JP3321474B2 - Control device for variable speed generator motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a variable speed generator motor.

[0002]

2. Description of the Related Art In general, when a synchronous machine is connected to a system, it is operated at a rotational speed synchronized with the frequency of the system. Since the starting torque of such a synchronous machine is almost zero, at the time of starting, the synchronous machine must use the power of another starting device to increase the speed up to or near the synchronous speed and pull into synchronization.

In general, as a starting device, a converter using a thyristor as a switching element excites a stator winding at a certain lead angle with respect to a rotor magnetic field to apply torque to the rotor and apply torque to the rotor. A stationary starter for raising the speed of the vehicle is employed. On the other hand, also in the case of starting the generator motor of the variable speed control, it can be started in the same manner as the synchronous machine by exciting the secondary winding of the generator motor with DC.

Here, a conventional stationary starter will be described with reference to FIG.

The generator motor 1 is a wound type generator motor in which a rotor is provided with three-phase windings. The stator winding of the generator motor 1 has a primary winding 1a, and the rotor winding has a secondary winding. 1b, the secondary winding 1b is connected to the
A power converter 2 is connected, and a power system 4 is connected to the other end of the power converter 2 by a converter transformer 3. The primary winding 1a of the generator motor 1 is connected to a frequency converter (hereinafter, abbreviated as a converter) 5 of the stationary starter, and the other end of the converter 5 is supplied with power via a converter transformer 6. The primary winding 1 a of the generator motor 1 is connected to the power system 4 via the circuit breaker 7.

A resolver 8 and a position sensor 9 are connected to a rotating shaft of the generator motor 1, an output signal of the position sensor 9 is input to a start control device 10, and an output voltage of the generator motor 1 is output from a voltage detector 11. A signal is to be input. The start control device 10 detects the phase of the generator motor 1 and outputs the gate pulse signal 10gc to the converter 5C of the converter 5, while outputting the gate pulse signal 10gc to the inverter 5I.
And outputs the gate pulse signal 10gi to the converter 5.

The converter 5 converts three-phase AC power of the power system 4 into three-phase AC of an arbitrary frequency, uses a thyristor as a switching element, and converts the three-phase AC power into DC. 5C and an inverter 5I for converting DC into power of an arbitrary frequency, and a reactor 5L connected between the converter 5C and the inverter 5I for reducing AC ripple included in DC.

Next, the operation when the generator motor 1 is started as a motor will be described. Although a turbine (not shown) is connected to the rotor of the generator motor 1, the turbine is in a no-load state, that is, a state in which water is not pumped.

First, when the rotor of the generator motor 1 is stopped, the angular velocity of the secondary excitation current of the generator motor 1 is set to ω = 0,
That is, when excited by DC, the generator motor 1 starts in the same manner as the synchronous machine. The start control device 10 detects the position of the magnetic flux generated by the excitation current of the rotor based on the signal from the position sensor 9 and outputs a gate pulse signal 10gi to the inverter 5I so that a start torque is generated for the rotor winding.
And a current flows from the inverter 5I to the primary winding 1a. Thus, when the rotor starts to rotate and turns to a certain angle, converter 5C throttles the current to zero. At this time, the inverter 5I waits for the thyristor to extinguish the arc and waits for the thyristor to extinguish.
The current is supplied to a.

Thereafter, when the rotation speed increases to, for example, about 5%, the primary winding 1 is activated by the starting force of the generator motor 1.
a is generated, a sufficient reverse voltage is obtained in the thyristor element, and natural commutation becomes possible. Further, when the voltage rises to around 10%, the output voltage of the voltage detector 11 rises, and the phase is detected by this signal.

When the speed of the rotor is increased within the operating range of the variable speed machine in this manner, the start control device 10 is stopped, and the current of the secondary winding 1b of the generator motor 1 is changed from DC excitation to AC. Change to excitation. Then, after equalizing the primary voltage of the generator motor 1 with the electric power system 4, the circuit breaker 7 is closed,
Move to synchronous paralleling. Thereby, the generator motor 1 can perform the pumping operation as the motor.

Here, the operation of the start control device 10 and the variable speed control device 12 will be described with reference to FIG.

In the drawing, the rotor angular speed (electrical angle conversion) of the rotor is ωr, and the angular speed of the voltage of the power system 4 is the system angular speed ω.
Assuming that the angular velocity ω2 of the exciting current flowing through the primary and secondary windings 1b and the rotational angular velocity (electrical angle conversion) in the variable speed operation region are ωsc, first, at the time of starting, the determination means 14 provided in the variable speed control device 12 It is determined whether Expression (1) holds.

[0014]

## EQU1 ## ωr ≧ ωsc (1)

When the above expression does not satisfy the expression (1), that is, when the rotor angular speed ωr is changed to the variable speed operation region angular speed ωsc
When it is smaller, the starter stop signal SS is not output,
Contact 15A is open and contact 15B remains closed. Therefore, the excitation current angular velocity ω2 = 0 is output via the contact 15B. That is, for a predetermined time from the start of starting,
The above-mentioned equation (1) does not hold, and DC excitation is performed.

Thereafter, when the equation (1) is satisfied, that is, when the rotor angular speed ωr is equal to or larger than the variable speed operation region angular speed ωsc, a starter stop signal SS is output, the contact 15A is closed, and the contact 15B Is opened. As a result, the system angular speed ω1 and the rotor angular speed ωr are added and subtracted by the addition / subtraction means 16, and the system angular speed ω1−the rotor angular speed ωr
Is output as the exciting current angular velocity ω2. That is, AC excitation corresponding to slip is performed.

According to the operation of the variable speed control device 12, if the inverter 5I of the converter 5 sets the rotor angular speed (electrical angle conversion) of the rotor when the thyristor can perform natural commutation as the initial excitation angular speed ωs, When the rotor angular velocity ωr is smaller than the initial excitation angular velocity ωs, the intermittent operation is performed. When the rotor angular velocity ωr becomes larger than the initial excitation angular velocity ωs, the natural commutation operation is performed. As described above, the generator motor 1 can be started by direct current excitation in the same manner as the synchronous machine.

[0018]

However, the conventional stationary starter shown in FIG. 4 has the following problems.

First, in order to excite the primary winding 1a, the phase of the rotor is always detected and the thyristor is switched at a certain lead angle with respect to the phase. Since the voltage is low, the phase cannot be detected with the voltage detected by the voltage detector 13. For this reason, the position sensor 9 and the resolver 8 are indispensable for detecting the phase even at the time of stop and at the time of low rotation speed,
There was a problem that it became complicated as a starting device.

The inverter 5I includes a U-phase, a V-phase, and a W-phase.
It is necessary to control the commutation to the phases one after another, but in a region where the induced voltage is low, the reverse voltage for turning off the thyristor is insufficient, so that natural commutation cannot be performed. Therefore, in order to move to the next phase, the current is cut off once, the current becomes zero, and then the intermittent control is performed to wait for the thyristor to extinguish and then fire the next phase. There is a problem that it takes time.

Further, since the current is intermittently supplied, there is a problem that the torque fluctuates greatly and a mechanical stress is applied to the coil and the iron core of the generator motor 1 to cause deterioration.

Accordingly, an object of the present invention is to provide a control device for a variable speed generator motor that does not require a position sensor and intermittent control when the variable speed generator motor is started.

According to the first aspect of the present invention, the stator winding is connected to the system via a frequency converter which is controlled to be fired by a start control device at the time of starting, while the stator winding is connected to the system via a breaker during steady operation. In addition, in the control device of the variable speed generator motor in which the rotor winding is connected to the system via the power converter, the phase detection is performed by the start control device from the power converter to the rotor winding. Start by applying an AC exciting current having an angular velocity that enables the variable speed generator motor to start, and the variable speed generator motor is capable of natural commutation by the frequency converter. Before the steady-state operation is performed, acceleration is performed by switching to and applying a DC excitation current, and during steady-state operation, variable-speed operation is performed by applying an AC excitation current. Characterized in that a variable speed control device for controlling the power converter.

According to a second aspect of the present invention, in the frequency converter according to the first aspect, a converter for converting three-phase AC power of a system into DC, and converting the converted DC in response to a command from the start control device. And a variable speed control device, wherein the variable speed control device enables the start control device to detect the phase of the rotor when the rotor of the generator motor is stopped, and the inverter is naturally driven. Initial excitation angular velocity setting means for setting an initial excitation angular velocity for inducing a voltage enabling commutation in the stator winding, rotor angular velocity detection means for detecting a rotational angular velocity of the rotor, and the initial excitation angular velocity. Angular velocity generating means for generating an angular velocity until a deviation angle from the rotor angular velocity becomes zero, and the power converter is generated by the angular velocity generated from the angular velocity generating means at the time of starting. It is characterized in that the exciting current of the corresponding angular velocity was allowed to flow in the rotor winding by us.

[0025]

According to the present invention, even if the rotor is stopped at the time of starting, a voltage having a frequency capable of detecting the phase and allowing natural commutation is induced on the stator side, which has been conventionally required. The position sensor and the intermittent operation are not required, so that the static start control device can be simplified, and the intermittent operation does not need to be performed, so that the starting time can be shortened and the mechanical stress on the generator motor can be suppressed.

[0026]

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a control device for a variable speed generator motor according to an embodiment of the present invention. The same reference numerals as those in FIG. 4 denote the same or corresponding parts. FIG. 1 differs from FIG. 4 in that the position sensor 9 is deleted and a variable speed control device 12A having a configuration different from that of the variable speed control device 12 is provided. That is.

As shown in FIG. 2, the variable speed controller 12A includes a judging means 14, contacts 15A and 15B,
6 and an addition / subtraction unit 17 and a determination processing unit 18.

Here, the judgment means 14 determines the rotor angular velocity ω
It is determined whether r is equal to or greater than the variable speed operation region angular velocity ωsc, and the starter stop signal SS is turned ON under this condition. The contact 15A performs a closing operation when the starting device stop signal SS is ON, and performs an opening operation when the starting device stop signal SS is OFF. The contact 15B is opened when the starter stop signal SS is ON, while the starter stop signal SS is OFF.
In this case, the closing operation is performed.

The addition / subtraction means 16 subtracts the rotor angular velocity ωr from the system angular velocity ω1 and outputs the result as the exciting current angular velocity ω2. The addition / subtraction unit 17 subtracts the rotor angular velocity ωr from the initial excitation angular velocity ωs and outputs the result as ωd.

As will be described later, the determination processing means 18
Is positive, the exciting current angular velocity ω2 is directly set to ωd, and when ωd is zero or negative, the exciting current angular velocity ω2 is set to 0.

Next, a procedure for increasing the speed of the rotor of the generator motor 1 from the stop state to the vicinity of the synchronous speed as the motor will be described with reference to FIG.

First, as a first step, when the rotor is stopped, an initial excitation angular velocity ωs, for example, 5 Hz, is passed through the secondary winding 1b of the generator motor 1 to 5H through the primary winding 1a.
A voltage of z is generated.

Specifically, when the rotor is stopped, the phase of the generator motor 1 can be detected by the start controller 10 and the inverter 5I generates a predetermined voltage that enables natural commutation. The angular velocity ωs is obtained in advance and set in the variable speed control device 12A.

At the time of starting, at time t0 the initial excitation angular velocity ω
s is output, but when the rotor angular speed ωr is zero, the initial excitation angular speed ωs−rotor angular speed ωr = ωd is naturally smaller than the variable speed operation region angular speed ωsc.
8 is input. In the determination processing means 18, since ωd> 0, the excitation current angular velocity ω2 = the initial excitation angular velocity ωs is output via the contact 15B.

In the variable speed control device 12A, the gate pulse signal 12g is supplied to the power converter 2 according to the initial excitation angular speed ωs.
Output to As a result, an AC exciting current having an initial exciting angular velocity ωs is supplied from the power converter 2 to the secondary winding 1b of the generator motor 1. At this time, if the value of the initial excitation angular velocity ωs is, for example, about 5 Hz (synchronous), a voltage of about 10% of the rated voltage is generated on the primary winding 1 a side of the generator motor 1. This voltage is detected by the voltage detector 11, and the starting controller 10 detects the phase of the magnetic flux generated in the rotor.

As a second step, the start control device 10 is started.

Since the predetermined voltage has already been generated in the primary winding 1a, the starting control device 10 sets the firing angle of the thyristor so that the starting torque is generated by the detected phase signal of the rotating magnetic flux. Determined and the gate pulse signal 10gi
Is output to the inverter 5I. At this time, an appropriate torque is given to the starting torque by controlling the firing phase of the thyristor and the current of the converter 5C. In the thyristor of the inverter 5I, a voltage required for commutation is generated from the beginning on the primary winding 1a side, so that natural commutation can be performed without any problem. That is, when the generator-motor 1 side is viewed from the starting device side, since the voltage of 5 Hz is generated from the beginning, the rotor is stopped even though the rotor is stopped.
It can be regarded as if it is turning with z. Therefore, natural commutation control can be performed from the beginning.

As a third step, the rotor starts rotating by the starting torque.

When the rotor starts to rotate and the rotation speed increases, the angular velocity ω1 of the voltage induced in the primary winding 1a (hereinafter referred to as the primary winding angular velocity) becomes equal to the rotor angular velocity ωr of the secondary winding 1b. It becomes a value obtained by adding the exciting current angular velocity ω2 (rotor angular velocity ωr + exciting current angular velocity ω2). That is,
A voltage having a frequency 5 Hz higher than the actual rotation speed is generated in the primary winding 1a. At this time, when the rotor angular speed ωr increases with an increase in the rotation speed of the rotor, the exciting current angular speed ω2 gradually decreases.

As a fourth step, when the condition of the initial excitation angular velocity ωs−rotor angular velocity ωr ≦ 0 is satisfied at time t1, the excitation current angular velocity ω
2 becomes zero.

Therefore, the secondary winding 1b is DC-excited by the power converter 2, and the rotational speed further increases.

As a fifth step, when the rotation speed rises to the variable speed operation region at time t2, the start control device 10 is stopped and the operation is shifted to the normal operation.

More specifically, when the rotor angular speed ωr further increases, the determination means 14 determines that the rotor angular speed ωr ≧
Since the condition of the variable speed operation region angular velocity ωsc is satisfied, the starter stop signal SS is output. Thereby, the contact 1
5A is closed and the contact 15B is opened, and the system angular velocity ω1-the rotor angular velocity ωr is output as the exciting current angular velocity ω2.

As a sixth step, the electric power is fed to the power system 4.

In this case, since the speed-up operation by the starting device is stopped, the rotor slowly decelerates, but before the rotation speed falls to the variable speed operation lower limit speed, the exciting current angular speed ω2
= Adjust the d-axis component of the exciting current that is equal to the system angular velocity ω1-the rotor angular velocity ωr so that it becomes equal to the voltage of the power system 4. Then, when the voltage and the phase on the primary winding 1a side of the generator motor 1 become equal to those of the power system 4, the circuit breakers 7 synchronize and connect them.

In the above description, when the speed of the rotor is increased to near the synchronous speed (more precisely, between the synchronous speed and the lower limit of the variable speed operation region of the generator motor 1), the frequency of the primary winding 1a becomes 50 Hz. Over. That is, it rises to around 55 Hz. Although not shown, a capacitor for suppressing harmonics, suppressing surge voltage and improving power factor may be connected to the circuit of the primary winding 1a. There is a problem that current flows. Therefore, it is necessary to prevent the frequency of the primary winding 1a from exceeding the rating near the synchronous speed.

For this purpose, the following measures are taken. That is, the rotor angular velocity ωr is subtracted from the initial excitation angular velocity ωs so that the excitation current angular velocity ω2 is obtained.
The angular speed of the primary winding 1a is kept constant at 5 Hz until the rotational speed of the rotor becomes, for example, 5 Hz. Subsequently, when the speed of the rotor becomes equivalent to 5 Hz, the exciting current angular speed ω2 is 0, that is, DC. Further, in a region where the rotor exceeds a speed corresponding to 5 Hz, if the exciting current angular speed ω2 is maintained at 0, in a region exceeding 5 Hz, the primary winding angular speed ω1 of the primary winding 1a becomes equal to the rotor angular speed ωr. . Therefore, even if the rotor rises to near the synchronous speed, 1
The frequency of the voltage of the next winding 1a does not exceed 50 Hz.

As described above, the position sensor 9 and the intermittent control which are necessary in the low-speed range in the stationary starter become unnecessary, and the thyristor can be controlled by the natural commutation from the beginning. Can be simplified.

In the intermittent operation, since the current cannot be continuously supplied, the torque has to be applied in a pulse form at a torque higher than the required average torque. Since the current can be switched by natural commutation, the torque fluctuation can be extremely small, the mechanical stress applied to the coil and the iron core of the generator motor 1 can be kept small, and the insulation durability can be prevented from deteriorating in the long term. .

As for the torque at the start of the start, an appropriate torque can be given by the phase control of the inverter 5I and the current control of the converter 5C, so that the start can be completed smoothly. On the other hand, since the torque can be continuously applied even after the rotor starts to rotate, the start-up is faster and the start-up time can be reduced as compared with the conventional intermittent operation.

In the present embodiment, the point at which the exciting current is switched from AC to DC is set to 5 Hz as an example. However, the switching point is not necessarily limited to 5 Hz, and may be changed until the rotor speed increases to 45 Hz. .

The initial excitation angular velocity ωs is not limited to 5 Hz. A voltage of the primary winding enough to cause the thyristor of the inverter 5I to commutate naturally can be secured, and the start control device 10 detects the phase. Any value can be used as long as a level that can perform is secured. In the present embodiment, the description is made with reference to a system of 50 Hz, but the present invention can be similarly applied to a system of 60 Hz.

[0055]

As described above, according to the present invention, the position sensor and the intermittent operation conventionally required are not required, so that the stationary start control device can be simplified, the start time can be reduced, and the generator motor can be shortened. There is a remarkable effect that mechanical stress on the substrate can be suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control device for a variable speed generator motor according to an embodiment of the present invention.

FIG. 2 is a control block diagram of the variable speed control device of FIG.

FIG. 3 is an explanatory diagram showing a timing at the time of starting in FIG. 1;

FIG. 4 is a configuration diagram corresponding to FIG. 1 of a control device for a variable-speed generator motor showing a conventional example.

FIG. 5 is a control block diagram of the variable speed control device of FIG. 4;

[Explanation of symbols]

 Reference Signs List 1 generator motor 2 power converter 3 converter transformer 4 power system 5 converter 6 converter transformer 7 circuit breaker 8 resolver 10 start control device 11 voltage detector 12A variable speed control device 13 voltage detector 14 determination means 15A contact 15B contact point 16 addition / subtraction means 17 addition / subtraction means 18 judgment processing means

Claims (2)

(57) [Claims] 1. A stator winding is connected to a system via a frequency converter which is controlled to be fired by a start control device at the time of starting. In a control device for a variable speed generator-motor in which a rotor winding is connected to a system via a converter, the starting control device can detect a phase from the power converter to the rotor winding, and the frequency conversion is performed. Starting by applying an AC exciting current having an angular velocity enabling natural commutation by the heat exchanger and enabling the variable speed generator motor to start,
From the time when the variable speed generator motor is accelerated to the angular velocity of the AC exciting current, to the time of steady operation, it is accelerated by switching to and applying the DC exciting current, and during the steady operation, applying the AC exciting current. A variable speed control device for controlling the power converter so as to perform variable speed operation according to the above. 2. The frequency converter includes a converter for converting three-phase AC power of a system into DC, and an inverter for converting the converted DC into power having a frequency according to a command from the start control device. At the same time, the variable speed control device allows the start control device to detect the phase of the rotor when the rotor of the generator motor is stopped, and sets the voltage at which the inverter enables natural commutation to the stator. Initial excitation angular velocity setting means for setting an initial excitation angular velocity induced in the winding, rotor angular velocity detection means for detecting a rotational angular velocity of the rotor, and a deviation angular velocity between the initial excitation angular velocity and the rotor angular velocity becomes zero. An angular velocity generating means for generating an angular velocity up to the point where the exciting current of the corresponding angular velocity is controlled by controlling the power converter with the angular velocity generated from the angular velocity generating means at the time of starting. Control device for a variable speed generator motor according to claim 1, characterized in that it has to flow in the rotor winding.