KR102224966B1 - Apparatus controlling commutation failure of hvdc system - Google Patents

Abstract

The present invention is a voltage scalar synthesis unit that generates a synthesized voltage value by synthesizing the three-phase voltage scalar, a current scalar synthesis unit that generates a synthesized current value by scalar synthesis of the three-phase current, a synthesized voltage value and a synthesized current value A first multiplier for generating a power command value by multiplying by, a first voltage comparator for comparing a synthesized voltage value with a preset first synthesized voltage reference value, a first current comparator for comparing a synthesized current value with a preset first synthesized current reference value, The first command value comparator that compares the power command value with the preset first power command reference value, the first voltage comparator, the first current comparator, and the first command value comparator to determine a single-phase failure of the HVDC system according to the comparison result. And a current controller that converts the power command value into a current command value and outputs the current command value as a current reference value for controlling the rectification failure of the HVDC system when it is determined as a single-phase fault as a result of the determination of the determination unit and the first determination unit. It is done.

Description

Control device for rectification failure of HVDC system {APPARATUS CONTROLLING COMMUTATION FAILURE OF HVDC SYSTEM}

The present invention relates to an apparatus for controlling rectification failure of an HVDC system, and more particularly, rectification of an HVDC system that predicts rectification failure in single and three phases in advance based on AC voltage and controls rectification failure in advance based on the prediction result. It relates to a failure control device.

Current type HVDC (High Voltage Direct Current) system consists of a rectifier side that converts AC power into DC power and an inverter side that converts DC power back to AC power. Current type HVDC basically constitutes a rectification process, which is an AC-DC-AC conversion process based on the line voltage of the AC system.

HVDC control of such a current type HVDC system consists of a hierarchical structure, and the highest level has a bipole level controller that controls the power transmission between the conversion stations by integrating the rectifier side and the inverter side. There is a pole level controller, and at the bottom is a valve group level controller that directly controls the converter valve. The valve group level controller controls the conduction of the thyristor valve by generating the firing angle and the firing angle.

The abnormal operation that occurs most often in such HVDC inverter is a rectification failure. A commutation failure is a failure in which the converter valve to be turned off fails to transfer current to the next valve in the firing sequence and continues to conduct.

In order to control the rectification failure of the HVDC system, the maximum extinction angle command method was used in the related art.

The maximum extinguishing angle command method is to change the maximum extinguishing angle command from the steady state value (165°) to the transient state value (135°) for 2 cycles after detecting a rectification failure due to the difference between DC current and AC current. However, it does not prevent the occurrence of rectification failure, but a great effect can be obtained in preventing the rectification failure that occurs continuously.

However, the rectification failure reduction method such as the conventional maximum extinguishing angle command method detects rectification failure by comparing AC current and DC current, so robustness against rectification failure is guaranteed, but prevention of rectification failure is not possible. That is, since the conventional rectification failure reduction method corrects the minimum extinguishing angle of 45 degrees to the maximum extinguishing angle of 45 degrees after the rectification failure occurs, there is a problem that it is not possible to prevent rectification failure caused by a voltage drop due to a distant failure.

The background technology of the present invention is disclosed in Korean Patent Application Publication No. 10-2014-0036797 (2014.03.26).

The present invention was invented to solve the above-described problem, and an object of the present invention is to predict the rectification failure in single and three phases based on the AC voltage and to control the rectification failure in advance based on the prediction result. It is to provide a control device.

Another object of the present invention is to provide an apparatus for controlling rectification failure of an HVDC system, which has a fast failure recovery rate and prevents additional rectification failure even if a failure occurs in the HVDC system.

An apparatus for controlling rectification failure of an HVDC system according to an aspect of the present invention comprises: a voltage scalar synthesizer configured to generate a synthesized voltage value by synthesizing a three-phase voltage scalar; A current scalar synthesis unit that generates a synthesized current value by synthesizing the three-phase current in a scalar manner; A first multiplier for generating a power command value by multiplying the synthesized voltage value and the synthesized current value; A first voltage comparator for comparing the synthesized voltage value and a preset first synthesized voltage reference value; A first current comparator for comparing the synthesized current value with a preset first synthesized current reference value; A first command value comparator for comparing the power command value with a preset first power command reference value; A first determination unit for determining a single-phase failure of the HVDC system according to a comparison result of the first voltage comparator, the first current comparator, and the first command value comparator; And a current controller converting the power command value into a current command value and outputting the current command value as a current reference value for controlling rectification failure of the HVDC system when it is determined as a single-phase failure as a result of the determination by the first determination unit. It is characterized by that.

In the present invention, the first determination unit, if the synthesized voltage value is equal to or greater than the first synthesized voltage reference value, the synthesized current value is equal to or greater than the first synthesized current reference value, and the power command value is greater than or equal to the first power command reference value It is characterized in that it is determined as a single phase failure.

In the present invention, the current controller includes a PCD (Power Command Drive) for converting the power command value into the current command value; And a selector for selecting the current command value as the current reference value.

In the present invention, the current controller further comprises a power controller that generates a current command value based on the power of the HVDC system, and a voltage dependent current order limit (VDCOL) module that detects a current command value set to the voltage of the HVDC system. Including, wherein the selection unit is characterized in that for selecting a minimum value of the current command values input from each of the PCD, the power controller, and the VDCOL module as the current reference value.

An apparatus for controlling rectification failure of an HVDC system according to an aspect of the present invention comprises: a voltage vector synthesis unit for generating a synthesized voltage value by vector synthesizing a three-phase voltage; A current vector synthesis unit for generating a synthesized current value by vector synthesizing the three-phase current; A second multiplier for generating a power command value based on the synthesized voltage value and the synthesized current value; A second voltage comparator for comparing the synthesized voltage value and a preset second synthesized voltage reference value; A second current comparator for comparing the synthesized current value and a preset second synthesized current reference value; A second command value comparator for comparing the power command value with a preset second power command reference value; A second determination unit for determining a three-phase fault of the HVDC system according to a comparison result of the second voltage comparator, the second current comparator, and the second command value comparator; And a current controller converting the power command value into a current command value and outputting the current command value as a current reference value for controlling rectification failure of the HVDC system when it is determined as a 3-phase failure as a result of the determination by the second determination unit. Characterized in that.

In the present invention, the second determination unit is characterized in that when the combined voltage value is greater than or equal to the combined voltage reference value, the combined current value is greater than or equal to the combined current reference value, and the power command value is greater than or equal to the sum reference value, it determines as a single-phase failure. It is done.

In the present invention, the current controller includes a PCD (Power Command Drive) for converting the power command value into the current command value; And a selector for selecting the current command value as the current reference value.

In the present invention, the current controller further comprises a power controller that generates a current command value based on the power of the HVDC system, and a voltage dependent current order limit (VDCOL) module that detects a current command value set to the voltage of the HVDC system. Including, wherein the selection unit is characterized in that for selecting a minimum value of the current command values input from each of the PCD, the power controller, and the VDCOL module as the current reference value.

The present invention predicts rectification failure in single-phase and three-phase based on the AC voltage, and controls the rectification failure in advance based on the prediction result.

According to the present invention, even if a failure occurs in an HVDC system, a failure recovery speed is fast and additional rectification failure can be prevented.

1 is a block diagram of an apparatus for controlling rectification failure of an HVDC system for single-phase failure according to an embodiment of the present invention.
2 is a block diagram of an apparatus for controlling rectification failure of an HVDC system for a three-phase failure according to an embodiment of the present invention.
3 is a block diagram of a current controller using a PCD according to an embodiment of the present invention.

Hereinafter, an apparatus for controlling rectification failure of an HVDC system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thickness of the lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of users or operators. Therefore, definitions of these terms should be made based on the contents throughout the present specification.

In general, AC system failures that cause rectification failure in HVDC (High Voltage Direct Current) systems are classified into single-phase failures and three-phase failures.

Accordingly, the apparatus for controlling rectification failure of the HVDC system according to an embodiment of the present invention is an embodiment for reducing the rectification failure of the HVDC system by determining a single-phase failure, and for reducing the rectification failure of the HVDC system by determining a three-phase failure. Each will be described with examples.

In particular, the apparatus for controlling rectification failure of the HVDC system according to an embodiment of the present invention synthesizes the three-phase voltage and the three-phase current in a scalar manner, respectively, in order to determine a single-phase failure, and the synthesized voltage and current are respectively synthesized as described above. After multiplying to generate a power command value, the power command value is converted into a current command value to finally output a current reference value for reducing rectification failure of the HVDC system.

In addition, the device for controlling rectification failure of the HVDC system according to an embodiment of the present invention synthesizes a three-phase voltage and a three-phase current in a vector manner to determine a three-phase fault, and combines the synthesized voltage and current, respectively, as described above. After multiplying to generate a power command value, the power command value is converted into a current command value to detect a current reference value for reducing rectification failure of the HVDC system.

Hereinafter, an apparatus for reducing rectification failure of an HVDC system according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3.

1 is a block diagram of an apparatus for controlling rectification failure of an HVDC system for a single-phase failure according to an embodiment of the present invention, and FIG. 2 is a block diagram of a rectification failure control of an HVDC system for a three-phase failure according to an embodiment of the present invention. It is a block diagram of the device, and FIG. 3 is a block diagram of a current controller using a PCD according to an embodiment of the present invention.

Referring to FIG. 1, the apparatus for controlling rectification failure of the HVDC system for single-phase failure according to an embodiment of the present invention includes a voltage scalar synthesis unit 110, a current scalar synthesis unit 120, a first multiplier 130, and 1 A voltage comparator 140, a first current comparator 150, a first command value comparator 160, a first discrimination unit 170, and a current controller 10 (shown in FIG. 3) are included.

First, the voltage scalar synthesis unit 110 _{generates an absolute value by synthesizing the three-phase voltage (u a} (t), u _b (t), u _c (t)) in a scalar manner, and the resulting synthesized voltage The value u _O is input to the first voltage comparator 140 and the first multiplier 130, respectively.

The first voltage comparator 140 compares the synthesized voltage value (u ₀ ) input from the voltage scalar synthesis unit 110 with a preset first synthesized voltage reference value (K _U0 u _M0 ), and compares the result of the comparison (1 or 0). ) To the first determination unit 170.

Here, the first combined voltage reference value K _UO u _MO is a voltage reference value set in advance to predict a single-phase failure of the HVDC system.

The current scalar synthesis unit 120 _{generates an absolute value by synthesizing the three-phase current (i an} (t), i _bn (t), i _cn (t)) in a scalar manner, and the resulting synthesized current value ( i _on ) is input to each of the first current comparator 150 and the first multiplier 130.

The first current comparator 150 compares the synthesized current value (i _on ) input from the current scalar synthesis unit 120 with a preset first synthesized current reference value (K _IO i _MOn ), and compares the result (1 or 0). ) To the first determination unit 170.

Here, the first _{combined current reference value K IO} i MOn is a current reference value set in advance to predict a single phase failure of the HVDC system.

The first multiplier 130 multiplies the synthesized voltage value u _{O input from the voltage scalar synthesizer 110 and the synthesized current value i on} input from the current scalar synthesizer 120 to obtain a power command value ( P _on ) is generated, and the generated power command value P _on is input to the first command value comparator 160. Here, the power command value P _on generated by the first multiplier 130 is input to the PCD (Power Command Drive) 11 of the current controller 10.

The first command value comparator 160 compares the power command value (P _on ) input from the first multiplier 130 with a preset first power command reference value (K _po P _NOn ), and compares the comparison result (1 or 0). ) Is input to the first determination unit 170.

Here, the first power command reference value K _po P _NOn is a power reference value set in advance to predict a single-phase failure of the HVDC system.

The first determination unit 170 determines a single-phase failure according to the comparison result of the first voltage comparator 140, the first current comparator 150, and the first command value comparator 160.

The first determination unit 170 has a synthesized voltage value (u _o ) equal to or greater than a first synthesized voltage reference value (K _U0 u _M0 ), and a synthesized current value (i _on ) is a first synthesized current reference value (K _IO i _MOn ) If it is abnormal and the power command value (P _on ) is more than the first power command reference value (K _po P _NOn ), it is determined as a single-phase fault. That is, the synthesized voltage value (u _o ) obtained by scalar synthesis of the three-phase voltage (u _a (t), u _b (t), u _c (t)) and the three-phase current (i _an (t), i The power command value (P _on ) generated by multiplying the synthesized current value (i _on ) and the synthesized voltage value (u _o ) and the synthesized current value (i _{on ) by scalar synthesis of bn} (t),i _{cn (t))} If) is more than each reference value, it can be considered that a single-phase failure has occurred due to excessive increase in the voltage or current value of the single phase among the three phases.

On the other hand, the first discrimination unit 170 is the synthesized voltage value (u _o ) is less than the first synthesized voltage reference value (K _UO u _MO ), or the synthesized current value (i _on ) is the first synthesized current reference value (K _IO i _MOn ) or if the power command value (P _on ) is less than the first power command reference value (K _po P _NOn ), it is determined that a single-phase failure has not occurred.

Here, in case of a single-phase failure, the current controller 10 receives the power command value P _on from the first multiplier 130 according to the determination result of the first determination unit 170, and calculates the power command value P _on It outputs the _{current reference value (I dcref} ) to control the rectification failure of the HVDC system. This will be described later with reference to FIG. 3.

2, a block diagram of an apparatus for controlling rectification failure of an HVDC system for a three-phase failure according to an embodiment of the present invention is shown.

Voltage vector synthesizer 210, current vector synthesizer 220, second multiplier 230, second voltage comparator 240, second current comparator 250, second command according to an embodiment of the present invention A value comparator 260, a second determination unit 270, and a current controller 10 (shown in FIG. 3) are included.

First, the voltage vector synthesis unit 210 converts the three-phase voltage (u _a (t), u _b (t), u _c (t)) into Park's Equation and then synthesizes it into a vector and generates an absolute value, The resulting synthesized voltage value u _nth is input to the second voltage comparator 240 and the second multiplier 230, respectively.

The second voltage comparator 240 compares the synthesized voltage value (u _nth ) input from the voltage vector synthesizer 210 with a preset second synthesized voltage reference value (K _Uth u _Nth ), and compares the result (1 or 0). ) Is input to the second determination unit 270.

Here, the second _combined voltage reference value K Uth u _Nth is a voltage reference value set in advance to predict a three-phase failure of the HVDC system.

The current vector synthesis unit 220 converts the three-phase current (i _an (t), i _bn (t), i _cn (t)) into Park's Equation, then synthesizes it in a vector, and generates an absolute value. The generated synthesized current value i _thn is input to the second current comparator 250 and the second multiplier 230, respectively.

The second current comparator 250 compares the synthesized current value (i _thn ) input from the current vector synthesizer 220 with a preset second synthesized current reference value (K _Ith i _Nthn ), and compares the result (1 or 0). ) To the second determination unit 270.

Here, the second _{combined current reference value K Ith} i Nthn is a current reference value set in advance to predict a three-phase failure of the HVDC system.

The second multiplier 230 multiplies the synthesized voltage value (u _{nth ) input from the voltage vector synthesis unit 210 and the synthesized current value (i thn} ) input from the current vector synthesis unit 220 to obtain a power command value ( ΔP _nth ) is generated, and the generated power command value ΔP _nth is input to the second command value comparator 260. Here, the power command value ΔP _nth generated by the second multiplier 230 is input to the PCD 11 of the current controller 10.

The second command value comparator 260 compares the power command value (ΔP _nth ) input from the second multiplier 230 with a preset second power command reference value (K _pth ΔP _Nth ), and the comparison result (1 or 0). ) Is input to the second determination unit 270.

Here, the second power command reference value K _pth ΔP _Nth is a power reference value set in advance to predict a three-phase failure of the HVDC system.

The second determination unit 270 determines a three-phase fault according to the comparison result of the second voltage comparator 240, the second current comparator 250, and the second command value comparator 260.

The second determination unit 270 has a synthesized voltage value u _nth equal to or greater than a second synthesized voltage reference value K _Uth u _Nth , and a synthesized current value i _thn is a second synthesized current reference value K _Ith i _Nthn If this is the case, and the power command value (ΔP _nth ) is equal to or greater than the second power command reference value (K _pth ΔP _Nth ), it is determined as a three-phase fault. In other words, the three-phase voltage (u _a (t), u _b (t), u _c (t)) is synthesized in a vector manner and the synthesized voltage value (u _nth ) and the three-phase current (i _an (t), i The power command value (ΔP _nth ) generated by multiplying the synthesized current value (i _thn ) and the synthesized voltage value (u _nth ) and the synthesized current value (i _{thn ) obtained by vector synthesis of bn} (t),i _{cn (t))} If) is greater than or equal to each of the reference values, it can be determined that a three-phase fault has occurred because the voltage value or current value of the entire three phases has risen excessively and the vector synthesis value has been excessively increased.

On the other hand, the second discrimination unit 270 has a synthesized voltage value u _nth less than a second synthesized voltage reference value K _Uth u _Nth , or a synthesized current value i _thn having a second synthesized current reference value K _Ith i _{If it} is less than Nthn) or the power command value (ΔP _nth ) is less than the second power command reference value (K _pth ΔP _Nth ), it is determined that a three-phase failure has not occurred.

Referring to FIG. 3, the current controller 10 receives one of the power command values (P _on or ΔP _nth ) according to a single-phase or three-phase failure, and uses the input power command values (P _on or ΔP _nth). And outputs the current reference value (I _dcref ).

That is, in case of a single-phase failure, the current controller 10 receives the power command value P _on from the first multiplier 130 according to the determination result of the first determination unit 170, and calculates the power command value P _on It outputs the _{current reference value (I dcref} ) to control the rectification failure of the HVDC system.

Alternatively, in the case of a three-phase failure, the current controller 10 receives the power command value (ΔP _nth ) from the second multiplier 230 according to the determination result of the second determination unit 270 and uses the power command value (ΔP _{nth ). Thus, the current reference value (I dcref} ) for controlling the rectification failure of the HVDC system is output.

To this end, the current controller 10 is a PCD (Power Command Drive) 11, a power controller 12, a voltage dependent current order limit (VDCOL) module 13 and a selection unit 14 as shown in FIG. Includes.

The PCD 11 converts the power command value P _on or ΔP _nth into a current command value I _ordl and inputs it to the selection unit 14.

The power controller 12 generates a _{current command value I ord2} based on the power of the HVDC system.

The VDCOL (Voltage Dependant Current Order Limit) module 13 detects the current command value set for the voltage of the HVDC system, and when the voltage of the system drops, the current command value ( It _{detects I ord3} and inputs this current command value (I _ord3 ) to the selection unit 14.

For reference, since the power controller 12 and the VDCOL module 13 can be easily implemented by a person skilled in the art, a detailed description thereof will be omitted here.

Selecting unit 14 is the current command value input from the one PCD (11) (I _ordl) the above can be selected as a current reference value (I _dcref), in addition to the current command value input from the PCD (11) (I _ordl ), and the minimum value of the current input from the power controller 12, the command value (I _ord2) and VDCOL module 13, a command current value (I _ord3) received from can be output by selecting a current reference value (I _dcref) .

In this embodiment, the rectification failure in single and three phases is predicted in advance based on the AC voltage, and the rectification failure is controlled in advance based on the prediction result.

In addition, the present embodiment makes it possible to prevent an additional rectification failure with a fast failure recovery speed even if a failure occurs in the HVDC system.

The present invention has been described with reference to the embodiments shown in the drawings, but these are only exemplary, and those of ordinary skill in the art to which the present technology pertains, various modifications and other equivalent embodiments are possible. I will understand. Therefore, the true technical protection scope of the present invention should be determined by the following claims.

10: current controller
11: PCD
12: power controller
13: VCDOL module
14: selection
110: voltage scalar synthesis unit
120: current scalar synthesis unit
130: first multiplier
140: first voltage comparator
150: first current comparator
160: first command value comparator
170: first discrimination unit
210: voltage vector synthesis unit
220: current vector synthesis unit
230: second multiplier
240: second voltage comparator
250: second current comparator
260: second command value comparator
270: second determination unit

Claims (8)

A voltage scalar synthesizer for generating a synthesized voltage value by synthesizing the three-phase voltage scalar;
A current scalar synthesizer for generating a synthesized current value by synthesizing the three-phase current scalar;
A first multiplier for generating a power command value by multiplying the synthesized voltage value and the synthesized current value;
A first voltage comparator for comparing the synthesized voltage value and a preset first synthesized voltage reference value;
A first current comparator for comparing the synthesized current value with a preset first synthesized current reference value;
A first command value comparator for comparing the power command value with a preset first power command reference value;
A first determination unit for determining a single-phase failure of the HVDC system according to a comparison result of the first voltage comparator, the first current comparator, and the first command value comparator; And
HVDC including a current controller that converts the power command value into a current command value and outputs the current command value as a current reference value for controlling rectification failure of the HVDC system when it is determined as a single-phase failure as a result of the determination by the first determination unit A device for controlling commutation failure of the system. The method of claim 1, wherein the first determining unit is the synthesized voltage value is equal to or greater than the first synthesized voltage reference value, the synthesized current value is equal to or greater than the first synthesized current reference value, and the power command value is the first power command reference value. If it is abnormal, the rectification failure control device of the HVDC system, characterized in that it is determined as a single-phase failure. The method of claim 1, wherein the current controller
A PCD (Power Command Drive) for converting the power command value into the current command value; And
And a selection unit for selecting the current command value as the current reference value. The method of claim 3, wherein the current controller
Further comprising a power controller that generates a current command value based on the power of the HVDC system, and a voltage dependent current order limit (VDCOL) module that detects a current command value set in the voltage of the HVDC system,
The selection unit selects a minimum value of the current command values input from each of the PCD, the power controller, and the VDCOL module as the current reference value. A voltage vector synthesizer for generating a synthesized voltage value by vector synthesizing the three-phase voltages;
A current vector synthesis unit for generating a synthesized current value by vector synthesizing the three-phase current;
A second multiplier for generating a power command value based on the synthesized voltage value and the synthesized current value;
A second voltage comparator for comparing the synthesized voltage value and a preset second synthesized voltage reference value;
A second current comparator for comparing the synthesized current value and a preset second synthesized current reference value;
A second command value comparator for comparing the power command value with a preset second power command reference value;
A second determination unit for determining a three-phase fault of the HVDC system according to a comparison result of the second voltage comparator, the second current comparator, and the second command value comparator; And
A current controller converting the power command value into a current command value and outputting the current command value as a current reference value for controlling a rectification failure of the HVDC system when it is determined as a 3-phase failure as a result of the determination by the second determination unit. Control device for commutation failure of HVDC system. The method of claim 5, wherein the second determination unit determines as a single-phase failure when the combined voltage value is greater than or equal to the combined voltage reference value, the combined current value is greater than or equal to the combined current reference value, and the power command value is greater than or equal to the sum reference value. Control device for rectification failure of the HVDC system, characterized in that. The method of claim 5, wherein the current controller
A PCD (Power Command Drive) for converting the power command value into the current command value; And
And a selection unit for selecting the current command value as the current reference value. The method of claim 7, wherein the current controller
Further comprising a power controller that generates a current command value based on the power of the HVDC system, and a voltage dependent current order limit (VDCOL) module that detects a current command value set in the voltage of the HVDC system,
The selection unit selects a minimum value of the current command values input from each of the PCD, the power controller, and the VDCOL module as the current reference value.

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