JPH0750997B2 - AC excitation power generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an AC excitation generator-motor apparatus, and more particularly to an AC excitation generator-motor apparatus suitable for detecting and protecting an abnormality on the secondary side of the AC excitation generator-motor. Regarding

[Conventional technology]

As a device in which a frequency conversion device is connected to the secondary side of a conventional AC excitation synchronous machine, Japanese Patent Publication Nos. 53-7628 and 57-60645 are available.
There is a description in the issue. No. 9 of the conventional AC excitation generator
Shown in the figure.

Reference numeral 1 is an AC system, 2 is an AC excitation synchronous machine connected to the AC system 1, 3 is a phase detector, and the slip is equal to the difference between the voltage phase of the AC system 1 and the rotation angle represented by the electrical angle of the AC excitation synchronous machine 2. Detect the phase. Reference numeral 4 denotes a device that generates a command value of a component (abbreviated as q-axis component) of the secondary current of the AC excitation synchronous machine 2 that is equal to the voltage phase of the AC system 1 when viewed from the primary side.
The q-axis component current command generator 4 generates a command value according to, for example, active power output of the AC excitation synchronous machine 2, torque, rotation speed, or a deviation between a frequency set value and a detected value of the AC system 1.

Reference numeral 5 generates a command value of a component (abbreviated as d-axis component) of the secondary current of the AC excitation synchronous machine 2 that differs in phase from the voltage phase of the AC system 1 by an electrical angle of π / 2 when viewed from the primary side. It is a device that does. The d-axis component current command generator 5 generates a command value according to, for example, the reactive power output of the AC excitation synchronous machine 2 or the deviation between the voltage set value of the AC system 1 and the detected value. 6 the output I _d * AC-excited synchronous from the output I _q * and d-axis component current command generator 5 of the phase One using the output signal cosθ and sinθ detector q-axis component current command generator 4 by the current command calculator The secondary side current commands I _a *, I _b *, I _c * of the machine 2 are calculated by the calculation formula (1).
However, K is a constant.

Reference numeral 7 is a frequency conversion device that supplies a current to each secondary side phase of the AC excitation synchronous machine 2 in accordance with the command value of the current calculator 6, and 8 is a power receiving transformer connected from the AC system 1 to the frequency conversion device 7. is there. 9 is a current control device 10 commands the thyristor firing angle by comparing the detected value I _M and the current command value I * in the secondary current detector AC-excited synchronous machine 2. It is particularly emphasized here that the secondary side of the induction machine 2 and the output side of the frequency conversion device 7 are composed of four lines of a phase, b phase, c phase and neutral point 0. When performing primary excitation in a variable speed drive induction machine for general industry, a three-wire system that does not include a neutral point is widely used, but when performing secondary excitation, the secondary circuit of an AC excitation synchronous machine is used. The 4-wire system including the neutral point can control the currents flowing through the secondary circuits independently, which simplifies the operation control and has a great advantage.

[Problems to be solved by the invention]

However, in the above-described conventional technique, when an abnormality such as a short circuit occurs on the output side of the frequency conversion device 7, the current control device 10 limits the current at a position closer to the frequency conversion device 7 than the abnormal point and does not reach the overcurrent detection level. However, there was a danger that a large abnormal current would flow from the short-circuit point to the AC excitation synchronous machine side, leading to a serious accident.

In view of the above points, an object of the present invention is to improve reliability in detecting an abnormality on the output side of a frequency conversion device in an AC excitation generator-motor device whose secondary circuit side is composed of four wires including a neutral wire. An object is to provide a high protection device for an AC excitation generator-motor device.

[Means for solving problems]

In order to achieve the above object, an AC excitation generator motor in which the primary winding is connected to the AC power system, and the secondary three-phase winding is star-connected, and the star-side neutral point side connection And a frequency converter connected to each phase winding on the secondary side, and a control device for detecting the current state between the frequency converter and the secondary winding to control the output current from the frequency converter In an AC excitation generator-motor device equipped with, a current detection device that detects the current state of the neutral point side connection, and a control signal when the neutral point current detected by this current detection device is outside the predetermined value range. And the frequency conversion device are controlled by a control signal from the abnormality detection device.

[Action]

When an abnormality such as a ground fault occurs on the output side of the frequency converter of the AC excitation generator-motor, the current at the secondary neutral point of the AC excitation generator-motor increases. By detecting this current state with the current detection device and determining that this neutral point current is out of the predetermined value range, the abnormal state of the AC excitation generator-motor device can be detected.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Items having the same numbers as those in FIG. 9 used for explaining the conventional example show the same items. Here, only the part of FIG. 1 different from that of FIG. 9 will be described. Reference numeral 11 denotes a current detector for detecting the secondary side neutral point current of the AC excitation synchronous machine, which is installed at a position as close to the AC excitation synchronous machine neutral point as possible to widen the protection range. 12 is a current abnormality detection device that inputs the neutral point current value detected by the current detector 11 and detects an abnormality thereof.
Reference numeral 13 is a protection logic which generates a signal for stopping the frequency conversion device according to the abnormality detection signal of the current abnormality detection device 12.

In a normal state, the output currents of the frequency converters 7a, 7b, 7c are controlled by the current controllers 10a, 10b, 10c in a three-phase sinusoidal waveform, so that the secondary side neutral of the AC excitation synchronous machine 2 is neutral. The point current has a smaller value than the output current of the frequency converter.

When an abnormality occurs on the output side of the frequency conversion device, the secondary side neutral point current exceeds the predetermined range and generates an abnormality detection signal. By promptly controlling the frequency converter via the protection logic 13 by this signal, the device can be protected.

The secondary side neutral point current of the AC excitation synchronous machine that occurs at the time of abnormality mainly has a DC component and a slip frequency component, and the magnitude thereof largely changes depending on the secondary side voltage of the AC excitation synchronous machine before the abnormality. When the secondary side voltage is low, the secondary side neutral point current also tends to be small at the time of abnormality. In this case, when an imbalance abnormality occurs on the primary side of the AC excitation synchronous machine, the secondary side The distinction from the current flowing in the sex point becomes unclear, and malfunctions are likely to occur. Further, when the secondary side voltage is high, the secondary side neutral point current also tends to be large, and the allowable current of the neutral point current detector 11 must be greater than or equal to the above maximum current.

Claims 2 to 6 described below are proposed to solve the above problems. Items 2 to 5 relate to the discrimination between the primary side abnormality and the secondary side abnormality of the AC excitation synchronous machine, and the sixth term is the neutral point current detector.
It is related to the allowable current reduction of 11. FIG. 2 shows an embodiment of the second aspect of the claims. Reference numeral 14 is a smoothing circuit that suppresses frequency components higher than the slip frequency. As described above, when the primary side of the AC exciter has an unbalanced abnormality, the secondary side mainly contains (2-s) ₀ (s: slip [PU], ₀ : system frequency) frequency components. A relatively high frequency current component appears. By passing the detection current signal of the current detection device 11 to the smoothing circuit 14, the error occurred on the primary side.
Since it is possible to suppress the input of the current signal on the secondary side to the current abnormality detection device, the distinction between the primary side abnormality and the secondary side abnormality of the AC excitation generator motor becomes clear.

FIG. 3 shows an embodiment of claim 3 of the present invention. Reference numeral 15 is a time circuit, which is a predetermined range T ₁ or more for a predetermined period from the time when the secondary side neutron current value exceeds the predetermined range I _max as shown in FIG.
Output is generated when I _max is exceeded.

By properly selecting T ₁ , in the case of a primary side abnormality in which a secondary side neutral point current of a relatively high frequency flows, no abnormality detection signal is generated and only the secondary side abnormality can be detected. The same effect as the second term can be obtained.

FIG. 5 shows an embodiment according to claim 4. The structure of the circuit is expressed as shown in FIG. 3 as in the case of the third claim. As shown in FIG. 5, the time limit circuit 15 calculates from the time when the secondary side neutral point current value exceeds the pushing range I _max , blocks the invention of the abnormality detection signal for a predetermined period T ₂ , and then the predetermined period T ₂
Generating an output when again exceeds the predetermined range I _max in the T ₃ from. If the output is not generated within the predetermined period T ₂ to T ₃ , it is reset.

FIG. 6 shows an embodiment of claim 5. Reference numeral 16 is an integrator that integrates the secondary side neutral point current value of the AC excitation synchronous machine. Although the method of integrating the absolute value of the neutral point current is adopted in FIG. 6, the same effect can be obtained by integrating the first or square of the neutral point current. Reference numeral 17 denotes a reset circuit, which acts to reset the secondary side neutral point current accumulated by the integrator 16 at a certain time. Reference numeral 18 denotes an abnormality detection device that produces an output when the value accumulated by the integrator 16 exceeds a predetermined value S _max . FIG. 7 shows the above-mentioned example, and has a configuration in which the value of the integrator 16 is reset when the neutral point current becomes zero. In this way, the integrated value immediately before resetting becomes almost constant regardless of the magnitude of slippage during operation, which is a suitable method for abnormality detection.

FIG. 8 shows an embodiment of claim 6 of the present invention. Reference numeral 19 represents an exciting power supply circuit of the current detecting device 11. Now, when the secondary side neutral point current exceeds a predetermined range, the abnormality detection device 12 generates an abnormality detection output and turns off the power supply circuit 19 to detect the secondary side neutral point current detection device 11. To stop. By doing this, the allowable current of the current detection device 11 is
Instead of the maximum neutral point current at the time of abnormality, it is possible to reduce to the abnormality detection range.

〔The invention's effect〕

According to the present invention, in the alternating-current excitation generator-motor device including the frequency conversion device for controlling the current flowing between the three-phase winding and the neutral point side connection for each phase, the abnormality on the output side of the frequency conversion device is provided. Can be reliably detected, so that a highly reliable AC excitation generator-motor device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of an AC excitation generator-motor apparatus according to an embodiment of claim 1 of the present invention, and FIG. 2 is an AC according to an embodiment of claim 2 of the present invention. A block diagram of the excitation generator / motor device, FIG. 3 is a block diagram of the AC excitation generator / motor device according to one embodiment of claims 3 and 4 of the present invention, and FIG. 4 is a claim 3 of the claims. FIG. 5 is an operation explanatory view of one embodiment of claim 4 and FIG. 6 is an alternating current according to one embodiment of claim 5 of the present invention. FIG. 7 is a block diagram of the excitation generator motor device, FIG. 7 is an operation explanatory diagram of one embodiment of the above-mentioned claim 5, and FIG. 8 is an AC excitation generator-motor according to one embodiment of the claim 6. FIG. 9 is a block diagram of the device, and FIG. 9 is a block diagram of a conventional AC excitation generator-motor device. 1 ... AC system, 2 ... AC excitation synchronous machine, 3 ... phase detector, 4,5 ... current command generator, 6 ... current command calculator, 7 ... frequency conversion device, 8 ... power reception Transformer, 9 ...
Secondary current detector, 10 ... current control device, 11 ... neutral point current detector, 12 ... current abnormality detection device, 13 ... protection logic, 14 ... smoothing circuit, 15 ... time circuit, 16 …… Integrator,
17 ... Reset circuit, 18 ... Abnormality detection device, 19 ... Excitation power supply circuit, 20 ... Excitation power supply.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Nagura 3-1, 1-1 Sachimachi, Hitachi City, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Hiroshi Kashiwazaki 3-chome, Hitachi City, Ibaraki Prefecture No. 1 Stock company Hitachi Ltd. Hitachi factory (72) Inventor Akio Ito 5-21 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Omika factory (72) Inventor Hidenori Sawa Omi Mita, Hitachi City, Ibaraki Prefecture 5-2-1, Machi Co., Ltd. Inside the Hitachi Omika Plant (72) Inventor Isao Yokoyama 3-22-3 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Inventor Ono Taisho Osaka Prefecture 3-3-22 Nakanoshima, Kita-ku, Kansai Electric Power Co., Ltd. (56) Reference JP-A-50-76542 (JP, A) JP-A-54-25446 (JP, A) JP-A-54-8674 2 (JP, A) JP-A-54-162149 (JP, A)

Claims (6)

[Claims] 1. An AC excitation generator motor in which a primary winding is connected to an AC power system and a secondary three-phase winding is star-connected, and the star-shaped neutral point side connection and the above-mentioned A frequency converter connected to each phase winding on the secondary side, and control for detecting the current state between the frequency converter and the secondary winding to control the output current from the frequency converter In an AC excitation generator-motor device equipped with a device, when the current detection device for detecting the current state of the neutral point side connection, the neutral point current detected by the current detection device is out of a predetermined value range, An abnormality-exciting generator that outputs a control signal, and the frequency converter is controlled by a control signal from the abnormality-detecting device. 2. The AC excitation generator-motor apparatus according to claim 1, further comprising a smoothing circuit for suppressing a frequency component higher than a slip frequency in a signal indicating the neutral point current detected by the current detector. An alternating-current excitation generator-motor device characterized by the above. 3. The AC excitation generator-motor device according to claim 1, wherein the control signal is applied when a predetermined period of time elapses after the neutral point current detected by the current detection device exceeds a predetermined value range. An alternating-current excitation power generator-motor device characterized in that: 4. The alternating-current excitation generator / motor according to claim 1, wherein the neutral point current detected by the current detector exceeds a predetermined value range, and then again within a predetermined value range within a predetermined period. An alternating-current excitation generator-motor apparatus, wherein the control signal is generated when the voltage exceeds the outside. 5. The AC excitation generator-motor apparatus according to claim 1, further comprising an integrator for accumulating a signal indicating a neutral point current detected by the current detecting device, the neutralizing device within a predetermined time period. An alternating-current excitation generator-motor apparatus, wherein the control signal is generated when the integrated value of the point current exceeds a predetermined value. 6. The AC excitation generator-motor apparatus according to claim 1, wherein the control signal is generated when the neutral point current detected by the current detector is out of a predetermined value range, and An AC excitation generator-motor device characterized by stopping the current detector function of the current detector.