CN112152215A - Filter capacitor operation control device and method of converter - Google Patents
Filter capacitor operation control device and method of converter Download PDFInfo
- Publication number
- CN112152215A CN112152215A CN201910579750.1A CN201910579750A CN112152215A CN 112152215 A CN112152215 A CN 112152215A CN 201910579750 A CN201910579750 A CN 201910579750A CN 112152215 A CN112152215 A CN 112152215A
- Authority
- CN
- China
- Prior art keywords
- module
- thyristor
- filter capacitor
- power grid
- trigger
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000003990 capacitor Substances 0.000 title claims abstract description 236
- 238000000034 method Methods 0.000 title claims abstract description 60
- 230000004044 response Effects 0.000 claims description 25
- 230000008034 disappearance Effects 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 6
- 238000004590 computer program Methods 0.000 claims description 5
- 230000007423 decrease Effects 0.000 claims description 2
- 230000008569 process Effects 0.000 description 16
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Abstract
The present disclosure provides a filter capacitor operation control device and method for a converter, wherein the converter comprises a filter capacitor module, and the device comprises: the converter controller is used for respectively sending filter capacitor input control signals to the trigger module and the contactor module; the trigger module is used for detecting a voltage signal of a power grid and sending a trigger signal to the thyristor module according to the filter capacitor input control signal and the voltage signal; the thyristor module is used for conducting a thyristor in the thyristor module according to the trigger signal and the voltage signal so as to connect the power grid and the filter capacitor module through the conducted thyristor; and the contactor module is used for connecting the filter capacitor module with the power grid according to the filter capacitor input control signal, wherein when the contactor module is switched on, the power grid is connected with the filter capacitor module through the contactor module so as to bypass the thyristor module.
Description
Technical Field
The present disclosure relates to the field of wind power generation technologies, and more particularly, to a filter capacitor operation control device for a converter and a filter capacitor operation control method executed by the filter capacitor operation control device.
Background
With the development of wind power technology, a full-power converter is widely applied to a full-power wind turbine generator, an LCL filter is a grid-side filter of the full-power converter and is used for filtering grid-side current harmonics, so that the electric energy quality of the wind turbine generator meets the requirement of a power grid and can be smoothly connected to the power grid, and the LCL filter is composed of a box transformer leakage inductance, a filter capacitor and a reactor.
At present, a contactor switching mode is adopted for switching a grid-side filter capacitor of a wind power converter. As shown in fig. 1, 1 denotes a circuit breaker, 2 denotes a reactor, 3 denotes a contactor, and 4 denotes a filter capacitor module. When the filter capacitor is put into a power grid, the contactor switching mode is adopted, and the contactor and the filter capacitor can be impacted by dozens of times of rated current when being put into the power grid, so that the service lives of the contactor and the filter capacitor are seriously influenced, and the conditions of filter capacitor damage, adhesion of main contacts of the contactor and the like can be caused.
Disclosure of Invention
Exemplary embodiments of the present disclosure provide a filter capacitor operation control apparatus and method of a converter, which solve at least the above technical problems and other technical problems not mentioned above and provide the following advantageous effects.
An aspect of the present disclosure is to provide a filter capacitor operation control apparatus of a converter, the converter including a filter capacitor module, the apparatus may include: the converter controller is used for respectively sending filter capacitor input control signals to the trigger module and the contactor module; the trigger module is used for detecting a voltage signal of a power grid and sending a trigger signal to the thyristor module according to the filter capacitor input control signal and the voltage signal; the thyristor module is used for conducting a thyristor in the thyristor module according to the trigger signal and the voltage signal so as to connect the power grid and the filter capacitor module through the conducted thyristor; and the contactor module is used for connecting the filter capacitor module with the power grid according to the filter capacitor input control signal, wherein when the contactor module is switched on, the power grid is connected with the filter capacitor module through the contactor module so as to bypass the thyristor module.
The thyristor module can comprise 6 thyristors, and the filter capacitor module comprises a three-phase filter capacitor, wherein the first thyristor and the second thyristor form a control valve of a power grid phase A for controlling the connection of the first filter capacitor and the power grid phase A, the third thyristor and the fourth thyristor form a control valve of a power grid phase B for controlling the connection of the second filter capacitor and the power grid phase B, and the fifth thyristor and the sixth thyristor form a control valve of a power grid phase C for controlling the connection of the third filter capacitor and the power grid phase C.
The trigger module can send a trigger signal to a gate pole of each thyristor in the 6 thyristors according to the amplitude and the phase of the power grid voltage, wherein each thyristor in the thyristor module is conducted according to the trigger signal received by the corresponding gate pole and the voltage signals at two ends of each thyristor, so that the phase A, the phase B and the phase C in the power grid are respectively connected with the corresponding filter capacitor in the filter capacitor module through the conducted thyristors.
When the amplitude of the power grid voltage is detected to be reduced to a low voltage standard, if the power grid and the filter capacitor module are connected through the contactor module, responding to a filter capacitor input control signal, a thyristor in the thyristor module is conducted, so that the power grid and the filter capacitor module are connected through the conducted thyristor module; and if the power grid and the filter capacitor module are not connected through the contactor module but are connected through the thyristor module, waiting for the voltage signal to be recovered to be normal.
When the voltage of the power grid is recovered to be normal, the contactor module is conducted, so that the power grid and the filter capacitor module are connected through the conducted contactor module, and the thyristor module is disconnected.
The trigger module can respond to a filter capacitor cut-out control signal sent by the converter controller and send a trigger signal to the thyristor module again, the thyristor module is conducted according to the trigger signal, the contactor module responds to the filter capacitor cut-out control signal and is disconnected, and the filter capacitor module is cut out from a power grid after a preset time.
The thyristor module may respond to the disappearance of the trigger signal, with the thyristors in the thyristor module being fully turned off according to the filtered current zero crossing and voltage signals from the trigger module.
Another aspect of the present disclosure is to provide a filter capacitor operation control method performed by a filter capacitor operation control device of a converter, where the converter includes a filter capacitor module, and the filter capacitor operation control device includes a converter controller, a trigger module, a thyristor module, and a contactor module, where the method may include: detecting a voltage signal of the power grid by a trigger module; sending a filter capacitor input control signal to a trigger module and a contactor module by a converter controller; the trigger module sends a trigger signal to the thyristor module according to the detected voltage signal and the filter capacitor input control signal; responding to the trigger signal, conducting a thyristor in the thyristor module according to the detected voltage signal by the thyristor module so as to enable the filter capacitor module in the power grid and the converter to be connected through the conducted thyristor; responding to the filter capacitor input control signal, connecting the power grid and the filter capacitor module through the contactor module, wherein when the power grid and the filter capacitor module are connected through the conducted contactor module, the thyristor module is bypassed.
The thyristor module can comprise 6 thyristors, and the filter capacitor module comprises a three-phase filter capacitor, wherein the first thyristor and the second thyristor form a control valve of a power grid phase A for controlling the connection of the first filter capacitor and the power grid phase A, the third thyristor and the fourth thyristor form a control valve of a power grid phase B for controlling the connection of the second filter capacitor and the power grid phase B, and the fifth thyristor and the sixth thyristor form a control valve of a power grid phase C for controlling the connection of the third filter capacitor and the power grid phase C.
The step of connecting the grid to the filter capacitor module by the thyristor module according to the detected voltage signal may comprise: and the trigger module sends a trigger signal to a gate pole of each thyristor in the 6 thyristors based on the amplitude and the phase of the voltage of the power grid, and conducts each thyristor in the thyristor module according to the trigger signal received by the corresponding gate pole and the voltage signals at two ends of each thyristor, so that the phase A, the phase B and the phase C in the power grid are respectively connected with the corresponding filter capacitor in the filter capacitor module through the conducted thyristors.
The method may further comprise: responding to a filter capacitor switching-out control signal sent by the converter controller, sending a trigger signal to the thyristor module again by the trigger module, and conducting the thyristor module according to the trigger signal; and responding to the filter capacitor switching-out control signal, disconnecting the contactor module, and switching out the filter capacitor module from the power grid after preset time.
The method may further comprise: and in response to the disappearance of the trigger signal, the thyristors in the thyristor module are all disconnected by the thyristor module according to the filtering current zero crossing points and the voltage signals from the trigger module.
Another aspect of the present disclosure is to provide a filter capacitor operation control method performed by a filter capacitor operation control device of a converter, where the converter includes a filter capacitor module, and the filter capacitor operation control device includes a converter controller, a trigger module, a thyristor module, and a contactor module, where the method may include: detecting a voltage signal of the power grid by a trigger module; when the detected voltage signal meets the low voltage standard, the trigger module determines whether the filter capacitor module is switched into the power grid by the contactor module; and when the filter capacitor module is determined to be switched into the power grid through the contactor module, responding to the filter capacitor switching control signal, switching on the thyristor in the thyristor module, and connecting the power grid and the filter capacitor module through the switched-on thyristor module.
The method may further comprise: and when the detected voltage signal meets the low voltage standard and the filter capacitor module is determined not to be put into the power grid through the contactor module, determining whether the filter capacitor module is put into the power grid through the thyristor module or not through the trigger module, wherein when the filter capacitor module is determined to be put into the power grid through the thyristor module, the converter is turned off when the voltage signal is waited to be recovered to be normal, and when the filter capacitor module is determined not to be put into the power grid through the thyristor module.
The method may further comprise: and when the voltage of the power grid is recovered to be normal, the contactor module is conducted, so that the power grid is connected with the filter capacitor module through the conducted contactor module, and the thyristor module is disconnected.
Another aspect of the present disclosure is to provide a computer comprising a readable medium storing a computer program, characterized in that the computer program comprises instructions for performing the above method.
Based on the method and the device, the switching characteristic of the thyristor is utilized to assist the contactor to switch the filter capacitor, so that the impact current of the filter capacitor is small, the required external signals are less, and the service lives of the contactor and the filter capacitor are prolonged. Meanwhile, the process of disconnecting the contactor can be passed by adopting a thyristor during low voltage ride through, and a control coil of the contactor is stripped from a power supply of the UPS, so that the capacity of the AC Uninterruptible Power Supply (UPS) is reduced.
Drawings
These and/or other aspects and advantages of the present disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a block diagram of a prior art filter capacitor switching device;
fig. 2 is a block diagram of a filter capacitor switching device of a converter according to an exemplary embodiment of the present disclosure;
fig. 3 is a flowchart of a filter capacitance operation control method of a converter according to a first exemplary embodiment of the present disclosure;
fig. 4 is a flowchart of a filter capacitor operation control method of a converter according to a second exemplary embodiment of the present disclosure;
fig. 5 is a flowchart of a filter capacitance operation control method of a converter according to a third exemplary embodiment of the present disclosure.
Detailed Description
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the embodiments of the disclosure as defined by the claims and their equivalents. Various specific details are included to aid understanding, but these are to be considered exemplary only. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
In the present disclosure, terms including ordinal numbers such as "first", "second", etc., may be used to describe various elements, but these elements should not be construed as being limited to only these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and vice-versa, without departing from the scope of the present disclosure.
Hereinafter, the apparatus and method of the present disclosure will be described with reference to the accompanying drawings, according to various embodiments of the present disclosure.
Fig. 2 is a block diagram of a filter capacitance operation control apparatus of a converter according to an exemplary embodiment of the present disclosure.
Referring to fig. 2, the filter capacitor operation control apparatus 200 of the converter may be included in a wind power converter (not shown). The converter filter capacitor operation control apparatus 200 may include a converter controller 201, a trigger module 202, a thyristor module 203, a contactor module 204, and a filter capacitor module 205. Each module in the apparatus 200 according to the present disclosure may be implemented by one or more modules, and names of the corresponding modules may vary according to types of the modules. In various embodiments, some modules in the apparatus 200 may be omitted, or additional modules may also be included. Furthermore, modules/elements according to various embodiments of the present disclosure may be combined to form a single entity, and thus may equivalently perform the functions of the respective elements prior to combination.
The converter controller 201 is a control module, and is mainly used for sending a filter capacitor input control signal and a filter capacitor output control signal. As shown in fig. 2, a first pin of the converter controller 201 is connected to a first pin of the trigger module 202, and a second pin of the converter controller 201 is connected to a second pin of the trigger module 202, so that 24V power is supplied to the trigger module 202 via the converter controller 201. The third pin of the converter controller 201 is connected to the third pin of the trigger module 202 and is also connected to the seventh pin of the contactor module 204, and the fourth pin of the converter controller 201 is connected to the fourth pin of the trigger module 202 and is also connected to the eighth pin of the contactor module 204, so that the converter controller 201 sends control signals to the trigger module 202 and the contactor module 204, respectively, that is, the converter controller is responsible for providing an input signal and a cut-out signal of the filter capacitor module 205 in the power grid.
The trigger module 202 is a module for acquiring and outputting a trigger signal, and is mainly used for detecting a voltage signal of a power grid and determining whether to send the trigger signal according to a filter capacitor input control signal and the voltage signal. As shown in fig. 2, the fifth pin of the trigger module 202 is connected to the first pin of the contactor module 204 (i.e., phase a of the grid), the sixth pin of the trigger module 202 is connected to the third pin of the contactor module 204 (i.e., phase B of the grid), and the seventh pin of the trigger module 202 is connected to the fifth pin of the contactor module 204 (i.e., phase C of the grid), so that the voltage signal of the grid is detected via the trigger module 202.
The thyristor module 203 may include 6 thyristors, a first thyristor T1, a second thyristor T2, a third thyristor T3, a fourth thyristor T4, a fifth thyristor T5, and a sixth thyristor T6, and is mainly configured to conduct the thyristors in the thyristor module according to the trigger signal and the voltage signal, so that the grid and the filter capacitor module 205 are connected through the conducted thyristors. Specifically, as shown in fig. 2, the eighth pin of the trigger module 202 is connected to the gate (G pole) of the thyristor T5 in the thyristor module 203, the ninth pin of the trigger module 202 is connected to the G pole of the thyristor T6 in the thyristor module 203, the tenth pin of the trigger module 202 is connected to the G pole of the thyristor T3 in the thyristor module 203, the eleventh pin of the trigger module 202 is connected to the G pole of the thyristor T4 in the thyristor module 203, the twelfth pin of the trigger module 202 is connected to the G pole of the thyristor T1 in the thyristor module 203, and the thirteenth pin of the trigger module 202 is connected to the G pole of the thyristor T2 in the thyristor module 203, so that a trigger signal is sent to the G pole of each thyristor in the thyristor module 203 via the trigger module 202.
In addition, the anode (i.e., the a pole) of the thyristor T1 is connected to the first pin of the contactor module 204, the cathode (i.e., the K pole) of the thyristor T1 is connected to the second pin of the contactor module 204, the a pole of the thyristor T2 is connected to the K pole of the thyristor T1, the K pole of the thyristor T2 is connected to the a pole of the thyristor T1, and the thyristor T1 and the thyristor group T2 constitute a control valve of the phase a of the grid. The A pole of the thyristor T3 is connected with the third pin of the contactor module 204, the K pole of the thyristor T3 is connected with the fourth pin of the contactor module 204, the A pole of the thyristor T4 is connected with the K pole of the thyristor T3, the K pole of the thyristor T4 is connected with the A pole of the thyristor T3, and the thyristor T3 and the thyristor T4 form a control valve of a B phase of a power grid. The A pole of the thyristor T5 is connected with the fifth pin of the contactor module 204, the K pole of the thyristor T5 is connected with the sixth pin of the contactor module 204, the A pole of the thyristor T6 is connected with the K pole of the thyristor T5, the K pole of the thyristor T6 is connected with the A pole of the thyristor T5, and the thyristor T5 and the thyristor T6 form a control valve of a C phase of a power grid.
In the disclosure, the thyristor module 203 is used for putting the thyristor into the grid according to the trigger signal of the G pole and the phase of the grid voltage by using the on-off characteristics of the thyristor under the condition that the thyristor T1 and the thyristor T2 form the control valve of the grid a phase, the thyristor T3 and the thyristor T4 form the control valve of the grid B phase, and the thyristor T5 and the thyristor T6 form the control valve of the grid C phase, so as to ensure that the surge current is not generated due to the overlarge difference between the grid voltage and the initial voltage of the capacitor, thereby prolonging the service life of the contactor and the service life of the filter capacitor.
The filter capacitor module 205 may include three-phase filter capacitors, i.e., a first filter capacitor C1, a second filter capacitor C2, and a third filter capacitor C3. The contactor module 204 connects the filter capacitor module 205 to the grid based on the filter capacitor input control signal. As shown in fig. 2, a first pin of the contactor module 204 is connected to a of the power grid, a second pin of the contactor module 204 is connected to a first pin of a capacitor C1 in the filter capacitor module 205, a third pin of the contactor module 204 is connected to B of the power grid, a fourth pin of the contactor module 204 is connected to a first pin of a capacitor C2 in the filter capacitor module 205, a fifth pin of the contactor module 204 is connected to C of the power grid, and a sixth pin of the contactor module 204 is connected to a first pin of a capacitor C3 in the filter capacitor module 205. Phase a, phase B, and phase C of the grid may be connected to filter capacitances C1, C2, and C3, respectively, via the touch module 204.
In addition, the second pins of the filter capacitors C1, C2 and C3 in the filter capacitor module 205 are all grounded.
When the filter capacitor module 205 is put into the grid, an LCL filter loop may be formed by the filter capacitor in the filter capacitor module 205, the inductor in the converter, and the leakage inductance in the box transformer of the grid. The LCL filtering loop can effectively filter harmonic waves in a high-power converter and an inverter, so that grid-connected equipment meets the requirement of a power grid, and the LCL filtering loop is the most widely applied power grid filtering loop of a new energy power generation system at present.
The operation of each module in the filter capacitance operation control device 200 will be described in detail below with reference to fig. 2.
After the converter is powered up, the trigger module 202 detects the voltage signal of the grid in real time. When the converter controller 201 sends the filter capacitor input control signal to the trigger module 202 and the contactor module 204, respectively, the trigger module 202 sends the trigger signal to the thyristor module 203 according to the filter capacitor input control signal and the voltage signal. Specifically, in response to that the filter capacitor input control signal is 1, the trigger module 202 acquires A, B, C three-phase voltage signals of the power grid through the fifth, sixth, and seventh pins as a basis for trigger determination, and sends a trigger signal to the G pole of each thyristor in the thyristor module 203 based on the amplitude and phase of the power grid voltage, and each thyristor can be turned on according to the trigger signal received by the corresponding G pole and the voltage signals at the two ends of each thyristor, so that the corresponding phases (i.e., the a phase, the B phase, and the C phase of the power grid) in the power grid are connected to the filter capacitor module 205 through the turned-on thyristors. Therefore, the characteristics of the thyristor can be used for assisting the contactor module 204 in switching the filter capacitor, and the service life of the contactor and the filter capacitor is prevented from being shortened due to the fact that the impact current is large when the filter capacitor is put into use.
In addition, in response to the filter capacitor input control signal being 1, the contactor in the contactor module 204 is closed, and the filter capacitor module 205 is connected to the grid via the contactor, so as to bypass the thyristor module, thereby reducing the loss of the system. Next, the thyristor module 203 is extinguished in response to the trigger signal, and the thyristors in the thyristor module 203 are all turned off according to the filtered current zero crossing and voltage signals from the trigger module 202.
It should be noted that since the contactor takes several tens of milliseconds from the reception of the filter capacitance input control signal to the closing of the contactor, and the thyristor can be operated immediately after the reception of the filter capacitance input control signal, the same control signal can be used by the thyristor module 203 and the contactor module 204.
After the filter capacitor module 205 is put into the power grid, it forms an LCL filter loop with the internal inductance of the converter and the leakage inductance of the box transformer.
In addition, the converter controller 201 may also send filter capacitor cut-out control signals to the contactor module 204. In response to the filter capacitor switching-out control signal being 1, the trigger module 202 sends out a trigger signal, and the contactor is opened, and the filter capacitor module 205 is switched into the grid through the thyristor module 203. The trigger module 202 turns off the trigger signal after detecting the feedback signal that the contactor is open. The thyristor turns off at the zero crossing of the filter current, so that the filter capacitance module 205 cuts out from the grid.
According to an embodiment of the present disclosure, during the grid and filter capacitor module 205 being connected via the contactor module 204, when it is detected that the magnitude of the grid voltage decreases to the low voltage standard, in response to the filter capacitor input control signal being 1, the contactor module 204 is voltage-loss switched off, and the thyristors in the thyristor module 203 are switched on such that the grid and filter capacitor module 205 is connected through the switched-on thyristor module 203. When the grid voltage returns to normal, the contactor module 204 is turned on so that the grid and filter capacitor module 205 is connected through the turned on contactor module 204 and the thyristor module 203 is turned off.
Fig. 3 is a flowchart of a filter capacitance operation control method of a converter according to an exemplary embodiment of the present disclosure. The filter capacitor operation control method of fig. 3 may be applied to a case where the power grid is in a normal operation mode.
In step S301, the converter is started.
After the converter is started, in step S302, the trigger module 202 in the filter capacitor operation control device 200 collects/detects the voltage signal of the power grid in real time.
In step S303, when the converter controller 201 transmits the filter capacitor input control signal, that is, when the filter capacitor input control signal is 1, the process proceeds to step S304. Here, it should be noted that the filter capacity put-in control signal is used to put the filter capacity into the grid only in the case where the transmitted filter capacity put-in control signal is 1. Otherwise, the voltage signal of the grid continues to be acquired/detected by the trigger module 202.
In step S304, the trigger module 202 sends a trigger signal to the G pole of the thyristor in the thyristor module 203 according to the collected voltage phase in response to receiving the filter capacitor input control signal.
In step S305, after the thyristor module 203 receives the trigger signal, the thyristor in the thyristor module 203 is turned on according to the trigger signal received by the G-pole and the voltage across the thyristor, so that the a phase, the B phase, and the C phase in the power grid are respectively connected to the filter capacitor in the filter capacitor module 205 through the turned-on thyristor. In this way, the filter capacitance can first be fed into the network via the thyristor module 203. In the method, the thyristor is input according to the trigger signal of the G pole and the phase of the grid voltage by utilizing the switching-on and switching-off characteristics of the thyristor, so that the situation that the surge current is generated due to overlarge difference between the grid voltage and the initial voltage of the capacitor is ensured.
In addition, in step S306, in response to receiving the filter capacitor input control signal, the contactor module 204 pulls in the contactor module 204 after a fixed time delay, i.e., turns on the contactor, and connects the grid with the filter capacitor module 205 via the turned-on contactor. The thyristor module 203 is bypassed when the grid is connected to the filter capacitor module 205 via the contactor module 204.
Because the contactor needs tens of milliseconds from receiving the filter capacitor input control signal to attracting, and the thyristor can act immediately after receiving the control signal, under the condition that the thyristor module 203 and the contactor module 204 use the same control signal, the filter capacitor is connected with the power grid through the conducted thyristor, then the filter capacitor is connected with the power grid through the conducted contactor, and at the moment, the thyristor module 203 is bypassed, thereby reducing the loss of the system.
In step S307, the trigger signal disappears in response to the contactor in the contactor module 204 being turned on, and the thyristor is switched out in response to the trigger signal disappearing due to the input of the contactor causing the current to be too small. The thyristors in the thyristor module 203 are all turned off by the thyristor module 203 based on the filtered current zero crossings and voltage signals from the trigger module 202. When the trigger signal of the trigger module 202 disappears, the thyristor module 203 is completely turned off under the action of the zero-crossing current and the voltage across the thyristor.
In the case where the filter capacitor is connected to the grid by the contactor module 204, when the converter controller 201 issues the filter capacitor cut-out control signal in step S308, the process proceeds to step S309, and in response to the filter capacitor cut-out control signal being 1, the trigger module 202 issues the trigger signal to the thyristor module 203.
In step S310, the thyristor module 203 is turned on in response to the trigger signal.
In step S311, in response to the filter capacitance cut-out control signal being 1, the contactor in the contactor module 204 is opened.
In step S312, the trigger turns off the trigger signal in response to the feedback signal that the contactor module 204 is open.
In step S313, in response to the disappearance of the trigger signal, the thyristor is turned off entirely according to the zero-crossing of the filter current and the voltage signal, thereby cutting the filter capacitor out of the grid.
Fig. 4 is a flowchart of a filter capacitor operation control method of a converter according to another exemplary embodiment of the present disclosure. The filter capacitor operation control method of fig. 4 may be applied to a case where a low voltage ride through occurs during the time when the filter capacitor module 205 is plunged into the grid via the contactor module.
Referring to fig. 4, in step S401, the trigger module 202 detects a voltage signal of the grid in real time when the converter is operating normally.
In step S402, when the detected voltage signal meets the low voltage standard, the process proceeds to step S403, otherwise, the converter continues to operate normally. Here, since the contactor in the contactor module 204 cannot normally operate due to a low voltage when the voltage signal of the grid reaches a low voltage standard, it may be necessary to put the filter capacitance into the grid using the thyristor module 203.
In step S403, when the filter capacitance input control signal transmitted from the converter controller 201 is 1, the process proceeds to step S404. Here, it should be noted that the filter capacity put-in control signal is used to put the filter capacity into the grid only in the case where the transmitted filter capacity put-in control signal is 1.
When the filter capacitor input control signal sent by the converter controller 201 is 0, the filter capacitor module 205 is not input into the power grid.
In step S404, in response to the filter capacitance input control signal being 1, the trigger module 202 sends a trigger signal to the G pole of the thyristor in the thyristor module 203 according to the phase of the detected voltage.
In step S405, after the thyristor module 203 receives the trigger signal, the thyristor in the thyristor module 203 is turned on according to the trigger signal received by the G-pole and the voltage across the thyristor, so that the a phase, the B phase, and the C phase in the power grid are respectively connected to the filter capacitor in the filter capacitor module 205 through the turned-on thyristor.
In step S406, after connecting the grid and the filter capacitor via the thyristor module 203, the contactor is opened due to the control coil being out of voltage.
After the delay time 2S specified by the low voltage ride through rule, in step S407, the trigger module 202 continues to detect the voltage signal of the power grid, and determines whether the voltage of the power grid is normal. When the detected voltage is a low voltage, the process proceeds to step S410. When the detected voltage returns to normal, the process proceeds to step S408.
In step S408, after the grid voltage returns to the normal state, if the converter controller 201 sends a filter capacitor input control signal, the process proceeds to step S409, where it waits for the contactor control coil of the contactor module 204 to be powered on and closed, the contactor module 204 is used to connect the grid to the filter capacitor, and then, in step S410, in response to the feedback signal of the contactor conduction, the trigger signal sent by the trigger module 202 is turned off, that is, the trigger signal disappears.
In step S411, in response to the disappearance of the trigger signal, the thyristor module is turned off at the current zero crossing point, so that the filter capacitor is connected to the grid via the contactor module, thereby restoring the normal operating state.
In step S407, if the voltage of the power grid is not restored to normal, the process proceeds to step S410, and the trigger signal generated by the trigger module 202 is turned off. Accordingly, the thyristor is turned off. Here, it should be noted that step S410 is only to turn off the trigger signal in the case where the voltage is not restored to normal.
Fig. 5 is a flowchart of a filter capacitance operation control method of a converter according to a third exemplary embodiment of the present disclosure. The filter capacitor operation control method of fig. 5 considers the case where neither the contactor module 204 nor the thyristor module 203 is interposed between the grid and the filter capacitor module 205.
Referring to fig. 5, in step S501, the trigger module 202 detects a voltage signal of the grid in real time when the converter is operating normally.
In step S502, when the detected voltage meets the low voltage standard, the process proceeds to step S503, otherwise, the converter continues to operate normally. Here, since the contactor in the contactor module 204 cannot normally operate due to a low voltage when the voltage of the grid reaches a low voltage standard, it may be necessary to put the filter capacitor module into the grid using the thyristor module 203.
At step S503, it is determined at the time of the low voltage ride through that whether the filter capacitance module 205 is now launched into the grid via the contactor module 204 is determined by the trigger module 202. Here, the trigger module 202 may determine whether to throw the filter capacitor module 205 into the grid via the thyristor module according to the feedback signal of the contactor opening and closing. When it is determined that the filter capacitor module 205 is connected to the grid via the contactor module 204, the process proceeds to step S504, the converter controller 201 sends a filter capacitor connection control signal, and in response to the filter capacitor connection control signal being 1, the trigger module 202 sends a trigger signal to the G pole of the thyristor in the thyristor module 203 according to the phase of the detected voltage.
In step S505, after the thyristor module 203 receives the trigger signal, the thyristor in the thyristor module 203 is turned on according to the trigger signal received by the G-pole and the voltage across the thyristor, so that the a phase, the B phase, and the C phase in the power grid are respectively connected to the filter capacitor in the filter capacitor module 205 through the turned-on thyristor.
In step S506, after the grid and filter capacitor module 205 are connected via the thyristor module 203, the contactor is opened due to the control coil being out of voltage.
After the delay time 2S specified by the low voltage ride through rule, in step S507, the trigger module 202 continues to detect the voltage signal of the power grid, and determines whether the voltage of the power grid is normal. When the detected voltage is a low voltage, the process proceeds to step S510. When the detected voltage returns to normal, the process proceeds to step S508.
In step S508, after the grid voltage returns to the normal state, if the converter controller 201 sends a filter capacitor input control signal, the process proceeds to step S509, where it waits for the contactor control coil of the contactor module 204 to be powered on and closed, the contactor module 204 is used to connect the grid to the filter capacitor, and then, in step S510, the trigger signal sent by the trigger module 202 is turned off, that is, the trigger signal disappears.
In step S511, in response to the disappearance of the trigger information, the thyristor module 203 is turned off, so that the filter capacitor is connected to the grid via the contactor module 204, thereby restoring the normal operating state.
In step S507, if the voltage of the power grid is not restored to normal, the process proceeds to step S510, and the trigger signal sent by the trigger module 202 is turned off. Accordingly, the thyristor is turned off. Here, it should be noted that step S510 is only to turn off the trigger signal in the case where the voltage is not restored to normal.
Further, when it is determined at step S503 that the filter capacitance module 205 is not to be placed into the grid via the contactor module 204, at step S512, it is determined by the trigger module 202 whether to place the filter capacitance module 205 into the grid via the thyristor module 203. Here, the trigger module 202 may determine whether to throw the filter capacitor module 205 into the grid via the thyristor module 203 according to the feedback signal of the thyristor being turned off and on.
When it is determined in step S512 that the filter capacitor module 205 is switched into the power grid via the thyristor module 203, the process proceeds to step S507, and the trigger module 202 detects whether the voltage of the power grid returns to normal.
When it is determined in step S512 that the filter capacitor module 205 is not put into the grid through the thyristor module 203, the converter is turned off, that is, the control flow is ended.
According to the embodiment of the disclosure, the contactor is assisted to switch the filter capacitor through the characteristics of the thyristor, so that the impact current is small when the filter capacitor is put into use, the service life of the contactor and the service life of the filter capacitor are greatly improved, and low-voltage ride-through can be smoothly completed under the condition that the contactor does not use a UPS (uninterrupted power supply) by controlling the switching of the thyristor.
The device and the method can be applied to the wind generating set which is already in operation to prolong the service life of the contactor and the filter capacitor, and can also be applied to the design of a novel wind generating set, so that the filter capacitor and the contactor meet the requirements of the wind generating set on service life and maintenance.
The method according to the present disclosure may be performed in accordance with computer program instructions. Since these program instructions may be embodied in a computer, special purpose processor, or programmable or dedicated hardware, the instructions executed therein may facilitate the performance of the functions described above. As will be appreciated by those skilled in the art, a computer, processor or programmable hardware includes a storage device that can store or receive software or computer code that, when accessed and executed by a computer, processor or hardware, implements the methods described in this disclosure.
While the disclosure has been shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.
Claims (16)
1. A filter capacitor operation control apparatus for a converter, said converter including a filter capacitor module, said apparatus comprising:
the converter controller is used for respectively sending filter capacitor input control signals to the trigger module and the contactor module;
the trigger module is used for detecting a voltage signal of a power grid and sending a trigger signal to the thyristor module according to the filter capacitor input control signal and the voltage signal;
the thyristor module is used for conducting a thyristor in the thyristor module according to the trigger signal and the voltage signal so as to connect the power grid and the filter capacitor module through the conducted thyristor;
a contactor module for connecting the filter capacitor module with the power grid according to the filter capacitor input control signal,
when the contactor module is conducted, the power grid is connected with the filter capacitor module through the contactor module to bypass the thyristor module.
2. The apparatus of claim 1, wherein the thyristor module comprises 6 thyristors and the filter capacitor module comprises a three-phase filter capacitor,
the first thyristor and the second thyristor form a control valve of a phase A of the power grid to control connection of the first filter capacitor and the phase A of the power grid, the third thyristor and the fourth thyristor form a control valve of a phase B of the power grid to control connection of the second filter capacitor and the phase B of the power grid, and the fifth thyristor and the sixth thyristor form a control valve of a phase C of the power grid to control connection of the third filter capacitor and the phase C of the power grid.
3. The apparatus of claim 2, wherein the trigger module sends a trigger signal to a gate of each of the 6 thyristors based on a magnitude and phase of a grid voltage,
each thyristor in the thyristor module is conducted according to the trigger signal received by the corresponding gate pole and the voltage signal at the two ends of each thyristor, so that the phase A, the phase B and the phase C in the power grid are respectively connected with the corresponding filter capacitor in the filter capacitor module through the conducted thyristors.
4. The apparatus of claim 1, wherein when a decrease in the magnitude of the grid voltage to a low voltage standard is detected, if the grid and filter capacitor modules are connected via the contactor module, in response to the filter capacitor enable control signal, a thyristor in the thyristor module is turned on so that the grid and filter capacitor modules are connected by the turned-on thyristor module; and if the power grid and the filter capacitor module are not connected through the contactor module but are connected through the thyristor module, waiting for the power grid voltage signal to be recovered to be normal.
5. The apparatus of claim 4, wherein when the grid voltage signal returns to normal, the contactor module is turned on so that the grid and the filter capacitor module are connected through the turned on contactor module, and the thyristor module is turned off.
6. The apparatus of claim 1, wherein the trigger module re-sends the trigger signal to the thyristor module in response to the filter capacitor cut-out control signal sent by the converter controller, the thyristor module being turned on according to the trigger signal, the contactor module being turned off in response to the filter capacitor cut-out control signal, the filter capacitor module being cut out from the grid after a preset time.
7. The apparatus of claim 1 or 6, wherein the thyristor module is responsive to the disappearance of the trigger signal, the thyristors in the thyristor module being fully turned off in response to the filtered zero crossing of the current and the voltage signal from the trigger module.
8. A filter capacitor work control method executed by a filter capacitor work control device of a converter, wherein the converter comprises a filter capacitor module, the filter capacitor work control device comprises a converter controller, a trigger module, a thyristor module and a contactor module, and the method comprises the following steps:
detecting a voltage signal of the power grid by a trigger module;
sending a filter capacitor input control signal to a trigger module and a contactor module by a converter controller;
the trigger module sends a trigger signal to the thyristor module according to the detected voltage signal and the filter capacitor input control signal;
responding to the trigger signal, conducting a thyristor in the thyristor module according to the detected voltage signal by the thyristor module so as to enable the filter capacitor module in the power grid and the converter to be connected through the conducted thyristor;
responding to the filter capacitor input control signal, connecting the power grid with the filter capacitor module by the contactor module,
when the power grid is connected with the filter capacitor module through the conducted contactor module, the thyristor module is bypassed.
9. The method of claim 8, wherein the thyristor module comprises 6 thyristors and the filter capacitor module comprises a three-phase filter capacitor,
the first thyristor and the second thyristor form a control valve of a phase A of the power grid to control connection of the first filter capacitor and the phase A of the power grid, the third thyristor and the fourth thyristor form a control valve of a phase B of the power grid to control connection of the second filter capacitor and the phase B of the power grid, and the fifth thyristor and the sixth thyristor form a control valve of a phase C of the power grid to control connection of the third filter capacitor and the phase C of the power grid.
10. The method of claim 9, wherein the step of connecting, by the thyristor module, the power grid to the filter capacitor module based on the detected voltage signal comprises:
sending, by the trigger module, a trigger signal to a gate of each of the 6 thyristors based on the magnitude and phase of the grid voltage,
and conducting each thyristor in the thyristor module according to the trigger signal received by the corresponding gate pole and the voltage signal at the two ends of each thyristor, so that the phase A, the phase B and the phase C in the power grid are respectively connected with the corresponding filter capacitor in the filter capacitor module through the conducted thyristors.
11. The method of claim 8, wherein the method further comprises:
responding to a filter capacitor switching-out control signal sent by the converter controller, sending a trigger signal to the thyristor module again by the trigger module, and conducting the thyristor module according to the trigger signal;
and responding to the filter capacitor switching-out control signal, disconnecting the contactor module, and switching out the filter capacitor module from the power grid after preset time.
12. The method of claim 8 or 11, wherein the method further comprises:
and in response to the disappearance of the trigger signal, the thyristors in the thyristor module are all disconnected by the thyristor module according to the filtering current zero crossing points and the voltage signals from the trigger module.
13. A filter capacitor work control method executed by a filter capacitor work control device of a converter, wherein the converter comprises a filter capacitor module, the filter capacitor work control device comprises a converter controller, a trigger module, a thyristor module and a contactor module, and the method comprises the following steps:
detecting a voltage signal of the power grid by a trigger module;
when the detected voltage signal meets the low voltage standard, the trigger module determines whether the filter capacitor module is switched into the power grid by the contactor module;
and when the filter capacitor module is determined to be switched into the power grid through the contactor module, responding to the filter capacitor switching control signal, switching on the thyristor in the thyristor module, and connecting the power grid and the filter capacitor module through the switched-on thyristor module.
14. The method of claim 13, wherein the method further comprises:
when the detected voltage signal meets a low voltage criterion and it is determined that the filter capacitor module is not to be launched into the grid via the contactor module, determining, by the trigger module, whether to launch the filter capacitor module into the grid via the thyristor module,
when the filter capacitor module is determined to be switched into the power grid through the thyristor module, the voltage signal is waited to be recovered to be normal, and when the filter capacitor module is determined not to be switched into the power grid through the thyristor module, the converter is closed.
15. The method of claim 13 or 14, wherein the method further comprises:
and when the voltage signal of the power grid is recovered to be normal, the contactor module is conducted, so that the power grid is connected with the filter capacitor module through the conducted contactor module, and the thyristor module is disconnected.
16. A computer arrangement comprising a readable medium having a computer program stored thereon, wherein the computer program comprises instructions for carrying out the method according to any one of claims 8 to 15.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910579750.1A CN112152215B (en) | 2019-06-28 | Filter capacitor operation control device and method of converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910579750.1A CN112152215B (en) | 2019-06-28 | Filter capacitor operation control device and method of converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112152215A true CN112152215A (en) | 2020-12-29 |
| CN112152215B CN112152215B (en) | 2024-05-17 |
Family
ID=
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63245274A (en) * | 1987-03-31 | 1988-10-12 | Toshiba Corp | Inverter for car body |
| CN101345419A (en) * | 2008-05-14 | 2009-01-14 | 西安交通大学 | Series voltage quality regulator and fast investment and cutting method |
| CN101572412A (en) * | 2009-06-12 | 2009-11-04 | 北京思能达电力技术有限公司 | High-capacity packet type switchgear |
| CN101783513A (en) * | 2009-11-27 | 2010-07-21 | 艾默生网络能源有限公司 | Wind energy converter, wind energy generating equipment and system |
| CN101917156A (en) * | 2010-08-30 | 2010-12-15 | 南车株洲电力机车研究所有限公司 | Method and device for protecting wind generating set during electric network voltage dip in short time |
| CN201860111U (en) * | 2010-11-03 | 2011-06-08 | 武汉理工大学 | Reactance controlling device of dynamic harmonic filter |
| CN202134922U (en) * | 2011-07-27 | 2012-02-01 | 山东先河悦新机电股份有限公司 | Mining low voltage reactive power compensation device |
| CN102904286A (en) * | 2012-10-23 | 2013-01-30 | 深圳市长昊机电有限公司 | Grid-connected inverter and control method thereof |
| WO2014075614A1 (en) * | 2012-11-14 | 2014-05-22 | 国家电网公司 | Thyristor-device-based mmc converter valve submodule device and control method thereof |
| CN106533147A (en) * | 2016-11-18 | 2017-03-22 | 深圳市禾望电气股份有限公司 | Standby method and device of converter system |
| CN208337164U (en) * | 2018-05-07 | 2019-01-04 | 成都市中朋达电气有限公司 | Capacitor switching combination switch control module |
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63245274A (en) * | 1987-03-31 | 1988-10-12 | Toshiba Corp | Inverter for car body |
| CN101345419A (en) * | 2008-05-14 | 2009-01-14 | 西安交通大学 | Series voltage quality regulator and fast investment and cutting method |
| CN101572412A (en) * | 2009-06-12 | 2009-11-04 | 北京思能达电力技术有限公司 | High-capacity packet type switchgear |
| CN101783513A (en) * | 2009-11-27 | 2010-07-21 | 艾默生网络能源有限公司 | Wind energy converter, wind energy generating equipment and system |
| CN101917156A (en) * | 2010-08-30 | 2010-12-15 | 南车株洲电力机车研究所有限公司 | Method and device for protecting wind generating set during electric network voltage dip in short time |
| CN201860111U (en) * | 2010-11-03 | 2011-06-08 | 武汉理工大学 | Reactance controlling device of dynamic harmonic filter |
| CN202134922U (en) * | 2011-07-27 | 2012-02-01 | 山东先河悦新机电股份有限公司 | Mining low voltage reactive power compensation device |
| CN102904286A (en) * | 2012-10-23 | 2013-01-30 | 深圳市长昊机电有限公司 | Grid-connected inverter and control method thereof |
| WO2014075614A1 (en) * | 2012-11-14 | 2014-05-22 | 国家电网公司 | Thyristor-device-based mmc converter valve submodule device and control method thereof |
| CN106533147A (en) * | 2016-11-18 | 2017-03-22 | 深圳市禾望电气股份有限公司 | Standby method and device of converter system |
| CN208337164U (en) * | 2018-05-07 | 2019-01-04 | 成都市中朋达电气有限公司 | Capacitor switching combination switch control module |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6630752B2 (en) | Uninterruptible transfer switch | |
| AU2018323422B2 (en) | Power supply system | |
| CN104158282A (en) | Dual-circuit switching control power circuit and high-voltage inverter | |
| CN101702360B (en) | Pre-magnetizing device of power supply transformer and pre-magnetizing method thereof | |
| CN105826063A (en) | Contactless on-load automatic positive and negative voltage regulating tap switch device for three-phase distribution transformer | |
| US10951057B1 (en) | Reliable power module for improved substation device availability | |
| CN104748288A (en) | Soft start charging circuit and control method thereof | |
| CN201374571Y (en) | Online UPS | |
| CN203660492U (en) | Microcomputer comprehensive protection device having active/passive automatic switching function | |
| CN104638753A (en) | Large direct-current uninterrupted power system and large direct-current uninterrupted power supply method | |
| CN102104359A (en) | Alternating current (AC) stepped controllable single-phase/three-phase shunt reactor | |
| CN112072741B (en) | Method and device for realizing one-key starting of household energy storage system | |
| CN103943396A (en) | Circuit breaker operation loop | |
| CN112152215B (en) | Filter capacitor operation control device and method of converter | |
| CN112152215A (en) | Filter capacitor operation control device and method of converter | |
| CN103715763A (en) | Energy-saving power supply system for IDC (internet data center) machine room | |
| CN110601351A (en) | Dual-power seamless switching device and method | |
| CN203671834U (en) | Soft start charging circuit | |
| JP2015164374A (en) | Power supply system, power supply control apparatus, and power supply control method and program in power supply system | |
| CN210167803U (en) | Voltage sag protector for contactor | |
| CN203721639U (en) | Anti-interference-electricity delay timer | |
| CN209844635U (en) | Intelligent redundant power supply conversion device | |
| Amin et al. | Re-synchronization of universal droop control distributed generation inverter to the grid | |
| WO2019159513A1 (en) | Power storage control device, power storage control method, and computer program | |
| CN204615638U (en) | A kind of the soft of high-voltage cascade frequency converter opens circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant |