Rotating rectifier fault detection device for brushless synchronous motors

Abstract

To provide a rotary rectifier fault detection device for a brushless synchronous motor that is capable of detecting faults without using a detection coil and without being affected by AC voltage fluctuations.SOLUTION: A rotary rectifier fault detection device for a brushless synchronous motors comprises: an excitation current calculation unit that calculates an operating point of the brushless synchronous motor as an admittance coordinate on the basis of an active power value, a reactive power value, and a terminal voltage value input to the brushless synchronous motor, and calculates an excitation current calculation value of the brushless synchronous motor, an excitation current difference value calculation unit that acquires an excitation current detection value that is a detection value of the excitation current supplied to the excitation circuit of the brushless synchronous motor, compares the excitation current calculation value calculated by the excitation current calculation unit with the acquired excitation current detection value, and calculates an excitation current difference value that indicates the difference between the excitation current calculation value and the excitation current detection value, and a failure determination unit that compares the excitation current difference value with an allowable value, and determines that a failure has occurred in the rotating rectifier when the excitation current difference value is equal to or greater than the allowable value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating rectifier fault detection device for a brushless synchronous motor. [Background technology]

[0002] Conventionally, there are rotary rectifier fault detection devices for brushless synchronous machines that use a detection coil and that do not use a detection coil (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-295252 [Patent Document 2] Japanese Patent Application Publication No. 11-346499 [Patent Document 3] Japanese Patent Application Publication No. 4-372559 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional methods using detection coils have the problem of making the structure complex, and conventional methods not using detection coils have the problem of being susceptible to voltage fluctuations in the AC bus voltage.

[0005] Therefore, an object of the present disclosure is to provide a rotating rectifier fault detection device for a brushless synchronous motor that is capable of detecting faults without using a detection coil and without being affected by AC voltage fluctuations. [Means for solving the problem]

[0006] A rotary rectifier fault detection device for a brushless synchronous motor according to one embodiment is a rotary rectifier fault detection device for a brushless synchronous motor, characterized by comprising: an excitation current calculation unit that calculates an operating point of the brushless synchronous motor as an admittance coordinate based on an active power value, a reactive power value, and a terminal voltage value input to the brushless synchronous motor, and calculates an excitation current calculation value for the brushless synchronous motor; an excitation current difference value calculation unit that acquires an excitation current detection value that is a detection value of the excitation current supplied to the excitation circuit of the brushless synchronous motor, compares the excitation current calculation value calculated by the excitation current calculation unit with the acquired excitation current detection value, and calculates an excitation current difference value that indicates the difference between the excitation current calculation value and the excitation current detection value; and a fault determination unit that compares the excitation current difference value with an allowable value, and determines that a fault has occurred in the rotary rectifier if the excitation current difference value is equal to or greater than the allowable value. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a rotating rectifier fault detection device for a brushless synchronous motor that is capable of detecting faults without using a detection coil and without being affected by AC voltage fluctuations. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of a brushless synchronous motor system according to an embodiment; [Figure 2] 2 is a diagram showing an example of an operating point display in PQ coordinates of the brushless synchronous motor shown in FIG. 1. FIG. [Figure 3] 2 is a diagram showing an example of an operating point display in admittance coordinates of the brushless synchronous motor shown in FIG. 1. FIG. [Figure 4] 2 is a diagram showing an example of an operating point display in admittance coordinates when the direct axis synchronous reactance and the quadrature axis synchronous reactance of the brushless synchronous motor shown in FIG. 1 are considered to be equal. FIG. [Figure 5] FIG. 2 is a diagram illustrating an example of the overall configuration of a brushless synchronous motor system according to a first modified example of an embodiment. [Figure 6]6 is a conceptual diagram showing an example of the hardware configuration of a processing circuit included in the rotary rectifier fault detection device in the embodiment shown in FIGS. 1 to 5. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotary rectifier fault detection device for a brushless synchronous motor according to the present disclosure will be described below with reference to the accompanying drawings.

[0010] <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.

[0011] In this embodiment, an example will be described in which the rotary rectifier fault detection device for a brushless synchronous motor disclosed herein is applied to a brushless synchronous motor 10 as an example of a brushless synchronous motor.

[0012] As shown in Fig. 1, brushless synchronous motor system 1 includes brushless synchronous motor 10, exciter 60, and rotary rectifier fault detection device 80. In brushless synchronous motor system 1, brushless synchronous motor 10 is connected to power receiving bus 75 via current transformer 71, voltage transformer 72, upper circuit breaker 73, and power receiving transformer 74, and exciter 60 is connected to external power supply 66. Current transformer 71 and voltage transformer 72 are connected to rotary rectifier fault detection device 80 via multimeter 76. Hereinafter, in this specification, brushless synchronous motor system 1 will also be simply referred to as "synchronous motor system 1."

[0013] Brushless synchronous motor 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, which is the primary-side main circuit input power supply (not shown) connected to power receiving bus 75. Brushless synchronous motor 10 includes a synchronous motor main body 20, a rotary rectifier 30, and an AC exciter 40, and a portion of synchronous motor main body 20, rotary rectifier 30, and a portion of AC exciter 40 form rotor 50. Hereinafter, in this specification, brushless synchronous motor 10 will also be simply referred to as "synchronous motor 10."

[0014] The synchronous motor body 20 has a synchronous motor armature 21 and a synchronous motor main excitation winding 22. The synchronous motor body 20 is an example of a "synchronous motor body."

[0015] The synchronous motor armature 21 is, for example, a stator connected to a power receiving bus 75, and a rotating magnetic field is created by the AC current supplied from the power receiving bus 75. The synchronous motor armature 21 is, for example, a cylindrical stator winding, and the synchronous motor main excitation winding 22, which is the rotor 50, is inserted inside the cylindrical shape.

[0016] The synchronous motor main excitation winding 22, for example, constitutes a rotor 50 inserted inside a cylindrical synchronous motor armature 21, and generates magnetic flux by the excitation current supplied from the AC exciter 40, and is attracted to the rotating magnetic field of the synchronous motor armature 21, causing it to follow and rotate.

[0017] The rotary rectifier 30 has a plurality of semiconductor elements 31 connected in a three-phase bridge, and rotates with its DC side connected to the synchronous motor main excitation winding 22 and its AC side connected to an AC exciter armature 41. In other words, the rotary rectifier 30 is mechanically connected to the rotating shaft of the rotor 50. The rotary rectifier 30 converts (rectifies) AC current supplied from the AC exciter armature 41 (described later) into DC current using the semiconductor elements 31, and supplies the converted DC current to the mechanically connected synchronous motor main excitation winding 22.

[0018] When a short circuit or an open circuit occurs in the semiconductor element 31, the semiconductor element 31 generates current ripples and voltage ripples that are different from normal current ripples during rectification. The generated voltage ripples are propagated to the AC exciter excitation coil 42.

[0019] The AC exciter 40 has an AC exciter armature 41 and an AC exciter excitation coil 42 .

[0020] The AC exciter armature 41 rotates within the magnetic field of the AC exciter excitation coil 42 , and is supplied with power from the AC exciter excitation coil 42 .

[0021] The AC exciter excitation coil 42 is connected to an external power supply 66 via an exciter 60. The AC exciter excitation coil 42 generates a magnetic field when an excitation current, which has been converted from an AC current to a DC current by the exciter 60, flows through it.

[0022] For example, one end of the exciter 60 is connected to the AC exciter excitation coil 42, and the other end is connected to an external power supply 66. The exciter 60 supplies an excitation current obtained by rectifying the AC current supplied from the external power supply 66 to the AC exciter excitation coil 42. The exciter 60 has a current sensor 61, a transducer 62, a thyristor rectifier 63, and a circuit breaker 64.

[0023] The current sensor 61 is disposed, for example, between the AC exciter excitation coil 42 and the thyristor rectifier 63, and has an output terminal connected to the transducer 62. The current sensor 61 detects the DC current output from the thyristor rectifier 63 and outputs it to the transducer 62.

[0024] The transducer 62 receives, for example, the output of the current sensor 61, converts it into a signal of an appropriate level, and the output is connected to the rotary rectifier fault detection device 80 and an excitation current control device (not shown). The transducer 62 converts the current signal output from the current sensor 61 into an excitation current detection value If, which is an instrumentation signal, and outputs it to the rotary rectifier fault detection device 80. In other words, the transducer 62 outputs the excitation current detection value If, which is a detection value of the excitation current supplied to the AC exciter 40, to the rotary rectifier fault detection device 80. Hereinafter in this specification, the transducer 62 is also referred to as a "TRD (Transducer) 62."

[0025] For example, one end of the DC output of the thyristor rectifier 63 is connected to the AC exciter excitation coil 42, and the other end of the AC input is connected to an external power supply 66 via a circuit breaker 64. The thyristor rectifier 63 converts (rectifies) the AC current supplied from the external power supply 66 into a DC current, and supplies the converted (rectified) DC current to the AC exciter excitation coil 42.

[0026] The circuit breaker 64 is provided, for example, in series between the external power supply 66 and the thyristor rectifier 63. The circuit breaker 64 cuts off the current flowing from the external power supply 66 to the thyristor rectifier 63 based on, for example, an operation signal TC output from the rotary rectifier fault detection device 80, thereby stopping the synchronous motor 10. In this way, the circuit breaker 64 protects the excitation circuit of the synchronous motor 10 and prevents the fault from spreading to the synchronous motor system 1 or the equipment in which the synchronous motor 10 is used.

[0027] The external power supply 66 is, for example, a three-phase AC power supply, and is connected to the thyristor rectifier 63 in the exciter 60 via a circuit breaker 64 to supply three-phase AC power to the thyristor rectifier 63 .

[0028] The current transformer 71 is disposed, for example, between the upper circuit breaker 73 and the synchronous motor armature 21, and converts the AC current supplied from the power receiving bus 75 into a current that can be detected by a multimeter 76. Hereinafter in this specification, the current transformer 71 is also referred to as a "CT (Current Transformer) 71."

[0029] The voltage transformer 72 is disposed, for example, between the upper circuit breaker 73 and the synchronous motor armature 21, and reduces the AC voltage supplied from the power receiving bus 75 to a voltage that can be detected by a multimeter 76. Hereinafter in this specification, the voltage transformer 72 is also referred to as a "VT (Voltage Transformer) 72."

[0030] The upper circuit breaker 73 is provided, for example, in series between the power receiving transformer 74 and the synchronous motor armature 21. The upper circuit breaker 73, for example, based on an operation signal TC output from the rotary rectifier fault detection device 80, cuts off the current flowing from the power receiving bus 75 to the thyristor rectifier 63 via the power receiving transformer 74, thereby stopping the synchronous motor 10. In this way, the upper circuit breaker 73 protects the synchronous motor 10 and prevents the fault from spreading to the synchronous motor system 1 and the equipment in which the synchronous motor 10 is used.

[0031] The power receiving transformer 74 is disposed, for example, between the power receiving bus 75 and the upper circuit breaker 73, and converts the AC voltage supplied from the power receiving bus 75 into a predetermined voltage.

[0032] For example, one end of the power receiving bus 75 is connected to a three-phase AC power supply (not shown), and the other end is connected to the synchronous motor armature 21 via the power receiving transformer 74 and the upper circuit breaker 73, and supplies three-phase AC power from the three-phase AC power supply to the synchronous motor armature 21.

[0033] The multimeter 76 is an instrument that integrates an indicating instrument and a converter, and is connected to the CT 71 and the VT 72, and measures values such as the current and terminal voltage of the AC power supplied from the power receiving bus 75 to the synchronous motor 10 via the CT 71 and the VT 72. The multimeter 76 also has functions such as an active power detector and a reactive power detector, and performs predetermined conversions on the measured values of the current, voltage, etc. to detect (calculate) values such as active power and reactive power.

[0034] The measured and detected values obtained by the multimeter 76 are acquired, for example, by a higher-level device or a control device (not shown) and are used to monitor the operating state of the synchronous motor 10 and to control the output of the exciter 60. In addition, a terminal voltage value V, which is the value of the terminal voltage signal measured by the multimeter 76, an active power value P, which is the value of the detected (calculated) active power signal, and a reactive power value Q, which is the value of the detected (calculated) reactive power signal, are acquired by a rotating rectifier fault detection device 80.

[0035] Rotary rectifier fault detection device 80 has a processor 91 (see FIG. 6), described below, such as a CPU (Central Processing Unit), which operates by executing a program. Rotary rectifier fault detection device 80 detects a fault (element fault) in rotary rectifier 30 by running a predetermined program stored in memory 92 (see FIG. 6), described below, to operate processor 91 (see FIG. 6), described below. Rotary rectifier fault detection device 80 detects a fault in rotary rectifier 30 based on an active power value P, a reactive power value Q, a terminal voltage value V, and an excitation current detection value If output from TRD 62.

[0036] The rotary rectifier fault detection device 80 has the configuration or functions of an input unit 81 , a coordinate conversion unit 82 , an excitation current calculator 83 , a difference calculator 84 , a comparator 85 , and a storage unit 86 .

[0037] <Operation of one embodiment> The input unit 81 acquires the active power value P, reactive power value Q, and terminal voltage value V output from the multimeter 76. The input unit 81 converts the acquired active power value P, reactive power value Q, and terminal voltage value V into values in the per-unit method, and outputs them to the coordinate conversion unit 82.

[0038] The coordinate conversion unit 82 converts the active power value P, reactive power value Q, and terminal voltage value V acquired from the input unit 81 into admittance coordinate values that indicate values in an admittance coordinate system. Note that, hereinafter, the admittance coordinates may also be referred to as "GB coordinates," and values (operating points) and the like expressed in the admittance coordinates may also be referred to as "GB coordinate values." Details of the GB coordinate conversion will be described later (see FIGS. 3 and 4). The coordinate conversion unit 82 outputs the converted GB coordinate values to the excitation current calculator 83. Note that the GB coordinates are an example of "admittance coordinates," and the coordinate conversion unit 82 is an example of a "coordinate conversion unit."

[0039] The excitation current calculator 83 calculates an excitation current calculation value If0 based on the GB coordinate value acquired from the coordinate conversion unit 82, the synchronous impedance Zs acquired from the storage unit 86, and the proportionality coefficient KL, and outputs the calculated excitation current value If0 to the difference calculator 84. The excitation current calculator 83 is an example of an "excitation current calculation unit."

[0040] The differentiator 84 acquires the excitation current calculation value If0 from the excitation current calculator 83, and acquires the excitation current detection value If, which is a detection value of the excitation current supplied to the AC exciter 40, from the TRD 62. Then, the differentiator 84 compares the acquired excitation current calculation value If0 with the excitation current detection value If, and calculates an excitation current difference value ΔIf indicating the difference between the excitation current calculation value If0 and the excitation current detection value If. The differentiator 84 outputs the calculated excitation current difference value ΔIf to the comparator 85. The differentiator 84 is an example of an "excitation current difference value calculation unit."

[0041] The output of the comparator 85 may be connected to the upper circuit breaker 73 or the circuit breaker 64, or to an upper control device or a display device (not shown). The comparator 85 compares the excitation current difference value ΔIf obtained from the difference calculator 84 with the allowable value ΔIf stored in the storage unit 86. th The comparator 85 obtains the excitation current difference value ΔIf from the difference calculator 84 and compares it with the allowable value ΔIf th The excitation current difference value ΔIf and the tolerance value ΔIf are obtained. th to detect a fault in the rotary rectifier 30.

[0042] When the rotary rectifier 30 is normal, the current flowing through the synchronous motor main excitation winding 22 is approximately equal to the excitation current detection value If, which takes into account the turns ratio and coupling ratio of the AC exciter excitation coil and the AC exciter 40. Therefore, the excitation current calculation value If0 and the excitation current detection value If are approximately equal. However, when a short-circuit fault occurs in the rotary rectifier 30, part of the output current of the AC exciter 40 flows to the short-circuited part, and the current flowing through the synchronous motor main excitation winding 22 is reduced by the amount of the short-circuit current. Therefore, the excitation voltage decreases, which causes an increase in reactive power and a decrease in active power, and the excitation current calculation value If0 decreases. Therefore, the excitation current detection value If becomes larger than the excitation current calculation value If0, and the excitation current difference value ΔIf increases.

[0043] Then, the comparator 85 checks whether the obtained excitation current difference value ΔIf is equal to the allowable value ΔIf th If the above conditions are met, the rotary rectifier 30 is determined to have failed, and a fault alarm AL indicating the failure of the rotary rectifier 30 is output, for example, to an external display device, control device, or higher-level device (not shown). In this case, the synchronous motor 10 is inspected or stopped, for example, by an operation by an operator (not shown) who sees the fault alarm AL displayed on the display device or by an instruction from a control device or the like. The comparator 85 may also output an operation signal TC, which is a trip command for the higher-level circuit breaker 73 or the circuit breaker 64, to an external control device or higher-level device (not shown), or directly to the higher-level circuit breaker 73 or the circuit breaker 64. In this case, the higher-level circuit breaker 73 or the circuit breaker 64 is opened (shut down), for example, by an instruction from a control device or the like that has acquired the operation signal TC, or by directly acquiring the operation signal TC. This shuts down the AC current supplied to the synchronous motor 10 and the exciter 60, and the synchronous motor 10 stops operating.

[0044] On the other hand, the comparator 85 determines whether the obtained excitation current difference value ΔIf is equal to the allowable value ΔIf thIf the difference is less than 0.05, the rotary rectifier 30 is determined to be normal and not faulty, and no signal is output to an external display device or control device (not shown). In this case, the synchronous motor 10 continues to operate. The comparator 85 is an example of a "fault determination unit."

[0045] A delay circuit such as an on-delay (not shown) may be provided before the external output of the fault alarm AL, which is the external output of the comparator 85. This allows the comparator 85 to detect when the excitation current difference value ΔIf transiently falls below the allowable value ΔIf due to the influence of the transient impedance of the synchronous motor 10 when the load on the synchronous motor 10 fluctuates. th Even if the voltage exceeds this limit, the comparator 85 does not output a fault alarm AL in this case, thereby preventing the erroneous determination that there is a fault in the rotary rectifier 30. The time limit of the delay circuit is determined taking into consideration the transient impedance of the synchronous motor 10, etc.

[0046] The storage unit 86 is, for example, a volatile or non-volatile storage medium such as an HDD (Hard Disk Drive), and stores programs necessary for the operation of the rotary rectifier fault detection device 80. The storage unit 86 stores, for example, various coefficients, various arithmetic expressions, various thresholds, various graphs, various tables, and the like used in calculations by the rotary rectifier fault detection device 80.

[0047] The storage unit 86 also stores the synchronous impedance Zs, the proportionality coefficient KL, and the like of the rotor 50 of the synchronous motor 10, which are used in the calculations by the excitation current calculator 83. The synchronous impedance Zs, the proportionality coefficient KL, and the like may be set in advance for each synchronous motor 10 and stored in the storage unit 86, or may be set based on an operation by an operator (not shown) or an instruction from a higher-level device and stored in the storage unit 86, for example.

[0048] The synchronous impedance Zs and the proportionality coefficient KL, etc. are calculated and set from, for example, design data of the synchronous motor 10, data from a factory test (type test or shipping test) of the synchronous motor 10, etc., and are stored in the storage unit 86. For example, in the case of a large synchronous motor 10, these values are confirmed to be preset values in a factory test before shipping. However, since these values are basically the same for synchronous motors 10 of the same model, some of the tests may be omitted. In this case, for example, the synchronous impedance Zs and the proportionality coefficient KL, etc. of synchronous motors 10 of the same model may be set and stored in the storage unit 86. When multiple values are stored, an appropriate value may be automatically retrieved and used in response to an instruction from an operator or a higher-level device (not shown).

[0049] The storage unit 86 stores the allowable value ΔIf used in the judgment of the comparator 85. th The allowable value ΔIf is stored. th may be stored in advance in the storage unit 86, or may be stored in the storage unit 86 based on, for example, an operation by an operator (not shown) or an instruction from a higher-level device. th Similarly to the synchronous impedance Zs and the proportional coefficient KL, multiple values for ΔIf may be stored, and an appropriate value may be automatically retrieved and used in response to an instruction from an operator (not shown) or a higher-level device. th Alternatively, only one type may be stored.

[0050] The storage unit 86 is connected to each unit of the rotary rectifier fault detection device 80 via a bus or the like (not shown). The storage unit 86 may be provided outside the rotary rectifier fault detection device 80 and connected to the rotary rectifier fault detection 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 86 may also be shared with a memory 92 (see FIG. 6 ), which will be described later. The storage unit 86 may also be shared with a control device or the like (not shown) other than the rotary rectifier fault detection device 80.

[0051] <Operation of the coordinate conversion unit and excitation current calculator> FIG. 2 is a diagram showing an example of an operating point representation of the synchronous motor 10 shown in FIG. 1 using so-called PQ coordinates, which represent the operating point of the synchronous motor 10 in an orthogonal coordinate system with an active power axis and a reactive power axis. The Q axis, which is the vertical axis and represents reactive power, and the P axis, which is the horizontal axis and represents active power, are perpendicular to each other. The P axis represents active power P input to the synchronous motor 10 from the power receiving bus 75 via the power receiving transformer 74, with the rightward direction on the diagram representing positive (powering). The Q axis represents lagging reactive power Q input to the synchronous motor 10 from the power receiving bus 75 via the power receiving transformer 74, with the upward direction on the diagram representing positive (lagging). In FIG. 2, the dashed line represents the locus of operating points when the terminal voltage of the synchronous motor 10 and the input current are constant, and the angle θ0 between the line L0 and the horizontal axis (P axis) is the power factor angle at the operating point A0 (P0, Q0).

[0052] First, the input unit 81 acquires the active power value P and the reactive power value Q from the multimeter 76. Then, the input unit 81 acquires the acquired active power value P and reactive power value Q as PQ coordinate values, which are the operating point of the synchronous motor 10, and converts them into values in the per-unit method based on the synchronous motor 10. Furthermore, the input unit 81 acquires the terminal voltage value V from the multimeter 76 and converts it into a value in the per-unit method. Here, it is desirable that the reference value 1PU is the rated capacity and rated voltage of the synchronous motor 10. The reason for this is that the synchronous impedance Zs is often described in catalogs, test reports, etc. in the unit method based on the rating of the motor.

[0053] Next, the coordinate conversion unit 82 acquires the PQ coordinate values (i.e., the input active power Pu and input reactive power Qu of the synchronous motor 10) and the terminal voltage value Vu converted in the unit method from the input unit 81. Then, the coordinate conversion unit 82 converts the PQ coordinate values acquired from the input unit 81 into admittance coordinate values. That is, for example, when the terminal voltage of the synchronous motor 10 is the terminal voltage value Vu, Pu / Vu 2 is the conductance (G) of the synchronous motor 10, and Qu / Vu 2 is the susceptance of the synchronous motor. Therefore, the horizontal axis (G axis) is (Pu / Vu2 ), and the vertical axis (B axis) is (Qu / Vu 2 ) the PQ coordinate values can be converted to GB coordinate values. Here, the lagging phase of reactive power is considered positive.

[0054] Here, if the operating point of the synchronous motor 10 is PU converted terminal voltage Va1, PU converted active power Pa1, and PU converted reactive power Qa1, then the operating point A1 can be expressed as coordinates (A1g, A1b), where A1g is equation (1) described below, and A1b is equation (2).

[0055] Here, synchronous impedance Zs is divided into armature resistance Rs and synchronous reactance Xs, but the voltage drop due to armature resistance Rs is generally small enough compared to the voltage drop due to synchronous reactance Xs that it can be ignored. Therefore, the following explanation will be given for an evaluation using only synchronous reactance Xs.

[0056] Fig. 3 is a diagram showing an example of an operating point representation in admittance coordinates of the brushless synchronous motor 10 shown in Fig. 1. Fig. 3 shows an example of an operating point of the synchronous motor 10 expressed in GB coordinate system by dividing the synchronous reactance by the two-reaction method into a direct-axis synchronous reactance Xd of the component on the magnetic pole center axis (called the direct axis or d-axis) and a quadrature-axis synchronous reactance Xq of the component on the axis between the magnetic poles (called the quadrature axis or q-axis).

[0057] When the synchronous motor 10 is a salient pole motor, the coordinate conversion unit 82 converts the PQ coordinate values converted by the input unit 81 into GB coordinates shown in Fig. 3 using the terminal voltage value V and Kirchhoff's law. In Fig. 3, the vertical axis (B axis) is the susceptance Bu=Qu / Vu 2 The horizontal axis (G axis) is the conductance Gu = Pu / Vu. 2 The B axis and the Q axis are perpendicular to each other.

[0058] When the synchronous motor 10 is a salient-pole motor, the quadrature-axis synchronous reactance Xq is smaller than the direct-axis synchronous reactance Xd. Therefore, as shown in Figure 3, the locus of operating points where the internal induced voltage is zero can be represented by a circle S whose diameter is the point C on the B axis at coordinate (0, 1 / Xd) and the point D on the B axis at coordinate (0, 1 / Xq). The dashed line represents the locus of operating points where the apparent power of the synchronous motor 10 is constant when the terminal voltage V is constant. Here, if the operating point of the synchronous motor 10 is a PU converted terminal voltage Va1, PU converted active power Pa1, and PU converted reactive power Qa1, then the operating point A1, i.e., the coordinates (A1g, A1b), can be expressed by equations (1) and (2).

[0059]

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[0060]

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[0061] Here, the angle θ1 between the line connecting point A1 and the origin O and the G axis is the power factor angle at operating point A1. The angle δ1 between the line connecting point A1 and point D and the line connecting point D and the origin is the internal operating angle. If the intersection of the line connecting point A1 and point D and circle S is defined as point B1, the length L1 of the line connecting point A1 and point B1 is a value proportional to the excitation current calculation value If0a1 at operating point A1. Then, the intersection B1 is defined as the point D, i.e., coordinate (0, 1 / Xq), which indicates the quadrature-axis synchronous susceptance of the synchronous motor 10 on the B axis, with the coordinate indicating operating point A1 of the synchronous motor 10, and circle S, which is the line indicating the locus of operating points where the internal induced voltage is zero. In this case, the length L1 on the coordinate between point A1 and point B1 can be calculated as a value proportional to the excitation current calculation value If0a1.

[0062] Here, if we set the coordinates of point B1 as (B1g, B1b) and set up an equation to find the intersection of the circle and the line, we get equation (3), which is a quadratic equation with B1g as an unknown, and its solution can be found with simple calculations.

[0063]

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[0064] Here, a to c are as shown in the following formulas (4) to (6).

[0065]

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[0066]

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[0067]

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[0068] Here, k1 to k4 are as shown in the following formulas (7) to (10).

[0069]

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[0070]

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[0071]

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[0072]

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[0073] The solution of equation (3) is equation (11) or equation (12).

[0074]

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[0075]

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[0076] Here, since equation (11) is 1 / Xq, B1g can be obtained by equation (12), which is given by the following equation (13).

[0077]

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[0078] Therefore, B1b is expressed by the following equation (14).

[0079]

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[0080] Therefore, by using Pythagoras' theorem, L1 can be found from the following equation (15).

[0081]

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[0082] As explained above, when the synchronous motor 10 is a salient pole machine, the excitation current calculator 83 calculates the value L1 corresponding to the excitation current calculated value If0 based on the GB coordinate value, direct-axis synchronous reactance Xd, and quadrature-axis synchronous reactance Xq shown in FIG. 3, based on the above equation (15). Furthermore, the excitation current calculated value If0 in the real unit system is obtained as a value in the real unit system by multiplying L1 in equation (15) by an appropriate proportionality coefficient KL1. That is, it is expressed as the following equation (16).

[0083]

number

[0084] The proportionality coefficient KL1 may be theoretically calculated, or may be determined in advance by operating the synchronous motor 10 at a test operating point AT during a factory test or the like when the rotary rectifier 30 is in good condition, and measuring the active power PAT, reactive power QAT, terminal voltage VAT, and detected excitation current value IfAT. In other words, if the value of L1 determined by the above equation (15) using these values is taken as L1AT, KL1 can be determined by the following equation (17).

[0085]

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[0086] FIG. 4 is a diagram showing an example of an operating point display in admittance coordinates when the direct axis synchronous reactance Xd and the quadrature axis synchronous reactance Xq of the brushless synchronous motor 10 shown in FIG. 1 are considered to be equal.

[0087] When the direct-axis synchronous reactance Xd and the quadrature-axis synchronous reactance Xq can be considered to be the same, as in the case of a cylindrical motor, the reactance can be determined using the method described above, but it can also be determined more simply by the following calculation. If the direct-axis synchronous reactance Xd and the quadrature-axis synchronous reactance Xq are equal, the diameter of the circle S shown in Figure 3 will be zero. Therefore, as shown in Figure 4, if the PU converted terminal voltage is Va2 and the PU converted active power is Pa2 and the PU converted reactive power is Qa2, then the operating point A2, i.e., the coordinates (A2g, A2b), can be expressed using only the direct-axis synchronous reactance Xd. Here, A2g and A2b are expressed by the following equations (18) and (19).

[0088]

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[0089]

number

[0090] Here, the angle θ2 between the G-axis and the line connecting point A2 and the origin O is the power factor angle at operating point A2. If the coordinate (0, 1 / Xd) on the G-axis is point B2, then the angle δ2 between the line connecting point A2 and point B2 and the line connecting point B2 and the origin is the internal operating angle, and the length L2 of the line connecting point A2 and point B2 is a value proportional to the excitation current calculation value If0a2 at operating point A2. Therefore, using Pythagoras' theorem, L2 can be found from the following equation (20).

[0091]

number

[0092] As explained above, when the direct-axis synchronous reactance and quadrature-axis synchronous reactance of the synchronous motor 10 can be considered to be equal, the excitation current calculator 83 calculates the value L2 equivalent to the excitation current calculated value If0 based on the GB coordinate value and the direct-axis synchronous reactance Xd shown in FIG. 4 and the above equation (20). Furthermore, the excitation current calculated value If0 in the real unit system can be obtained as a value in the real unit system by multiplying L2 in equation (20) by an appropriate proportionality coefficient KL2. That is, the following equation (21) is obtained. Note that in this case, the direct-axis synchronous reactance Xd and the quadrature-axis synchronous reactance Xq can be considered to be the same value, so the quadrature-axis synchronous reactance Xq may be used instead of the direct-axis synchronous reactance Xd.

[0093]

number

[0094] The method for determining KL2 is the same as that for KL1 described above.

[0095] <Effects of one embodiment> 1 to 4, it is possible to provide a rotating rectifier fault detection device 80 for a brushless synchronous motor 10 that is capable of detecting faults without using a detection coil. Furthermore, when detecting faults simply based on reactive power or active power, fluctuations in the AC power supply voltage of the power receiving bus 75 can have an effect. However, in this embodiment, the admittance of the excitation circuit is calculated using the GB admittance coordinate system. Therefore, it is possible to provide a rotating rectifier fault detection device 80 for a synchronous motor 10 that is not affected by fluctuations in the AC power supply voltage.

[0096] <First Modification of One Embodiment> Fig. 5 is a diagram showing an example of the overall configuration of a brushless synchronous motor system 1A according to a first modified example of an embodiment. In Fig. 5, the same or similar components as those in the embodiment shown in Figs. 1 to 4 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted or simplified.

[0097] 5 differs from FIG. 1 in that the rotary rectifier fault detection device 80A has a judgment value calculation unit 87, and further, the storage unit 86 outputs a judgment criterion auxiliary value ΔKfh to the judgment value calculation unit 87. The excitation current detection value If output from the transducer 62 to the rotary rectifier fault detection device 80A is input to the judgment value calculation unit 87 together with a difference calculator 84. The judgment value calculation unit 87 then calculates the allowable value ΔIf based on the judgment criterion auxiliary value ΔKfh and the excitation current detection value If. th and outputs the result to comparator 85. In FIG. 5, rotary rectifier fault detection device 80A has the same or similar configuration as rotary rectifier fault detection device 80 shown in FIG. 1, except that it has judgment value calculation unit 87.

[0098] For example, the judgment value calculation unit 87 calculates the allowable value ΔIf th is not a fixed value, but is calculated by varying it in accordance with the excitation current detection value If based on the auxiliary judgment reference value ΔKfh. th is output to the comparator 85.

[0099] For example, the judgment value calculation unit 87 calculates the product of the auxiliary judgment reference value ΔKfh and the excitation current detection value If input from the storage unit 86 as the allowable value ΔIf th may be output to the comparator 85 as

[0100] The auxiliary judgment criterion value ΔKfh may be composed of a plurality of values. For example, the auxiliary judgment criterion value ΔKfh may be composed of a first auxiliary judgment criterion value ΔKfh1, a second auxiliary judgment criterion value ΔKfh2, a third auxiliary judgment criterion value ΔKfh3, a fourth auxiliary judgment criterion value ΔKfh4, and a fifth auxiliary judgment criterion value ΔKfh5. When the excitation current detection value If is equal to or smaller than the first auxiliary judgment criterion value ΔKfh1, the second auxiliary judgment criterion value ΔKfh2 is set to the allowable value ΔIf. th If the excitation current detection value If exceeds the fourth auxiliary judgment criterion value ΔKfh4, the fifth auxiliary judgment criterion value ΔKfh5 is set to the allowable value ΔIf th If the excitation current detection value If exceeds the first auxiliary judgment criterion value ΔKfh1 and is equal to or smaller than the fourth auxiliary judgment criterion value ΔKfh4, the product of the third auxiliary judgment criterion value ΔKfh3 and the excitation current detection value If is set to the allowable value ΔIf th Alternatively, the allowable value ΔIf may be set to a value that takes into account the saturation characteristics of the excitation current. th =ΔKfh(If) th may be calculated.

[0101] As described above, in the first modified example of the embodiment shown in FIG. 5, the configuration and operation other than those described above are the same as or similar to those of the embodiment shown in FIGS. 1 to 4, and therefore description thereof will be omitted.

[0102] <Operation and effect of the first modified example of the embodiment> As described above, the first modification of the embodiment shown in Fig. 5 has the same effects as the embodiment shown in Fig. 1 to Fig. 4. Furthermore, by changing the judgment criterion of the comparator 85 based on the excitation current detection value If, it is possible to more accurately judge a fault in the rotary rectifier 30 for various operating points of the synchronous motor 10. Therefore, it is possible to provide a rotary rectifier fault detection device 80A for a synchronous motor 10 that does not use a detection coil, performs simple calculations, and is not affected by voltage fluctuations in the AC power supply.

[0103] <Second Modification of One Embodiment> The second modification is different from the first modification in that the rotary rectifier fault detection device 80B has a judgment value calculation unit 87B instead of the judgment value calculation unit 87. The excitation current calculation value If0 output from the excitation current calculator 83 is input to the comparator 85 and the judgment value calculation unit 87B. The judgment value calculation unit 87B calculates the allowable value ΔIf based on the auxiliary judgment criterion value ΔKfhb and the excitation current calculation value If0. th is determined and output to the comparator 85. Other points are the same as those in the first modified example, and therefore are not shown in the drawings.

[0104] For example, the judgment value calculation unit 87B calculates the allowable value ΔIf th is not a fixed value, but is calculated based on the auxiliary judgment reference value ΔKfh and is varied in accordance with the excitation current calculation value If0. th is output to the comparator 85.

[0105] For example, the judgment value calculation unit 87B calculates the product of the auxiliary judgment reference value ΔKfhb and the excitation current detection value If input from the storage unit 86 as the allowable value ΔIf th may be output to the comparator 85 as

[0106] Furthermore, the auxiliary judgment criterion value ΔKfhb may be composed of a plurality of values. For example, the auxiliary judgment criterion value ΔKfhb is composed of a b1st auxiliary judgment criterion value ΔKfhb1, a b2nd auxiliary judgment criterion value ΔKfhb2, a b3rd auxiliary judgment criterion value ΔKfhb3, a b4th auxiliary judgment criterion value ΔKfhb4, and a b5th auxiliary judgment criterion value ΔKfhb5. When the excitation current calculated value If0 is equal to or smaller than the b1st auxiliary judgment criterion value ΔKfhb1, the judgment value calculation unit 87B sets the b2nd auxiliary judgment criterion value ΔKfhb2 to the allowable value ΔIf th If the excitation current calculation value If0 exceeds the b4th auxiliary criterion value ΔKfhb4, the b5th auxiliary criterion value ΔKfhb5 is set to the allowable value ΔIf th If the excitation current calculation value If0 exceeds the b1 auxiliary criterion value ΔKfhb1 and is equal to or smaller than the b4 auxiliary criterion value ΔKfhb4, the product of the b3 auxiliary criterion value ΔKfhb3 and the excitation current calculation value If0 is set to the allowable value ΔIf th The allowable value ΔIf may be set to a value that takes into account the saturation characteristics of the excitation current. th =ΔKfhb(If0) th may be calculated.

[0107] <Operation and effect of the second modified example of the embodiment> As described above, the second modification of the embodiment provides the same effects as the embodiment shown in Figures 1 to 4. Furthermore, by changing the judgment criterion of the comparator 85 using the excitation current calculated value If0, it is possible to more accurately judge a fault in the rotary rectifier 30 for various operating points of the synchronous motor 10. Therefore, it is possible to provide a rotary rectifier fault detection device 80B for a synchronous motor 10 that does not use a detection coil, performs simple calculations, and is not affected by voltage fluctuations in the AC power supply.

[0108] <Hardware configuration example> FIG. 6 is a conceptual diagram showing an example of the hardware configuration of the processing circuit 90 included in the rotary rectifier fault detection devices 80, 80A, and 80B in the embodiment shown in FIGS.

[0109] Each of the above-described functions is realized by a processing circuit 90. In one embodiment, the processing circuit 90 includes at least one processor 91 and at least one memory 92. In another embodiment, the processing circuit 90 includes at least one dedicated hardware 93.

[0110] 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.

[0111] 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.

[0112] The functions of the rotary rectifier fault detection devices 80, 80A, and 80B may be partially or entirely configured by hardware, or may be configured as a program executed by a processor. That is, the rotary rectifier fault detection devices 80, 80A, and 80B can also be realized by a computer and a program, and the program can be stored on a storage medium or provided over a network.

[0113] <Supplementary information on the embodiment> 1 to 6, one aspect of the present disclosure has been described in terms of the case where rotary rectifier fault detection devices 80, 80A, and 80B are applied to brushless synchronous motor system 1. However, the present disclosure is not limited to this, and rotary rectifier fault detection devices 80, 80A, and 80B can be applied to all brushless synchronous motors, regardless of whether they are synchronous motors or synchronous generators.

[0114] 1 to 6, the comparator 85 outputs the failure alarm AL and the operation signal TC, but this is not limiting. The comparator 85 may output either or both of the failure alarm AL, which is information indicating a failure in the rotary rectifier 30, and the operation signal TC, which is a trip command for the upper circuit breaker 73, the circuit breaker 64, etc., to an external display device, control device, or higher-level device (not shown).

[0115] 1 to 6, when the comparator 85 outputs a fault alarm AL or an operation signal TC, the synchronous motor 10 stops operating in response to an operation by an operator (not shown) or a command from a control device or the like. However, this is not limiting. The synchronous motor 10 may stop operating automatically when the comparator 85 outputs a fault alarm AL or an operation signal TC, or may stop operating automatically when it receives both the fault alarm AL or the operation signal TC and a signal from another protection device (not shown).

[0116] 1 to 6, one aspect of the present disclosure has been described using rotary rectifier fault detection devices 80, 80A, and 80B provided in brushless synchronous motor system 1 as an example, but the present disclosure is not limited to this. The present disclosure can also be realized as an independent rotary rectifier fault detection device or rotary rectifier fault detection system.

[0117] The present disclosure can also be realized as a rotary rectifier fault detection method in which processing steps are performed in each of the rotary rectifier fault detection devices 80, 80A, and 80B.

[0118] The present disclosure can also be realized as a rotary rectifier fault detection program that causes a computer to execute the processing steps in each of the rotary rectifier fault detection devices 80, 80A, and 80B.

[0119] The present disclosure can also be realized as a storage medium (non-transitory computer-readable storage medium) on which a rotating rectifier fault detection program is stored. The rotating rectifier fault detection program can be stored and distributed on removable media such as a CD (Compact Disc), a DVD (Digital Versatile Disc), or a USB (Universal Serial Bus) memory. These programs may be uploaded to a network via a network interface (not shown) included in the synchronous motor system 1, or may be downloaded from the network and stored in memory 92.

[0120] The features and advantages of the embodiments will be apparent from the above detailed description. It is intended that the claims encompass the features and advantages of the above-described embodiments without departing from the spirit and scope of the claims. Furthermore, any improvements and modifications will be readily apparent to those skilled in the art. Therefore, it is not intended that the scope of the inventive embodiments be limited to the above-described embodiments, and appropriate improvements and equivalents within the scope of the disclosed embodiments may be utilized. [Explanation of symbols]

[0121] 1,1A...Brushless synchronous motor system (synchronous motor system); 10...Brushless synchronous motor (synchronous motor); 20...Synchronous motor body; 21...Synchronous motor armature; 22...Synchronous motor main excitation winding; 30...Rotating rectifier; 31...Semiconductor element; 40...AC exciter; 41...AC exciter armature; 42...AC exciter excitation coil; 50...Rotor; 60...Exciter; 61...Current sensor; 62...Transducer (TRD); 63...Thyristor rectifier; 64...Circuit breaker; 66...External power supply 71...Current transformer (CT); 72...Voltage transformer (VT); 73...Upstream circuit breaker; 74...Receiving transformer; 75...Receiving bus; 76...Multimeter; 80, 80A, 80B...Rotary rectifier fault detection device; 81...Input section; 82...Coordinate conversion section; 83...Excitation current calculator (excitation current calculation section); 84...Differentiator (excitation current difference value calculation section); 85...Comparator (fault judgment section); 86...Memory section; 87, 87B...Judgment value calculation section; 90...Processing circuit; 91...Processor; 92...Memory; 93...Hardware Software; A0, A1, A2... operating point (point); AL... fault alarm; AT... test operation point; B1, B2... point; Bu... susceptance; C... point; D... operating point (point); Gu... conductance; If... excitation current detection value; If0, If0a1, If0a2... excitation current calculation value; IfAT... excitation current detection value; KL, KL1, KL2... proportional coefficient; L0... line; L1, L2... length (value); O... origin; P... active power value (active power); Pa1, Pa2... PU converted active power; PAT... active power; Pu... input Active power; Q... reactive power value (reactive power); Qa1, Qa2... PU converted reactive power; QAT... reactive power; Qu... input reactive power; Rs... armature resistance; S... circle; TC... operating signal; V... terminal voltage value (terminal voltage); Va1, Va2... PU converted terminal voltage; VAT... terminal voltage; Vu... terminal voltage value; Xd... direct axis synchronous reactance; Xq... quadrature axis synchronous reactance; Xs... synchronous reactance; Zs... synchronous impedance; δ, δ1, δ2... internal phase difference angle (angle); ΔIf... excitation current difference value; ΔIf th...Tolerance value; ΔKfh...Auxiliary judgment criterion value; ΔKfh1...First auxiliary judgment criterion value; ΔKfh2...Second auxiliary judgment criterion value; ΔKfh3...Third auxiliary judgment criterion value; ΔKfh4...Fourth auxiliary judgment criterion value; ΔKfh5...Fifth auxiliary judgment criterion value; ΔKfhb...Auxiliary judgment criterion value; ΔKfhb1...B1st auxiliary judgment criterion value; ΔKfhb2...B2nd auxiliary judgment criterion value; ΔKfhb3...B3rd auxiliary judgment criterion value; ΔKfhb4...B4th auxiliary judgment criterion value; ΔKfhb5...B5th auxiliary judgment criterion value; θ0, θ1, θ2...Angle

Claims

1. 1. A rotating rectifier fault detection device for a brushless synchronous motor, comprising: an excitation current calculation unit that calculates an operating point of the brushless synchronous motor as an admittance coordinate based on an active power value, a reactive power value, and a terminal voltage value input to the brushless synchronous motor, and calculates an excitation current calculation value of the brushless synchronous motor; an excitation current difference value calculation unit that acquires an excitation current detection value that is a detection value of an excitation current supplied to an excitation circuit of the brushless synchronous motor, compares the excitation current calculation value calculated by the excitation current calculation unit with the acquired excitation current detection value, and calculates an excitation current difference value that indicates the difference between the excitation current calculation value and the excitation current detection value; a failure determination unit that compares the excitation current difference value with a tolerance and determines that the rotary rectifier is faulty if the excitation current difference value is equal to or greater than the tolerance; A rotating rectifier fault detection device for a brushless synchronous motor, comprising:

2. 2. The rotating rectifier fault detection device for a brushless synchronous motor according to claim 1, The excitation current calculation unit further calculates the excitation current calculation value based on the synchronous impedance of the brushless synchronous motor. A rotating rectifier fault detection device for a brushless synchronous motor.

3. 3. The rotating rectifier fault detection device for a brushless synchronous motor according to claim 2, The excitation current calculation unit uses a direct axis synchronous reactance and a quadrature axis synchronous reactance as the synchronous impedance. A rotating rectifier fault detection device for a brushless synchronous motor.

4. 3. The rotating rectifier fault detection device for a brushless synchronous motor according to claim 2, The excitation current calculation unit uses either a direct axis synchronous reactance or a quadrature axis synchronous reactance as the synchronous impedance. A rotating rectifier fault detection device for a brushless synchronous motor.

5. 2. The rotating rectifier fault detection device for a brushless synchronous motor according to claim 1, The tolerance is a value that varies based on the excitation current detection value or the excitation current calculation value. A rotating rectifier fault detection device for a brushless synchronous motor.

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