JP2018050446A - Device and method for controlling doubly-fed alternator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the prompt zero cross of a primary current in a doubly-fed alternator.SOLUTION: A control device in the doubly-fed alternator includes: secondary current measurement means CT5A which measures a secondary side current of a doubly-fed alternator 1; DC component measurement means 6 which measures the DC component or the low-frequency component of the secondary current measured by the secondary current measurement means CT5A; DC command value generation means 7 which generates a DC conduction command or a low frequency conduction command to power conversion control means 3, according to the DC component or the low frequency component measured by the DC component measurement means 6; and switchover means 8 which outputs or suspends the signal of the DC command value generation means 7. When a predetermined condition is satisfied, the switchover means 8 outputs the signal of the DC command value generation means 7 to the power conversion control means 3.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a control device and a control method for a double-feed AC machine.

  In a double-feed 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), the power system or electrical circuit can When a failure occurs, a transient phenomenon such as a voltage drop on the primary side of the double-feed AC machine, a DC component superposition, an overcurrent, etc. occurs, and an overvoltage occurs on the secondary side. At this time, on the primary side of the double-feed AC machine, a phenomenon called zero miss where the primary current does not cross zero when the circuit breaker is opened may occur due to superposition of the DC component. Several techniques for solving the zero-miss problem have been proposed.

Japanese Patent No. 2816020

  If a zero error occurs, the circuit breaker cannot cut off the current, the circuit breaker will be damaged, electrical faults will not be removed, power system operation will not be continued, main transformers and double There is a possibility of damage to the feeding AC machine. Therefore, it is required to quickly zero-cross the primary current of the double-feed AC machine so that no zero error occurs.

  Several techniques have been proposed to solve the zero-miss problem, but no effective method for quickly zero-crossing the primary current of a double-fed AC machine after an electrical 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-feed AC machine that allows a primary current of a double-feed AC machine to be zero-crossed quickly. To do.

  According to the embodiment, the double-feed AC machine in which the primary winding is connected to the electric circuit through the switching means, and the power conversion means for supplying a variable frequency current to the secondary winding of the double-feed AC machine And a power conversion control means for controlling the voltage or current of the power conversion means, and a control device for a double-feed AC machine applied to a power generation system. The control device for the double-feed AC machine includes a secondary current measurement unit that measures a current on the secondary side of the double-feed AC machine, and a DC component or a low component of the secondary current measured by the secondary current measurement unit. DC component measuring means for measuring a frequency component, and a DC command 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 Value generating means and switching means for outputting or stopping the signal of the DC command value generating means, and the switching means converts the signal of the DC command value generating means to the power conversion control when a predetermined condition is satisfied. Output to the means.

  According to the present invention, it is possible to quickly zero-cross the primary current of a double-feed AC machine.

The figure which shows an example of a structure of the electric 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 a structure of the electric 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 illustrating an example of a configuration of a power generation system according to the first embodiment.

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

  The power generation system has, as basic components, for example, a double-feed AC machine 1 (hereinafter referred to as “generator motor 1”) that is a generator motor connected to the pump turbine 101, an electric power having a converter 2A and an inverter 2B. Converter 2, Main transformer 102, System side circuit breaker 103, Parallel circuit breaker 104, Excitation transformer 105, Excitation circuit breaker 106, Speed governor 107, Servo motor 108, Angle detector KA, Instrument transformation Equipment such as a transformer VT, current transformers CT, CT5A, and a system failure detection function DT.

  In addition, the power generation system includes a power conversion control unit 3 having a converter control unit 3A and an inverter control unit 3B, a reactive power control unit 111, an active power control unit 112, a generator motor voltage control unit 113, and a normal operation inverter voltage command value calculation. Unit 114, governor control unit 115, converter voltage command value calculation unit 116, generator motor primary current AC conversion control calculation unit 120, calculation units A 1 and A 2, and the like.

  The arithmetic unit A1 is configured to detect the voltage detected through the instrument transformer VT installed in the electric circuit between the primary transformer 102 on the primary side of the generator motor 1 and the parallel circuit breaker 104, and the primary side of the generator motor 1. This is a function of calculating active power and reactive 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 is configured to detect the voltage detected through the instrument transformer VT installed in the electric circuit between the primary transformer 102 on the primary side of the generator motor 1 and the parallel circuit breaker 104, and the excitation circuit breaker 106. This function calculates active power and reactive power based on current detected through a current transformer CT installed downstream.

  The reactive power control unit 111 calculates a control target value of 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 includes an active power calculated by the calculation unit A1, an active power command value input from the input unit T2, a drop measurement value input from the input unit T3, and guide vane opening from the servo motor 108. This is a function for calculating each control target value of active power, rotational speed, and opening degree of the guide vane G based on the degree feedback signal.

  The generator motor voltage control unit 113 controls the reactive 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 generator motor 1 and the generator motor 1. This function calculates and outputs the control target value of the generator motor voltage in accordance with the reactive power control target value 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 converts the voltage detected through the instrument transformer VT installed in the electric circuit between the primary transformer 102 on the primary side of the generator motor 1 and the parallel circuit breaker 104. Based on the calculated frequency and output, the control target value of the rotational speed calculated by the active power control unit 112, the angle signal of the generator motor 1 output from the angle detector KA, and the secondary side of the generator motor 1 In accordance with the control target value of the generator motor voltage from the generator motor voltage control unit 113 based on the current detected by the current transformer CT5A installed in the electric circuit of the secondary of the generator motor 1 through the inverter control unit 3B and the inverter 2B This function controls the current and controls the voltage, active power, and rotational speed of the generator motor 1.

  The inverter voltage command value calculation unit 114 during normal operation is based on the voltage detected through the instrument transformer VT installed in the electric circuit between the primary transformer 102 on the primary side of the generator motor 1 and the parallel circuit breaker 104. A frequency calculation function a that calculates a frequency and outputs a calculation result to the governor control unit 115, an angle signal input function b that inputs an angle signal of the generator motor 1 output from the angle detector KA, and the angle signal An angular velocity calculation function c for calculating the angular velocity from the calculation function d, a calculation function d for calculating and outputting the difference between the control signal from the active power control unit 112 (the target value of the rotation speed / guide vane opening) and the angular velocity, and the difference Reset based on a current detected by a slip frequency control function e for generating a slip frequency control signal corresponding to the current and a current transformer CT5A installed in an electric circuit on the secondary side of the generator motor 1 A reset control function f for generating a control signal (but not used in the present embodiment), a three-phase two-phase conversion function g for performing three-phase to two-phase conversion of the current detected by the current transformer CT5A, and a slip frequency A calculation function h for calculating and outputting the difference between the control signal or the reset control signal and the signal after the three-phase to two-phase conversion, a control signal from the generator motor voltage control unit 113 (control target value of the generator motor voltage) and three An arithmetic function j that calculates and outputs a difference from the signal after the phase-to-two-phase conversion, a control function k that outputs a control signal according to the arithmetic result of the arithmetic function h, and a control according to the arithmetic result of the arithmetic function j A control function m that outputs a signal, a two-phase three-phase conversion function n that performs a two-phase three-phase conversion by inputting a control signal from the control function k and a control signal from the control function m, and after the two-phase three-phase conversion The inverter voltage command value according to the control signal Calculated to an inverter voltage command value computing function p to be output to inverter control unit 3B.

  The speed governor control unit 115 is controlled by 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 servo motor 108. The servo motor 108 is controlled through the speed governor 107 in accordance with the above signals (control target value of active power and control target value of the opening degree of the guide vane G), and the opening degree of the guide vane G is controlled.

  The converter voltage command value calculation unit 116 is detected through the reactive 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 excitation transformer 105. This function controls the reactive power and 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. Converter control unit 3A has a function of controlling converter 2A of power converter 2 in accordance with the converter voltage command value output from converter voltage command value calculation unit 116. The inverter control unit 3B has 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 detection means) 4 measures electrical quantities (for example, current or voltage) on the primary side of the electric circuit or generator motor 1 connected to the electric power system S, and the electric power system S and / or An electrical failure of the electrical circuit is detected.

  The DC component measuring function 6 measures a DC component or a low frequency component (slip frequency component of the generator motor 1 or a 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 low frequency energization command signal to the power conversion control unit 3 according to the DC component or 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. This switching function 8B generates a DC command value when a predetermined condition is satisfied, for example, when the short circuit detection function (electrical failure detection means) 4 detects a failure such as a short circuit in the primary side of the generator motor 1. The function 7 signal is output to the power conversion control unit 3.

  Here, an example of a circuit configuration of the DC component measuring function 6 is shown in FIG. The DC component measurement function 6 shown in FIG. 2 includes a moving average calculation unit 6A that repeats a process for calculating a moving average of each phase of the secondary current measured by the current transformer CT5A, and a moving average calculation unit 6A. And a polarity discriminating unit 6B that outputs the information of the moving average of each phase including the polarity information.

  Note that 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 only the low-frequency component of the secondary current measured by the current transformer CT5A may be employed.

(Function)
For example, when a short circuit fault or a ground fault occurs in the power system, the primary voltage of the generator motor 1 decreases, an overcurrent flows, and the primary and secondary primary DC components of the main transformer 102 and the generator motor 1 are superimposed. To 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 generator motor primary voltage drop and outputs an input command to the switching function 8B. The DC component measurement function 6 measures a DC component contained in the generator motor secondary current and outputs a 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 directing the generator motor secondary current according to the DC component measurement value, and outputs the inverter control command to the inverter control unit 3. Inverter 2B turns on and off each phase switching element in accordance with a command from 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 contained in the generator 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 generator 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 errors can be prevented.

<Second Embodiment>
Next, a second embodiment will be described.
(Constitution)
FIG. 3 is a diagram illustrating an example of a configuration of a power generation system according to the second embodiment. In addition, the same code | symbol is attached | subjected to the element which is common in 1st Embodiment (FIG. 1), and the overlapping description is abbreviate | omitted. Below, it demonstrates centering on a different part from 1st Embodiment.

  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 secondary-side electric circuit, and further, the generator motor primary current alternating current control operation unit 120 Instead, a generator motor primary current alternating current control calculation unit 120 ′ is provided. The generator motor primary current alternating current control calculation unit 120 ′ includes a short circuit operation / recovery determination function 10 instead of the short circuit detection function (electrical failure detection means) 4 described above. In addition, the inverter voltage command value calculation unit 114 during normal operation is further provided with switching functions 8C and 8D.

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

  The short-circuit operation / recovery determination function 10 indicates that the short-circuit 9 is operating (short-circuited and current is flowing through the short-circuit 9) or has been recovered (electrically opened, short-circuit 9 This is a function to detect that no current is flowing in.

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

(Function)
For example, when a short circuit fault or a ground fault occurs in the power system, the primary voltage of the generator motor 1 decreases, an overcurrent flows, and the primary and secondary DC components of the primary transformer and the generator motor 1 are superimposed. . Further, an overvoltage is generated on the secondary side of the generator motor due to a transient phenomenon and a 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 occurs on the secondary side of the generator motor, the short circuit 9 short-circuits the secondary electric circuit and protects the generator motor 1 and the power converter 2 from the overvoltage. While the short circuit 9 is in operation, the generator motor secondary current flows through the short circuit 9, so that the generator motor secondary current cannot be controlled. Therefore, after the short circuit 9 operates, the inverter control unit 3B shifts the current of the short circuit 9 to the inverter 2B in accordance with the control command value of the inverter voltage command value calculation unit 114 during normal operation, and the current of the short circuit 9 is changed. It is reduced to zero and the short circuit 9 is returned. When the short circuit 9 is restored, the inverter 2B can control the generator motor secondary current.

  The short circuit operation / recovery determination function 10 receives the DC voltage signal from the DC voltage detection function 2 </ b> C and determines the operation of the short circuit 9. Moreover, the electric current from current transformer CT5B is measured, and the return | restoration of the short circuit 9 is determined. Before the short-circuiting operation and during the short-circuiting 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 “Off”, and the switching function 8D is in the “On” state. When the short-circuit operation / recovery determination function 10 determines that the short-circuit has returned after the short-circuit has been operated, it issues a switching command to the switching function 8A and the switching function 8B. Further, 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 a DC component contained in the generator motor secondary current and outputs a 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 directing the generator motor secondary current according to the DC component measurement value, and outputs the inverter control command to the inverter control unit 3. Inverter 2B turns on / off switching elements of each phase in accordance with a command value from 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 secondary current of the generator motor is measured, and the inverter control command is calculated immediately after the short circuit 9 is restored in accordance with the DC component measurement value. 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 errors can be prevented.

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

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  In the above example, the detection amount, the measurement amount, and the control amount are described as examples of current or voltage, but electrical quantities such as voltage and magnetic flux may be used instead of current, or current, Various electrical quantities such as magnetic flux may be used.

  DESCRIPTION OF SYMBOLS 1 ... Double feeding AC machine, 2 ... Power converter, 2A ... Converter, 2B ... Inverter, 3 ... Power conversion control part, 2C ... DC voltage detection function, 3A ... Converter control part, 3B ... Inverter control part, 4 ... Parallel circuit breaker, 8A, 8B, 8C, 8D ... switching function, 101 ... pump turbine, 102 ... main transformer, 103 ... system side circuit breaker, 105 ... excitation transformer, 106 ... excitation circuit breaker, 107 ... Speed governor, 108 ... servo motor, 111 ... reactive power control unit, 112 ... active power control unit, 113 ... generator motor voltage control unit, 114 ... inverter voltage command value calculation unit during normal operation, 115 ... governor control unit 116, converter voltage command value calculation unit, 120, 120 '... generator motor primary current alternating current control calculation unit, KA ... angle detector, PT ... instrument transformer, CT, CT5A, CT5B ... current transformation , DT ... system fault detection function, G ... guide vanes.

Claims (6)

A double-feed AC machine in which a primary winding is connected to an electric circuit via an opening / closing means; a power conversion means for supplying a variable frequency current to a secondary winding of the double-feed AC machine; and the power conversion means A power conversion control means for controlling the voltage or current of the double-feed AC machine applied to the power generation system,
Secondary current measuring means for measuring the current on the secondary side of the double-feed AC machine;
DC component measuring means for measuring the DC component or low frequency component of the secondary current measured by the secondary current measuring means;
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 low frequency component measured by the DC component measurement means;
Switching means for outputting or stopping the signal of the DC command value generating means,
The switching device outputs a signal from the DC command value generating means to the power conversion control means when a predetermined condition is satisfied, and controls the double-feed AC machine. Short-circuit means for short-circuiting each phase of the secondary-side electric circuit when an overvoltage occurs on the secondary side of the double-feed AC machine,
A short-circuit operation / recovery determination means for detecting that the short-circuit means has been operated or returned,
The switching means outputs the signal of the DC command value generation means to the power conversion control means when the short-circuit operation / recovery determination means detects a return after detecting the short-circuit operation of the short-circuit means. The control device for a double-feed AC machine according to claim 1.   The DC component measuring unit includes a moving average calculating unit that repeats a process of calculating a moving average of each phase of the secondary current measured by the secondary current measuring unit over a certain period. The control apparatus of the double electric power feeding AC machine of 2.   4. The dual component according to claim 3, wherein the DC component measuring means includes polarity determining means for outputting the information of the moving average of each phase calculated by the moving average calculating means together with polarity information. Control device for feeding AC machine.   3. The DC component measuring unit includes a low-pass filter that allows only a DC component or only a low-frequency component of a secondary current measured by the secondary current measuring unit to pass therethrough. Control device for heavy power supply AC machine. A double-feed AC machine in which a primary winding is connected to an electric circuit via an opening / closing means; a power conversion means for supplying a variable frequency current to a secondary winding of the double-feed AC machine; and the power conversion means A power conversion control means for controlling the voltage or current of
By the secondary current measuring means, measure the current on the secondary side of the double-feed AC machine,
The direct current component measuring means measures the direct current component or low frequency component of the secondary current measured by the secondary current measuring means,
The DC command value generating means generates a DC energization command or low frequency energization command signal to the power conversion control means according to the DC component or low frequency component measured by the DC component measuring means,
A control method for a double-feed AC machine, characterized in that a signal from the DC command value generating means is output to the power conversion control means when a predetermined condition is established by the switching means.