JP2016167903A - Power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of generation of imbalance in loads of respective field windings caused by changing field winding wire connection of an AC exciter or variation in an AC brushless excitation device's output characteristic accompanying a variation in power generator rotation speed, in the AC brushless excitation device and power generation system in which the field winding wire connection of the AC exciter needs changing because AC voltage is applied at the time of start-up by an SFC and DC voltage is applied at the time of rated operation, to multiphase field windings of the AC exciter.SOLUTION: A power generation system performs AC excitation on an AC exciter by making AC exciter's d-axis winding and q-axis winding constitute a dq orthogonal axis, when an SFC is connected to a synchronous power generator armature winding, and performs DC excitation on the AC exciter by making a thyristor excitation device rectify AC current supplied from a power supply and making the d-axis winding and q-axis winding be connected in series, at the time of normal operation of a synchronous power generator. The power generation system also comprises means for estimating a synchronous power generator field voltage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power generation system, and more particularly to a power generation system including an AC excitation brushless excitation device in which a field winding of an AC exciter is a multiphase winding.

Generally, a synchronous generator supplies a direct current to a rotor field winding and outputs an induced electromotive force generated by a magnetic flux generated on the rotor side on the stator side. As a typical method for exciting the rotor field winding, there are a thyristor excitation method and a brushless AC excitation method.
Of these, the brushless AC excitation method is induced in the armature winding of the AC exciter consisting of the field winding on the stator side and the armature winding on the rotor side that is directly connected to the rotating shaft of the generator. The current is rectified by a rotary rectifier and supplied to the field winding of the generator. Generally, the voltage applied to the field winding of an AC exciter during generator rated operation is DC.

As a method of starting the synchronous generator, the generator is gradually increased in frequency by using a static frequency converter (SFC: Static Frequency Converter; hereinafter abbreviated as SFC), that is, the motor. There is a way to accelerate as.
In the brushless AC excitation method, when the voltage applied to the field winding of the AC exciter is DC and the field current is kept constant, the generator field current cannot flow when the generator is stationary. The field current of the generator changes according to the speed. For this reason, direct current excitation cannot be applied to the alternating current exciter when the generator is started.

  In order to use an AC exciter when starting up using an SFC, there is one that uses a wound induction motor as an AC exciter (see, for example, Patent Document 1). When the generator speed is less than a predetermined value, an AC voltage is applied to the field winding of the AC exciter, and when it exceeds the specified value, the connection of the field winding of the AC exciter is changed and the thyristor exciter is connected to the DC A voltage is applied. In addition, there is a configuration in which an AC magnetic field opposite to the fixed side is generated in the three-phase winding of the AC exciter when the generator is started (see, for example, Patent Document 2). In addition, there is an apparatus provided with an SFC for a brushless exciter used during low-speed rotation (see, for example, Patent Document 3). The brushless exciter SFC applies a current of constant amplitude to the stator field winding of the exciter at a frequency that keeps the relative rotational speed of the rotating magnetic field viewed from the rotor at the rated rotational speed. Yes.

JP-A-4-96698 JP2013-236480A Japanese Patent Laid-Open No. 7-245998

  In such an AC brushless exciter and a power generation system, an AC voltage is applied to the multi-phase field winding of the AC exciter when the generator is started by SFC, and the multi-phase field winding of the AC exciter is used during rated operation. Therefore, it is required to apply a DC voltage to AC, and the field winding connection of the AC exciter is changed by AC excitation and DC excitation. However, there is a problem that unbalance is generated in the load of each field winding by changing the connection. Furthermore, there has been a problem that the output characteristics of the brushless exciter change as the generator speed changes.

  The present invention has been made to solve such a problem, and even when an AC exciter having a multiphase field winding is DC-excited, the load of each field winding is kept even, and the generator An object of the present invention is to obtain a power generation system including a brushless exciter capable of controlling the output to be constant even when the rotation speed changes.

The power generation system according to the present invention includes:
A power converter that outputs AC power supplied from a power source as variable voltage or variable frequency three-phase AC power;
The primary side has a three-phase winding, the secondary side has a first single-phase winding and a second single-phase winding, and the three-phase winding is connected to the output end of the power converter, A Scott transformer that outputs AC power having a phase difference between the first single-phase winding and the second single-phase winding when three-phase AC power from a power converter is input;
A thyristor exciter that rectifies an alternating current supplied from a power source;
An AC exciter having a d-axis winding and a q-axis winding on the primary side and a rotary multiphase winding on the secondary side;
The output line of the thyristor excitation device, the first single-phase winding, and the second single-phase winding are connected to the primary side, and the d-axis winding and the q-axis winding are connected to the secondary side. The d-axis winding is connected to the first single-phase winding or the second single-phase winding, and the q-axis winding is connected to the other single-phase winding. Switching between excitation methods by selecting either one connection or the second connection in which the d-axis winding and the q-axis winding are connected in series and the output line of the thyristor excitation device is connected to both ends thereof An excitation method switching device for performing
A rotary rectifier connected to the rotary multiphase winding and rectifying a multiphase output from the AC exciter;
A synchronous generator field winding, a synchronous generator armature winding, and the synchronous generator field winding connected to the output terminal of the rotary rectifier;
When connected to the synchronous generator armature winding, it is driven to flow a current output having a frequency and phase according to the position of the synchronous generator rotor to the synchronous generator armature winding. Type frequency converter,
A voltage detector for detecting an output voltage of the power converter;
A synchronous generator field voltage estimator for estimating a field voltage of the synchronous generator based on the voltage detected by the voltage detector;
With
When the static frequency converter is connected to the synchronous generator armature winding, the first connection is selected by the excitation method switching device, and the d-axis winding and the q-axis winding are dq orthogonal. The AC exciter is AC-excited by applying a variable voltage or variable frequency power to the d-axis winding and the q-axis winding, and the thyristor excitation is performed during normal operation of the synchronous generator. The device rectifies the AC current from the power source, and the excitation method switching device selects the second connection, and the d-axis winding and the q-axis winding are connected in series so that the AC exciter is DC-excited. To do.

Moreover, the power generation system according to the present invention includes:
A power converter having a first single-phase output and a second single-phase output for outputting AC power supplied from a power source as two sets of single-phase AC power of variable voltage or variable frequency;
A first single-phase transformer in which the first single-phase output is connected to a primary winding; and a second single-phase transformer in which the second single-phase output is connected to a primary winding;
A thyristor exciter that rectifies an alternating current supplied from a power source;
An AC exciter having a d-axis winding and a q-axis winding on the primary side and a rotary multiphase winding on the secondary side;
An output line of the thyristor excitation device, a secondary winding of the first single-phase transformer, and a secondary winding of the second single-phase transformer are connected to the primary side, and the secondary side, A d-axis winding and a q-axis winding are connected, and the d-axis winding and the secondary winding of the first single-phase transformer or the secondary winding of the second single-phase transformer The first connection for connecting the q-axis winding and the other secondary single-phase winding, or the d-axis winding and the q-axis winding are connected in series, and the thyristor excitation is connected to both ends thereof. An excitation method switching device for selecting one of the second connections for connecting the output lines of the device and switching the excitation method;
A rotary rectifier connected to the rotary multiphase winding and rectifying a multiphase output from the AC exciter;
A synchronous generator field winding, a synchronous generator armature winding, and the synchronous generator field winding connected to the output terminal of the rotary rectifier;
When connected to the synchronous generator armature winding, it is driven to flow a current output having a frequency and phase according to the position of the synchronous generator rotor to the synchronous generator armature winding. Type frequency converter,
A voltage detector for detecting an output voltage of the power converter;
A synchronous generator field voltage estimator for estimating a field voltage of the synchronous generator based on the voltage detected by the voltage detector;
With
When the static frequency converter is connected to the synchronous generator armature winding, the first connection is selected by the excitation method switching device, and the d-axis winding and the q-axis winding are dq orthogonal. The AC exciter is AC-excited by applying a variable voltage or variable frequency power to the d-axis winding and the q-axis winding, and the thyristor excitation is performed during normal operation of the synchronous generator. The device rectifies the AC current from the power source, and the excitation method switching device selects the second connection, and the d-axis winding and the q-axis winding are connected in series so that the AC exciter is DC-excited. To do.

  According to the present invention, by making the input of the AC exciter a variable power source, it is possible to suppress the fluctuation of the generator field current accompanying the increase in the generator rotational speed at the time of starting the SFC and control it to a constant value. In addition, since the generator field voltage can be estimated when the SFC is activated, it is not necessary to detect the generator field voltage. As a result, it is possible to provide a power generation system that is small in size and low in cost.

It is a block diagram which shows an example of the electric power generation system provided with the alternating current brushless exciting device by Embodiment 1 of this invention. It is a block diagram which shows the detail of the electric power generation system provided with the alternating current brushless exciting device by Embodiment 1 of this invention. It is a block diagram of the power converter of FIG. It is a block diagram of the inverter control part of FIG. It is a block diagram of the generator field voltage control part of FIG. It is a block diagram of the inverter current control part of FIG. It is a figure which shows the dq axis | shaft equivalent circuit of the alternating current exciter by Embodiment 1 of this invention. It is a figure which shows the equivalent circuit of the Scott transformer by Embodiment 1 of this invention. It is a figure which shows the equivalent circuit of the rotary rectifier and synchronous generator field winding by Embodiment 1 of this invention. It is a block diagram of the inverter control part by Embodiment 2 of this invention. It is a block diagram of the inverter control part by Embodiment 3 of this invention. It is a block diagram of the synchronous generator field voltage estimated value correction | amendment part of FIG. It is a figure which shows an example of the table of FIG. It is a block diagram which shows an example of the electric power generation system provided with the alternating current brushless excitation device by Embodiment 4 of this invention.

  Hereinafter, an embodiment of a power generation system including an AC brushless excitation device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram illustrating an example of a power generation system including an AC brushless excitation device according to a first embodiment of the present invention. The power generation system 100 includes a synchronous generator 1, an AC brushless exciter 2, a rotary rectifier 3, and a static frequency converter (SFC) 4. The synchronous generator 1 is a field winding type and includes a synchronous generator armature winding 21 and a synchronous generator field winding 22. The AC output of the AC brushless excitation device 2 is connected to the rotary rectifier 3 and rectified by the rotary rectifier 3, and then DC-excites the synchronous generator field winding 22. During normal power generation, the generated power is transmitted via the output line 6 of the synchronous generator armature winding 21. The switch 5 is open during normal power generation. When the synchronous generator 1 is started, the switch 5 is closed and the SFC 4 supplied with power from the power source 7 is connected to the synchronous generator armature winding 21 and accelerated. Here, the power source 7 corresponds to, for example, the output of a transformer (not shown) connected to the power system in the power plant. The output voltage of the transformer is a voltage suitable for the input of SFC4.

  The AC brushless exciter 2 is an AC exciter 11, a power converter 12, an excitation method switching device 13, a thyristor exciter 14, and a transformer capable of obtaining two sets of single-phase AC from three-phase AC. A Scott transformer 15 is provided.

  The AC exciter 11 includes an AC exciter armature winding 23, an AC exciter d-axis field winding 24, and an AC exciter q-axis field winding 25. Hereinafter, they may be collectively referred to as AC exciter field windings 24 and 25. The AC exciter armature winding 23 is a rotor and is directly connected to the rotating shaft of the synchronous generator 1. The AC exciter armature winding 23 is a three-phase winding and is an AC output of the AC brushless exciter 2. The AC exciter field windings 24 and 25 are stators. These stators have a two-phase winding configuration and are connected to the excitation method switching device 13. The same explanation holds true even if the d-axis and q-axis of the AC exciter field windings 24 and 25 are interchanged.

  The excitation system switching device 13 is a device that switches between DC excitation and AC excitation of the AC exciter field windings 24 and 25. When performing DC excitation, the switches 34a and 34b are opened, and 35a, 35b and 35c are closed. At this time, the AC exciter field windings 24 and 25 are connected in series. When AC excitation is performed, the switches 34a and 34b are closed and 35a, 35b and 35c are opened. At this time, the AC exciter field windings 24 and 25 constitute the dq orthogonal axis of the AC exciter as described above. The output of the thyristor excitation device 14 and the output of the Scott transformer 15 are connected to the input portion of the excitation method switching device 13. When performing DC excitation, the output of the thyristor excitation device 14 is connected to the AC exciter field windings 24 and 25. When performing AC excitation, the output of the Scott transformer 15 is connected to the AC exciter field windings 24 and 25.

During normal operation of the synchronous generator 1, the alternating current supplied from the power source 9 is rectified by the thyristor excitation device 14, and the alternating current exciter 11 is operated by direct current excitation. Here, the power source 9 is supplied by, for example, a permanent magnet generator (not shown) directly connected to the rotating shaft of the AC exciter 11. It can also be supplied from a power supply system in the power plant via a transformer (not shown).
Here, the thyristor exciter 14 is used when the AC exciter 11 is operated by DC excitation. However, the AC exciter field windings 24 and 25 are supplied with the AC supplied from the power supply 9 as an input and the DC output. It is obvious that another form of rectifier can be used, such as a voltage-type power converter capable of passing a direct current through.

  Next, the startup time of the synchronous generator 1 will be described. The power source 8 supplies power to the power converter 12. The power source 8 is obtained, for example, from a power system in the power plant via a transformer (not shown). The power converter 12 includes a diode rectifier 31, a smoothing capacitor 32, and a voltage source three-phase inverter 33, for example. The voltage-type three-phase inverter 33 includes, for example, a diode connected in antiparallel with an IGBT (Insulated Gate Bipolar Transistor) that is a self-extinguishing semiconductor switching element. Further, although not shown here, it is also apparent that the control unit generates an IGBT gate signal and performs a protection function. The control unit may further have a function of exchanging signals with a detector (not shown) in the power generation system 100 (for example, a current detector, a voltage detector, a speed detector, etc.) and other control means. . Needless to say, a reactor may be connected to the input or output of the diode rectifier 31.

The AC power supplied from the power supply 8 is rectified by the diode rectifier 31. The output of the power converter 12 is the output of the voltage-type three-phase inverter 33, and is a three-phase alternating current of variable voltage or variable frequency (there may be either one of the three-phase alternating currents or both three-phase alternating currents). Is input to the Scott transformer 15.
The Scott transformer 15 is a transformer that can obtain two sets of single-phase alternating current from three-phase alternating current. Specifically, as a means for obtaining two-phase (dq axis) alternating current having a phase difference of 90 °. I use it. By applying one of the outputs of the Scott transformer 15 to the AC exciter d-axis field winding 24 and the other to the AC exciter q-axis field winding 25, the AC exciter 11 operates with dq-axis AC excitation. Let

  Since the output voltage of the voltage-type three-phase inverter 33 has a rectangular wave shape, the harmonic component is removed to prevent the surge voltage from being applied to the AC exciter field windings 24 and 25, and the voltage is sine. For the purpose of making it wavy, a filter for removing high frequency components may be provided on the input side or output side of the Scott transformer 15.

Next, a mechanism for generating an output voltage in the AC exciter armature winding 23 when the AC exciter 11 is AC-excited will be described. When the number of pole pairs of the AC exciter 11 is p and the excitation frequency applied to the AC exciter field windings 24 and 25 is f1 [Hz], the synchronous speed Ns [r / min] is expressed by the equation (1). Become. The slip s can be expressed by Equation (2) when the rotation speed is N [r / min].
Ns = 60 × f1 / p (1)
s = (Ns−N) / Ns (2)

When stationary, that is, when N = 0, s = 1, and when a rotating magnetic field is excited in the same direction as the rotation direction, the slip s decreases and the rotation speed is N = Ns. s = 0. When a rotating magnetic field is excited in the direction opposite to the rotating direction, the slip s increases. When rotating at N = −Ns, s = 2. When the voltage of the AC exciter armature winding 23, that is, the input voltage of the rotary rectifier 3 is E2 [V] and the voltage applied to the AC exciter field windings 24 and 25 is E1 [V], E2 is an expression. It can be expressed as (3).
E2 = K1 × f1 × s × E1 (3)
However, K1 is a constant value.

Further, when a rotating magnetic field is excited in the direction opposite to the rotating direction (N ≦ 0), the rotation frequency f2 [Hz] can be expressed by the equation (4), and when slip is expressed using f1 and f2, the equation (5 )become that way.
f2 = −N × p / 60 (4)
s = (f1 + f2) / f1 (5)
In addition, since the frequency of E2 becomes a slip frequency, it can be shown by Formula (6).
s × f1 = f1 + f2 (6)

  According to Equations (3) and (6), E2 is obtained when AC excitation (f1 ≠ 0) is performed even when stationary (s = 1), and the excitation frequency f1 [Hz] is input to the rotary rectifier 3. ] Of alternating current can be passed. Further, according to equation (3), it is clear that E2 is proportional to the product of the excitation frequency f1 and the slip s if E1 is constant. Therefore, when it is desired to obtain a predetermined E2 at rest (s = 1), E1 can be reduced by increasing f1. In addition, if a rotating magnetic field is excited in the direction opposite to the rotating direction, the slip s increases with acceleration. Therefore, if f1 is kept constant, E1 decreases.

Next, operation | movement of the electric power generation system 100 at the time of starting is demonstrated. The synchronous generator 1 is mechanically torqued by an external device (not shown) at the start of startup, and rotates at an extremely low speed of, for example, 3 r / min (3 min ⁻¹ ). The AC brushless exciter 2 is connected to the AC exciter armature winding so that the synchronous generator field voltage Vf is applied to the synchronous generator field winding 22 so that the required synchronous generator field current If flows at startup. 23 voltage E2 is output. If the necessary E2 is determined, the voltage E1 to be applied to the AC exciter field windings 24 and 25 is determined from the equation (3). The power converter 12 outputs a voltage having an excitation frequency f1 and an amplitude Vinv so that the determined E1 can be obtained. From equation (3), it is clear that Vinv can be reduced by increasing f1. When the synchronous generator field current If rises, the SFC 4 detects or estimates the position of the rotor of the synchronous generator 1, outputs a current of a frequency and a phase corresponding thereto, and the synchronous generator armature winding 21 is applied. Thereby, the synchronous generator 1 accelerates gradually.

  In general, the SFC 4 provides an output current so that the armature voltage of the synchronous generator 1 increases in proportion to the operating frequency when the synchronous generator 1 rotates at the extremely low speed as described above. Thereby, the operating frequency of the synchronous generator 1 increases and the synchronous generator 1 is accelerated. At this time, if f1 is kept constant, Vinv is reduced as acceleration is performed so that the synchronous generator field voltage Vf becomes constant (Vinv is a variable voltage). Alternatively, Vinv may be kept constant and f1 may be reduced (f1 is a variable frequency), or both f1 and Vinv may be changed so that the synchronous generator field voltage Vf becomes constant.

  The armature voltage when the operation frequency of the synchronous generator 1 increases and reaches the operation mode switching frequency fsg1 is defined as Vsg1. The armature voltage Vsg1 in this case is less than the rated value of the armature voltage of the synchronous generator 1, and is, for example, the rated output voltage of SFC4. Thereafter, in the region where the operating frequency exceeds fsg1, the operation is performed under the condition that the armature voltage is constant. At this time, since Vf is reduced according to the operating frequency in order to keep the value of Vsg1 at a constant value for the armature voltage, Vinv and f1 can be further reduced with acceleration.

  Here, the reference for switching Vf from a constant value to a variable value is the operating frequency, but it is needless to say that it may be an armature voltage or a signal given from other control means in the power generation system 100.

  Here, a method for controlling the synchronous generator field voltage Vf to be constant will be described. FIG. 2 is a detailed configuration diagram of the power generation system including the AC brushless excitation device according to the first embodiment of the present invention, and the configuration diagram of the power generation system 100 including the AC brushless excitation device 2 of FIG. 1 is further detailed. It is shown.

The voltage transformer 26 is provided to detect the armature voltage Vs of the synchronous generator 1, and the voltage on the low voltage side is Vt here. The secondary side of the instrument transformer 26 is Y-connected, and the phase voltages Vtu, Vtv, Vtw on the secondary side are input to the power converter 12. The AC brushless exciter 2 is further provided with current detectors 16a and 16b and voltage detectors 17a, 17b and 17c. The detection values obtained by these detectors are input to the power converter 12. Yes.
The current detectors 16a and 16b detect the output currents (inverter output currents) Iiu and Iiw of the power converter 12, and the remaining one-phase Iiv is represented by the formula because the power converter 12 is a three-phase three-wire system. Although the calculation is performed in (7), it goes without saying that a current detector may be provided.
Iiv = −Iiu−Iiw (7)

  Furthermore, the phase for detecting the current is not limited to the U phase and the W phase, and two phases out of the three phases may be selected. The voltage detectors 17a, 17b, and 17c detect the output phase voltages (inverter output phase voltages) Viu, Viv, and Viw of the power converter 12. Although the phase voltage is detected here, it may be detected as a line voltage or may be obtained by detecting two phases out of the three phases and calculating the remaining one phase. Furthermore, the secondary side of the instrument transformer 26 may be a Δ connection instead of a Y connection.

  FIG. 3 is a configuration diagram of the power converter 12 of FIG. The power converter 12 in FIG. 3 includes an inverter control unit 36. The detected values Vtu, Vtv, Vtw, Iiu, Iiw, Viu, Viv, and Viw are input to the inverter control unit 36, and the gate signal of the voltage-type three-phase inverter 33 is output. In addition, it is not necessary to directly input the phase voltages Vtu, Vtv, Vtw on the secondary side of the instrument transformer 26 into the inverter control unit 36, and a level suitable for the inverter control unit 36 by using another instrument transformer. Needless to say, it can be converted to and input.

  Alternatively, a line voltage or two-phase may be used, and finally the armature phase voltages Vsu, Vsv, Vsw of the synchronous generator 1 can be obtained by the detection value input to the inverter control unit 36 and internal calculation. I can do it.

Below, the structure of the inverter control part 36 is demonstrated. FIG. 4 is a block diagram of the inverter control unit 36 of FIG.
The synchronous generator field voltage command value Vfref is held as a fixed value in the inverter control unit 36, for example. Or the value according to states, such as a constant of the synchronous generator 1, ambient temperature, may be received from the other control means which is not illustrated. During constant field voltage control, Vfref has a constant value. However, since the circuit is inductive, the voltage-type three-phase inverter 33 is released from the stopped state, and in the initial stage when the output current is 0, the voltage is excessive. In order to prevent current, Vfref should be gradually increased.

  In order to control the synchronous generator field voltage Vf to the synchronous generator field voltage command value Vfref, it is preferable to perform feedback control using the detected value of the synchronous generator field voltage Vf. However, since the power converter 12 is stationary but the synchronous generator field winding 22 is rotating, a slip ring is required to directly detect the synchronous generator field voltage Vf. Therefore, in the power generation system 100 of FIG. 2, the synchronous generator field voltage Vf is not detected directly, and the synchronous generator field voltage Vf is kept constant by using the synchronous generator field voltage estimated value Vfh. To control.

  Vfref and the synchronous generator field voltage estimated value Vfh are input to the synchronous generator field voltage control unit 41. FIG. 5 is a block diagram of the synchronous generator field voltage control unit 41 of FIG. The synchronous generator field voltage control unit 41 performs feedback control and outputs an inverter current amplitude command value Iiref. The synchronous generator field voltage controller 47 is, for example, a proportional integration controller.

Since Iiref is obtained as a current amplitude, the inverter current command value generation unit 42 generates an instantaneous value of each phase of the inverter. The inverter frequency command value f1ref is further input to the inverter current command value generation unit. Using Iiref and f1ref, inverter current command values Iiuref, Iivref, and Iiref are generated as shown in equations (8) to (10).
Iiuref = Iiref × sin (2π × f1ref × t) (8)
Iivref = Iiref × sin (2π × f1ref × t−2π / 3) (9)
Iiwref = Iiref × sin (2π × f1ref × t + 2π / 3)
... (10)

  Here, t is a time and does not necessarily need to be synchronized with the SFC 4 or the like, and may be created internally. It is not necessary to determine the phase as in equations (8) to (10) as long as the phase is three-phase balanced. f1ref may be held internally as a fixed value, or may be changed according to the system state such as a rotation speed. As for the sine wave calculation, the calculation may be performed sequentially or by referring to a table.

  The inverter current command values Iiuref, Iivref, Iiwref and the inverter output currents Iiu, Iiv, Iiw are input to the inverter current control unit 43. FIG. 6 is a block diagram of the inverter current control unit 43 of FIG. The inverter current control unit 43 performs feedback control, and outputs inverter voltage command values Viuref, Vivref, and Viwref. Since the phase current control units 48a, 48b, and 48c have the same configuration, the U-phase phase current control unit 48a will be described as a representative example. The phase current control unit 48a inputs Iiuref and Iiu, performs feedback control, and outputs Viuref. The inverter current controller 49 can be realized by a proportional-integral controller or a proportional controller.

  The inverter voltage command values Virefref, Vivref, and Viwref are input to the gate signal generation unit 44, and the gate signal of the IGBT of the voltage-type three-phase inverter 33 is output. The gate signal generation unit 44 generates a gate signal so that the output phase voltage of the voltage-type three-phase inverter 33 corresponds to the inverter voltage command values Viuref, Vivref, and Viwref. For example, after superimposing a zero-phase voltage in order to improve the voltage utilization factor, it is normalized with the voltage across the smoothing capacitor 32 and compared with a triangular wave carrier.

  Here, an example is shown in which the inverter current command value generation unit 42 generates a three-phase current command value, and the inverter current control unit 43 performs the current control for each of the three phases. , And current control is performed on the dq axis, and the inverter voltage command values Viuref, Vivref, and Viwref may be obtained by converting the dq axis to three phases.

Alternatively, once the inverter current amplitude detection value is obtained from the inverter output currents Iiu, Iiv, and Iiw, and the inverter current amplitude control is performed using the inverter current amplitude command value Iiref and the inverter current amplitude detection value, individual current control is performed. May be performed.
Further, the detection value may be provided with a low pass filter by hardware or software to remove noise and high frequency components unnecessary for control.

  Next, a method for estimating the synchronous generator field voltage estimated value Vfh will be described. The synchronous generator field voltage estimation value Vfh is estimated by the synchronous generator field voltage estimation unit 46 from the inverter output phase voltages Viu, Viv, Viw and the rotor mechanical angular rotation angular velocity estimation value ωh.

  The estimated rotational angular velocity value ωh of the rotor mechanical angle is estimated by the rotational angular velocity estimation unit 45 of the rotor mechanical angle from the phase voltages Vtu, Vtv, Vtw on the secondary side of the instrument transformer 26. Vtu, Vtv, and Vtw can be regarded as equivalent to the waveforms of the armature phase voltages Vsu, Vsv, and Vsw of the synchronous generator 1 in general. Since the synchronous generator 1 is now driven by the SFC 4, the armature phase voltages Vsu, Vsv, Vsw are waveforms including harmonics, but the fundamental frequency is regarded as the electrical angular rotation speed of the synchronous generator 1. Good.

  Further, since the number of pole pairs of the synchronous generator 1 is known and is generally 1, if the fundamental frequency of Vsu, Vsv, Vsw or Vtu, Vtv, Vtw can be estimated, the rotor mechanical angular rotation angular velocity can be estimated. The rotational angular velocity estimation unit 45 of the rotor mechanical angle has, for example, a phase synchronizer, and estimates the phase of Vsu, Vsv, Vsw or Vtu, Vtv, Vtw, and calculates the rotational angular velocity estimated value ωh of the rotor mechanical angle. Output. In this embodiment, the rotational angular velocity of the rotor mechanical angle is estimated. However, the rotational angular velocity ω of the rotor mechanical angle may be directly detected by providing a speed detector, or from the SFC 4 or the like. Of course, the detected value may be received.

  Next, an equivalent circuit viewed from the AC exciter field windings 24 and 25 when the AC exciter 11 is AC-excited is shown in FIG. Here, E1d is a d-axis field voltage, E1q is a q-axis field voltage, E2d is a d-axis armature voltage, E2q is a q-axis armature voltage, I1d is a d-axis field current, and I1q is a q-axis field current. , I2d is a d-axis armature current, and I2q is a q-axis armature current. That is, the voltages applied to the AC exciter field windings 24 and 25 are E1d and E1q. E2d and E2q represent the output voltage of the AC exciter armature winding 23 on the dq axis. RphF is a field resistance, RphA is an armature resistance, LlF is a field leakage inductance, LlA is an armature leakage inductance, LadF is a d-axis field magnetization inductance, LaqF is a q-axis field magnetization inductance, and LadA is a d-axis armature. Magnetization inductance, LaqA is a q-axis armature magnetization inductance, ωF is a field excitation frequency, and ωA is an armature output frequency.

Here, ωF can be expressed by Equation (11) using the inverter frequency command value f1ref. ωA can be expressed as Equation (12) using ωF, the pole pair number p of the AC exciter 11, and the estimated rotational angular velocity ωh of the rotor mechanical angle.
ωF = 2π × f1ref (11)
ωA = ωF + p × ωh (12)

  Secondary windings of the Scott transformer 15 are connected to the AC exciter field windings 24 and 25. An equivalent circuit of the Scott transformer 15 is shown in FIG. Here, Rtr is converted to the secondary side by winding resistance and Ltr is a leakage inductance. The equivalent circuit of FIG. 8 is a dq-axis equivalent circuit, which converts the three input phases of the Scott transformer 15 into the dq-axis and then converts the voltage with an ideal transformer. The inverter output phase voltages Viu, Viv, Viw converted to dq axis are Vid, Viq, and the inverter output currents Iiu, Iiv, Iiw converted to dq axis are Iid, Iiq. It goes without saying that these conversions are performed so as to match the equivalent circuit constants of the Scott transformer 15 and the AC exciter 11.

  The rotary rectifier 3 is connected to the AC exciter armature winding 23. A synchronous generator field winding 22 of the synchronous generator 1 is connected to the output of the rotary rectifier 3. FIG. 9 is an equivalent circuit of this part. The rotary rectifier 3 receives the voltage E2 between the armature wires of the AC exciter 11 and the armature current I2, and outputs the synchronous generator field voltage Vf and the synchronous generator field current If. The frequency of E2 is ωA. Rf is the synchronous generator field resistance, and Lf is the synchronous generator field winding inductance. Since the value of Lf is sufficiently larger than the value of Rf, If is regarded as substantially constant.

Here, it is assumed that the rotary rectifier 3 is a diode rectifier. The average voltage when the AC voltage is rectified can be expressed using the armature line voltage effective value V2. Furthermore, a decrease in the average voltage caused by commutation from the AC side inductance Lc, ωA, If is considered. Since the relationship between Vf and If can be expressed as in Expression (13), Vf can be expressed by an expression using V2, ωA, Lc, and Rf.
Vf = Rf × If (13)

  Rf is a constant of the synchronous generator 1. Lc can be obtained from the equivalent circuits of FIGS. ωA can be derived from f1ref and the estimated rotational angular velocity value ωh of the rotor mechanical angle from the equations (11) and (12). Therefore, it can be understood that if E2 can be derived, the synchronous generator field voltage estimated value Vfh can be obtained.

  E2 can be estimated from the effective values of Vid and Viq by simplifying the equivalent circuit of FIGS. 7 and 8 by ignoring the resistance component. That is, when Viu, Viv, Viw, and ωh are input to the synchronous generator field voltage estimation unit 46, Vfh calculated using the equations obtained from the circuits of FIGS. 7, 8, and 9 is output. It is. At this time, it goes without saying that each value is converted in consideration of the transformation ratio of the Scott transformer 15 and the turn ratio of the AC exciter 11. Further, it is possible to consider saturation of the inductance component or to consider the rotation speed by using a part of the constant as a variable value.

  In addition, although an example in which the phase voltage instantaneous values Viu, Viv, and Viw are input to the synchronous generator field voltage estimation unit 46 has been described here, a value after conversion to the dq axis or an effective value equivalent is input. Needless to say, you can.

  Further, it is of course possible not to directly use Vfh calculated using the equations obtained from the circuits of FIGS. 7, 8, and 9, but to output the value after correction by gain or offset superposition as Vfh. .

  Thus, since the power converter 12 can output a variable voltage or a variable frequency, the Scott transformer 15 can obtain a two-phase variable voltage or variable frequency output having a phase difference of 90 °. . The output voltage of the Scott transformer 15 is input to the excitation method switching device 13, and the output is applied to the AC exciter field windings 24 and 25. Therefore, a variable voltage or variable frequency having a phase difference of 90 ° can be input to the AC exciter field windings 24 and 25.

  When the input voltage of the AC exciter field windings 24 and 25 is changed, the AC output of the AC brushless exciter 2 that is input to the rotary rectifier 3 changes, so Vf is a synchronous generator using the SFC 4 as described above. It is possible to control to a constant value suitable for activation of 1. In addition, although the case where SFC4 was used for starting of the synchronous generator 1 was demonstrated here, this AC brushless exciting device 2 is used also when driving the synchronous generator 1 using SFC4 for purposes other than starting. Obviously you can.

  Further, since the inverter control unit 36 includes the synchronous generator field voltage control unit 41 and the inverter current control unit 43, the synchronous generator field is also detected when the slip of the AC exciter 11 changes as the synchronous generator 1 accelerates. The magnetic voltage Vf can be controlled to be constant.

  Therefore, even when the synchronous generator 1 is excited using the AC exciter 11, the SFC 4 is synchronized with the period in which the output current is applied so that the armature voltage of the synchronous generator 1 increases in proportion to the operating frequency. By keeping the generator field voltage Vf constant, the synchronous generator field current If can be kept constant, and the synchronous generator 1 can be favorably accelerated.

Further, the field input capacity of the AC exciter 11 is adjusted by changing the excitation frequency f1 of the AC exciter 11 as the synchronous generator 1 is accelerated while controlling the synchronous generator field voltage Vf constant. Is also possible.
In addition, since the inverter control unit 36 includes a synchronous generator field voltage estimation unit 46, the synchronous generator field voltage estimation value Vfh is obtained and used for control to keep the generator field voltage constant. Since it is not necessary to detect the magnetic voltage Vf, a slip ring is not required, and the size and cost can be reduced, and maintainability is also improved.

In addition, in this Embodiment 1, although the case where SFC4 was used for the drive of the synchronous generator 1 was demonstrated, the electric current of the frequency and amplitude according to a rotational speed required when driving the synchronous generator 1 as a synchronous motor is demonstrated. It is obvious that other power converters can be used instead of SFC4, such as a voltage source inverter that can apply.
Further, it is obvious that the synchronous generator 1 is not limited to supplying a reactive power by connecting a turbine or the like, and may supply only a reactive power.

  Here, the timing for switching the excitation method of the AC exciter 11 will be described. When the rotational angular velocity ω of the rotor mechanical angle is low, such as during startup, AC excitation is performed to obtain the required synchronous generator field voltage Vf. If the necessary Vf can be obtained even with direct current excitation as ω rises, it can be switched to direct current excitation. At least during normal operation of the synchronous generator 1, DC excitation is performed using the thyristor excitation device 14 as in the prior art.

  As described above, the power generation system 100 including the AC brushless exciter 2 according to the present embodiment includes the AC exciter d-axis field winding 24, the AC exciter q-axis field winding 25, and the excitation method. The switching device 13 is provided, and the AC exciter 11 can be AC excited when the synchronous generator 1 is started and can be DC excited during normal operation. Further, when performing direct current excitation, the alternating current exciter d-axis field winding 24 and the alternating current exciter q-axis field winding 25 are connected in series so that a direct current flows. The currents flowing in 24 and 25 are equal, the loss generated in both is balanced, and the effect of keeping the temperature change uniform is shown.

  Since the power generation system 100 including the AC brushless exciter 2 according to the present embodiment includes the power converter 12, the AC exciter field windings 24 and 25 of the AC exciter 11 have variable voltage or variable frequency AC excitation. It can be performed. For this reason, the synchronous generator field voltage Vf and the synchronous generator field current If when the synchronous generator is activated can be kept constant regardless of the rotational speed.

In addition, since the power converter 12 can output a variable frequency AC, the AC exciter field windings 24 and 25 of the AC exciter 11 can be excited at a frequency higher than the commercial frequency. For this reason, the field input capacity of the AC exciter 11 can be reduced even in a region where the rotational speed of the synchronous generator 1 is low, and an unprecedented remarkable effect is achieved. As a result, the capacity of the power converter 12 can be reduced, and the size and cost can be reduced.
Furthermore, when the thyristor excitation device 14 is used only during normal operation as an alternating current for performing direct current excitation, the same specification as in the conventional case can be applied.

Embodiment 2. FIG.
FIG. 10 is a block diagram of the inverter control unit 36 of the power generation system 100 including the AC brushless excitation device according to the second embodiment of the present invention. Hereinafter, the same reference numerals are given to the same parts as those of the first embodiment, and the description thereof is omitted, and only different parts will be described here. 4 differs from the inverter control unit 36 of FIG. 4 in that the synchronous generator field voltage estimation unit 46 adds the inverter output phase voltages Viu, Viv, Viw and the rotor mechanical angular rotation angular velocity estimation value ωh, as well as the inverter output current Iiu, Iiv and Iiw are also input.

  When the inverter output current is used, an equation for obtaining the synchronous generator field current If can be derived from the circuits of FIGS. 7, 8, and 9. As a result, the estimated value of If can also be used to obtain the synchronous generator field voltage estimated value Vfh in consideration of the decrease in average voltage caused by commutation. Although the example in which the three-phase instantaneous values Iiu, Iiv, and Iiw are input to the synchronous generator field voltage estimation unit 46 has been described here, it goes without saying that the values after conversion to the dq axis can be input. Yes.

  As described above, in the power generation system 100 including the AC brushless exciter 2 according to the second embodiment, the synchronous generator field voltage estimation unit 46 has the inverter output phase voltages Viu, Viv, Viw and the rotor mechanical angle. Inverter output currents Iiu, Iiv, and Iiw are input in addition to the estimated rotational angular velocity value ωh. Therefore, in addition to the effect of the first embodiment, there is an effect that the synchronous generator field voltage estimated value Vfh considering the synchronous generator field current If can be obtained.

Embodiment 3 FIG.
FIG. 11 is a block diagram of the inverter control unit 36 of the power generation system 100 including the AC brushless excitation device according to the third embodiment of the present invention. Hereinafter, the same reference numerals are given to the same parts as those of the first embodiment, and the description thereof is omitted, and only different parts will be described here. 4 differs from the inverter control unit 36 of FIG. 4 in that the synchronous generator field voltage estimation value Vfh and the rotor mechanical angular rotation angular velocity estimation value ωh output from the synchronous generator field voltage estimation unit 46 are input, and synchronous power generation is performed. A synchronous generator field voltage estimated value correction unit 50 that outputs a machine field voltage correction value Vfh2 is provided. The synchronous generator field voltage control unit 41 is supplied with Vfh2 and controlled so that the synchronous generator field voltage Vf becomes the synchronous generator field voltage command value Vfref.

The synchronous generator field voltage estimation unit 46 estimates Vfh by an expression derived from the circuits of FIGS. 7, 8, and 9. For this reason, there is a possibility of an error with respect to the actual value Vf.
First, a case where there is an error of Vfh> Vf will be described. At this time, when field voltage control is performed using Vfh, Vfh = Vfref is generally satisfied, so that Vf <Vfref and the field voltage is insufficient. Conversely, if there is an error of Vfh <Vf, Vf> Vfref and the field voltage becomes excessive. When the field voltage is insufficient, the acceleration of the synchronous generator 1 is delayed, and when the field voltage is excessive, the acceleration is accelerated.

  The rotational speed change rate of the synchronous generator 1 needs to be maintained within a range that can be activated by the SFC 4. Therefore, the field voltage control is performed using Vfh2 obtained by correcting Vfh with the rotation speed change rate in the estimated value correction unit 50 of the synchronous generator field voltage. FIG. 12 is a block diagram of the synchronous generator field voltage estimated value correction unit 50 of FIG. ωh is input to the change amount calculator 51. The change amount calculator 51 calculates, for example, the change amount per unit time of ωh from the difference from the previous input value, and outputs the rotation speed change amount dωh. dωh is converted to a positive rotational speed change amount absolute value | dωh | by the absolute value calculator 52 and then input to the table 53 to determine the correction gain Kdω. The multiplier 54 multiplies Vfh and Kdω and outputs Vfh2.

FIG. 13 is an example of the table 53. When | dωh | is within the allowable range, Kdω = 1 is output, and when | dωh | is larger than the allowable range, Kdω> 1 and when | dωh | is smaller than the allowable range, Kdω <1 is output. It is designed to output. Thus, if | dωh | is large, Kdω> 1 is output, so Vfh2> Vfh, and the field voltage decreases. Conversely, if | dωh | is small, Kdω <1 is output, so Vfh2 <Vfh, and the field voltage increases.
The table 53 may be configured to obtain Kdω depending on ωh in addition to dωh, or Kdω may be obtained by an arithmetic expression.

  As described above, since the power generation system 100 including the AC brushless exciter 2 according to the third embodiment includes the estimated value correction unit 50 for the synchronous generator field voltage in the inverter control unit 36, the synchronous generator field The estimated value can be corrected when the error of the magnetic voltage estimated value Vfh is large and the rotational speed change rate is out of the desired range. Therefore, in addition to the effect of the first embodiment or the second embodiment, the synchronous generator field voltage estimated value Vfh becomes Vf because the synchronous generator field voltage Vf is not directly detected using the slip ring. On the other hand, even when there is an error, a remarkable effect is obtained in that the synchronous generator 1 can be maintained in a state where it can be driven by the SFC 4 by adjusting the rotation speed change rate.

Embodiment 4 FIG.
FIG. 14: is a block diagram of the electric power generation system 100 provided with the alternating current brushless exciting device concerning Embodiment 4 of this invention. Hereinafter, the same parts as those in the first, second, and third embodiments are denoted by the same reference numerals and the description thereof is omitted, and only different parts are described here. The power generation system 100 having the AC brushless exciter 2 of FIG. 2 differs from the power generation system 100 in that the power converter 12 includes voltage-type single-phase inverters 37a and 37b instead of the voltage-type three-phase inverter 33, and the Scott transformer 15 Instead of the single-phase transformers 18a and 18b.

  In the fourth embodiment, the secondary winding of the single-phase transformer 18a is connected to the AC exciter d-axis field winding 24, and the secondary winding of the single-phase transformer 18b is connected to the AC exciter q-axis. The field winding 25 is connected. The output of the voltage source single phase inverter 37a is connected to the primary winding of the single phase transformer 18a, and the output of the voltage source single phase inverter 37b is connected to the primary winding of the single phase transformer 18b. The voltage-type single-phase inverters 37a and 37b output voltages so that the amplitude and frequency of the output current are equal and have a phase difference of 90 °. Thus, the voltage-type single-phase inverters 37a and 37b and the single-phase transformer 18a are exchanged in the same manner as the AC-type exciter field windings 24 and 25 are AC-excited using the voltage-type three-phase inverter 33 and the Scott transformer 15. 18b can be used for AC excitation of the AC exciter field windings 24 and 25.

  Since the output voltage of the voltage-type single-phase inverters 37a and 37b has a rectangular wave shape, the harmonic component is removed to prevent the surge voltage from being applied to the AC exciter field windings 24 and 25. For example, a filter that removes high-frequency components may be provided on the input side or output side of the single-phase transformers 18a and 18b.

  Although the diode rectifier 31 and the smoothing capacitor 32 are common here, they can be provided separately. Furthermore, electric power can be supplied from different power sources, and the single-phase transformers 18a and 18b may be omitted when the outputs of the voltage-type single-phase inverters 37a and 37b are insulated.

Current detectors 16a and 16b and voltage detectors 17a and 17b are provided at outputs of the voltage-type single-phase inverters 37a and 37b, respectively.
The power converter 12 includes an inverter control unit 36, and supplies a gate signal to the voltage source single-phase inverters 37a and 37b. The inverter control unit 36 includes secondary phase voltages Vtu, Vtv, and Vtw of the instrument transformer 26, detection values Iid and Iiq of the current detectors 16a and 16b, and detection values Vid of the voltage detectors 17a and 17b. , Viq are input. Although not shown in FIG. 14 that constitutes the inverter control unit 36, the inverter current command value generation unit 42 and the inverter current control unit 43 are handled as dq axes instead of three phases, and similarly, the gate signal generation unit 44 (not shown) d The gate signal of the voltage type single phase inverter 37a may be generated from the voltage command value of the axis, and the gate signal of the voltage type single phase inverter 37b may be generated from the voltage command value of the q axis.

  Similarly, although not shown in FIG. 14, Vid, Viq, Iid, and Iiq are also input to the synchronous generator field voltage estimation unit 46, but these can be treated as values after conversion to the dq axis. That's fine.

  As described above, in the power generation system 100 including the AC brushless excitation device 2 according to the fourth embodiment, the power converter 12 includes the voltage-type single-phase inverters 37 a and 37 b instead of the voltage-type three-phase inverter 33. Since the single-phase transformers 18a and 18b are provided instead of the Scott transformer 15, in addition to the effect of the power generation system 100 including the AC brushless excitation device 2 according to any one of the first to third embodiments, Without using the Scott transformer 15, the AC exciter field windings 24 and 25 can be AC-excited using the single-phase transformers 18a and 18b having a simple structure. It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

DESCRIPTION OF SYMBOLS 1 Synchronous generator, 2 AC brushless exciter, 3 Rotary rectifier, 4 Static type frequency converter (SFC), 5 Switch, 6 Output line of synchronous generator armature winding, 7, 8, 9 Power supply,
DESCRIPTION OF SYMBOLS 11 AC exciter, 12 Power converter, 13 Excitation system switching device, 14 Thyristor excitation device, 15 Scott transformer, 16a, 16b Current detector, 17a, 17b Voltage detector, 18a, 18b Single phase transformer, 21 Synchronization Generator armature winding, 22 Synchronous generator field winding, 23 AC exciter armature winding, 24 AC exciter d-axis field winding, 25 AC exciter q-axis field winding, 26 For instrumentation Transformer, 31 Diode rectifier, 32 Smoothing capacitor, 33 Voltage type three-phase inverter, 34a, 34b, 35a, 35b, 35c Switch, 36 Inverter control unit, 37a, 37b Voltage type single phase inverter, 46 Synchronous generator field Voltage estimation unit, 100 power generation system

Claims (5)

A power converter that outputs AC power supplied from a power source as variable voltage or variable frequency three-phase AC power;
The primary side has a three-phase winding, the secondary side has a first single-phase winding and a second single-phase winding, and the three-phase winding is connected to the output end of the power converter, A Scott transformer that outputs AC power having a phase difference between the first single-phase winding and the second single-phase winding when three-phase AC power from a power converter is input;
A thyristor exciter that rectifies an alternating current supplied from a power source;
An AC exciter having a d-axis winding and a q-axis winding on the primary side and a rotary multiphase winding on the secondary side;
The output line of the thyristor excitation device, the first single-phase winding, and the second single-phase winding are connected to the primary side, and the d-axis winding and the q-axis winding are connected to the secondary side. The d-axis winding is connected to the first single-phase winding or the second single-phase winding, and the q-axis winding is connected to the other single-phase winding. Switching between excitation methods by selecting either one connection or the second connection in which the d-axis winding and the q-axis winding are connected in series and the output line of the thyristor excitation device is connected to both ends thereof An excitation method switching device for performing
A rotary rectifier connected to the rotary multiphase winding and rectifying a multiphase output from the AC exciter;
A synchronous generator field winding, a synchronous generator armature winding, and the synchronous generator field winding connected to the output terminal of the rotary rectifier;
When connected to the synchronous generator armature winding, it is driven to flow a current output having a frequency and phase according to the position of the synchronous generator rotor to the synchronous generator armature winding. Type frequency converter,
A voltage detector for detecting an output voltage of the power converter;
A synchronous generator field voltage estimator for estimating a field voltage of the synchronous generator based on the voltage detected by the voltage detector;
With
When the static frequency converter is connected to the synchronous generator armature winding, the first connection is selected by the excitation method switching device, and the d-axis winding and the q-axis winding are dq orthogonal. The AC exciter is AC-excited by applying a variable voltage or variable frequency power to the d-axis winding and the q-axis winding, and the thyristor excitation is performed during normal operation of the synchronous generator. The device rectifies the AC current from the power source, and the excitation method switching device selects the second connection, and the d-axis winding and the q-axis winding are connected in series so that the AC exciter is DC-excited. A power generation system characterized by The synchronous generator field voltage estimator is
An instrument transformer for detecting the armature voltage of the synchronous generator;
From the frequency of the armature voltage detected by this instrument transformer, a rotational angular velocity estimation unit that estimates the rotational angular velocity of the synchronous generator,
2. The power generation according to claim 1, wherein a field voltage of the synchronous generator is estimated based on a voltage detected by the voltage detector and a rotation angular velocity estimation value estimated by the rotation angular velocity estimation unit. system. The synchronous generator field voltage estimator is
A current detector for detecting an output current of the power converter and converting it into a control signal;
Based on the voltage detected by the voltage detector, the estimated rotational angular velocity estimated by the rotational angular velocity estimator, and the current detected by the current detector, the field voltage of the synchronous generator is calculated. The power generation system according to claim 2, wherein the power generation system is estimated. A change amount calculator for obtaining a change amount of the rotational angular velocity estimated value;
4. The estimated value of the synchronous generator field voltage estimated by the synchronous generator field voltage estimation unit is corrected by the amount of change obtained by the change amount calculator. The power generation system described. A power converter having a first single-phase output and a second single-phase output for outputting AC power supplied from a power source as two sets of single-phase AC power of variable voltage or variable frequency;
A first single-phase transformer in which the first single-phase output is connected to a primary winding; and a second single-phase transformer in which the second single-phase output is connected to a primary winding;
A thyristor exciter that rectifies an alternating current supplied from a power source;
An AC exciter having a d-axis winding and a q-axis winding on the primary side and a rotary multiphase winding on the secondary side;
An output line of the thyristor excitation device, a secondary winding of the first single-phase transformer, and a secondary winding of the second single-phase transformer are connected to the primary side, and the secondary side, A d-axis winding and a q-axis winding are connected, and the d-axis winding and the secondary winding of the first single-phase transformer or the secondary winding of the second single-phase transformer The first connection for connecting the q-axis winding and the other secondary single-phase winding, or the d-axis winding and the q-axis winding are connected in series, and the thyristor excitation is connected to both ends thereof. An excitation method switching device for selecting one of the second connections for connecting the output lines of the device and switching the excitation method;
A rotary rectifier connected to the rotary multiphase winding and rectifying a multiphase output from the AC exciter;
A synchronous generator field winding, a synchronous generator armature winding, and the synchronous generator field winding connected to the output terminal of the rotary rectifier;
When connected to the synchronous generator armature winding, it is driven to flow a current output having a frequency and phase according to the position of the synchronous generator rotor to the synchronous generator armature winding. Type frequency converter,
A voltage detector for detecting an output voltage of the power converter;
A synchronous generator field voltage estimator for estimating a field voltage of the synchronous generator based on the voltage detected by the voltage detector;
With
When the static frequency converter is connected to the synchronous generator armature winding, the first connection is selected by the excitation method switching device, and the d-axis winding and the q-axis winding are dq orthogonal. The AC exciter is AC-excited by applying a variable voltage or variable frequency power to the d-axis winding and the q-axis winding, and the thyristor excitation is performed during normal operation of the synchronous generator. The device rectifies the AC current from the power source, and the excitation method switching device selects the second connection, and the d-axis winding and the q-axis winding are connected in series so that the AC exciter is DC-excited. A power generation system characterized by

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