JP6991747B2 - Control device and control method for dual power supply alternator - Google Patents

Description

An embodiment of the present invention relates to a control device and a control method for a dual power supply alternator.

In a dual power supply AC machine in which the primary side is connected to the power system via the main transformer and the secondary side is connected to the frequency converter (AC exciter), electricity such as short circuits and ground faults in the power system or electric circuit. When a failure occurs, transient phenomena such as voltage drop, DC component superimposition, and overcurrent on the primary side of the dual power supply AC machine occur, and overvoltage occurs on the secondary side. At this time, on the primary side of the dual power supply AC device, a phenomenon called zero miss may occur in which the primary current does not cross zero when the circuit breaker is opened due to the superimposition of the DC component. Several techniques have been proposed to solve the zero-miss problem.

Japanese Patent No. 2816020

When a zero error occurs, the circuit breaker cannot cut off the current, the circuit breaker is damaged, the electrical failure cannot be eliminated, the power system cannot continue to operate, or the main transformer or double. There is a possibility of damaging the power supply AC machine, etc. Therefore, it is required to quickly zero-cross the primary current of the dual power supply AC so that zero error does not occur.

Although some techniques for solving the problem of zero mistake have been proposed, no effective method for quickly zero-crossing the primary current of the dual power supply AC after the occurrence of an electric failure has been proposed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device and a control method for a double power supply AC machine that can quickly zero-cross the primary current of the double power supply AC machine. do.

According to the embodiment, a dual power supply AC machine in which the primary winding is connected to an electric circuit via an opening / closing means, and a power conversion means for supplying a variable frequency current to the secondary winding of the double power supply AC machine. , A power conversion control means for controlling the voltage or current of the power conversion means, and a control device for a dual power supply AC device applied to a power generation system having the power conversion means. The control device of the double power supply AC is described by a secondary current measuring means for measuring the secondary current on the secondary side of the double power supply AC and an overcurrent flowing through the primary side of the double power supply AC. DC component measurement to measure the DC component or low frequency component superimposed on the secondary current measured by the secondary current measuring means when the transient DC component is superimposed on the primary side and secondary side of the dual power supply AC machine. The means, a DC command value generating means for generating a DC energization command or a low frequency energization command signal to the power conversion control means according to the DC component or the low frequency component measured by the DC component measuring means, and the DC command. The switching means includes a switching means for outputting or stopping the signal of the DC energization command or the low frequency energization command generated by the value generating means, and the switching means is a DC component or low in which the DC component measuring means is superimposed on the secondary current. When the signal of the DC energization command or the low frequency energization command generated by the DC command value generating means when the frequency component is measured, a failure of the electric circuit on the primary side of the double power supply AC machine is detected, or the above two. When a return after the short-circuit operation of the short-circuit device that short-circuits each phase of the electric circuit on the secondary side of the heavy power supply AC machine is detected, the output is output to the power conversion control means, and the power conversion control means is output. A command corresponding to the signal of the DC energization command or the low frequency energization command is output to the power conversion means, and the power conversion means outputs a DC or low frequency current according to the command from the power conversion control means. It flows through the secondary winding of the heavy power supply AC machine .

According to the present invention, it is possible to quickly zero-cross the primary current of the dual power supply AC machine.

The figure which shows an example of the structure of the power generation system which concerns on 1st Embodiment. The figure which shows an example of the circuit structure of the DC component measurement function 6 in FIG. The figure which shows an example of the structure of the power generation system which concerns on 2nd Embodiment.

Hereinafter, embodiments will be described with reference to the drawings.

<First Embodiment>
First, the first embodiment will be described.
(Constitution)
FIG. 1 is a diagram showing an example of a configuration of a power generation system according to the first embodiment.

The power generation system shown in FIG. 1 is, for example, a variable speed pumped storage power generation system installed in a pumped storage power plant, and is electrically connected to the power system S.

The power generation system has, as basic components, for example, a power supply AC machine 1 (hereinafter referred to as “power generation motor 1”) which is a power generation motor connected to a pump water wheel 101, a converter 2A, and an inverter 2B. Converter 2, main transformer 102, system side breaker 103, parallel breaker 104, exciting transformer 105, exciting breaker 106, speed controller 107, servo motor 108, angle detector KA, instrument transformer It is equipped with equipment such as an instrument VT, a current transformer CT, CT5A, and a system failure detection function DT.

Further, the power generation system includes a power conversion control unit 3 having a converter control unit 3A and an inverter control unit 3B, an ineffective power control unit 111, an active power control unit 112, a power generation motor voltage control unit 113, and an inverter voltage command value calculation during normal operation. It is equipped with various control functions such as a speed controller control unit 115, a converter voltage command value calculation unit 116, a power generation motor primary current AC control calculation unit 120, and calculation units A1 and A2.

The calculation unit A1 has a voltage detected through an instrument transformer VT installed in an electric circuit between the main transformer 102 on the primary side of the power generation motor 1 and the parallel circuit breaker 104, and the primary side of the power generation motor 1. It is a function to calculate active power and ineffective power based on the current detected through the current transformer CT installed in the electric circuit between the main transformer 102 and the parallel circuit breaker 104.

The calculation unit A2 includes the voltage detected through the instrumental transformer VT installed in the electric circuit between the main transformer 102 on the primary side of the power generation electric power unit 1 and the parallel circuit breaker 104, and the exciting circuit breaker 106. It is a function to calculate active power and invalid power based on the current detected through the transformer CT installed downstream.

The reactive power control unit 111 calculates a control target value of the reactive power supplied from the power generation system to the power system based on the difference between the reactive power command value input from the input unit T1 and the reactive power calculated by the calculation unit A1. It is a function to output.

The active power control unit 112 has the active power calculated by the calculation unit A1, the active power command value input from the input unit T2, the head measurement value input from the input unit T3, and the guide vane opening from the servomotor 108. It is a function to calculate each control target value of the active power, the rotation speed, and the opening degree of the guide vane G based on the degree feedback signal.

The power generation motor voltage control unit 113 controls ineffective power based on the voltage detected through the instrument transformer VT installed in the electric circuit between the parallel breaker 104 on the primary side of the power generation motor 1 and the power generation motor 1. It is a function to calculate and output the control target value of the generator motor voltage according to the control target value of the ineffective power from the unit 111 or the voltage increase / decrease command input from the input unit T4.

During normal operation, the inverter voltage command value calculation unit 114 determines the voltage detected through the instrument transformer VT installed in the electric circuit between the main transformer 102 on the primary side of the power generator 1 and the parallel breaker 104. Based on this, the frequency is calculated and output, the control target value of the rotation speed calculated by the active power control unit 112, the angle signal of the power generation electric power unit 1 output from the angle detector KA, and the secondary side of the power generation electric power unit 1. Based on the current detected by the current transformer CT5A installed in the electric circuit of the above, the secondary of the generator 1 is passed through the inverter control unit 3B and the inverter 2B according to the control target value of the generator voltage from the generator voltage control unit 113. It is a function of controlling the current and controlling the voltage, the active power, and the rotation speed of the power generation motor 1.

During normal operation, the inverter voltage command value calculation unit 114 is based on the voltage detected through the instrument transformer VT installed in the electric circuit between the main transformer 102 on the primary side of the generator motor 1 and the parallel breaker 104. The frequency calculation function a that calculates the frequency and outputs the calculation result to the speed controller control unit 115, the angle signal input function b that inputs the angle signal of the power generation motor 1 output from the angle detector KA, and the angle signal thereof. The angular speed calculation function c that calculates the angular speed from, and the calculation function d that calculates and outputs the difference between the control signal (target value of rotation speed / guide vane opening) from the active power control unit 112 and the angular speed, and the difference thereof. The slip frequency control function e that generates the slip frequency control signal according to the above, and the reset control that generates the reset control signal based on the current detected by the current transformer CT5A installed in the electric circuit on the secondary side of the power generation motor 1. A function f (however, not used in this embodiment), a three-phase two-phase conversion function g that performs three-phase two-phase conversion of the current detected by the current transformer CT5A, and a slip frequency control signal or a reset control signal. Calculation function h that calculates and outputs the difference from the signal after three-phase two-phase conversion, the control signal from the power generation motor voltage control unit 113 (control target value of the power generation motor voltage), and the signal after three-phase two-phase conversion. A calculation function j that calculates and outputs the difference between the two, a control function k that outputs a control signal according to the calculation result of the calculation function h, and a control function m that outputs a control signal according to the calculation result of the calculation function j. The two-phase and three-phase conversion function n that inputs the control signal from the control function k and the control signal from the control function m to perform two-phase and three-phase conversion, and the inverter corresponding to the control signal after the two-phase and three-phase conversion. It includes an inverter voltage command value calculation function p that calculates a voltage command value and outputs it to the inverter control unit 3B.

The speed governor control unit 115 is operated from the active power control unit 112 based on the frequency calculated by the frequency calculation function a of the inverter voltage command value calculation unit 114 during normal operation and the guide vane opening feedback signal from the servomotor 108. This is a function of controlling the servomotor 108 through the governor 107 to control the opening degree of the guide vane G according to the signal (control target value of active power and control target value of opening degree of the guide vane G).

The converter voltage command value calculation unit 116 is detected through the invalid power calculated by the calculation unit A2, the DC voltage signal from the DC voltage detection function 2C, and the current transformer CT installed downstream of the exciting transformer 105. It is a function to control the invalid power and the DC voltage of the converter 2A by calculating the converter voltage command value based on the current and sending it to the converter control unit 3A.

The power conversion control unit 3 includes a converter control unit 3A and an inverter control unit 3B. The converter control unit 3A is a function of controlling the converter 2A of the power converter 2 according to the converter voltage command value output from the converter voltage command value calculation unit 116. The inverter control unit 3B is a function of controlling the inverter 2B according to the inverter voltage command value output from the inverter voltage command value calculation unit 114 during normal operation.

The generator motor primary current AC control calculation unit 120 includes a short-circuit detection function (electrical failure detection means) 4, a DC component measurement function 6, a DC command value generation function 7, and a switching function 8B.

The short circuit detection function (electrical failure detecting means) 4 measures the electric quantities (for example, current or voltage) on the primary side of the electric circuit or the power generation electric motor 1 connected to the power system S, and measures the power system S and / or Detects an electrical failure in the electrical circuit.

The DC component measuring function 6 measures the DC component or the low frequency component (the slip frequency component of the power generation motor 1 or the frequency component close to the slip frequency) of the secondary current measured by the current transformer CT5A.

The DC command value generation function 7 generates a DC energization command or a low frequency energization command signal to the power conversion control unit 3 according to the DC component or the low frequency component measured by the DC component measurement function 6.

The switching function 8B outputs or stops the signal of the DC command value generation function 7. The switching function 8B generates a DC command value when a predetermined condition is satisfied, for example, when the short circuit detection function (electrical failure detecting means) 4 detects a failure such as a short circuit of the electric circuit on the primary side of the generator motor 1. The signal of the function 7 is output to the power conversion control unit 3.

Here, an example of the circuit configuration of the DC component measuring function 6 is shown in FIG. The DC component measuring function 6 shown in FIG. 2 has a moving average calculation unit 6A and a moving average calculation unit 6A that repeat a process of calculating a moving average of each phase of the secondary current measured by the current transformer CT5A for a certain period. It is provided with a polarity discriminating unit 6B that includes the polarity information in the moving average information of each phase calculated by the above method and outputs the information.

The circuit configuration of the DC command value generation function 7 is not limited to the example of FIG. For example, instead of the moving average calculation unit 6A and the polarity determination unit 6B, a low-pass filter that passes only the DC component or the low frequency component of the secondary current measured by the current transformer CT5A may be adopted.

(Action)
For example, when a short-circuit failure or a ground fault occurs in the power system, the primary voltage of the power generation motor 1 drops, an overcurrent flows, and the primary and secondary transient DC components of the main transformer 102 and the power generation motor 1 are superimposed. do.

The system failure detection function DT detects a system failure and issues an open command to the circuit breaker 103. The short-circuit detection function 4 detects a decrease in the primary voltage of the generator motor and outputs an input command to the switching function 8B. The DC component measurement function 6 measures the DC component included in the secondary current of the generator motor, and outputs the DC component measurement value to the DC command value generation function 7. The DC command value generation function 7 calculates an inverter control command for each phase suitable for converting the secondary current of the generator motor to DC according to the DC component measurement value, and outputs the inverter control command to the inverter control unit 3. The inverter 2B turns on and off the switching element of each phase in response to a command from the inverter control unit 3, and causes a direct current or a low frequency current to flow through the secondary winding of the generator motor.

(effect)
According to this embodiment, the DC component included in the power generation motor secondary current is measured, the inverter voltage control command value is calculated according to the DC component measurement value, and the DC or low frequency current of the power generation motor secondary winding is calculated. Therefore, the primary current and the secondary current of the main transformer and the generator motor 1 can be quickly crossed to zero, and zero mistakes can be prevented.

<Second embodiment>
Next, the second embodiment will be described.
(Constitution)
FIG. 3 is a diagram showing an example of the configuration of the power generation system according to the second embodiment. The elements common to the first embodiment (FIG. 1) are designated by the same reference numerals, and duplicate description will be omitted. Hereinafter, the parts different from the first embodiment will be mainly described.

The second embodiment is different from the first embodiment in that a short circuit 9 and a current transformer CT5B are provided in each phase of the electric circuit on the secondary side, and further, the power generation motor primary current AC control calculation unit 120 is provided. Instead, a power generation motor primary current AC control calculation unit 120'is provided. The generator motor primary current AC control calculation unit 120'is provided with a short circuit operation / recovery determination function 10 instead of the short circuit detection function (electrical failure detection means) 4 described above. Further, the inverter voltage command value calculation unit 114 during normal operation is further provided with switching functions 8C and 8D.

The short-circuiter 9 has a function of short-circuiting the phases of the electric circuit (three-phase AC circuit) on the secondary side when an overvoltage occurs on the secondary side of the generator motor 1.

The short-circuiting device operation / recovery determination function 10 indicates that the short-circuiting device 9 is operating (short-circuited and current is flowing through the short-circuiting device 9) or that the short-circuiting device 9 has returned (electrically opened and the short-circuiting device 9). It is a function to detect that no current is flowing through the circuit.

The switching function 8B outputs the signal of the DC command value generation function 7 to the power conversion control unit 3 when the short-circuit operation / return determination function 10 detects the short-circuit operation of the short-circuit device 9 and then detects the return.

(Action)
For example, when a short-circuit failure or a ground fault occurs in the power system, the primary voltage of the power generation motor 1 drops, an overcurrent flows, and the primary and secondary transient DC components of the main transformer and the power generation motor 1 are superimposed. .. Further, an overvoltage is generated on the secondary side of the generator motor due to the transient phenomenon and the transient DC component on the primary side of the generator motor.

The system failure detection function DT detects a system failure and issues an open command to the circuit breaker 103. When an overvoltage is generated on the secondary side of the generator motor, the short-circuiter 9 short-circuits the electric circuit on the secondary side to protect the generator motor 1 and the power converter 2 from the overvoltage. While the short-circuit device 9 is in operation, the secondary current of the generator motor flows through the short-circuit device 9, so that the secondary current of the generator motor cannot be controlled. Therefore, after the short-circuiter 9 operates, the inverter control unit 3B shifts the current of the short-circuiter 9 to the inverter 2B according to the control command value of the inverter voltage command value calculation unit 114 during normal operation, and transfers the current of the short-circuiter 9 to the inverter 2. It is squeezed to zero and the short circuiter 9 is restored. When the short-circuiter 9 is restored, the inverter 2B can control the secondary current of the generator motor.

The short-circuit device operation / recovery determination function 10 inputs a DC voltage signal from the DC voltage detection function 2C and determines the operation of the short-circuit device 9. Further, the current from the current transformer CT5B is measured, and the return of the short circuit device 9 is determined. Before the short-circuit device operates and during the short-circuit device operation, the switching function 8A is "on" and the switching function 8B is "off", and the slip frequency control signal side of the switching function 8C is "on" and the reset control signal side is. It is in the "off" state and the switching function 8D is in the "on" state. When the short-circuit device operation / return determination function 10 determines that the short-circuit device has returned after operating, it issues a switching command to the switching function 8A and the switching function 8B, turns the switching function 8A "off", and switches the switching function 8B "on". The reset control signal side of the switching function 8C is set to "ON", the slip frequency control signal side is set to "Off", and the switching function 8D is set to "Off".

The DC component measurement function 6 measures the DC component included in the secondary current of the generator motor, and outputs the DC component measurement value to the DC command value generation function 7. The DC command value generation function 7 calculates an inverter control command suitable for converting the secondary current of the generator motor to DC according to the DC component measurement value, and outputs the inverter control command to the inverter control unit 3. The inverter 2B turns on and off the switching element of each phase according to the command value from the inverter control unit 3, and causes a direct current or a low frequency current to flow through the secondary winding of the generator motor.

(effect)
According to the present embodiment, the DC component included in the secondary current of the power generation motor is measured, and the inverter control command is calculated immediately after the short circuit controller 9 is restored according to the measured value of the DC component, and the secondary winding of the power generation motor is performed. Since the direct current or low frequency current of the line is controlled, the primary current and the secondary current of the main transformer and the generator motor 1 can be quickly crossed to zero, and zero mistakes can be prevented.

As described in detail above, according to each embodiment, it is possible to quickly zero-cross the primary current of the dual power supply AC machine.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

In the above example, an example in which the detected amount, the measured amount, and the controlled amount are current or voltage has been described, but electrical quantities such as voltage and magnetic flux may be used instead of current, and current instead of voltage. Various electrical quantities such as magnetic flux may be used.

1 ... Double power supply AC machine, 2 ... Power converter, 2A ... Converter, 2B ... Inverter, 3 ... Power conversion control unit, 2C ... DC voltage detection function, 3A ... Converter control unit, 3B ... Inverter control unit, 4 ... Parallel breaker, 8A, 8B, 8C, 8D ... Switching function, 101 ... Pump water wheel, 102 ... Main transformer, 103 ... System side breaker, 105 ... Excitation transformer, 106 ... Excitation breaker, 107 ... Speed controller, 108 ... Servo motor, 111 ... Invalid power control unit, 112 ... Active power control unit, 113 ... Power generator voltage control unit, 114 ... Inverter voltage command value calculation unit during normal operation, 115 ... Speed controller control unit , 116 ... Converter voltage command value calculation unit, 120, 120'... Generation motor primary current AC control calculation unit, KA ... Angle detector, PT ... Instrument transformer, CT, CT5A, CT5B ... Transformer, DT ... System failure detection function, G ... Guide vane.

Claims (6)

A double power supply AC machine in which the primary winding is connected to an electric circuit via an opening / closing means, a power conversion means for supplying a variable frequency current to the secondary winding of the double power supply AC machine, and the power conversion means. It is a control device of a double power supply AC machine applied to a power generation system having a power conversion control means for controlling the voltage or current of the electric current.
A secondary current measuring means for measuring the secondary current on the secondary side of the dual power supply alternator, and
The secondary current measured by the secondary current measuring means when an overcurrent flows through the primary side of the double power supply AC and a transient DC component is superimposed on the primary side and the secondary side of the double power supply AC. A DC component measuring means for measuring a DC component or a low frequency component superimposed on the
A DC command value generating means that generates a DC energization command or a low frequency energization command signal to the power conversion control means according to the DC component or the low frequency component measured by the DC component measuring means.
It is provided with a switching means for outputting or stopping a signal of a DC energization command or a low frequency energization command generated by the DC command value generating means.
The switching means outputs a DC energization command or low frequency energization command signal generated by the DC command value generating means when the DC component measuring means measures a DC component or a low frequency component superimposed on the secondary current. , When a failure of the electric circuit on the primary side of the double power supply AC machine is detected, or after a short circuit operation of the short circuit that short-circuits each phase of the electric circuit on the secondary side of the double power supply AC machine, recovery is detected. When it is done, it is output to the power conversion control means.
The power conversion control means outputs a command corresponding to the output DC energization command or low frequency energization command signal to the power conversion means, and the power conversion means responds to a command from the power conversion control means. A control device for a double-powered AC machine, characterized in that a direct current or a low-frequency current is passed through the secondary winding of the double-powered AC machine. A short-circuiting means for short-circuiting each phase of the electric circuit on the secondary side when an overvoltage occurs on the secondary side of the dual power supply AC device.
Further provided with a short-circuit operation / recovery determination means for detecting that the short-circuit means has been operated or restored.
The switching means outputs a DC energization command or low frequency energization command signal generated by the DC command value generating means when the short-circuit operation / return determination means detects a short-circuit operation of the short-circuit means and then detects a return. The control device for a dual power supply AC device according to claim 1, wherein the power is output to the power conversion control means. The DC component measuring means is characterized by comprising a moving average calculation means that repeats a process of calculating a moving average of each phase of the secondary current measured by the secondary current measuring means for a certain period of time. 2. The control device for the dual power supply AC device according to 2. The double according to claim 3, wherein the DC component measuring means includes a polarity discriminating means for outputting the moving average information of each phase calculated by the moving average calculating means including the polarity information. Control device for power supply AC. 2. The second aspect of claim 1 or 2, wherein the DC component measuring means includes a low-pass filter that allows only the DC component or the low frequency component of the secondary current measured by the secondary current measuring means to pass through. Control device for heavy-duty alternator. A double power supply AC machine in which the primary winding is connected to an electric circuit via an opening / closing means, a power conversion means for supplying a variable frequency current to the secondary winding of the double power supply AC machine, and the power conversion means. It is a control method of a double power supply AC machine applied to a power generation system having a power conversion control means for controlling the voltage or current of the power supply.
The secondary current on the secondary side of the dual power supply AC machine is measured by the secondary current measuring means.
When an overcurrent flows to the primary side of the double power supply AC by the DC component measuring means and the transient DC component is superimposed on the primary side and the secondary side of the double power supply AC, the secondary current measuring means Measure the DC component or low frequency component superimposed on the measured secondary current,
The DC command value generating means generates a DC energization command or a low frequency energization command signal to the power conversion control means according to the DC component or the low frequency component measured by the DC component measuring means.
When the DC component measuring means measures the DC component or the low frequency component superimposed on the secondary current by the switching means, the DC command value generating means generates a DC energization command or a low frequency energization command signal. When a failure of the electric circuit on the primary side of the double power supply AC machine is detected, or after a short circuit operation of the short circuit that short-circuits each phase of the electric circuit on the secondary side of the double power supply AC machine, recovery is detected. At that time, it is output to the power conversion control means.
The power conversion control means outputs a command corresponding to the output DC energization command or low frequency energization command signal to the power conversion means, and the power conversion means responds to a command from the power conversion control means. Direct current or low frequency current is passed through the secondary winding of the dual power supply AC machine.
A control method for a dual power supply AC machine, which is characterized by this.

Images