JP3097745B2 - AC excitation rotating electric machine control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC-excited rotating electrical machine control device that performs variable-speed rotation operation by AC excitation of a power converter, and in particular, drastically changes operating conditions. The present invention relates to an AC-excited rotating electrical machine control device with improved operation stability even in the case where it is performed.

[Prior Art] With the progress of semiconductor power converters for power, it has a primary winding and a secondary winding having a winding structure similar to that of a wound-type induction machine, and is driven by AC excitation using a frequency converter. Synchronous machines that enable variable speed operation have been widely put into practical use.

By the way, such a system using a so-called AC-excited rotating electric machine has been widely adopted in the past for load adjustment and phase adjustment in a power system, utilizing its characteristic function of quickly adjusting active power and reactive power. However, in the conventional apparatus, for example, as seen in the proposal of Japanese Patent Application No. 63-55518, the excitation frequency is suppressed to a set value or less as a response when the AC power system is cut off. Thereby, the self-excited operation similar to that of the ordinary synchronous machine of DC excitation is provided.

Such a conventional example will be described below with reference to FIG.

This conventional example is an example in which an AC-excited rotating electric machine is applied to a pumped-storage power generation system, and a main transformer 3 is connected to an AC system 1 via a system or a breaker 2a, and a low-voltage side of the main transformer 3 is connected. Is connected to a primary winding 5a of an AC excitation synchronous machine 5 having a winding structure similar to that of a wound induction machine, which is directly connected to a reversible pump-turbine 4 via a synchronous inputting device and a breaker 2b. ing.

On the other hand, the frequency conversion device 6 includes a thyristor power conversion device 8 for exchanging power from the AC system 1 stepped down by the excitation transformer 7 into low-frequency AC power, and the like. It is provided for each phase.

Slip phase detector 9 for obtaining AC excitation frequency signal
Is a voltage transformer 10 for detecting the system voltage phase θ _v
If, consisting voltage phase calculator 11, a resolver apparatus 12 for detecting a rotational phase theta _r expressed in electrical angle of the AC energization synchronous machine 5, the phase calculator 13 slip on it.

The voltage phase calculator 11 functions to output a two-phase signal of (cos θv, sin θv), and the resolver device 12 outputs (cos θr, sin θ
r) The two-phase signal is output. And the slip phase calculator
13 outputs a two-phase signal of (cos θs, sin θs).

The excitation current command calculator 14 makes the amplitude and phase of the three-phase AC current command rotating together with the slip phase θs orthogonal to each other.
It works to adjust by the axis current commands Iq, Id. Here, the three-phase current command values Iuref, Ivref, Iwref are represented by the following equations.

Iuref = Iqcosθs + Idsinθs The current control device 15 functions to output the firing angle signal of the thyristor to the automatic pulse phase shifter 16 so that the secondary winding current of the AC excitation synchronous machine 5 matches the current command, and The phaser 16 serves to output a firing pulse signal 17 of the thyristor power converter 8. The current command signal to be adjusted by the secondary current command calculator 14 is described in JP-B-53-7628.
It is provided by the method described in each publication of JP-B-57-60645. That is, the active power output is controlled by adjusting the current component Iq having the same phase as the slip phase θs, and the voltage is controlled by adjusting the current component Id having a phase delayed by 90 ° from the slip phase signal θs. .

The active power output and voltage to the AC system 1 are taken out by an instrument current transformer 18 and an instrument voltage transformer 10, and the signal is converted into a DC signal by a measuring instrument 19 to be used as an automatic active power controller (APR). It is controlled by inputting to an automatic voltage controller (AVR) 21 and 20.

The output Iq of the automatic active power control device 20 is controlled by the limiter 22 so that the upper and lower limits are within a preset value range. The upper and lower limits of the output Id of the automatic voltage controller 21 are limited by a limiter 23 to a range of a preset value. Both the limiters 22 and 23 are provided to prevent the current command from exceeding the thyristor power converter 8's capability.

[Problem to be Solved by the Invention] In the above-described conventional technology, the control of the generator operation is continuously maintained even when the operation state changes transiently such as disconnection from the AC system during operation. For this purpose, the lower limit value of the vertical axis current command must be set to a positive finite value, so that there is a problem that the reactive current output range cannot be widened.

This will be described in detail. First, FIG. 4 (b) shows the case where the equivalent circuit of the AC excitation synchronous machine 5 is as shown in FIG. Is a vector diagram of driving in the state of, and in this state,
Secondary current I ₂ in the longitudinal axis current Id negative direction is decreased to the normal direction.

Now, in this state, if it is cut off from the AC system,
Since the terminal voltage of the generator drops from V ₁ to E, it is necessary to increase the secondary current,
As shown in FIG. 5, the value of the secondary current is the value I _{2 at} this time.
The current command value must be changed so that the current command value changes to the predetermined value I ₂ ′.

Thus, the automatic voltage control device 21 changes the vertical axis current command value from a negative value to a positive value in the process of increasing the terminal voltage, so that a positive feedback state occurs in this process.

In such a positive feedback state, the voltage is lost, and it is difficult to shift to the self-excited operation.

Therefore, in the above-described conventional technology, a negative value cannot be set as the lower limit value of the vertical axis current Id.

Next, FIG. 6 is a vector diagram when the operation is performed in a state where the vertical axis current command is in the positive direction. The secondary current I ₂ is directed downward, and the vertical axis current Id is a positive predetermined value. Value.

In this state, when the same has been cut off from the AC system, since the terminal voltage of the generator this time is raised from V ₁ to the E, in turn, it is necessary to reduce the secondary current in the opposite.

However, at this time, the horizontal axis current (Iq) changes from the predetermined value Iq due to the interruption from the AC system, as shown in FIG.
It changes to Iq '. Here, the horizontal axis current Iq changes in the positive direction for the following reason.

First, when the horizontal axis current Iq is based on an output command from the rotation speed control system, the power is increased and the rotation speed tends to increase. The current changes in the positive direction.

Next, when the horizontal axis current Iq is based on an output command from the active power control system, the active power output detected at the same time as the interruption is zero.

However, since the control system operates to hold the output of the generator at the command value, the active power command rapidly changes in the positive direction, so that the secondary current value increases and the voltage E increases.

As described above, in the above-described related art, there is a problem that the secondary current increases, and as a result, the terminal voltage becomes excessively large, and it is not possible to shift to the automatic operation.

An object of the present invention is to provide an AC-excited rotating electrical machine control device that enhances the stability of operation even when the operation state suddenly changes, for example, when the AC system is cut off.

Means for Solving the Problems To achieve the above object, according to the present invention, an induction machine having a primary winding and a secondary winding, a power converter for exciting the secondary winding by AC, An AC-excited rotating electrical machine control device comprising: an active power control unit that outputs an active power command to the power converter; and a reactive power control unit that outputs a reactive power command to the power converter. Current detecting means for detecting a current; reactive power command limiting means for limiting a reactive power command given to the power converter; and reactive power by the reactive current command limiting means according to a current detection result by the current detecting means. And a reactive power limit range changing means for changing the limit range of the command.

In order to achieve the above object, according to the present invention, there is provided an induction machine having a primary winding and a secondary winding, a power converter for exciting the secondary winding by AC, and an active power supply for the power converter. Current detecting means for detecting a current of the primary winding in an AC-excited rotating electrical machine control device comprising: an active power control means for outputting a command; and a reactive power control means for outputting a reactive power command to the power converter. An active power command limiting unit for limiting an active power command given to the power converter; and a limiting range of the active power command by the active current command limiting unit in accordance with a current detection result by the current detecting unit. Active power limiting range changing means is provided.

[Operation] According to the present invention, the primary winding current of the induction machine is detected,
Since the upper and lower limits of the active power command or the reactive power command are changed, the active power output range or the reactive power output range can be made variable according to the operating conditions.

Embodiment An embodiment of the present invention will be described below with reference to FIG. Note that the devices having the same reference numerals as those in the conventional example of FIG. 3 are the same, and therefore the description is omitted to avoid duplication.

The primary current vector computing unit 24 is a
The following equation is calculated from the secondary current signals I _u1 , I _v1 , I _w1 and the voltage phase signals cos θv, sin θv from the voltage phase calculator 11 to output the d-axis component I _d1 and the peak value I _1p of the primary current. .

When the peak value I _1p from the primary current vector calculator 24 is equal to or more than the set value I _1po , the upper and lower limits of the q-axis command limiter 26 are −Iqmax ₁ ≦ Iq ₂ ≦ Iqmax ₁ ; When the next current peak value I ₁ q is smaller than the set value I ₁ po, it determined to have been cut off from the AC system, the upper and lower limits of the control value is the operation of switching the _{-Iqmax 2 ≦ Iq 2 ≦ Iqmax 2} . Here, Iqmax ₁ and Iqmax ₂ are set so that Iqmax ₂ <Iqmax ₁ .

As a result, when the primary current peak value is smaller than the set value I1po, Iq ₂ can be suppressed to a value near zero.

The d-axis command limiter 27 is configured to receive the signal Id ₁ from the primary current vector calculator 24 and set the upper and lower limits of the limit value variably by the following equation. -Id performs an operation for limiting the upper and lower limit in ₁ Id ₂ Idmax-Id _1.

Here, Idmin and Idmax are preset constants,
Id ₁ increases in the negative direction as the AC excitation synchronous machine 5 is more strongly excited.

As a result, as the excitation becomes stronger, the upper and lower limit values move in the positive direction.

Therefore, according to this embodiment, the limit range of the q-axis command limiter or the d-axis command limiter does not change during normal operation, and is in the limit range according to the normal operation of the prior art.
Does not affect the secondary current control.

According to such a configuration, when disconnected from the AC system, the lower limit value changes from negative to positive as the vertical axis Id of the armature current changes from positive to 0.
R does not malfunction.

Generally, such a primary current vector calculator 24 has a drawback that it is more susceptible to noise and disturbance than the excitation current command calculator 14 which handles a slip frequency because the AC system frequency signal is once converted to DC. However, in this embodiment, since it is not normally used for the secondary current control, there is an effect of obtaining an active power output and a reactive power output with small pulsation.

FIG. 2 shows another embodiment of the reactive power control means of the present invention. In this embodiment, a current-voltage converter 28 converts a system output current signal detected by a current transformer 18 into a voltage. Then, the peak value Ilp of the system output current is rectified by the diode bridge circuit 29 and input to the q-axis limiter 30.

As with the q-axis command limiter 26 in the embodiment of FIG. 1, the q-axis current limiter 30 determines that it has been cut off from the AC system when it becomes smaller than the set value Ilpo, and performs an operation of switching between upper and lower limits. .

According to this embodiment, 1 which is definitely 0 after the interruption phenomenon
Since the current value from the secondary winding to the system is detected, the disconnection from the AC system is detected more reliably than the self-excited current determined by the remaining primary winding current as in the embodiment of FIG. Can,
Therefore, a more reliable operation can be obtained.

[Effects of the Invention] According to the present invention, the primary current of the AC-excited rotating electrical machine is detected and the upper and lower limits of the secondary current command value are changed, so that the reactive power output range is sufficiently widened. Thus, even when the AC power system is cut off, the effect of stably and reliably transferring to the self-excited operation can be obtained.

Further, according to the present invention, the primary winding current of the AC rotating electric machine is detected to change the upper and lower limits of the active power command value. Approaches 0, the upper and lower limit values of Iq are reduced to around 0, so that the effect that the active power command control does not malfunction is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an AC-excited rotary electric machine control device according to the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, and FIG. FIG. 4, FIG. 5, FIG. 6, FIG.
FIG. 7 is an equivalent circuit and a vector diagram for explaining the operation. 1 ... AC system, 3 ... Main transformer, 5 ... AC excitation synchronous machine, 6 ... Frequency converter, 9 ... Slip phase detector,
20 ... automatic active power control device, 21 ... automatic voltage control device, 24 ... primary current vector calculator, 26 ... q-axis command limiter, 27 ... d-axis command limiter.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Junichi Shiozaki 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (72) Inventor Hirotada Fukuda 3-1-1 Sachimachi, Hitachi-shi, Ibaraki No. 1 Inside Hitachi, Ltd.Hitachi Plant (72) Inventor Yasuteru Ohno 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Inside Kansai Electric Power Company (72) Inventor Satoshi Kuzusaka Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture 3-2-2, Kansai Electric Power Co., Inc. (72) Inventor Hiroto Nakagawa 3-2-2, Nakanoshima, Kita-ku, Osaka-shi, Osaka Kansai Electric Power Co., Inc. (58) Field surveyed (Int. Cl. ⁷ , (DB name) H02P 9/00

Claims (3)

(57) [Claims] 1. An induction motor having a primary winding and a secondary winding, a power converter for exciting the secondary winding by AC, and an active power control unit for outputting an active power command to the power converter. And a reactive power control unit that outputs a reactive power command to the power converter. A current detection unit that detects a current of the primary winding; A reactive power command limiting means for limiting the reactive power command; and a reactive power limiting range changing means for changing a limiting range of the reactive power command by the reactive current command limiting means in accordance with a current detection result by the current detecting means. An AC-excited rotating electrical machine control device, characterized in that: 2. The power supply system according to claim 1, wherein the primary winding is connected to a power system, and a system current detecting means for detecting a current of the power system; and a power system detected by the system current detecting means. An AC-excited rotating electrical machine control device, further comprising: an active power limiting range changing unit that narrows a limiting range of an active power command by the active power control unit when the current is equal to or less than a set value. 3. An induction motor having a primary winding and a secondary winding, a power converter for exciting the secondary winding by AC, and an active power control means for outputting an active power command to the power converter. And a reactive power control unit that outputs a reactive power command to the power converter. A current detection unit that detects a current of the primary winding; Active power command limiting means for limiting the active power command; and, when the primary winding current value detected by the current detecting means is equal to or less than a set value, narrowing a limit range of the active power command by the active current command limiting means. An AC-excited rotating electrical machine control device, comprising: an active power limiting range changing unit.