JPH0345991B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention]

The present invention relates to a synchronous motor starting device for starting a synchronous motor such as a generator motor of a pumped storage power plant. Recently, the operation of pumped storage power plants has become closely linked to nuclear power plants, and as pumped storage power plants have increased their capacity, further improvements in operational reliability have become closely required. It's coming. This is conditional on the requirement that the pumping operation can be started immediately if a request for pumping operation is received from the central power dispatch center, and in this case, of course, the synchronous motor starter It is important that it is always normal.

[Prior art]

A conventional device of this type is shown in FIG. In the figure, 1 is a three-phase rectifier in the main circuit section;
Reference numeral 2 denotes a DC reactor into which a DC circuit is inserted, 3 a three-phase inverter, 4 an AC reactor, and 5 a pulse generator 8 which is shaft-coupled with a generator motor. 7 is a distributor, 6 is an input transformer, 9 is a current transformer, and 10 is a thyristor element. In addition, 11 shows the overall configuration of the control circuit, and the control circuit 1
1 includes a speed controller (SC) 12 that controls the speed of the generator motor 5, a current controller (CC) 13 that controls the current, a current limiter circuit 31, a current detection circuit (CS) 15, and a speed detection circuit ( SS) 16, rectifier gate circuit (RECGPG) 14, inverter gate circuit (INVGPG) 17, etc. Next, the operation of the main circuit in FIG. 1 will be explained below. First, the main circuit includes an input transformer 6, a three-phase rectifier 1, a DC reactor 2, a three-phase inverter 3, an AC reactor 4, a generator motor 5, and the like. The electric power once converted from AC to DC voltage by the three-phase rectifier 1 is converted again into variable frequency AC power by the three-phase inverter 3, and is supplied to the generator motor 5. The output frequency of the three-phase inverter 3 is used to control the thyristor element 10 in synchronization with the generator motor 5 by a distributor 7 (rotor position sensor) directly connected to the generator motor 5. Therefore, the generator motor 5 is smoothly accelerated without stepping out. In Figure 1, DC reactor 2 has a DC current Id
28, the AC reactor 4 is connected to the thyristor element 1 of the three-phase inverter 3.
This is installed to protect 0 from rush current. Next, the operation of the control circuit 11 will be explained below. Basically, the current value flowing into the generator motor 5 (=√
2/3Id) to control torque. In general, starting devices for generator motors for large-capacity pumped storage power plants implement constant current control (constant torque control) to keep the DC current Id constant after AC/DC conversion. In other words, when starting the generator motor, the speed reference signal (Nref)
18 and the speed feedback signal (N _FB ) 26, there is a relationship of Nref>N _FB , the output 25 of the speed controller (SC) 12 is saturated, and the current reference (Iref) 24 is connected to the current limiter circuit 31. It's decided by then. Therefore, in order to increase the direct current (Id) 28, the thyristor firing angle α of the three-phase rectifier 1 is decreased and the rectifier output voltage (E _R ) 29 is increased. Since the conventional synchronous motor starting device has the circuit configuration as described above, the control circuit 11 does not have an automatic diagnostic circuit, so it is difficult to check whether the control circuit operates normally before starting the synchronous motor. Because it was not possible to confirm this, if the generator motor were to be started with the control circuit in an abnormal state, there is a possibility that an overcurrent would flow through the thyristor. Further, even if an abnormality in the control circuit 11 is discovered by some method before starting, it takes time to investigate the abnormal location, replace abnormal parts, etc., and the generator motor cannot be started immediately.

[Summary of the invention]

The present invention was made in order to eliminate the drawbacks of the conventional devices as described above.In order to improve the reliability of the starting device, a plurality of control circuits are provided, each having a self-diagnosis function, and a self-diagnosis function is provided before starting. It is an object of the present invention to provide a starting device for a synchronous motor, which is characterized in that a normal control circuit is selected depending on the result of diagnosis.

[Embodiments of the invention]

An embodiment of the present invention will be described below. In FIG. 2, the same parts as in FIG. 1 are designated by the same reference numerals. In FIG. 2, 31A is a simulated current feedback generation circuit, 32 is a simulated speed feedback generation circuit, and 33 is a simulated distributor signal generation circuit. Next, the operation of the circuit shown in FIG. 2 will be explained below. First, the self-diagnosis circuit side will be explained. Various systems are conceivable for the self-diagnosis function of the starter, but in the field it is preferable to use a system that can completely simulate everything from the generator stopped state to the generator rated speed, similar to when starting an actual machine. The reason is as follows. In other words, by simulating the generator motor from a stopped state to its rated speed (acceleration completed), it is possible to check not only the control circuit but also the sequential operation of relay circuits, etc. (starting the actual machine can be completely simulated). In the case of synchronous motors and thyristor starters, when the motor is running at high speed and the motor output voltage is large, load commutation (commutation based on the motor voltage) is performed, and when the motor is running at low speed and the motor output voltage is small, intermittent commutation (commutation) is performed. The converter performs commutation to reduce the DC current to zero. It is possible to check these two different commutation modes and to check whether there is a smooth transition from intermittent commutation to load commutation. In order to configure a system that completely simulates the actual circuit as described above, a simulated generator speed feedback creation circuit 32 and a simulated current feedback creation circuit 31 are required.
A and a simulated distributor signal generation circuit 33 need to be created. FIG. 2 shows an example of a control circuit incorporating each of these simulated signal generation circuits, and the bold line portion in the figure is a circuit added for self-diagnosis. In other words, the simulated current feedback creation circuit 3
1A performs gain adjustment (K: proportional gain) on the output signal of the current controller (CC) 13 to create a simulated current feedback (I' _FB ) 34. The simulated speed feedback creation circuit 32 creates a simulated speed feedback (N' _FB ) 35 by inputting the output of the current controller (CC) 13 to a first-order delay circuit (approximately, an integrating circuit may be used).
The simulated distributor signal generation circuit 33 converts the simulated speed feedback (N' _FB ) 35 into voltage/frequency (V/F).
By converting and dividing the frequency by 6, 3-phase inverter 3
A simulated distributor signal 36 corresponding to the firing signal of the six thyristor elements 10 is created. Each simulated signal is the first, second, and second signal for normal operation mode and self-diagnosis mode.
It is selected by the third changeover switches 38, 39, and 37 (the self-diagnosis mode is entered when each changeover switch 37, 38, and 39 is closed to the contact B side). Like an abnormality, the simulated current feedback creation circuit 31, the simulated speed feedback creation circuit 32,
By adding the simulated distributor signal generation circuit 33 to the conventional circuit, it becomes possible to simulate the completely same mode as the actual operation even without a feedback signal from the main circuit. Next, FIG. 3 shows the input/output characteristics of each of the simulated signal generating circuits 31A, 32, and 33. First, when performing self-diagnosis on the starting circuit according to the present invention shown in FIG. 2, there is a method of checking the following items as an example of abnormality detection in the circuit. (1) After the thyristor starter starts operating, confirm that the simulated speed feedback (N' _FB ) 35 reaches the rated speed within a certain period of time (normally, to shorten the self-diagnosis time, the simulated speed feedback (N' _FB ) 35's speed increase rate is faster than the actual machine). (2) While the simulated speed feedback (N' _FB ) 35 reaches the rated speed from zero speed, make sure that the fault detection circuit (opening, missing arc, distributor abnormality, etc.) does not operate. Next, multiple control circuits as shown in Figure 2,
An example of a control circuit switching method will be described below. Here, for the sake of simplicity, we will discuss the case of dual control circuits. FIG. 4 shows an example of a block diagram when control circuits are duplicated (No. A control circuit and No. B control circuit). The figure shows a relay circuit 42, a No.A self-diagnosis function control circuit 43A, and a No.B self-diagnosis function control circuit 4 in the thyristor starter control panel 45.
It stores 3B. The inside of the No. A control circuit 43A is composed of a No. A logic operation section 40 and a No. A switching section 41 corresponding to FIG. The same applies to No. B control circuit 43B. The thyristor firing signals outputted from each logic operation section 40 are selected by a No. A switching section 41 and a No. B switching section 41. Current feedback 21, speed feedback 19, distributor signal 2
0 is input in parallel to the No. A or B logic operation section 40 and the No. A or B switching section 41. In the case of the system shown in FIG. 4, the selection command for the No. A and No. B control circuits is normally issued by the upper controller 4 as the selection means.
4, the control circuit is automatically selected. Next, FIG. 5 shows an example of a flowchart when performing self-diagnosis and switching of the control circuit using the thyristor starting device shown in FIG. 4. As shown in the figure, when a starter control circuit check command comes from the host controller (44 in Figure 4), first the No.
Checks the A self-diagnosis function control circuit, and if No. A is normal, the check ends and the No. A control circuit actually starts. If No.A is abnormal, the self-diagnosis function control circuit is automatically switched from No.A to No.B, and the No.B self-diagnosis function control circuit is checked. If No.B is normal, the check ends and the No.B self-diagnosis function control circuit actually starts. If No.B is abnormal, the check ends, the start is stopped, and the failure location is investigated. The flowchart shown in FIG. 5 above is normally performed automatically. The above description has been made using a thyristor starter for a pumped storage power plant as an example of the present invention, but it goes without saying that the present invention can also be applied to a synchronous machine starter for other uses such as a thyristor starter for a blast furnace blower.

【Effect of the invention】

Since the present invention is constructed as described above, the control circuit of the frequency converter using semiconductor elements is equipped with a self-diagnosis function, and since a plurality of control circuits are multiplexed, it can be used in the actual generator motor. Since it is possible to select a self-diagnosis function control circuit that operates normally before starting, failures can be discovered early, and even if a failure occurs, self-diagnosis is performed before starting without applying actual voltage, which prevents damage from increasing. This has the effect of greatly improving the reliability of the starting device.

[Brief explanation of drawings]

Figure 1 is a control circuit block diagram of a conventional device;
FIG. 3 is a block diagram of a control circuit showing an embodiment of the present invention, FIG. 3 is an input/output characteristic diagram of a simulated signal generation circuit of the present invention, and FIG. 4 is a configuration diagram of a plurality of control circuits according to the present invention. , FIG. 5 shows a flowchart of self-diagnosis and switching of a plurality of control circuits according to the present invention. 1...3-phase rectifier, 2...DC reactor, 3
... 3-phase inverter, 4 ... AC reactor, 5
... Generator motor, 6 ... Input transformer, 7 ... Distributor, 8 ... PG (pulse generator), 9 ... CT (current transformer), 10 ... Thyristor element, 11 ... Control circuit, 12... Speed controller, 13... Current controller, 14... Rectifier gate circuit, 15...
...Current detection circuit, 16...Speed detection circuit, 17...
... Inverter gate circuit, 31A ... Simulated current feedback creation circuit, 32 ... Simulated speed feedback creation circuit, 33 ... Simulated distributor signal creation circuit, 40 ... Control circuit logic operation section, 41 ... Control signal switching section, 42...Relay circuit, 43...
...Self-diagnosis function control circuit, 44...Upper controller, 45...Starting device control panel.

Claims (1)

[Claims] 1 A rectifier 1 that converts alternating current into direct current, an inverter 3 that converts the direct current output of this rectifier 1 into variable frequency alternating current power and supplies it to the synchronous motor 5, and an alternating current detection signal before the direct current conversion and the synchronous motor 5. a plurality of self-diagnosis function control circuits 43A, 43B which input rotational speed signals of and output control signals for the rectifier 1 and the inverter 3; and a selection means 44 which instructs selection of the self-diagnosis function control circuits 43A, 43B. and each self-diagnosis function control circuit 4.
3A and 43B are a simulated current feedback generation circuit 31A that generates a simulated current feedback;
A simulated speed feedback creation circuit 32 that generates a simulated speed feedback, a simulated distributor signal creation circuit 33 that creates a simulated distributor signal, and a distributor 7
an inverter gate circuit 17 that controls the inverter 3 by selectively inputting the output signal of the output signal and the output signal of the simulated distributor signal generation circuit 33 using a first changeover switch 38; and a speed detection circuit 16 that inputs the rotational speed signal. and the output signal of the simulated speed feedback creation circuit 32 through a second changeover switch 39, and a speed controller 12 into which a speed reference signal is input, and a current detection circuit into which the AC detection signal before DC exchange is input. circuit 15
Output signal and simulated speed feedback creation circuit 3
a current controller 13 into which a 1A output signal is selectively inputted by a third changeover switch 37 and an output signal from the speed controller 12; and a rectifier gate into which the output signal of the current controller 13 is inputted to control the rectifier 1. A starting device for a synchronous motor characterized by comprising a circuit 14.