JPS5924633B2 - Synchronous motor driving device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronous motor operating device suitable for operating a synchronous motor for pumped storage power generation using a high-voltage synchronous method.

FIG. 1 is a block diagram showing an example of a synchronous motor operating device using a high-voltage synchronous method conventionally used in pumped storage power plants.

In FIG. 1, reference numeral 1 denotes a shield disconnector connected to a power source (not shown), 2 a reactor, and 3 converts the power supplied via the power source disconnector 1 and reactor 2 into direct current. A rectifier, 4 a DC reactor, 5 a thyristor inverter that converts the DC output of the rectifier 3 into a variable frequency AC output, and 6 a circuit breaker, these constitute a cycle starter T. Reference numeral 8 denotes a cable breaker connected to a power source (not shown); 9 a transformer; 10 a cable used between the primary side of the cable breaker 8 and the transformer 9;
These constitute the main power supply system 11.

12 is a synchronous motor for pumped storage power generation driven by each output of the thyristor starter TN main power system 11.

In this case, the area above the dashed-dotted line corresponds to above-ground equipment, and the area below it corresponds to underground equipment. Next, the operation will be explained.

When power is supplied to the rectifier 3VC from the power supply section via the disconnector 1 and the reactor 2, this power is exchanged to DC at the rectifier 3, and is supplied to the thyristor/inverter 5 via the DC reactor 4 to convert the variable frequency. is converted to AC output. When this converted AC output is supplied to the synchronous motor 12 via the shield breaker 6, the synchronous motor 12 is accelerated from a stopped state to the same frequency as the AC power supply frequency, and after being made uniform in speed, At the time of quick completion, the rated load operation is completed with the power supplied by turning on the main power supply system 11 by turning on the disconnect switch 8, thereby completing the addition. In addition, rectifier 3
, control of the thyristor inverter 5, uniform speed, synchronization, etc. are operated by control signals from a control device (not shown). By the way, when a synchronous motor is operated using the high-voltage synchronous method, the main power supply system 11 is represented by an equivalent circuit shown in FIG. 2 when the motor is driven.

That is, as shown in FIG. 2, the transformer 9 has a leakage inductance LT, the cable 10 has an equivalent stray capacitance CK, and the synchronous motor 12 has an inductance LM and an internal voltage E, and these circuit elements have a leakage inductance LT. LT
A kind of parallel resonant circuit is formed by the sum of the inductance LM and the stray capacitance CK. It is assumed that the rectifier 3 and the thyristor inverter 5 constituting the thyristor starting device 7 are formed by a three-phase full-wave rectifier circuit. Therefore, as described above, when the synchronous motor 12 is driven, the disconnector 8 of the main power supply system 11 is opened before synchronous connection, so that the inverter 5 outputs the power as shown in FIG. 3a.
As shown in FIG. 3c, a rectangular waveform output current 11 containing high-order harmonics is output as an excitation current to the motor 12VC, but as shown in FIG. An excitation current 12 in which a current component corresponding to the resonance frequency is superimposed flows. Therefore, in the synchronous motor driving device configured in this way, the arm voltage waveform of the thyristor/inverter 5 that performs commutation operation becomes the third waveform.
As shown in FIG. Bf) V1, the arm margin angle voltage is influenced by the parallel resonant circuit and oscillates at its resonance frequency, so the margin angle becomes substantially shorter. As a result, for example, some thyristors turn off and others do not turn off between the thyristors in the arm of the inverter 5, which is composed of thyristors connected in series, and the arm breakdown voltage equivalently decreases, causing damage to the thyristors. However, there were drawbacks such as failure of commutation. The present invention has been made to eliminate the drawbacks of such conventional devices, and the present invention has been made to remove the excitation current output from the thyristor inverter from an equivalent parallel resonant circuit formed by the main power supply system and the synchronous motor. Synchronous motor operation that ensures the commutation operation of the inverter by blocking the component corresponding to the resonant frequency and preventing the current of this component from being output to the main power system transformer or motor. It provides equipment.

Hereinafter, the present invention will be explained in detail using the drawings. FIG. 4 is a block diagram showing one embodiment of the synchronous motor operating device of the present invention, and the same parts in this figure as in FIG. 1 are given the same numbers and the explanation thereof will be omitted.

In FIG. 4, reference numeral 13 denotes an excitation current blocking device connected between the thyristor inverter 5 and the breaker 6, that is, the output end of the inverter 5. The excitation current of the component corresponding to the resonant frequency of the parallel resonant circuit formed by the ground capacity up to the disconnector 8 and the inductance of the transformer 9 and the synchronous motor 12 is blocked. As shown in FIG. 5a, the excitation current blocking device 13 includes a reactor 14 connected in series between the inverter 5 and the shimmer breaker 6, and a connection point between the reactor 14 and the inverter 5 and the ground. It consists of a filter circuit in which a capacitor 15, a reactor 16, and a resistor 17 are connected in series, and this filter circuit has a characteristic of bypassing the excitation current of the component corresponding to the resonant frequency of the parallel resonant circuit. According to the device configured in this way, the excitation current of the resonant frequency component of the parallel resonant circuit out of the excitation current output from the thyristor inverter 5 is bypassed by the filter circuit constituting the blocking device 13. , the excitation current does not flow to the transformer 9 or the synchronous motor 12, and the oscillating voltage at the resonant frequency does not appear in the voltage of the motor.

As a result, the margin angular voltage of the arm of the inverter 5 does not oscillate, and the commutation operation of the inverter 5 can be performed reliably. 5b and 5c show modified examples of the excitation current blocking device 13, and in FIG. A reactor 14, a capacitor 18 and a resistor 19 connected in series between the reactor 14 and the connection point of the shear breaker 6 and the ground are provided, and these elements generate an excitation corresponding to the resonant frequency of the parallel resonant circuit. A filter circuit is formed to bypass the current.

In addition, in the ClfC shown in FIG. 5, by connecting a capacitor 20 in parallel with the reactor 14 to form a filter circuit, the excitation current is transferred to the transformer 9 and the synchronous motor 1.
2VC. This is to prevent it from leaking.
Therefore, these excitation current blocking devices 13 also have the same effect as the above embodiment. Although the above-mentioned embodiments have been described with respect to a synchronous motor for pumped storage power generation used in a pumped storage power plant, it goes without saying that the present invention can also be applied to a normal synchronous motor.

As explained above, according to the synchronous motor operating device of the present invention, the excitation current output from the thyristor inverter corresponds to the resonant frequency of the equivalent parallel resonant circuit formed by the main power supply system and the motor. Since the excitation current is prevented from flowing into the transformer and the motor, there is an effect that the commutation operation of the thyristor inverter can be performed reliably.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional synchronous motor driving device, Figure 2
The figure is an equivalent circuit diagram during driving, Figures 3a to 3c are signal waveform diagrams of the main parts, Figure 4 is a block diagram showing one embodiment of the synchronous motor driving device of the present invention, and Figures 5a to 5. 4. e is a circuit diagram showing a specific embodiment of the excitation current blocking device shown in FIG. 4. 1... Converter or disconnection, 2... Reactor, 3
... Rectifier, 4 ... DC reactor,
5... Thyristor inverter, 6...
・Shiya breaker, 7...Thyristor starting device, 8・
・・・Converter or disconnector, 9...Transformer, 10...
... Cable, 11... Main power system, 12...
...Synchronous motor, 13...Excitation current blocking device.

Claims (1)

[Claims] 1. A synchronous motor is driven from a stopped state to a synchronous speed by a thyristor starting device composed of a rectifier, a thyristor inverter, etc., and after the speed is equalized, the motor is connected to the primary side of a transformer in the main power system. In the synchronous motor operation device, the synchronous motor is operated in parallel with the power supplied through the transformer by turning on a disconnector, and the synchronous motor is connected to the output end of the inverter from the transformer. and an excitation current blocking device configured to block an excitation current of a component corresponding to the resonant frequency of a parallel resonant circuit formed by the ground capacity up to the disconnector and the inductance of the transformer and the synchronous motor. Characteristic synchronous motor driving device. 2. The excitation current blocking device consists of a reactor connected in series to the output end of the thyristor inverter, and a filter circuit including a resistor, a capacitor, and a reactor connected in series between the connection point of the reactor and the inverter and the ground. A synchronous motor driving device according to claim 1, characterized in that: 3. The excitation current blocking device consists of a reactor connected in series to the output end of the thyristor inverter, and a series circuit including a capacitor and a resistor connected in series between the output end of the reactor and the ground, and the reactor and the The synchronous motor operating device according to claim 1, wherein the filter circuit is formed by a series circuit. 4. The synchronous motor operating device according to claim 1, wherein the excitation current blocking device comprises a filter circuit in which a reactor and a capacitor are connected in parallel to the output end of a thyristor inverter.