with the relay for apparatus protection, the transformer for instruments, the switchgear, and various protective devices. There are also various devices that take in the generated power as in-house power.

  Furthermore, in this embodiment, an overspeed relay 10, a power relay 11, and a clutch mechanism 12 are provided.

The overspeed relay 10 compares the actual rotational speed of the permanent magnet generator 1 detected by the rotational speed detector 4 with a preset rotational speed (set value), and the actual rotational speed is higher than the set rotational speed. When it becomes larger, it is determined that the permanent magnet generator 1 is in an overspeed operation, and an overspeed generation signal A is output toward the power relay 11.
The rotational speed detector 4 and the overspeed relay 10 constitute “overspeed detection means”.

  When the overspeed generation signal A is not input, the power relay 11 enters an inoperative state (demagnetization state), and when the overspeed generation signal A is input, the power relay 11 enters an operation state (excitation state).

  The clutch mechanism 12 is interposed on the main shaft 3. The clutch mechanism 12 is in a connected state when the power relay 11 is in an inoperative state, and transmits the rotational force of the turbine 2 to the generator shaft of the permanent magnet generator 1. The clutch mechanism 12 is opened when the power relay 11 is in an operating state, and interrupts transmission of rotational force from the turbine 2 to the generator shaft of the permanent magnet generator 1.

  In this embodiment, when the rotational speed of the permanent magnet generator 1 increases to become overspeed and reaches a set value, the overspeed generation signal A is output from the overspeed relay 10 and the power relay 11 is activated. For this reason, the clutch mechanism 12 is opened, and the rotational force generated in the water turbine 2 is blocked from being input and transmitted to the permanent magnet generator 1. For this reason, there is no mechanical input to the permanent magnet generator 1, an increase in the rotational speed thereof is suppressed, no overvoltage is generated from the permanent magnet generator 1, and the elements of the converter 5a and the inverter 5b are exposed to the overvoltage. Nothing will happen. For this reason, the element of the inverter apparatus 5 can be protected from destruction.

  In this way, since the elements of the inverter device 5 can be protected from overvoltage and can be prevented from being destroyed, when the load interruption state is resolved, the connection state of the clutch mechanism 12 is recovered and the rotational force of the turbine 2 is changed to a permanent magnet generator. 1 to resume normal power generation.

  The present invention can be applied to a hydroelectric power generation system (permanent magnet power generation device) in which an excitation control device and a speed control device are omitted, a permanent magnet generator is applied as a power generator, and the generated power is frequency-converted by an inverter device. It is.

The circuit diagram which shows the Example of this invention. The circuit diagram which shows a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Permanent magnet generator 2 Turbine 3 Spindle 4 Rotational speed detector 5 Inverter device 5a Converter 5b Inverter 5c Gate circuit 6 Feeding line 7 Distribution line (commercial power system)

Claims (1)

In a permanent magnet power generator that connects a turbine and a permanent magnet generator with a main shaft, and converts the electric power generated in the permanent magnet generator into a commercial frequency by an inverter device and then supplies the commercial power system,
Overspeed detecting means for detecting the rotational speed of the permanent magnet generator and outputting an overspeed generation signal when the rotational speed becomes greater than a predetermined set rotational speed;
When an overspeed generation signal is output from the overspeed detection means, the relay is activated, and at other times the relay is inactivated,
The main shaft is interposed, and when the relay is in an inactive state, it is in a connected state and transmits the rotational force of the turbine to the permanent magnet generator. A permanent magnet power generator, comprising: a clutch mechanism that interrupts transmission of rotational force to the permanent magnet generator.

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