JPH01103173A - Control method for inverter - Google Patents

Abstract

PURPOSE:To improve availability, by stopping an inverter upon occurrence of such external condition as deviating from the control capacity of the inverter, thereafter starting the inverter again automatically. CONSTITUTION:In control method of an inverter, a circuit 2 holds a starting signal when a flip-flop circuit 1 is brought to device operation through a logic 1 or when a critical fault occurs in the device. A circuit 3 produces restart pulses when external conditions satisfy restart conditions after automatic protection stoppage. A circuit 4 for calculating DC voltage produced with a minimum allowable commutation margin time, comparators 5, 7, a circuit 6 for detecting over/under AC voltage and a time delay circuit 13 are provided, while furthermore, a circuit 8 for detecting AC overcurrent having critical fault level and DC overvoltage and over current detecting circuits 9, 10 are provided. It is judged whether external conditions are within the range of regenerative operation capacity, and operational sequence is set to provide automatic restart.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement in a control method for a separately excited inverter device for a DC electric railway that performs power and regenerative operation.

(Prior Art) FIGS. 3 and 4 show examples of control patterns for separately excited inverter devices.

In FIGS. 3 and 4, symbol A is a point indicating the DC voltage at which the inverter device starts regenerative operation,
When the line voltage rises from this point A, power is regenerated from the line to the AC side. Reference numeral B indicates a constant current control region, which is an operating region when regenerative power from the regenerative vehicle is small. code C
is a constant voltage control region in which the line voltage is kept constant when the regenerated power increases from the operating region indicated by symbol B. The symbol indicates the current limit operation area at the rated current of the regenerative inverter device. Reference numeral E in FIG. 4 indicates a constant margin angle control operation region, and this control is a control operation for preventing failure of commutation of the inverter device. Symbol J is an overcurrent detection point.

The symbol G in FIG. 3 is a line indicating the maximum DC voltage that the inverter device can output without commutation failure, and the symbol H indicates the intersection of the symbol G and the line.

What should be noted here is the current limit operation (symbol D
), and in the case of the control pattern shown in Figure 3, if the regenerative power from the regenerative vehicle becomes larger or the AC voltage of the inverter device becomes lower, the thyristor of the inverter device will have insufficient commutation margin angle, Commutation failure occurs, and as a result, the inverter device loses the ability to control the DC voltage, and the DC side of the inverter device becomes short-circuited, causing a DC overcurrent and resulting in a single failure shutdown. Further, in the case of the control pattern shown in FIG. 4, when an increase in regenerative power similar to that described above occurs, the inverter device enters constant margin angle control operation. In this case, commutation failure of the inverter device does not occur, but constant margin angle control operates in the direction of increasing the current.
It becomes a DC overcurrent or an AC overcurrent.

(Problems to be Solved by the Invention) As described above, with the conventional control pattern and the conventional protection circuit (serious failure shutdown due to overvoltage or overcurrent), when the regenerative power suddenly increases or when the AC side voltage When the power decreases, a serious failure and stoppage of the inverter cannot be avoided. However, the serious failure and stoppage in the above control pattern is not due to a failure of the inverter, but is due to a lack of capacity of the inverter.

In the present invention, the control capability of the inverter device is clearly determined, and when external conditions that deviate from this range occur, the inverter device is stopped (light failure mode), and then when the external conditions return to the controllable range, The purpose is to improve the operating rate of the inverter device by automatically restarting the device.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention uses alternating current voltage and alternating current as inputs, as shown in FIG.

A circuit 4 calculates the DC voltage that can be generated at the minimum permissible commutation margin angle of the inverter device, and the output of this circuit 4 is compared with the line voltage (DC voltage), and the output value of the circuit 4 is determined to be DC voltage. “Logic 1” occurs when the voltage is lower than the
a comparator circuit 5 that outputs “logic 1”, and a circuit 6 that generates “logic 1” when detecting an excess or deficiency of AC voltage.
The overcurrent detection circuit (QC-1) outputs "logic 1" at a value slightly higher than the rated current value of the inverter device, and the comparator is set to a value lower than the overcurrent (QC-2) for serious fault detection. The circuit 7 includes a time play circuit 13 that generates "logic 1" when the output of the comparator circuit 7 continues for a predetermined period of time or more.

(Function) The comparator circuit 5 or the circuit 6 for detecting excess or insufficient voltage of AC voltage or the time play circuit 13
'', the flip-flop circuit 1 that holds the start signal is reset, and the inverter device automatically stops.In addition, the comparator circuit 5, the circuit 6 for detecting excess/deficiency voltage of the AC voltage, and the time play circuit 13 return to "logic 0" and the DC zero current detection circuit 11 detects zero current and outputs "logic 1", a set signal is input to the flip-flop circuit 1 after the time play circuit 12 elapses, and the automatic restart automatically.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention, in which a flip-flop circuit 1 that holds a start signal becomes a "logic 1 fin" when the start switch is turned on, and the device is operated. , when the stop switch is turned on, it becomes "logic O" and the equipment stops. 2 is a circuit to hold the serious fault signal when a serious fault occurs in the equipment. 3 is a circuit that holds the serious fault signal after automatic protection stop. This is a circuit that generates a restart pulse to restart the device when (the value of AC voltage, DC voltage, or DC current) satisfies the restart conditions.

8 is a detection circuit for an AC overcurrent at a serious failure level, 9 is a DC overcurrent detection circuit, and 10 is a DC overcurrent detection circuit.
FIG. 2 is a single line diagram of an electric railway circuit using a well-known separately excited inverter device, in which 101 is a thyristor-to-AC/DC converter, 1o2 is a DC reactor, 103 is a DC high-speed circuit breaker, 104 is a transformer, and 105 106 is an instrument transformer for detecting AC voltage; 108 is a DC voltage divider for detecting line voltage (DC voltage); 109
110 is a shunt for detecting direct current, and 110 is a regenerative vehicle.

The AC/DC conversion device No. 101 is normally operated in the inverter control region, and when electric power is output from the regenerative vehicle to the line, it sends that electric power to the AC side to keep the line voltage (DC voltage) constant. be driven. This operating state is indicated by C in the control patterns shown in FIGS. 3 and 4. Furthermore, if the power output from the regenerative vehicle increases, the DC current will increase in order to maintain the line voltage constant. As the regenerated power increases, when the DC current reaches the rated value of the device, in the pattern shown in Figure 3, it reaches code H and commutation failure of the inverter occurs, and in the pattern shown in Figure 4, it reaches code J. AC overcurrent will occur, resulting in a serious failure and shutdown. As described above, when the regenerated power exceeds the capacity of the inverter device or when the alternating current voltage decreases and the regenerative ability of the inverter device decreases, the above-mentioned serious failure stop occurs. However, this serious failure stop was not due to a failure of the inverter device. In the present invention, it is determined whether the external conditions (line voltage or AC voltage) are within the regenerative operation capability range of the inverter device using reference numerals 4 and 5 in FIG. The operation sequence is configured such that the device is automatically stopped when the regeneration capacity of the inverter device is exceeded, and after the stop, if the external conditions return to within the regeneration capacity range of the inverter device, the device is automatically restarted.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to automatically distinguish between external conditions and internal equipment failures in cases where a major failure has conventionally been stopped, and the availability of the equipment is improved. . Furthermore, since the system automatically stops before it reaches a serious failure level, stress on the equipment is reduced.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a single line diagram of a well-known electric railway circuit using a separately excited inverter device, and Figs. 3 and 4 are control pattern diagrams of trains in the electric railway circuit. It is a figure showing an example. 1.2...Flip-flop, 3...Restart pulse generation circuit, 4...DC voltage calculation circuit, 5...Comparison circuit 6...Overvoltage/undervoltage detection circuit, 7.8...・AC overcurrent detection circuit. 9...DC overvoltage detection circuit, 10...DC overcurrent detection circuit, 11...DC zero current detection circuit, 12.13...Time play. Agent Patent Attorney Nori Ken Yudo Daishimaru Kenkai μJ Hayabusa Figure 1 JL Current Voltage (E7 Mouse IIF, ;^) Figure 3 (Etari Kame; Akira)

Claims (1)

[Claims] In a separately excited inverter device for converting DC regenerative power of a load that performs power regeneration and regeneration to AC power, the allowable minimum value of the thyristor of the inverter device is determined from the detected values of the AC voltage and DC current or AC current of the device. The DC output voltage that can be generated at the commutation margin angle is calculated, and the load-side DC voltage value below that value and the allowable maximum current value of the inverter device or below are set as the operable range, and those that deviate from this range and are heavy If an operating condition that does not lead to a breakdown occurs,
A method for controlling an inverter device, comprising automatically stopping the inverter device, and automatically restarting the inverter device when the AC voltage and the DC voltage value on the load side return to an operable range after the stop.