Brushless Synchronous Machine Protection Device

Abstract

To provide a brushless synchronous machine protecting device capable of stopping a synchronous motor only during a normal operation.SOLUTION: When a failure in a semiconductor element 25 is reported by an element failure detecting device 30, a differential current between a first excitation current feedback value which is an excitation current feedback value stored in excitation current feedback storing means at a clock time of the report of the failure in the semiconductor element 25, and a second excitation current feedback value which is an excitation current feedback value stored in the excitation current feedback storing means at a clock time that is prior to the clock time of the report of the failure in the semiconductor element 25 by a prescribed current change monitoring time, is calculated. When the calculated differential current is larger than a prescribed current threshold, it is determined that a failure has occurred in the semiconductor element 25, and a command to stop a brushless synchronous machine is outputted. When the differential current is equal to or smaller than the prescribed current threshold, it is determined that the element failure detecting device 30 has failed or malfunctioned, a command to stop the brushless synchronous machine is not outputted but a prescribed alarm is outputted.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a protection device capable of preventing unwanted operation of a rotating rectifier fault detection device for a brushless synchronous machine. [Background technology]

[0002] Generally, in a brushless synchronous motor, the exciter rotor rotates within the magnetic field of the exciter stator, generating a three-phase AC voltage in the exciter rotor, which is rectified by a rotating rectifier and supplies a DC current to the synchronous motor field winding.

[0003] Conventionally, a rotating rectifier in a synchronous motor uses a semiconductor element, and therefore a rotating rectifier fault detection device is often provided to detect faults in the semiconductor element. For example, when a fault occurs in the semiconductor element, a large voltage ripple different from that during normal operation occurs during rectification by the rotating rectifier. Since the voltage ripple is propagated to the exciter stator, the rotating rectifier fault detection device detects the voltage ripple via a fault detection winding to detect a fault in the semiconductor element (see, for example, Patent Document 1). When the rotating rectifier fault detection device is activated, the AC input to the synchronous motor is cut off to stop the synchronous motor from the viewpoint of equipment protection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-285457 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if the rotary rectifier fault detection device operates, it is difficult to determine whether the semiconductor element in the rotary rectifier is actually at fault or whether the rotary rectifier fault detection device is at fault or malfunctioning. For this reason, in the past, when a fault is detected by the rotary rectifier fault detection device, the synchronous motor in operation is immediately stopped (immediately stopped) for safety. That is, in the past, when a fault is reported by the rotary rectifier fault detection device, the synchronous motor is stopped regardless of the reason for the fault report, such as a fault in the semiconductor element in the rotary rectifier or a fault or malfunctioning of the rotary rectifier fault detection device. For example, if a semiconductor element in the rotary rectifier of a synchronous motor is actually at fault, if the synchronous motor is continued to be operated as it is, the synchronous motor will suffer an expanded fault (failure in a part other than the relevant part of the rotary rectifier or failure of the main body of the synchronous motor), and repair will take a long time. In this case, since it will have a large impact on the production process in the factory, the synchronous motor is stopped in an emergency and an inspection is immediately carried out to identify the faulty part.

[0006] Incidentally, examples of failures of the rotary rectifier include element failures such as short circuit or open circuit of a semiconductor element, while examples of failures or malfunctions of the rotary rectifier failure detection device include failures due to a fault in a connected fault detection winding, accidental failures of electronic components mounted on a board of an internal circuit (e.g., a filter circuit, a level detection circuit, etc.) or defects due to aging.

[0007] For this reason, in the conventional method, when the rotating rectifier fault detection device fails or malfunctions, there is a problem that the synchronous motor is unnecessarily stopped even though the operation of the synchronous motor is not affected. Note that this is not limited to synchronous motors, but is the same for synchronous generators.

[0008] Therefore, an object of the present disclosure is to provide a protection device for a brushless synchronous machine that is capable of determining whether a rotating rectifier fault detection device is operating normally or has a fault or malfunction, and stopping the synchronous motor only when the rotating rectifier is operating normally. [Means for solving the problem]

[0009] A protection device for a brushless synchronous machine according to one embodiment is a protection device for use in a brushless synchronous machine having a brushless exciter, a rotary rectifier having a semiconductor element disposed on a rotor in the brushless exciter, and an element failure detection device for detecting a failure of the semiconductor element in the rotary rectifier, During the current or past specified period and an excitation current feedback storage means for acquiring an excitation current feedback value of the brushless excitation device and storing it in association with the time of acquisition, and when a failure of a semiconductor element is reported by the element failure detection device, a differential current is calculated between a first excitation current feedback value, which is the excitation current feedback value stored in the excitation current feedback storage means at the time when the failure of the semiconductor element was reported, and a second excitation current feedback value, which is the excitation current feedback value stored in the excitation current feedback storage means at a time that is a predetermined current change monitoring time prior to the time when the failure of the semiconductor element was reported, and when the calculated differential current is greater than a predetermined current threshold, it is determined that a failure has occurred in the semiconductor element and a command to stop the brushless synchronous machine is output, and when the differential current is equal to or less than the predetermined current threshold, it is determined that a failure or malfunction of the element failure detection device has occurred, and a command to stop the brushless synchronous machine is not output, but a predetermined alarm is output.

[0010] A protection device for a brushless synchronous machine according to another aspect is a protection device for use in a brushless synchronous machine having a brushless exciter, a rotary rectifier having a semiconductor element disposed on a rotor in the brushless exciter, and an element failure detection device for detecting a failure of the semiconductor element in the rotary rectifier, During the current or past specified period an active power storage means for acquiring an active power value of the brushless synchronous machine and storing the acquired value in association with a time of acquisition; During the current or past specified period,and reactive power storage means for acquiring reactive power values ​​with a leading phase component of the brushless synchronous machine being positive and a lagging phase component being negative, and storing the reactive power values ​​in association with the time of acquisition, wherein, when a semiconductor element failure is reported by the element failure detection device, a differential active power is calculated between a first active power value which is the active power value stored in the active power storage means at the time when the semiconductor element failure was reported, and a second active power value which is the active power value stored in the active power storage means at a time preceding the time when the semiconductor element failure was reported by a predetermined active power change monitoring time, and when the calculated differential active power is greater than the predetermined active power threshold value, the differential active power is calculated based on the first active power value stored in the active power storage means at the time when the semiconductor element failure was reported. and calculating a differential reactive power between a first reactive power value, which is a reactive power value detected by the reactive power storage means at a time a predetermined reactive power change monitoring time prior to the time when a semiconductor element failure was reported, and a second reactive power value, which is a reactive power value stored in the reactive power storage means at a time a predetermined reactive power change monitoring time prior to the time when a semiconductor element failure was reported, and when the calculated differential reactive power is smaller than a predetermined reactive power threshold, determining that a failure has occurred in the semiconductor element and outputting a command to stop the brushless synchronous machine, and when the differential active power is equal to or less than the predetermined active power threshold or when the differential reactive power is equal to or more than the predetermined reactive power threshold, determining that a failure or malfunction has occurred in the element failure detection device, not outputting a command to stop the brushless synchronous machine, but outputting a predetermined alarm.

[0011] A protection device for a brushless synchronous machine according to another aspect is a protection device for use in a brushless synchronous machine having a brushless exciter, a rotary rectifier having a semiconductor element disposed on a rotor in the brushless exciter, and an element failure detection device for detecting a failure of the semiconductor element in the rotary rectifier, During the current or past specified period, an excitation current feedback storage means for acquiring an excitation current feedback value corresponding to an input current of an exciter stator winding of a brushless excitation device, and storing the value in association with the time of acquisition; During the current or past specified period an active power storage means for acquiring an active power value of the brushless synchronous machine and storing the acquired value in association with a time of acquisition; During the current or past specified period,The present invention is provided with reactive power storage means for acquiring reactive power values ​​of the brushless synchronous machine with a leading phase component being positive and a lagging phase component being negative, and storing the reactive power values ​​in association with the time of acquisition, and means for acquiring a signal for determining whether the brushless synchronous machine is operated under a power factor control control method or a constant excitation control control method, and when the brushless synchronous machine is operated under the power factor control control method and a semiconductor element failure is reported by the element failure detection device, a first excitation current feedback value which is an excitation current feedback value stored in the excitation current feedback storage means at the time when the semiconductor element failure is reported, and a second excitation current feedback value which is a delay time of the semiconductor element failure are stored in the excitation current feedback storage means. A differential current is calculated between the second excitation current feedback value, which is the excitation current feedback value stored in the excitation current feedback storage means at a time a predetermined current change monitoring time prior to the time when the fault was reported, and when the calculated differential current is greater than a predetermined current threshold, it is determined that a fault has occurred in the semiconductor element, and a command to stop the brushless synchronous machine is output, and when the differential current is equal to or less than the predetermined current threshold, it is determined that a fault or malfunction has occurred in the element fault detection device, a command to stop the brushless synchronous machine is not output, and a predetermined alarm is output, and the brushless synchronous machine is operated in a control method of constant excitation control. and when a semiconductor element failure is reported by the element failure detection device, a differential active power is calculated between a first active power value which is an active power value stored in the active power storage means at the time when the semiconductor element failure is reported and a second active power value which is an active power value stored in the active power storage means at a time preceding the time when the semiconductor element failure is reported by a predetermined active power change monitoring time, and when the calculated differential active power is greater than the predetermined active power threshold, the first reactive power value which is a reactive power value stored in the reactive power storage means at the time when the semiconductor element failure is reported and the second active power value which is a reactive power value stored in the reactive power storage means at the time when the semiconductor element failure is reported are calculated. a differential reactive power between the first reactive power value and a second reactive power value stored in the reactive power storage means at a time preceding the time when the semiconductor element failure was reported by a predetermined reactive power change monitoring time, and when the calculated differential reactive power is smaller than a predetermined reactive power threshold, it is determined that a failure has occurred in the semiconductor element and a command to stop the brushless synchronous machine is output; when the differential active power is equal to or smaller than the predetermined active power threshold or when the differential reactive power is equal to or larger than the predetermined reactive power threshold, it is determined that a failure or malfunction has occurred in the element failure detection device and a command to stop the brushless synchronous machine is not output;The present invention is characterized in that a predetermined warning is output. Effect of the Invention

[0012] According to the present disclosure, it is possible to provide a protection device for a brushless synchronous machine in which a rotating rectifier fault detection device is capable of determining whether the synchronous motor is operating normally or has a fault or malfunction, and stopping the synchronous motor only if the rectifier is operating normally. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of a brushless synchronous motor system according to an embodiment; [Diagram 2] 2 is a diagram showing an example of the configuration of a protection device and an unnecessary operation prevention circuit of the synchronous motor system shown in FIG. 1. [Diagram 3] 3 is a flowchart showing an example of the operation of the unnecessary operation prevention circuit in the protection device for the synchronous motor system shown in FIGS. 1 and 2. [Figure 4] 4 is a flowchart showing a continuation of the process in the flowchart shown in FIG. 3. [Diagram 5] 5 is a conceptual diagram showing an example of the hardware configuration of a processing circuit included in an exciter control unit and a protection device in the embodiment shown in FIGS. 1 to 4. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a protection device for a brushless synchronous machine according to the present disclosure will be described with reference to the drawings.

[0015] <Configuration of one embodiment> FIG. 1 is a diagram showing an example of the overall configuration of a brushless synchronous motor system 1 according to an embodiment.

[0016] In this embodiment, an example will be described in which protection device 80 for a brushless synchronous machine is applied to a brushless synchronous motor system 1 as an example of a brushless synchronous machine. Details of protection device 80 for a brushless synchronous machine will be described later.

[0017] 1, the brushless synchronous motor system 1 includes a brushless synchronous motor main body 10, a brushless exciter 20, a rotary rectifier fault detection device 30, an exciter main circuit section 40, an exciter control section 50, and a protection device 80. The brushless synchronous motor system 1 also includes a first circuit breaker 61, an instrument transformer 62, a second circuit breaker 71, and a multimeter 64. In the brushless synchronous motor system 1, the brushless synchronous motor main body 10 is connected to a three-phase AC power source 60 via an AC circuit 67 and the first circuit breaker 61, and the exciter main circuit section 40 is connected to a three-phase AC power source 70 via an AC circuit 72 and the second circuit breaker 71.

[0018] The brushless synchronous motor body 10 is also called a synchronous motor (SM), and is an electric motor whose rotating shaft rotates at a synchronous speed determined by the frequency of an AC power supply 60, which is the main circuit input power supply on the primary side. The brushless synchronous motor body 10 is generally of a fixed speed, and its rotation speed changes when the frequency of the primary voltage changes. The brushless synchronous motor body 10 converts the electric energy supplied from the AC power supply 60 into mechanical energy (rotational energy) by rotating the rotating shaft, and outputs the converted energy. Hereinafter, in this specification, the brushless synchronous motor system 1 is also simply called the "synchronous motor system 1." Moreover, the brushless synchronous motor body 10 and the brushless excitation device 20 are collectively also simply called the "synchronous motor."

[0019] The brushless synchronous motor body 10 has a synchronous motor excitation winding 11 and a synchronous motor stator winding 12. Hereinafter in this specification, the brushless synchronous motor body 10 is also simply referred to as the "synchronous motor body 10."

[0020] The synchronous motor excitation winding 11 constitutes a rotor 24 that is inserted inside the cylindrical synchronous motor stator winding 12, and generates a magnetic flux by the excitation current supplied by the brushless excitation device 20. The synchronous motor excitation winding 11 is attracted to the rotating magnetic field of the synchronous motor stator winding 12 and rotates by following it.

[0021] The synchronous motor stator winding 12 is a stator connected to an AC power supply 60, and a rotating magnetic field is created by the AC current supplied by the AC power supply 60. The synchronous motor stator winding 12 is, for example, a cylindrical stator winding, and the synchronous motor excitation winding 11 of the rotor 24 is inserted inside the cylinder.

[0022] The brushless exciter 20 has an exciter stator winding 21, an exciter rotor 22, and a rotary rectifier 23. The exciter rotor 22 and the rotary rectifier 23, together with the synchronous motor excitation winding 11, form a rotor 24. Hereinafter in this specification, the brushless exciter 20 is also simply referred to as the "exciter 20."

[0023] The exciter stator winding 21 is connected to an AC power supply 70 via the exciter main circuit section 40. The exciter stator winding 21 generates a magnetic field when an excitation current that has been converted from AC to DC by the exciter main circuit section 40 flows through it. The exciter stator winding 21 is, for example, a cylindrical stator winding, and the exciter rotor 22 of the rotor 24 is inserted into the cylindrical interior.

[0024] The exciter rotor 22 generates a three-phase AC voltage by rotating within the magnetic field of the exciter stator winding 21. The exciter rotor 22 supplies the generated AC current to a rotating rectifier 23 that is mechanically connected to the rotor 24 by a rotating shaft.

[0025] The rotary rectifier 23 is, for example, configured with a plurality of semiconductor elements 25 connected in a three-phase bridge, with the DC side connected to the synchronous motor excitation winding 11 and the AC side connected to the exciter rotor 22. The rotary rectifier 23 converts (rectifies) the AC current supplied from the exciter rotor 22 into a DC current by the semiconductor elements 25, and supplies the converted DC current to the synchronous motor excitation winding 11 to which it is mechanically connected.

[0026] The rotor 24 is configured by mechanically fixing the synchronous motor excitation winding 11, the rotary rectifier 23, the exciter rotor 22, and a rotor core (not shown) to the rotating shaft from one end to the other end, and rotates together with the rotating shaft. The synchronous motor main body 10 rotates the rotor 24, thereby outputting mechanical energy (rotational energy) through the rotation of the rotating shaft.

[0027] The semiconductor element 25 is, for example, a diode, and, for example, six of them are arranged in the rotating rectifier. The semiconductor element 25 converts (rectifies) the AC current supplied from the exciter rotor 22 into a DC current. When, for example, a short circuit or an open circuit fault occurs, the semiconductor element 25 generates a voltage ripple different from normal during rectification. The generated voltage ripple is propagated to the exciter stator winding 21.

[0028] The rotary rectifier fault detection device 30 has an element fault detection winding 31, and a filter circuit, a level detection circuit, etc. (not shown). The rotary rectifier fault detection device 30 judges whether or not a fault has occurred in the semiconductor element 25 by judging the voltage ripple detected via the element fault detection winding 31 using an internal filter circuit, a level detection circuit, etc. (not shown). The rotary rectifier fault detection device 30 is connected to a protection device 80, and when it is judged that a fault has occurred in the semiconductor element 25, it issues an element fault detection signal of, for example, H level to the protection device 80. Hereinafter, in this specification, the rotary rectifier fault detection device 30 is also referred to as the "element fault detection device 30".

[0029] The element failure detection winding 31 is disposed near the exciter stator winding 21, and detects a voltage ripple propagated to the exciter stator winding 21 during commutation when, for example, a failure occurs in the semiconductor element 25. The element failure detection winding 31 outputs the detected voltage ripple to the element failure detection device 30.

[0030] In addition, the element failure detection device 30 normally issues a failure detection signal to the protection device 80 as an H level when a failure occurs in the semiconductor element 25, but there is a possibility that the element failure detection device 30 also issues an H level to the protection device 80 when the rotary rectifier failure detection device 30 fails or malfunctions. For example, the element failure detection device 30 may issue an H level to the protection device 80 in the case of a failure in the element failure detection winding 31 or a failure in an electronic component mounted on a board of an internal circuit such as a filter circuit or a level detection circuit (not shown). In the following description, when the element failure signal is issued as an H level due to a failure or malfunction of the rotary rectifier failure detection device 30, this is also simply referred to as an "unnecessary operation". In addition, when an abnormality occurs inside the excitation device 20, for example, when an abnormality occurs in the semiconductor element 25, the rotary rectifier failure detection device 30 issues an element failure signal as an H level, this is also referred to as a "normal operation".

[0031] The exciter main circuit section 40 has a thyristor rectifier 41 for the excitation circuit and a shunt 42 for detecting the excitation current.

[0032] The thyristor rectifier 41 for the excitation circuit has one end of a DC output connected to one end of the exciter stator winding 21, and the other end of the DC output connected to the other end of the exciter stator winding 21 via an excitation current detection shunt 42. The AC input of the thyristor rectifier 41 for the excitation circuit is connected to a three-phase AC power source 70 via a second circuit breaker 71. The thyristor rectifier 41 for the excitation circuit is also connected to an exciter control unit 50. The thyristor rectifier 41 for the excitation circuit converts (rectifies) the AC current supplied from the AC power source 70 into a DC current according to a thyristor rectifier control signal output from the exciter control unit 50, and supplies the converted DC current to the exciter stator winding 21. Hereinafter, in this specification, the thyristor rectifier 41 for the excitation circuit is also simply referred to as the "thyristor rectifier 41".

[0033] The excitation current detection shunt (DC current detector) 42 detects the DC current output from the thyristor rectifier 41, and outputs an excitation current feedback signal using the detected value to the exciter control unit 50 and the protection device 80. The excitation current detection shunt 42 may be a Hall CT. Also, instead of the excitation current detection shunt 42, a CT or the like may be provided on the AC input side of the exciter main circuit unit 40, and the output of the CT or the like may be rectified to DC and used as the excitation current feedback signal.

[0034] The exciter control unit 50 has a processor 91, described later, such as a CPU (Central Processing Unit) that operates by executing a program, for example. The exciter control unit 50 operates the processor 91, described later, by executing a predetermined program stored in a memory 92, described later, for example, to control the exciter main circuit unit 40. The exciter control unit 50 controls the thyristor rectifier 41 for the excitation circuit by, for example, transmitting a thyristor rectifier control signal to the thyristor rectifier 41 for the excitation circuit, thereby controlling the exciter main circuit unit 40 and generally controlling the synchronous motor main body 10.

[0035] The exciter control unit 50 has an excitation current setter 51, a first subtractor 52, a current control unit 53, a power factor setter 54, a second subtractor 55, a power factor control unit 56, a changeover switch 57, and an excitation mode setter 58.

[0036] The excitation current setter 51 receives instructions from a higher-level device (not shown) or an operator or instructions from a predetermined program, sets a predetermined excitation current set value for the excitation current, and outputs it to the first subtractor 52. Note that the constant excitation control is an excitation current control that adjusts the excitation current of the synchronous motor body 10 so that it follows the excitation current set value even if the load of the synchronous motor body 10 or the AC power supply 70 fluctuates.

[0037] The first subtractor 52 outputs a control signal obtained by subtracting the value of the excitation current feedback signal acquired from the excitation current detection shunt 42 from the value set by the excitation current setting device 51 to the current control unit 53 .

[0038] The current control unit 53 performs a predetermined calculation in response to the control signal obtained from the first subtractor 52, and outputs to the changeover switch 57 a thyristor rectifier control signal for performing a constant excitation control operation.

[0039] The power factor setter 54 accepts instructions from a higher-level device (not shown) or an operator or instructions from a predetermined program, sets the power factor to a predetermined command power factor value, and outputs it to the second subtracter 55. Note that the power factor control is an excitation current control that adjusts the excitation current of the synchronous motor body 10 so that the power factor of the synchronous motor body 10 becomes the predetermined command power factor value of the power factor control even if the load of the synchronous motor body 10 fluctuates. For example, in the case of power factor control, when the load increases, the power factor decreases with the same back electromotive force, and the efficiency decreases as the consumption of reactive power of the synchronous motor body 10 increases. Therefore, the excitation current is increased to increase the back electromotive force of the synchronous motor body 10, and the input AC current phase of the synchronous motor body 10 is adjusted to a predetermined phase.

[0040] The second subtractor 55 outputs a control signal obtained by subtracting the value of the power factor signal obtained from the multimeter 64 from the value set by the power factor setter 54 to the power factor control unit 56 .

[0041] The power factor control unit 56 performs a predetermined calculation in response to the control signal obtained from the second subtractor 55, and outputs to the changeover switch 57 a thyristor rectifier control signal for performing a power factor control operation.

[0042] The changeover switch (SW) 57 is, for example, a c-contact, and switches between constant excitation control and power factor control according to a mode set by an excitation mode setting device 58. For example, when the constant excitation control mode is set by the excitation mode setting device 58, the changeover switch 57 connects contact 2 and contact 3 in FIG. 1. That is, the output of the current control device 53 is output to the excitation circuit thyristor rectifier 41 as a thyristor rectifier control signal. On the other hand, when the power factor control mode is set by the excitation mode setting device 58, the changeover switch 57 connects contact 1 and contact 3 in FIG. 1. That is, the output of the power factor control device 56 is output to the excitation circuit thyristor rectifier 41 as a thyristor rectifier control signal. Hereinafter, in this specification, the changeover switch 57 is also referred to as a "changeover SW 57".

[0043] The excitation mode setter 58 receives, for example, instructions from an operator via an operation panel (not shown) or instructions from a predetermined program from a higher-level device (not shown) and sets a mode (control method) of either a constant excitation control mode or a power factor control mode. The excitation mode setter 58 is connected to the switch 57 and the protection device 80, and outputs the set mode (control method) to the switch 57 and the protection device 80, respectively.

[0044] The AC power source 60 is connected to the synchronous motor stator winding 12 of the synchronous motor main body 10 via an AC circuit 67 and a first circuit breaker 61, and supplies three-phase AC power to the synchronous motor stator winding 12. A potential transformer 62 is connected to the AC circuit 67, and the voltage of the AC bus is measured and output to a multimeter 64 and an out-of-step relay 65. A current transformer 63 is connected to the side of the first circuit breaker 61 of the AC circuit 67 that is connected to the synchronous motor main body 10, and the input current of the synchronous motor main body 10 is measured and output to the out-of-step relay 65 and an overcurrent relay 66.

[0045] The first circuit breaker 61 cuts off the AC current flowing from the AC power source 60 to the synchronous motor stator winding 12 of the synchronous motor main body 10 based on a trip command TC1 output from the protection device 80. This stops the synchronous motor system 1. In this way, the first circuit breaker 61 protects the synchronous motor system 1 and prevents the failure from spreading to the synchronous motor system 1 and the equipment in which it is used.

[0046] In the following, in this specification, the potential transformer (PT) 62 is also referred to as "PT 62." In the following, in this specification, the current transformer (CT) 63 is also referred to as "CT 63."

[0047] The multimeter 64 is an instrument in which an indicator and a converter are integrated, and is connected to the PT 62 and the CT 63, and measures values ​​such as the current and voltage of the AC circuit 67 output from the AC power source 60 via the PT 62 and the CT 63. The multimeter 64 has the functions of an active power detector, a reactive power detector, and a power factor detector, and performs a predetermined conversion or the like on the measured values ​​of the current, voltage, etc. to detect (calculate) values ​​such as active power, reactive power, and power factor. The multimeter 64 outputs an active power signal, which is the value of the detected active power, and a reactive power signal, which is the value of the detected reactive power, to the protection device 80, and outputs a power factor signal, which is the value of the detected power factor, to the second subtractor 55 of the exciter control unit 50. In the embodiment shown in FIG. 1, since the target synchronous machine is an electric motor, the value of the active power is defined to be a positive value when the electric motor is powered. The value of the reactive power is defined to be a positive value when the target synchronous machine outputs a leading phase reactive power, and a negative value when it outputs a lagging phase reactive power.

[0048] The out-of-step relay 65 is a protective relay that is connected to the PT 62 and the CT 63, and outputs an out-of-step signal to the protection device 80 to protect the synchronous motor system 1 when the synchronous motor main body 10 is unable to maintain synchronous speed due to significant fluctuations in the load or the AC power supply 60, and so goes out of step.

[0049] The overcurrent relay 66 is a protective relay that is connected to the CT 63 and outputs an overcurrent signal to the protective device 80 to protect the synchronous motor system 1 when an excessive current, a short circuit, or the like occurs.

[0050] The AC power supply 70 is, for example, a three-phase AC power supply, and is connected to the thyristor rectifier 41 for the excitation circuit of the excitation device main circuit section 40 via a second circuit breaker 71 and an AC circuit 72, and outputs three-phase AC power to the thyristor rectifier 41 for the excitation circuit.

[0051] The second circuit breaker 71 cuts off the AC current (excitation current) flowing from the AC power supply 70 to the thyristor rectifier 41 based on the trip command TC2 output from the protection device 80. This stops the synchronous motor system 1. This allows the second circuit breaker 71 to protect the excitation circuit of the synchronous motor (synchronous motor excitation winding 11, exciter 20, and exciter main circuit section 40), and prevents the failure from spreading to the synchronous motor system 1 and the equipment in which it is used.

[0052] The AC circuit 72 is a circuit that connects the AC power supply 70 and the thyristor rectifier 41, and includes a second circuit breaker 71.

[0053] The protection device 80 has a function of protecting the synchronous motor system 1 when an abnormality occurs in any of the components of the synchronous motor system 1, and has a brushless synchronous machine element fault detection and unnecessary operation prevention circuit 81. The protection device 80 has a processor 91, described below, such as a CPU that operates by executing a program, for example. The protection device 80 operates the processor 91, described below, by executing a predetermined program stored in a memory 92, described below, for example, to protect the synchronous motor system 1 and prevent unnecessary operation.

[0054] The configuration and function of brushless synchronous machine element fault detection unnecessary operation prevention circuit 81 will be described later (see FIG. 2, etc.). In the following description, brushless synchronous machine element fault detection unnecessary operation prevention circuit 81 is also simply referred to as "unnecessary operation prevention circuit 81."

[0055] Fig. 2 is a diagram showing an example of the configuration of the protection device 80 and the unnecessary operation prevention circuit 81 of the synchronous motor system 1 shown in Fig. 1. Note that the configuration or function of the protection device 80 or the unnecessary operation prevention circuit 81 may be possessed by another configuration, such as the excitation device control unit 50 in the synchronous motor system 1, or may be possessed by an external protection device or unnecessary operation prevention device connected to the synchronous motor system 1.

[0056] 2, protection device 80 has a brushless synchronous machine element fault detection unnecessary operation prevention circuit (unnecessary operation prevention circuit) 81, and unnecessary operation prevention circuit 81 has the configuration or functions of a determination unit 87, an acquisition unit 82, a timer 83, a storage unit 84, and an output unit 85. In unnecessary operation prevention circuit 81, the determination unit 87, the acquisition unit 82, the timer 83, the storage unit 84, and the output unit 85 are connected to each other via a system bus 86, for example.

[0057] When an element failure detection signal of H level, which is a failure detection level, is issued from element failure detection device 30, determination section 87 determines whether element failure detection device 30 is operating normally or whether an unnecessary operation of element failure detection device 30 has occurred.

[0058] When the determination unit 87 determines that the semiconductor device 25 is operating normally, the unnecessary operation prevention circuit 81 outputs the trip command TC1 and the trip command TC2, and stops the operation of the synchronous motor system 1. When the unnecessary operation prevention circuit 81 determines that an element failure has occurred in the semiconductor device 25, the unnecessary operation prevention circuit 81 may output a serious fault alarm AL2 in addition to outputting the trip command TC1 and the trip command TC2.

[0059] On the other hand, when the determination unit 87 determines that an unnecessary operation of the element failure detection device 30 has occurred, the unnecessary operation prevention circuit 81 outputs a minor fault alarm AL1 but does not output the trip command TC1 or the trip command TC2, thereby preventing unnecessary operation shutdown of the synchronous motor system 1. The detailed function and operation of the unnecessary operation prevention circuit 81 will be described later (see Figs. 3 and 4, etc.).

[0060] The acquiring unit 82 is connected to the element failure detection device 30, and acquires an element failure detection signal of H level, which is a failure detection level issued from the element failure detection device 30, when the element failure detection device 30 determines that a failure has occurred in the semiconductor element 25. The acquiring unit 82 is also connected to the excitation current detection shunt 42 of the exciter main circuit unit 40, and acquires an excitation current feedback signal output from the excitation current detection shunt 42. The acquiring unit 82 is also connected to the excitation mode setter 58 of the exciter control unit 50, and acquires a signal that can distinguish between a constant excitation control mode or a power factor control mode output by the excitation mode setter 58.

[0061] The acquiring unit 82 is also connected to the multimeter 64 and acquires the active power signal and the reactive power signal output from the multimeter 64. The acquiring unit 82 is also connected to the out-of-step relay 65 and acquires the out-of-step signal output from the out-of-step relay 65. The acquiring unit 82 is also connected to the overcurrent relay 66 and acquires the overcurrent signal output from the overcurrent relay 66.

[0062] The acquisition unit stores the acquired H-level element failure detection signal, excitation current feedback signal, control mode, active power signal, reactive power signal, out-of-step signal, and overcurrent signal in the memory unit 84 via the system bus 86.

[0063] The timer 83 starts or ends counting based on the control of the determination unit 87 or a predetermined condition, and also clears the counted time T based on the control of the determination unit 87 or a predetermined condition. The timer 83 also stores the counted time T in the memory unit 84 based on the control of the determination unit 87 or a predetermined condition, and also resets the time T stored in the memory unit 84 based on the control of the determination unit 87 or a predetermined condition.

[0064] The storage unit 84 is, for example, a volatile or non-volatile storage medium such as an HDD (Hard Disk Drive), and stores a program required for the operation of the unnecessary operation prevention circuit 81. The storage unit 84 stores, for example, various values ​​such as a current or past H-level element failure detection signal, an excitation current feedback signal, a control mode, an active power signal, a reactive power signal, a step-out signal, and an overcurrent signal acquired by the acquisition unit 82, in association with, for example, a measurement time. The storage unit 84 also stores, for example, a current or past time T counted by the timer 83.

[0065] The storage unit 84 may store, for example, various coefficients, various calculation expressions, various thresholds, and various tables used in calculations by the protection device 80 (unwanted operation prevention circuit 81). The storage unit 84 may be provided outside the protection device 80 and connected to the protection device 80 by wire or wirelessly, or may be an external storage medium such as a memory card or a DVD (Digital Versatile Disc). The storage unit 84 may be shared with a memory 92 (see FIG. 5) described later. The storage unit 84 may be shared with parts of the protection device 80 other than the unnecessary operation prevention circuit 81. The storage unit 84 is an example of an "excitation current feedback storage means", an example of an "active power storage means", and an example of a "reactive power storage means".

[0066] The output unit 85 is connected to the first circuit breaker 61, and outputs a trip command TC1 to the first circuit breaker 61 based on the control of the determination unit 87 or other protective units (not shown), causing the first circuit breaker 61 to open, thereby interrupting the AC current flowing from the AC power supply 60. The output unit 85 is also connected to the second circuit breaker 71, and outputs a trip command TC2 to the second circuit breaker 71 based on the control of the determination unit 87 or other protective units (not shown), causing the second circuit breaker 71 to open, thereby interrupting the AC current flowing from the AC power supply 70. The output unit 85 is also connected to a display unit, control device, higher-level device, etc. (not shown), and outputs various warnings (alarms) AL to the display unit, control device, higher-level device, etc. (not shown), based on the control of the determination unit 87 or other protective units (not shown).

[0067] For example, when the determining unit 87 determines that the operation is normal, the output unit 85 outputs a trip command TC1 and a trip command TC2, and also outputs a major fault alarm AL2. On the other hand, when the determining unit 87 determines that an unwanted operation has occurred in an internal circuit (not shown) of the element fault detection device 30, the element fault detection winding 31, or the like, the output unit 85 outputs a minor fault alarm AL1.

[0068] The system bus 86 is a data transmission path (bus) that connects each component inside the protection device 80. The system bus 86 interconnects the determination unit 87, the acquisition unit 82, the timer 83, the storage unit 84, and the output unit 85, and information is transmitted between them depending on the configuration of each connected unit. The system bus 86 may also be connected to parts other than the unwanted operation prevention circuit 81 inside the protection device 80 and transmit data therebetween.

[0069] <Operation of one embodiment> Fig. 3 is a flowchart showing an example of the operation of the unnecessary operation prevention circuit 81 in the protection device 80 of the synchronous motor system 1 shown in Fig. 1 and Fig. 2. The flowchart shown in Fig. 3 starts when the synchronous motor system 1 starts operating.

[0070] In step S102, the unnecessary operation prevention circuit 81 clears the timer 83 to reset the time T counted by the timer 83.

[0071] In step S104, the unnecessary operation prevention circuit 81 causes the acquisition unit 82 to acquire the value of the active power signal and the value of the reactive power signal output from the multimeter 64, and reads the acquired active power value P and reactive power value Q. The unnecessary operation prevention circuit 81 also causes the acquisition unit 82 to acquire the value of the excitation current feedback signal output from the excitation current detection shunt 42, and reads the acquired value as the excitation current feedback value If. The excitation current feedback value If corresponds to the input current of the exciter stator winding 21 of the brushless exciter 20.

[0072] In step S106, the unnecessary operation prevention circuit 81 associates the active power value P read in step S104 with the measurement time and stores it in the storage unit 84. The unnecessary operation prevention circuit 81 also associates the reactive power value Q read in step S104 with the measurement time and stores it in the storage unit 84. The unnecessary operation prevention circuit 81 also associates the excitation current feedback value If read in step S104 with the measurement time and stores it in the storage unit 84.

[0073] In step S108, the unnecessary operation prevention circuit 81 judges whether the element failure detection signal is at H level. That is, the unnecessary operation prevention circuit 81 judges whether the acquisition unit 82 has acquired an element failure detection signal of H level, which is a failure detection level, from the element failure detection device 30. The acquisition unit 82 may acquire the failure detection signal issued from the element failure detection device 30 at any time or at predetermined intervals, or may acquire the failure detection signal issued from the element failure detection device 30 only when an element failure detection signal of H level is issued.

[0074] When the unnecessary operation prevention circuit 81 determines that the element failure detection signal is at H level (Yes side), it shifts the process to step S110. On the other hand, when the unnecessary operation prevention circuit 81 determines that the element failure detection signal is not at H level (No side), it shifts the process to step S202.

[0075] In step S110, the unnecessary operation prevention circuit 81 causes the timer 83 to start counting the time T. Note that, if the timer 83 has already started counting the time T, the unnecessary operation prevention circuit 81 causes the timer 83 to continue counting the time T.

[0076] In step S112, the unnecessary operation prevention circuit 81 judges whether the control mode of the synchronous motor system 1 is the power factor control mode. That is, the unnecessary operation prevention circuit 81 judges whether the signal indicating the control mode acquired from the excitation mode setter 58 by the acquisition unit 82 is the power factor control mode or the constant excitation control mode. Note that the acquisition unit 82 may acquire the control mode from the excitation mode setter 58 at any time or at predetermined intervals, or may acquire the control mode from the excitation mode setter 58 only when the control mode is changed.

[0077] When the unnecessary operation prevention circuit 81 determines that the control mode of the synchronous motor system 1 is the power factor control mode (Yes side), it shifts the process to A (step S302 in FIG. 4). On the other hand, when the unnecessary operation prevention circuit 81 determines that the control mode of the synchronous motor system 1 is the constant excitation control mode (No side), it shifts the process to B (step S402 in FIG. 4).

[0078] In step S202, when the unnecessary operation prevention circuit 81 determines in step S108 that the element failure detection signal is not at H level, it clears from the storage unit 84 the recorded values ​​of the active power value P, the reactive power value Q, and the excitation current feedback value If that are earlier than the current time by the holding time T6. Then, the unnecessary operation prevention circuit 81 shifts the process to step S102, and repeats the operations from step S102 to step S108. By the process of step S202, it is possible to limit the storage capacity of the storage unit 84 for the active power value P, the reactive power value Q, and the excitation current feedback value If that are stored in association with the measurement time.

[0079] In this embodiment, the length of each time is the holding time T6≧T4≧T1, T6≧T7≧T2, and T6≧T5≧T3. The predetermined time T2 and the predetermined time T3 may be equal. The predetermined time T1 is an example of a "current change monitoring time". The predetermined time T2 is an example of an "active power change monitoring time". The predetermined time T3 is an example of a "reactive power change monitoring time". The predetermined time T4 is an example of an "unnecessary operation confirmation time for excitation current feedback judgment". The predetermined time T5 is an example of an "unnecessary operation confirmation time for reactive power judgment". The predetermined time T7 is an example of an "unnecessary operation confirmation time for active power judgment".

[0080] Fig. 4 is a flowchart showing a continuation of the processing of the flowchart shown in Fig. 3. In the flowchart shown in Fig. 4, when the unnecessary operation prevention circuit 81 determines in step S112 of Fig. 3 that the control mode of the synchronous motor system 1 is the power factor control mode, the operation of A is started. On the other hand, when the unnecessary operation prevention circuit 81 determines in step S112 of Fig. 3 that the control mode of the synchronous motor system 1 is the constant excitation control mode, the operation of B is started.

[0081] In step S302, the unnecessary operation prevention circuit 81 calculates the differential excitation current ΔIe, which is the difference between the excitation current feedback value If1 at the latest time and the excitation current feedback value If2 at a time going back from the latest time to the predetermined time T1. In step S202, the excitation current feedback value If before the holding time T6 from the current time is cleared from the storage unit 84. On the other hand, as described above, since the time T is T6≧T4≧T1, the excitation current feedback value If2 at a time going back from the predetermined time T1 is stored in the storage unit 84. Therefore, the unnecessary operation prevention circuit 81 can calculate the differential excitation current ΔIe, which is the difference between the excitation current feedback value If1 at the latest time and the excitation current feedback value If2 at a time going back from the latest time to the predetermined time T1, by referring to the storage unit 84.

[0082] The differential excitation current ΔIe is calculated by the following formula (1). The excitation current feedback value If1 is an example of a "first excitation current feedback value," and the excitation current feedback value If2 is an example of a "second excitation current feedback value." The differential excitation current ΔIe is an example of a "difference current."

[0083] ΔIe = If1 - If2 (1)

[0084] In step S304, the unnecessary operation prevention circuit 81 judges whether the differential excitation current ΔIe calculated in step S302 is larger than a predetermined threshold value Iet (ΔIe>Iet). The predetermined threshold value Iet is a positive value, and may be a fixed value or a variable value, for example, a ratio to the excitation current feedback value If2 (If2×k (k is a positive value smaller than 1)), or may be a fixed value+variable value. The predetermined threshold value Iet is an example of a "current threshold value."

[0085] Here, when the control mode of the synchronous motor system 1 is the power factor control mode, when an element failure occurs in the semiconductor element 25 of the rotary rectifier 23, the current of the synchronous motor excitation winding 11 decreases, the lagging reactive power increases, the active power decreases, and the power factor decreases. At this time, the exciter control unit 50 of the synchronous motor system 1 controls the exciter main circuit unit 40 in a direction to increase the excitation current in order to recover the power factor. Therefore, the value of the excitation current feedback signal increases. For this reason, when the element failure detection device 30 is operating normally, the element failure detection device can be determined to be operating normally by comparing the excitation current feedback value If2 before the generation of the H-level failure detection signal with the excitation current feedback value If1 at the time of power factor recovery until the predetermined time T1 has elapsed after the generation of the signal. In other words, if the differential excitation current ΔIe is larger than the predetermined threshold value Iet, it is determined that the rotary rectifier 23 is abnormal and the element failure detection device is operating normally.

[0086] On the other hand, when no element failure occurs in the semiconductor element 25, the power factor does not change when the element failure detection device 30 issues an H-level failure detection signal. Therefore, even when comparing the excitation current feedback value If1 with the excitation current feedback value If2 before the predetermined time T1 from the time of the issuance of the signal, the differential excitation current ΔIe is equal to or smaller than the predetermined threshold value Iet. That is, in this case, it can be determined that an unnecessary operation of the element failure detection device 30 has occurred.

[0087] Even in the case of normal operation, for example, immediately after the element failure detection device 30 issues an H-level failure detection signal, the differential excitation current ΔIe may be equal to or smaller than the predetermined threshold value Iet due to the response time of the power factor control unit 56. However, if the process of steps S104 to S308 of this flowchart is repeated and a predetermined time T1 has elapsed since the issue of the H-level failure detection signal, the differential excitation current ΔIe is considered to be greater than the predetermined threshold value Iet. That is, in this case, the differential excitation current ΔIe between the excitation current feedback value If1 at the latest time and the excitation current feedback value If2 at the time the predetermined time T1 before the latest time is considered to be greater than the predetermined threshold value Iet. For this reason, the unnecessary operation prevention circuit 81 can determine whether or not the operation is normal by repeating the process of this flowchart and determining whether or not the differential excitation current ΔIe is greater than the predetermined threshold value Iet (ΔIe>Iet). Therefore, it is preferable to set the predetermined time T1 in consideration of the response time of the power factor control unit 56 (integral time constant if the power factor control unit 56 is a circuit including PI control or first-order delay).

[0088] When the unnecessary operation prevention circuit 81 determines that the differential excitation current ΔIe is larger than the predetermined threshold value Iet (ΔIe>Iet) (Yes side), it determines that the operation is normal and shifts the process to step S306. On the other hand, when the unnecessary operation prevention circuit 81 determines that the differential excitation current ΔIe is equal to or smaller than the predetermined threshold value Iet (ΔIe≦Iet) (No side), it determines that the operation is unnecessary and shifts the process to step S308.

[0089] In step S306, the unnecessary operation prevention circuit 81 determines that the element failure detection device 30 has operated normally, and outputs various protection commands to stop the synchronous motor main body 10, the exciter 20, and the exciter main circuit unit 40 by various protection operations, and ends the operation of this flowchart. That is, the unnecessary operation prevention circuit 81 determines that the device is operating normally, outputs a trip command TC1 and a trip command TC2 to the output unit 85, and ends the operation of this flowchart. As a result, the unnecessary operation prevention circuit 81 opens the first circuit breaker 61 and the second circuit breaker 71 to cut off the current, and stops the synchronous motor system 1 for safety. The unnecessary operation prevention circuit 81 may output the trip command TC1 and the trip command TC2 to the output unit 85 and also output a major fault alarm AL2. The unnecessary operation prevention circuit 81 may also output a command to gate block the thyristor rectifier control signal of the exciter control unit 50.

[0090] As a result, when an element failure detection signal of H level, which is a failure detection level, is issued from the element failure detection device 30 and normal operation is determined, the operation of the synchronous motor system 1 can be stopped. This prevents the failure from spreading to the synchronous motor system 1 and the equipment in which the synchronous motor system 1 is used, and makes it possible to protect the synchronous motor system 1 and the equipment in which the synchronous motor system 1 is used.

[0091] In step S308, the unnecessary operation prevention circuit 81 determines whether the time T counted by the timer 83 is greater than a predetermined time T4 (timer>T4).

[0092] Here, as described above, since the time T is T6≧T4≧T1, if the time T counted by the timer 83 is greater than the predetermined time T4 (timer>T4), a time equal to or greater than the predetermined time T1 has elapsed since the fault detection signal of the H level was issued. In this case, even if a time equal to or greater than the predetermined time T1 has elapsed since the fault detection signal of the H level was issued, it is determined in step S304 that the differential excitation current ΔIe is equal to or less than the predetermined threshold value Iet (ΔIe≦Iet). Therefore, when the time T counted by the timer 83 is greater than the predetermined time T4 (timer>T4), it is considered that no abnormality has occurred in the rotary rectifier 23, and an unnecessary operation has occurred in the element fault detection device 30.

[0093] In step S308, when the unnecessary operation prevention circuit 81 determines that the time T counted by the timer 83 is greater than the predetermined time T4 (timer>T4) (Yes side), it shifts the process to step S310. On the other hand, when the unnecessary operation prevention circuit 81 determines that the time T counted by the timer 83 is less than or equal to the predetermined time T4 (timer≦T4) (No side), it shifts the process to C (step S104 in FIG. 3), and repeats the operations from step S104 to step S304.

[0094] This is because, as described above, it takes a certain amount of time for the power factor control unit 56 to respond, and therefore it takes time for the excitation current feedback value If to increase even if an element failure occurs in the semiconductor element 25. The predetermined time T4 is a time for the element failure detection device 30 to check for unnecessary operations during power factor control operation, and is preferably set longer than the predetermined time T1 and sufficiently longer than the response time of the power factor control unit 56. That is, as described above, it is preferable that the predetermined time T1 is set in consideration of the response time of the power factor control unit 56 (an integral time constant if the power factor control unit 56 is a circuit including PI control or first-order delay).

[0095] In step S310, the unnecessary operation prevention circuit 81 outputs an element failure detection circuit unnecessary operation alarm (minor failure alarm AL1), and ends the operation of this flowchart. That is, the unnecessary operation prevention circuit 81 determines that an unnecessary operation has occurred in the element failure detection device 30, and causes the output unit 85 to output a minor failure alarm AL1 to, for example, a display unit, a control device, or a higher-level device (not shown), and ends the operation of this flowchart. The minor failure alarm AL1 is an example of a "predetermined alarm."

[0096] That is, even if an element failure detection signal of H level, which is a failure detection level, is issued, if it is determined that the element failure detection device 30 is operating in an unnecessary manner, the unnecessary operation prevention circuit 81 does not output the trip command TC1 and the trip command TC2. In this case, the unnecessary operation prevention circuit 81 outputs only the minor fault alarm AL1 and does not stop the synchronous motor system 1. As a result, even if an element failure detection signal of H level, which is a failure detection level, is issued from the element failure detection device 30, in the case of an unnecessary operation of the element failure detection device 30, an unnecessary operation of stopping the operation of the synchronous motor system 1 can be prevented. Therefore, by the protection device 80 having the unnecessary operation prevention circuit 81, an unnecessary operation of stopping the operation of the synchronous motor system 1 can be prevented, and an operator can know the unnecessary operation of the element failure detection device 30 by issuing the minor fault alarm AL1. In addition, it is possible to perform a planned stop of the synchronous motor system 1 at an appropriate timing to inspect the element failure detection device 30, etc., which can contribute to improving the productivity of the process in which the synchronous motor system 1 is used.

[0097] Here, when the control mode of the synchronous motor system 1 is the constant excitation control mode, the input current of the brushless exciter 20 controlled by the exciter control unit 50 of the synchronous motor system 1 is constant. At this time, when an element failure (common to both short circuit failure and open circuit failure) occurs in the semiconductor element 25 of the rotary rectifier 23, the actual current flowing through the synchronous motor excitation winding 11 decreases. Therefore, the back electromotive force of the synchronous motor main body 10 decreases, the reactive power increases in the lagging phase direction, and the active power decreases. This principle is used from step S402 onwards. In general, a synchronous motor is operated at a power factor of approximately 1 to reduce copper loss, so that the reactive power during normal operation is small, but when an element failure occurs, the back electromotive force decreases and the current vector shifts from the power supply phase, so that the change in the reactive power is larger than that of the active power.

[0098] In step S402, the unnecessary operation prevention circuit 81 calculates the differential active power ΔP, which is the difference between the active power value P1 at the latest time and the active power value P2 at a time going back from the latest time to the predetermined time T2. In step S202, the active power value P before the holding time T6 from the current time is cleared from the storage unit 84. However, as described above, since the time T is T6≧T7≧T2, the active power value P2 at the time going back from the latest time to the predetermined time T2 is stored in the storage unit 84. Therefore, the unnecessary operation prevention circuit 81 can calculate and calculate the differential active power ΔP, which is the difference between the active power value P1 at the latest time and the active power value P2 at a time going back from the latest time to the predetermined time T2, by referring to the storage unit 84. In addition, the active power value P1 is an example of the "first active power value", and the active power value P2 is an example of the "second active power value". The differential active power ΔP is obtained by the following formula (2).

[0099] ΔP = P1 - P2 (2)

[0100] In step S404, the no-unnecessary-operation prevention circuit 81 determines whether the differential active power ΔP calculated in step S402 is less than a predetermined threshold value Pt (ΔP < Pt). Note that the predetermined threshold value Pt is an example of an "active power threshold value". Also, the differential active power ΔP is an example of "differential active power". Here, the predetermined threshold value Pt is a negative value. The predetermined threshold value Pt may be a fixed value, or may be a variable value, for example, a ratio with respect to the active power value P2 (P2 × k (k is a negative value whose absolute value is less than -1)), or may be a fixed value + variable value.

[0101] That is, the no-unnecessary-operation prevention circuit 81 determines whether there is a variation in the active power value P (motor output). When the no-unnecessary-operation prevention circuit 81 determines that the differential active power ΔP is less than the predetermined threshold value Pt (ΔP < Pt), it is determined that there is a decreasing variation in the active power value P (motor output) (determined as normal operation). On the other hand, when the no-unnecessary-operation prevention circuit 81 determines that the differential active power ΔP is greater than or equal to the predetermined threshold value Pt (ΔP ≥ Pt), it is determined that there is no decreasing variation in the active power value P (motor output) (determined as unnecessary operation).

[0102] When the no-unnecessary-operation prevention circuit 81 determines that the differential active power ΔP is less than the predetermined threshold value Pt (ΔP < Pt) (Yes side: determined as normal operation), the process proceeds to step S406. On the other hand, when the no-unnecessary-operation prevention circuit 81 determines that the differential active power ΔP is greater than or equal to the predetermined threshold value Pt (ΔP ≥ Pt) (No side: determined as unnecessary operation), the process proceeds to step S405.

[0103] In step S405, the unnecessary operation prevention circuit 81 judges whether the time T counted by the timer 83 is greater than a predetermined time T7 (timer>T7). The predetermined time T7 is the unnecessary operation confirmation time in the active power judgment. When the unnecessary operation prevention circuit 81 judges that the time T is greater than the predetermined time T7 (timer>T7) (Yes side), it judges that the element failure detection device 30 is operating in an unnecessary manner, and shifts the process to step S310. On the other hand, when the unnecessary operation prevention circuit 81 judges that the time T is equal to or less than the predetermined time T7 (timer≦T7) (No side), it judges that the time during which it can be judged that the element failure detection device 30 is operating in an unnecessary manner has not elapsed, and shifts the process to C (step S104 in FIG. 3). Here, the predetermined time T7 is equal to or less than the predetermined time T2.

[0104] In step S406, the unnecessary operation prevention circuit 81 calculates a differential reactive power ΔQ, which is the difference between the reactive power value Q1 at the latest time and the reactive power value Q2 at a time going back from the latest time to the predetermined time T3. Here, a leading phase of reactive power is a positive value, and a lagging phase is a negative value. In step S202, the reactive power value Q before the holding time T6 from the current time is cleared from the storage unit 84. However, as described above, since the time T is T6>T3, the reactive power value Q2 at a time going back from the predetermined time T3 is stored in the storage unit 84. Therefore, the unnecessary operation prevention circuit 81 can calculate a differential reactive power ΔQ, which is the difference between the reactive power value Q1 at the latest time and the reactive power value Q2 at a time going back from the latest time to the predetermined time T3, by referring to the storage unit 84. In addition, the reactive power value Q1 is an example of the "first reactive power value", and the reactive power value Q2 is an example of the "second reactive power value". The differential reactive power ΔQ is calculated by the following equation (3).

[0105] ΔQ = Q1 - Q2 (3)

[0106] In step S408, the unnecessary operation prevention circuit 81 determines whether the differential reactive power ΔQ calculated in step S406 is smaller than a predetermined threshold value Qt (ΔQ < Qt). Note that the predetermined threshold value Qt is an example of a "reactive power threshold value". Also, the differential reactive power ΔQ is an example of "differential reactive power". Here, the predetermined threshold value Qt is a negative value. The predetermined threshold value Qt may be a fixed value, or may be a variable value, for example, a ratio with respect to the reactive power value Q2 (Q2 × k2 (k2 is a value whose absolute value is smaller than 1)), or may be a fixed value + variable value.

[0107] In step S408, when the unnecessary operation prevention circuit 81 determines that the differential reactive power ΔQ is smaller than the predetermined threshold value Qt (ΔQ < Qt), that is, when it determines that the lagging reactive power has increased (Yes side), it determines that the element failure detection device 30 is operating normally and transfers the process to step S306. On the other hand, in step S408, when the unnecessary operation prevention circuit 81 determines that the differential reactive power ΔQ is equal to or greater than the predetermined threshold value Qt (ΔQ ≧ Qt) (No side), it transfers the process to step S410.

[0108] In this case, when there is a transmission of an H-level failure detection signal and there is a change in the decreasing direction of the active power value P (motor output), the reactive power value Q1 at the latest time at or after the transmission and the reactive power value Q2 traced back a predetermined time T3 from the latest time at or after the transmission are compared. Then, if the differential reactive power ΔQ is smaller than the predetermined threshold value Qt (if there is a change in the reactive power in the lagging direction), it can be determined that there is an abnormality in the rotating rectifier 23.

[0109] In step S410, the unnecessary operation prevention circuit 81 judges whether the time T counted by the timer 83 is greater than a predetermined time T5 (timer>T5). When the unnecessary operation prevention circuit 81 judges that the time T is greater than the predetermined time T5 (timer>T5) (Yes side), it judges that the element failure detection device 30 is operating in an unnecessary manner, and shifts the process to step S310. On the other hand, when the unnecessary operation prevention circuit 81 judges that the time T is equal to or less than the predetermined time T5 (timer≦T5) (No side), it judges that the time during which it can be judged that the element failure detection device 30 is operating in an unnecessary manner has not elapsed, and shifts the process to C (step S104 in FIG. 3). Then, the unnecessary operation prevention circuit 81 repeats the operations from step S104 to step S408.

[0110] It is to be noted that even if element failure detection device 30 operates normally, for example, there may be cases where the differential active power ΔP and the differential reactive power ΔQ maintain the predetermined threshold value Pt and the predetermined threshold value Qt immediately after the generation of an H-level failure detection signal by element failure detection device 30. Thus, in steps S405 and S410, unnecessary operation prevention circuit 81 can determine that an element failure has occurred in semiconductor element 25 while repeating the processes of steps S104 to S410 of this flowchart.

[0111] That is, when the element failure detection device 30 is normal, if a predetermined time T7 has passed since the issuance of an H-level failure detection signal, the differential active power ΔP at the latest time becomes smaller than a predetermined threshold Pt (a decrease in active power that exceeds a predetermined active power). Also, when the element failure detection device 30 is normal, if a predetermined time T5 has passed since the issuance of an H-level failure detection signal, the differential reactive power ΔQ at the latest time becomes smaller than a predetermined threshold Qt (generation of a lagging-phase reactive power that exceeds a predetermined lagging-phase reactive power). This allows the unnecessary operation prevention circuit 81 to determine that an element failure has occurred in the semiconductor element 25 (normal operation of the element failure detection device 30). On the other hand, when the differential active power ΔP or the differential reactive power ΔQ does not satisfy the above condition even if the predetermined time T7 or the predetermined time T5 has passed since the issuance of an H-level failure detection signal, the unnecessary operation prevention circuit 81 can determine that the element failure detection device 30 is operating unnecessarily.

[0112] Here, in step S405, as described above, since time T is T6≧T7≧T2, if time T counted by timer 83 is greater than predetermined time T7 (timer>T7), a time equal to or greater than the predetermined time T2 has elapsed since the issuance of an H-level fault detection signal. In this case, even if a time equal to or greater than the predetermined time T2 has elapsed since the issuance of an H-level fault detection signal, it is determined in step S404 that no fluctuation in active power has occurred in which the differential active power ΔP has exceeded the predetermined threshold value Pt.

[0113] Similarly, in step S410, since the time T is T6≧T5≧T3, if the time T counted by the timer 83 is greater than the predetermined time T5 (timer>T5), a time equal to or greater than the predetermined time T3 has elapsed since the fault detection signal of H level was issued. In this case, even if a time equal to or greater than the predetermined time T3 has elapsed since the fault detection signal of H level was issued, it is determined in step S408 that no lagging reactive power has been generated in which the differential reactive power ΔQ exceeds the predetermined threshold value Qt.

[0114] Therefore, when the time T counted by timer 83 is greater than predetermined time T5 (timer>T5), it is considered that no abnormality has occurred in rotary rectifier 23, and an unwanted operation has occurred in element failure detection device 30.

[0115] The predetermined time T7 is a time to check for unnecessary operation in determining active power, and is set to be equal to or greater than the predetermined time T2, and the predetermined time T5 is a time to check for unnecessary operation in determining reactive power, and is set to be equal to or greater than the predetermined time T3. These are set to be longer than the predetermined time T2, taking into consideration the time of fluctuation in active power and reactive power caused by load fluctuations expected in normal operation. Alternatively, when the predetermined time T7 or the predetermined time T5 is set to be shorter than the above-mentioned fluctuation times, the amount of fluctuation in active power and reactive power caused by load fluctuations expected in normal use is taken into consideration. In this way, the predetermined threshold Pt or the predetermined threshold Qt is set so as not to erroneously determine that an operation is unnecessary.

[0116] The order may be changed so that if step S112 is No, steps S406 and S408 are performed before step S402. Also, if step S408 is No, the process proceeds to step S402, and if step S404 is Yes, the process proceeds to step S410.

[0117] <Effects of one embodiment> 1 to 4, the unnecessary operation prevention circuit 81 associates the active power value P, the reactive power value Q, and the excitation current feedback value If with the measurement time, and stores them in the storage unit 84. This allows the active power value P, the reactive power value Q, and the excitation current feedback value If at each time to be stored.

[0118] Furthermore, when the element failure detection signal is not at H level, the unnecessary operation prevention circuit 81 clears from the storage area the recorded values ​​of the active power value P, the reactive power value Q, and the excitation current feedback value If that are recorded before the retention time T6 from the current time. This makes it possible to prevent the storage area in the storage unit 84 for the active power value P, the reactive power value Q, and the excitation current feedback value If that are stored in association with the measurement time from becoming excessively large.

[0119] 1 to 4, the unnecessary operation prevention circuit 81 causes the timer 83 to count the time T when the element failure detection signal is at H level. This allows the unnecessary operation prevention circuit 81 to grasp the active power value P1, the reactive power value Q1, and the excitation current feedback value If1 at the latest time. Furthermore, the unnecessary operation prevention circuit 81 can grasp the active power value P2, the reactive power value Q2, and the excitation current feedback value If1 at a time that is a predetermined time (for example, T1, T2, or T3) prior to the current time. Furthermore, the unnecessary operation prevention circuit 81 can calculate the differential active power ΔP, the differential reactive power ΔQ, and the differential excitation current ΔIe as the differences between these values.

[0120] 1 to 4, the unnecessary operation prevention circuit 81 determines whether the control mode of the synchronous motor system 1 is a power factor control mode or a constant excitation control mode. This allows the unnecessary operation prevention circuit 81 to switch the unnecessary operation detection method of the element fault detection device 30 between a case where the unnecessary operation detection method is determined based on the excitation current fluctuation and a case where the unnecessary operation detection method is determined based on the active power fluctuation and the reactive power fluctuation in accordance with the control mode of the synchronous motor system 1. This allows the unnecessary operation prevention circuit 81 to make a determination in accordance with the operation of the excitation device.

[0121] 1 to 4, when the unnecessary operation prevention circuit 81 determines that the element failure detection signal is not at H level, it clears the recorded values ​​that are older than the current time by the retention time T6 from the storage unit 84. This makes it possible to prevent the storage area in the storage unit 84 for the active power value P, the reactive power value Q, and the excitation current feedback value If that are stored in association with the measurement time from becoming extremely large.

[0122] According to the embodiment shown in FIG. 1 to FIG. 4, the unnecessary operation prevention circuit 81 performs the following judgment only when the element failure detection signal is at H level during constant power factor operation, and judges that the element failure detection device 30 has operated normally. That is, when the unnecessary operation prevention circuit 81 judges that the differential excitation current ΔIe is greater than a predetermined threshold Iet (ΔIe>Iet), it judges that the element failure detection device 30 has operated normally. In this case, the unnecessary operation prevention circuit 81 causes the output unit 85 to output the trip command TC1 and the trip command TC2, opens the first circuit breaker 61 and the second circuit breaker 71 to cut off the current, stops the operation of the synchronous motor system 1, and outputs a serious fault alarm AL2. On the other hand, when the state in which the element failure detection signal is at H level and the differential excitation current ΔIe is not greater than the predetermined threshold Iet (ΔIe≦Iet) exceeds a predetermined time T4, the unnecessary operation prevention circuit 81 judges that the element failure detection device 30 has operated unnecessarily. In this case, the unnecessary operation prevention circuit 81 outputs a minor fault alarm AL1, and does not output the trip command TC1 and the trip command TC2 to the output unit 85. This makes it possible to prevent unnecessary stoppage of the synchronous motor system 1 in the case of unnecessary operation of the element fault detection device 30, and also prevents the fault from spreading or expanding to the synchronous motor system 1, the facility in which the synchronous motor system 1 is used, and other devices. This also makes it possible to protect the synchronous motor system 1, the facility in which the synchronous motor system 1 is used, and other devices.

[0123] 1 to 4, the unnecessary operation prevention circuit 81 performs the following judgment only when the element failure detection signal is at H level during constant excitation operation, and judges that the element failure detection device 30 has operated normally. That is, when the unnecessary operation prevention circuit 81 judges that the differential active power ΔP fluctuates in a direction decreasing from a predetermined threshold value Pt and that the differential reactive power ΔQ fluctuates in a direction increasing in a lagging phase direction from a predetermined threshold value Qt, it judges that the element failure detection device 30 has operated normally. In this case, the unnecessary operation prevention circuit 81 causes the output unit 85 to output the trip command TC1 and the trip command TC2, opens the first circuit breaker 61 and the second circuit breaker 71 to cut off the current, stops the operation of the synchronous motor system 1, and outputs a major fault alarm AL2. On the other hand, when the state where the element failure detection signal is at H level and the differential active power ΔP is determined not to have decreased below the predetermined threshold Pt exceeds a predetermined time T7, the unnecessary operation prevention circuit 81 determines that the element failure detection device 30 has performed an unnecessary operation. Alternatively, when the state where the element failure detection signal is at H level and the change in the differential reactive power ΔQ in the retarding phase direction is determined to be smaller than the predetermined threshold Qt exceeds a predetermined time T5, the unnecessary operation prevention circuit 81 determines that the element failure detection device 30 has performed an unnecessary operation. In this case, the unnecessary operation prevention circuit 81 outputs a minor fault alarm AL1 and does not output the trip command TC1 and the trip command TC2 to the output unit 85. In this way, in the case of an unnecessary operation of the element failure detection device 30, unnecessary stop of the synchronous motor system 1 can be prevented, and the spread or expansion of the failure to the synchronous motor system 1, the equipment in which the synchronous motor system 1 is used, and other equipment can be prevented. In addition, this also makes it possible to protect the synchronous motor system 1, the equipment in which the synchronous motor system 1 is used, and other equipment.

[0124] As described above, according to the present disclosure, when an element failure detection signal is issued from the element failure detection device 30, the unnecessary operation prevention circuit 81 can determine whether the operation is normal or unnecessary. Therefore, according to the present disclosure, in the case of normal operation, the synchronous motor system 1 is stopped, and in the case of unnecessary operation, unnecessary operation of stopping the operation of the synchronous motor system 1 can be prevented. In addition, since a minor fault alarm AL1 is output in the case of unnecessary operation, a planned stop of the synchronous motor system 1 can be performed as early as possible, and inspection and repair of the element failure detection device 30 can be performed. Even if the synchronous motor system 1 is stopped in the case of a planned stop, the impact can be reduced by using an alternative synchronous machine or changing the production plan. For this reason, it is very significant to separate an immediate stop from a planned stop. As a result, the protection device 80 having the unnecessary operation prevention circuit 81 can contribute to improving the productivity of the process in which the synchronous motor system 1 is used.

[0125] As described above, according to the present disclosure, unwanted operation prevention circuit 81 determines whether rotating rectifier fault detection device 30 is operating normally or has a fault or malfunction (unwanted operation). Therefore, according to the present disclosure, it is possible to provide a protection device for a brushless synchronous machine that outputs an alarm in the case of unwanted operation and is capable of stopping the synchronous motor only in the case of normal operation.

[0126] <Hardware configuration example> 5 is a conceptual diagram showing an example of a hardware configuration of a processing circuit 90 included in the excitation device control unit 50 and the protection device 80 in the embodiment shown in FIGS. 1 to 4. The above-mentioned functions are realized by the processing circuit 90. In one aspect, the processing circuit 90 includes at least one processor 91 and at least one memory 92. In another aspect, the processing circuit 90 includes at least one dedicated hardware 93.

[0127] When the processing circuit 90 includes a processor 91 and a memory 92, each function is realized by software, firmware, or a combination of software and firmware. At least one of the software and firmware is written as a program. At least one of the software and firmware is stored in the memory 92. The processor 91 realizes each function by reading and executing the program stored in the memory 92.

[0128] When the processing circuitry 90 comprises dedicated hardware 93, the processing circuitry 90 may be, for example, a single circuit, multiple circuits, a programmed processor, or a combination thereof. Each function is implemented by the processing circuitry 90.

[0129] Each function of the exciter control unit 50 and the protection device 80 may be partially or entirely configured by hardware, or may be configured as a program executed by a processor. That is, the exciter control unit 50 and the protection device 80 can also be realized by a computer and a program, and the program can be stored in a storage medium or provided through a network.

[0130] <Supplementary information for the embodiment> 1 to 5, as one aspect of the present disclosure, a case has been described in which the unnecessary operation prevention circuit 81 is applied to the brushless synchronous motor system 1. However, the present disclosure is not limited to this, and the unnecessary operation prevention circuit 81 can be applied to all brushless synchronous machines, regardless of whether they are synchronous motors or synchronous generators.

[0131] 1 to 5, in step S306, the unnecessary operation prevention circuit 81 causes the output unit 85 to output the trip command TC1 and the trip command TC2, but this is not limited to this. The unnecessary operation prevention circuit 81 may cause the output unit 85 to output either the trip command TC1 or the trip command TC2, or may cause the output unit 85 to output a serious fault alarm AL2 simultaneously with at least one of the trip command TC1 or the trip command TC2.

[0132] 1 to 5, the unwanted operation prevention circuit 81 in the protection device 80 has been described as an example of one aspect of the present disclosure, but the present disclosure is not limited to this. The present disclosure can also be realized as an independent unwanted operation prevention device or unwanted operation prevention system.

[0133] The present disclosure can also be realized as an unwanted operation prevention method in which processing steps are performed in each part of the unwanted operation prevention circuit 81 in the protection device 80.

[0134] The present disclosure can also be realized as an unwanted operation prevention program that causes a computer to execute the processing steps in each part of the unwanted operation prevention circuit 81 in the protection device 80.

[0135] The present disclosure can also be realized as a storage medium (non-transitory computer-readable medium) on which an unnecessary operation prevention program is stored. The unnecessary operation prevention program can be stored in a removable disk such as a CD (Compact Disc), a DVD (Digital Versatile Disc), or a USB (Universal Serial Bus) memory and distributed. These programs may be uploaded onto a network via a network interface (not shown) or the like included in the synchronous motor system 1, or may be downloaded from the network and stored in the memory 92 or the like.

[0136] The features and advantages of the embodiments will be apparent from the above detailed description. It is intended that the claims cover the features and advantages of the embodiments as described above without departing from the spirit and scope of the claims. In addition, any improvements and modifications can be easily made by a person having ordinary skill in the art. Therefore, it is not intended to limit the scope of the inventive embodiments to the above, and appropriate improvements and equivalents within the scope of the embodiments disclosed can be used. [Explanation of symbols]

[0137] 1...brushless synchronous motor system (synchronous motor system); 10...brushless synchronous motor main body (synchronous motor main body); 11...synchronous motor excitation winding; 12...synchronous motor stator winding; 20...brushless exciter (exciter); 21...exciter stator winding; 22...exciter rotor; 23...rotary rectifier; 24...rotor; 25...semiconductor element; 30...rotary rectifier fault detection device (element fault detection device); 31...element fault detection winding; 40...exciter main circuit 41: Thyristor rectifier for excitation circuit (thyristor rectifier); 42: Shunt for excitation current detection (DC current detector); 50: Excitation device control section; 51: Excitation current setting device; 52: First subtractor; 53: Current control section; 54: Power factor setting device; 55: Second subtractor; 56: Power factor control section; 57: Changeover switch (changeover SW); 58: Excitation mode setting device; 60: AC power source; 61: First circuit breaker; 62: Potential transformer (PT); 63: Current transformer (CT); 64: Ma Routine meter; 65...out of step relay; 66...overcurrent relay; 67...AC circuit; 70...AC power supply; 71...second circuit breaker; 72...AC circuit; 80...protective device; 81...element fault detection and unnecessary operation prevention circuit for brushless synchronous machine (unnecessary operation prevention circuit); 82...acquisition unit; 83...timer; 84...storage unit; 85...output unit; 86...system bus; 90...processing circuit; 91...processor; 92...memory; 93...hardware; AL...alarm; AL1...minor fault Fault alarm; AL2...serious fault alarm; Iet...predetermined threshold (current threshold); If, If1, If2...excitation current feedback value; P, P1, P2...active power value; Pt...predetermined threshold (active power threshold); Q, Q1, Q2...reactive power value; Qt...predetermined threshold (reactive power threshold); T...time; T1~T5...predetermined time; T6...holding time; T7...predetermined time; TC1, TC2...trip command; ΔIe...differential excitation current (differential current); ΔP...differential active power; ΔQ...differential reactive power

Claims

1. A brushless excitation device; a rotary rectifier having a semiconductor device disposed on a rotor in the brushless exciter; an element failure detection device for detecting a failure of the semiconductor element in the rotary rectifier; A protection device for use in a brushless synchronous machine having an excitation current feedback storage means for acquiring an excitation current feedback value of the brushless excitation device during a current or past predetermined period, and storing the value in association with the time of acquisition; Equipped with When the element failure detection device reports a failure of the semiconductor element, calculating a differential current between a first excitation current feedback value, which is the excitation current feedback value stored in the excitation current feedback storage means at the time when the failure of the semiconductor device was reported, and a second excitation current feedback value, which is the excitation current feedback value stored in the excitation current feedback storage means at a time that is a predetermined current change monitoring time prior to the time when the failure of the semiconductor device was reported; When the calculated difference current is greater than a predetermined current threshold, it is determined that a failure has occurred in the semiconductor element, and a command to stop the brushless synchronous machine is output. When the differential current is equal to or less than a predetermined current threshold, it is determined that a failure or malfunction has occurred in the element failure detection device, and a command to stop the brushless synchronous machine is not output, but a predetermined alarm is output. A protection device for a brushless synchronous machine.

2. A brushless excitation device; a rotary rectifier having a semiconductor device disposed on a rotor in the brushless exciter; an element failure detection device for detecting a failure of the semiconductor element in the rotary rectifier; A protection device for use in a brushless synchronous machine having an active power storage means for acquiring an active power value of the brushless synchronous machine for a current or past predetermined period, and storing the acquired active power value in association with the time of acquisition; a reactive power storage means for acquiring reactive power values ​​of the brushless synchronous machine, the leading phase of which is positive and the lagging phase of which is negative, during a current or past predetermined period, and storing the values ​​in association with the time of acquisition; Equipped with When the element failure detection device reports a failure of the semiconductor element, calculating a differential active power between a first active power value, which is the active power value stored in the active power storage means at the time when the failure of the semiconductor device was reported, and a second active power value, which is the active power value stored in the active power storage means at a time that is a predetermined active power change monitoring time prior to the time when the failure of the semiconductor device was reported; When the calculated differential active power is greater than a predetermined active power threshold, calculating a differential reactive power between a first reactive power value, which is the reactive power value stored in the reactive power storage means at the time when the failure of the semiconductor element was reported, and a second reactive power value, which is the reactive power value stored in the reactive power storage means at a time preceding the time when the failure of the semiconductor element was reported by a predetermined reactive power change monitoring time; When the calculated differential reactive power is smaller than a predetermined reactive power threshold, it is determined that a failure has occurred in the semiconductor element, and a command to stop the brushless synchronous machine is output. When the differential active power is equal to or less than a predetermined active power threshold, or when the differential reactive power is equal to or more than a predetermined reactive power threshold, it is determined that a failure or malfunction has occurred in the element failure detection device, and a command to stop the brushless synchronous machine is not output, but a predetermined alarm is output. A protection device for a brushless synchronous machine.

3. A brushless excitation device; a rotary rectifier having a semiconductor device disposed on a rotor in the brushless exciter; an element failure detection device for detecting a failure of the semiconductor element in the rotary rectifier; A protection device for use in a brushless synchronous machine having an excitation current feedback storage means for acquiring an excitation current feedback value corresponding to an input current of an exciter stator winding of the brushless excitation device during a current or past predetermined period, and storing the value in association with the time of acquisition; an active power storage means for acquiring an active power value of the brushless synchronous machine for a current or past predetermined period, and storing the acquired active power value in association with the time of acquisition; a reactive power storage means for acquiring reactive power values ​​of the brushless synchronous machine, the leading phase of which is positive and the lagging phase of which is negative, during a current or past predetermined period, and storing the values ​​in association with the time of acquisition; a means for acquiring a signal for determining whether the brushless synchronous machine is operated under a power factor control control method or a constant excitation control control method; Equipped with When the brushless synchronous machine is operated in the power factor control mode and a failure of the semiconductor element is notified by the element failure detection device, calculating a differential current between a first excitation current feedback value, which is the excitation current feedback value stored in the excitation current feedback storage means at the time when the failure of the semiconductor device was reported, and a second excitation current feedback value, which is the excitation current feedback value stored in the excitation current feedback storage means at a time that is a predetermined current change monitoring time prior to the time when the failure of the semiconductor device was reported; When the calculated difference current is greater than a predetermined current threshold, it is determined that a failure has occurred in the semiconductor element, and a command to stop the brushless synchronous machine is output. When the differential current is equal to or less than a predetermined current threshold, it is determined that a failure or malfunction has occurred in the element failure detection device, and a command to stop the brushless synchronous machine is not output, but a predetermined alarm is output; When the brushless synchronous machine is operated in the constant excitation control mode and a fault in the semiconductor element is notified by the element fault detection device, calculating a differential active power between a first active power value, which is the active power value stored in the active power storage means at the time when the failure of the semiconductor device was reported, and a second active power value, which is the active power value stored in the active power storage means at a time that is a predetermined active power change monitoring time prior to the time when the failure of the semiconductor device was reported; When the calculated differential active power is greater than a predetermined active power threshold, calculating a differential reactive power between a first reactive power value, which is the reactive power value stored in the reactive power storage means at the time when the failure of the semiconductor element was reported, and a second reactive power value, which is the reactive power value stored in the reactive power storage means at a time preceding the time when the failure of the semiconductor element was reported by a predetermined reactive power change monitoring time; When the calculated differential reactive power is smaller than a predetermined reactive power threshold, it is determined that a failure has occurred in the semiconductor element, and a command to stop the brushless synchronous machine is output. When the differential active power is equal to or less than a predetermined active power threshold, or when the differential reactive power is equal to or more than a predetermined reactive power threshold, it is determined that a failure or malfunction has occurred in the element failure detection device, and a command to stop the brushless synchronous machine is not output, but a predetermined alarm is output. A protection device for a brushless synchronous machine.

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