CN111181137A - Contactor protection method and circuit of wind energy converter - Google Patents
Contactor protection method and circuit of wind energy converter Download PDFInfo
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- CN111181137A CN111181137A CN201811339266.3A CN201811339266A CN111181137A CN 111181137 A CN111181137 A CN 111181137A CN 201811339266 A CN201811339266 A CN 201811339266A CN 111181137 A CN111181137 A CN 111181137A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
- H02H7/222—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices for switches
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Abstract
A contactor protection method of a wind energy converter comprises the following steps: s1, connecting at least two contactors in parallel between a generator of a wind energy converter and a grid-connected switch; s2, cross-disconnecting a first contactor and a second contactor of the two contactors based on the alarm signal to clean the first contactor and the second contactor. The invention also relates to a contactor protection circuit of the wind energy converter. By implementing the contactor protection method and the circuit of the wind energy converter, the parallel contactors are switched off in a time-sharing manner, so that the main contact of the contactor is cleaned by utilizing the generated electric arc, and the condition that the main contact of the contactor is heated seriously due to the abnormal resistance of the main contact of the contactor caused by dust deposition, and the insulating part is overheated and aged in advance can be avoided.
Description
Technical Field
The invention relates to the field of converters, in particular to a contactor protection method and circuit of a wind energy converter.
Background
With the common application of high-power wind energy converters, such as double-fed 2.5MW, double-fed 3MW, direct-driven 3MW and the like, the current situation of low cost competition of the wind energy converters and the difficulty in developing large-current contactors, more and more wind energy converter manufacturers and complete machine manufacturers tend to use contactors in parallel, the requirements on high power can be met, the system cost can be reduced, and mature contactor products are applied to machines.
In the existing wind energy converter, contactors are usually directly connected in parallel and are synchronously closed according to control logic, the current of the parallel contactors is realized by the contact resistance of a main contact of the parallel contactors, the condition that the current of the parallel contactors is uneven inevitably exists due to the difference of the contact resistance, and when the parallel contactors are disconnected, the current difference generates different degrees of arc discharge, arc discharge time and arc extinguishing time difference, so that the main contacts of the parallel contactors are ablated to different degrees, and the difference can be further aggravated by the contact resistance of the main contacts. On the other hand, the contact resistance is also significantly affected by the difference in the dust coverage on the main contacts of the grid-connected contactor. Due to contact resistance problems, premature degradation of one or some of the parallel contacts due to overheating of the insulation may result.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method and a circuit for protecting a contactor of a wind energy converter, which can avoid serious heating of a main contact of the contactor due to abnormal resistance of the main contact of the contactor caused by dust deposition, and lead to overheating and premature aging of an insulating member, aiming at the above defects of the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: the contactor protection method for constructing the wind energy converter comprises the following steps:
s1, connecting at least two contactors in parallel between a generator of a wind energy converter and a grid-connected switch;
s2, cross-disconnecting a first contactor and a second contactor of the two contactors based on the alarm signal to clean the first contactor and the second contactor.
In the contactor protection method of the wind power converter according to the present invention, the step S2 further includes:
s21, opening the first contactor to transfer the load current to the second contactor based on the alarm signal; opening the second contactor to generate an arc discharge on the second contactor to clean the second contactor;
s22, opening the second contactor again to transfer the load current to the first contactor; and opening the first contactor again to generate arc discharge on the first contactor so as to clean the first contactor.
In the method for protecting a contactor of a wind power converter according to the present invention, the step S2 further includes, before the step S21, the step S20: and comparing the sampling current value of the first contactor with a first design current value and/or comparing the sampling current value of the second contactor with a second design current value, and outputting a normal operation signal or the alarm signal based on the comparison result.
In the contactor protection method of the wind power converter according to the present invention, the step S21 further includes:
s211, sampling the stator current of the wind energy converter;
s212, judging whether the stator current is smaller than a preset current value, if so, executing a step S213, otherwise, returning to the step S211;
s213, canceling the driving signal of the first contactor to transfer the load current to the second contactor;
s214, detecting whether the state of a feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S215, otherwise, continuously detecting;
s215, canceling a driving signal of the second contactor to generate arc discharge on the second contactor so as to clean the second contactor;
s216, detecting whether the state of the feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S22, otherwise, continuing the detection.
In the contactor protection method of the wind power converter according to the present invention, the step S22 further includes:
s221, sampling the stator current of the wind energy converter;
s222, judging whether the stator current is smaller than a preset current value, if so, executing the step S223, otherwise, returning to the step S221;
s223, canceling a driving signal of the second contactor to transfer load current to the first contactor;
s224, detecting whether the state of a feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S225, otherwise, continuously detecting;
s225, canceling a driving signal of the first contactor to generate arc discharge on the first contactor so as to clean the first contactor;
s226, detecting whether the state of the feedback contact of the first contactor changes, if so, judging that the breaking is successful, returning to the step S21, and if not, continuing the detection.
In the method for protecting a contactor of a wind energy converter according to the present invention, in step S1, three contactors are connected in parallel between a generator of the wind energy converter and a grid-connected switch; in the step S2, a first contactor, a second contactor, and a third contactor are alternately opened to clean the first contactor, the second contactor, and the third contactor based on an alarm signal.
In the contactor protection method of the wind power converter according to the present invention, the step S2 further includes:
s2a, opening the first contactor to transfer load current to the second contactor and the third contactor based on the alarm signal; opening the second contactor to transfer the load current to the third contactor; opening the third contactor to generate an arc discharge on the third contactor to clean the third contactor;
s2b, opening the second contactor again to transfer the load current to the first contactor and the third contactor; re-opening the third contactor to divert load current to the first contactor; re-opening the first contactor to generate an arc discharge on the first contactor to clean the first contactor;
s2c, opening the third contactor again to transfer the load current to the first contactor and the second contactor; re-opening the first contactor to divert load current to the second contactor; and opening the second contactor again to generate arc discharge on the second contactor so as to clean the second contactor.
In the method for protecting a contactor of a wind power converter according to the present invention, the step S2a further includes:
s2a1, sampling the stator current of the wind energy converter;
s2a2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2a3, otherwise, returning to the step S2a 1;
s2a3, canceling the driving signal of the first contactor to transfer the load current to the second contactor and the third contactor;
s2a4, detecting whether the state of a feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S2a5, otherwise, continuing the detection;
s2a5, canceling the driving signal of the second contactor to transfer the load current to the third contactor;
s2a6, detecting whether the state of a feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S2a7, otherwise, continuing the detection;
s2a7, canceling the driving signal of the third contactor to generate arc discharge on the third contactor so as to clean the third contactor;
s2a8, detecting whether the state of the feedback contact of the third contactor changes, if so, judging that the breaking is successful, and executing the step S2b, otherwise, continuing the detection.
In the method for protecting a contactor of a wind power converter according to the present invention, the step S2b further includes:
s2b1, sampling the stator current of the wind energy converter;
s2b2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2b3, otherwise, returning to the step S2b 1;
s2b3, canceling the driving signal of the second contactor to transfer the load current to the first contactor and the third contactor;
s2b4, detecting whether the state of a feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S2b5, otherwise, continuing the detection;
s2b5, canceling the driving signal of the third contactor to transfer the load current to the first contactor;
s2b6, detecting whether the state of a feedback contact of the third contactor changes, if so, judging that the breaking is successful, and executing the step S2b7, otherwise, continuing the detection;
s2b7, canceling the driving signal of the first contactor to generate arc discharge on the first contactor so as to clean the first contactor;
s2b8, detecting whether the state of the feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S2c, otherwise, continuing the detection.
In the method for protecting a contactor of a wind power converter according to the present invention, the step S2c further includes:
s2c1, sampling the stator current of the wind energy converter;
s2c2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2c3, otherwise, returning to the step S2c 1;
s2c3, canceling a driving signal of the third contactor to transfer load current to the first contactor and the second contactor;
s2c4, detecting whether the state of a feedback contact of the third contactor changes, if so, judging that the breaking is successful, and executing the step S2c5, otherwise, continuing the detection;
s2c5, canceling the driving signal of the first contactor to transfer the load current to the second contactor;
s2c6, detecting whether the state of a feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S2c7, otherwise, continuing the detection;
s2c7, canceling the driving signal of the second contactor to generate arc discharge on the second contactor so as to clean the second contactor;
s2c8, detecting whether the state of the feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S2a, otherwise, continuing the detection.
The technical scheme adopted for solving the technical problems is that a contactor protection circuit of a wind energy converter is constructed, and the contactor protection circuit comprises: the protection method comprises a grid-connected switch, a generator, a rotor side module, a grid side module, a main contactor module and at least two contactors connected in parallel between the generator and the grid-connected switch, wherein the grid-connected switch, the generator, the rotor side module, the grid side module and the main contactor module are sequentially connected in series, the protection method further comprises a control module used for controlling the at least two contactors, and a computer program is stored on the control module.
By implementing the contactor protection method and the circuit of the wind energy converter, the parallel contactors are switched off in a time-sharing manner, so that the main contact of the contactor is cleaned by utilizing the generated electric arc, and the condition that the main contact of the contactor is heated seriously due to the abnormal resistance of the main contact of the contactor caused by dust deposition, and the insulating part is overheated and aged in advance can be avoided. Further, the contactor protection method and circuit of the wind energy converter can be applied to the condition that two or more contactors are connected in parallel.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
fig. 1 is a flow chart of a first embodiment of the contactor protection method of a wind energy converter of the present invention;
FIG. 2 is a flow chart of a second embodiment of the contactor protection method of the wind energy converter of the present invention;
FIG. 3 is a flow chart of a second contactor cleaning step of a third embodiment of the contactor protection method of the wind energy converter of the present invention;
FIG. 4 is a flow chart of the first contactor cleaning step of the third embodiment of the contactor protection method of the wind energy converter of the present invention;
FIG. 5 is a flow chart of a fourth embodiment of the contactor protection method of the wind energy converter of the present invention;
fig. 6 is a schematic circuit diagram of a first exemplary embodiment of a contactor protection circuit of a wind energy converter according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention relates to a contactor protection method of a wind energy converter, which comprises the following steps: s1, connecting at least two contactors in parallel between a generator of a wind energy converter and a grid-connected switch; s2, cross-disconnecting a first contactor and a second contactor of the two contactors based on the alarm signal to clean the first contactor and the second contactor. By implementing the contactor protection method of the wind energy converter, the parallel contactors are switched off in a time-sharing manner, so that the main contacts of the contactors are cleaned by utilizing the generated electric arc, and the condition that the main contacts of the contactors are heated seriously due to the abnormal resistance of the main contacts of the contactors caused by dust deposition, and the insulators are overheated and aged in advance can be avoided.
Fig. 1 is a flow chart of a first embodiment of the contactor protection method of a wind energy converter of the present invention. As shown in fig. 1, at step S1, at least two contactors are connected in parallel between the generator of the wind energy converter and the grid-connected switch. In a preferred embodiment of the invention, the first contactor and the second contactor are connected in parallel. In another preferred embodiment of the present invention, a plurality of contactors, such as a first contactor, a second contactor, a third contactor, and the like, may be connected in parallel.
In step S2, a first contactor and a second contactor of the two contactors are cross-opened based on an alarm signal to clean the first contactor and the second contactor. In a preferred embodiment of the invention, the alert signal may be generated based on current sensing of the first contactor and the second contactor. For example, the respective phase current values of the first contactor and the second contactor may be collected respectively, and the phase current values may be compared with the design current value, and when one of the phase current values exceeds the design current value, the alarm signal may be output. For example, the current value of each phase can be detected by adding three current transformers to the three-phase copper bars of the first contactor and the second contactor respectively. In another preferred embodiment of the present invention, the total current of each phase of the first contactor and the second contactor after being connected in parallel may be collected, then the current of each phase of the first contactor or the second contactor may be collected, and then the current of each phase of the second contactor or the first contactor may be calculated. And then comparing the current value of each phase of the first contactor and the second contactor with the designed current value, and outputting the alarm signal when one phase of the current value exceeds the designed current value. In a further preferred embodiment of the present invention, the respective phase voltage values of the first contactor and the second contactor may be selected to be compared with respective design voltage values, and an alarm signal may be generated when any one of the phase voltage values is greater than the design voltage value. In a further preferred embodiment of the present invention, the voltage comparison scheme may be designed with reference to the various current comparison schemes described above. In another preferred embodiment of the present invention, the alarm signal may be generated based on time, such as by automatically cross-cutting the first contactor and the second contactor at certain intervals. In other preferred embodiments of the present invention, the alert signal may also be generated based on other conditions.
In a preferred embodiment of the present invention, the sequence of the opening of the first contactor and the second contactor may be adjusted according to the actual situation, for example, the first contactor is opened for the first time, and the second contactor is opened again. The second contactor is then opened a second time, followed by opening the first contactor. In another preferred embodiment of the invention, the first contactor is disconnected first, and then the second contactor is disconnected within a certain period of time (e.g., 10 days). The second contactor is first opened and then the first contactor is opened for a certain period of time (e.g., 10 days).
When the first contactor is switched off firstly, the load current is naturally transferred to the second contactor, so that the arc discharge on the first contactor is not obvious; when the second contactor is cut off again, the load current is completely cut off by the second contactor, so that the second contactor has obvious arc discharge, and the arc has the function of cleaning the main contact of the second contactor.
When the second contactor is switched off firstly, the load current is naturally transferred to the first contactor, so that the arc discharge on the second contactor is not obvious; when the first contactor is re-opened, the load current is completely opened by the first contactor, so that the first contactor has obvious arc discharge, and the arc has the function of cleaning the main contact of the first contactor.
By implementing the contactor protection method of the wind energy converter, the parallel contactors are switched off in a time-sharing manner, so that the main contacts of the contactors are cleaned by utilizing the generated electric arc, and the condition that the main contacts of the contactors are heated seriously due to the abnormal resistance of the main contacts of the contactors caused by dust deposition, and the insulators are overheated and aged in advance can be avoided.
Fig. 2 is a flow chart of a second embodiment of the contactor protection method of the wind energy converter of the present invention. As shown in fig. 2, at step S1, at least two contactors are connected in parallel between the generator of the wind energy converter and the grid-connected switch. In a preferred embodiment of the invention, the first contactor and the second contactor are connected in parallel. In another preferred embodiment of the present invention, a plurality of contactors, such as a first contactor, a second contactor, a third contactor, and the like, may be connected in parallel.
In step S2, the sampled current value of the first contactor is compared with a first design current value and/or the sampled current value of the second contactor is compared with a second design current value, and a normal operation signal or the alarm signal is output based on the comparison result. For example, the respective phase current values of the first contactor and the second contactor may be collected respectively, and the phase current values may be compared with the design current value, and when one of the phase current values exceeds the design current value, the alarm signal may be output. For example, the current value of each phase can be detected by adding three current transformers to the three-phase copper bars of the first contactor and the second contactor respectively. In another preferred embodiment of the present invention, the total current of each phase of the first contactor and the second contactor after being connected in parallel may be collected, then the current of each phase of the first contactor or the second contactor may be collected, and then the current of each phase of the second contactor or the first contactor may be calculated. And then comparing the current value of each phase of the first contactor and the second contactor with the designed current value, and outputting the alarm signal when one phase of the current value exceeds the designed current value.
In step S3, opening the first contactor to divert load current to the second contactor based on the alarm signal; opening the second contactor to generate an arc discharge on the second contactor to clean the second contactor. In the embodiment, when the first contactor is disconnected firstly, the load current is naturally transferred to the second contactor, so that the arc discharge on the first contactor is not obvious; when the second contactor is cut off again, the load current is completely cut off by the second contactor, so that the second contactor has obvious arc discharge, and the arc has the function of cleaning the main contact of the second contactor.
In step S4, opening the second contactor again to transfer the load current to the first contactor; and opening the first contactor again to generate arc discharge on the first contactor so as to clean the first contactor. In the embodiment, when the second contactor is disconnected firstly, the load current is naturally transferred to the first contactor, so that the arc discharge on the second contactor is not obvious; when the first contactor is re-opened, the load current is completely opened by the first contactor, so that the first contactor has obvious arc discharge, and the arc has the function of cleaning the main contact of the first contactor.
By implementing the contactor protection method of the wind energy converter, the parallel contactors are switched off in a time-sharing manner, so that the main contacts of the contactors are cleaned by utilizing the generated electric arc, and the condition that the main contacts of the contactors are heated seriously due to the abnormal resistance of the main contacts of the contactors caused by dust deposition, and the insulators are overheated and aged in advance can be avoided.
Fig. 3 is a flow chart of the second contactor cleaning step of the third embodiment of the contactor protection method of the wind energy converter of the present invention. Fig. 4 is a flow chart of the first contactor cleaning step of the third embodiment of the contactor protection method of the wind energy converter of the present invention. In the preferred embodiment shown in fig. 3-4, a preferred step of breaking cleaning is shown for some breaks requiring longer time or arcs requiring larger contactors.
As shown in fig. 3, in step S1, the stator current of the wind energy converter is sampled. In a preferred embodiment of the invention, the stator current can be detected by adding a current transformer to the stator of the wind energy converter. In step S2, it is determined whether the stator current is less than a preset current value, if so, step S3 is performed, otherwise, step S2 is returned to. In the step S2, the preset current value refers to a current that can be reliably cut off by a single grid-connected contactor, and the preset current value can generate an arc. It may be a built-in parameter of the grid-connected contactor, or may be set by a person skilled in the art. In step S3, the driving signal of the first contactor is cancelled to transfer the load current to the second contactor. And canceling the driving signal of the first contactor, namely, opening the first contactor. Since the breaking time of different contactors may be different, in order to avoid performing subsequent operations when the contactors are not fully broken, step S4 may be performed, i.e., whether the state of the feedback contact of the first contactor is changed or not is detected, if so, the breaking is determined to be successful, and step S5 is performed, otherwise, the detection is continued until the state of the feedback contact of the first contactor is changed. In step S5, the driving signal of the second contactor is cancelled to generate an arc discharge on the second contactor to clean the second contactor. In step S6, it is detected whether the feedback contact state of the second contactor changes, if yes, the disconnection is determined to be successful, the cleaning step of the second contactor is ended, step S22 shown in fig. 2 or the embodiment shown in fig. 4 may be further executed to perform the cleaning step of the first contactor, otherwise, the detection is continued. In the embodiment, when the first contactor is disconnected firstly, the load current is naturally transferred to the second contactor, so that the arc discharge on the first contactor is not obvious; when the second contactor is cut off again, the load current is completely cut off by the second contactor, so that the second contactor has obvious arc discharge, and the arc has the function of cleaning the main contact of the second contactor.
As shown in fig. 4, in step S1, the stator current of the wind energy converter is sampled. In a preferred embodiment of the invention, the stator current can be detected by adding a current transformer to the stator of the wind energy converter. In step S2, it is determined whether the stator current is less than a preset current value, if so, step S3 is performed, otherwise, step S2 is returned to. In the step S2, the preset current value refers to a current that can be reliably cut off by a single grid-connected contactor, and the preset current value can generate an arc. It may be a built-in parameter of the grid-connected contactor, or may be set by a person skilled in the art. In step S3, the driving signal of the second contactor is cancelled to transfer the load current to the first contactor. And canceling the driving signal of the second contactor, namely, opening the second contactor. Since the breaking time of different contactors may be different, in order to avoid performing subsequent operations when the contactor is not fully broken, step S4 may be performed, i.e., whether the state of the feedback contact of the second contactor is changed is detected, if so, the breaking is determined to be successful, and step S5 is performed, otherwise, the detection is continued until the state of the feedback contact of the second contactor is changed. In step S5, the driving signal of the first contactor is cancelled to generate an arc discharge on the first contactor to clean the first contactor. In step S6, it is detected whether the feedback contact state of the first contactor changes, if yes, the disconnection is determined to be successful, the cleaning step of the first contactor is ended, step S21 shown in fig. 2 or the cleaning step of the second contactor in the embodiment shown in fig. 3 can be further executed, otherwise, the detection is continued. In the embodiment, when the second contactor is disconnected firstly, the load current is naturally transferred to the first contactor, so that the arc discharge on the second contactor is not obvious; when the first contactor is re-opened, the load current is completely opened by the first contactor, so that the first contactor has obvious arc discharge, and the arc has the function of cleaning the main contact of the first contactor.
By implementing the contactor protection method of the wind energy converter, the parallel contactors are switched off in a time-sharing manner, so that the main contacts of the contactors are cleaned by utilizing the generated electric arc, and the condition that the main contacts of the contactors are heated seriously due to the abnormal resistance of the main contacts of the contactors caused by dust deposition, and the insulators are overheated and aged in advance can be avoided.
Fig. 5 is a flow chart of a fourth embodiment of the contactor protection method of the wind energy converter of the present invention. Fig. 5 shows a case where three contactors are provided in parallel. The principle is in fact similar to the case of two contactors in parallel as shown in fig. 1-4. In step S1, three contactors are connected in parallel between the generator of the wind energy converter and the grid-connected switch. In step S2, a first contactor, a second contactor, and a third contactor are alternately opened to clean the first contactor, the second contactor, and the third contactor based on an alarm signal.
In a preferred embodiment of the present invention, the alarm signal may be generated based on current detection of the first contactor, the second contactor, and the third contactor. For example, the respective phase current values of the first contactor, the second contactor and the third contactor may be respectively collected, and the phase current values may be compared with the design current value, and when one of the phase current values exceeds the design current value, the alarm signal may be output. For example, the detection of the current value of each phase can be performed by adding three current transformers to the three-phase copper bars of the first contactor, the second contactor and the third contactor respectively. In another preferred embodiment of the present invention, the total current of each phase of the first contactor, the second contactor and the third contactor after being connected in parallel may be collected, then the current of each phase of the first contactor and the second contactor may be collected, and then the current of each phase of the third contactor may be calculated. And then comparing the current value of each phase of the first contactor, the second contactor and the third contactor with the respective design current value, and outputting the alarm signal when one phase of the current value exceeds the design current value. Of course, the phase currents of any two contactors may be collected, and the phase currents of the other contactor may be calculated. In a further preferred embodiment of the invention, it is also possible to only compare the total current of the phases with the total design current and to generate an alarm signal when the total current of the phases is higher than the total design current. In still another preferred embodiment of the present invention, each phase voltage value of each of the first contactor, the second contactor, and the third contactor may be selected to be compared with a design voltage value, and the alarm signal may be output when one of the phase voltage values exceeds the design voltage value. Of course, the voltage of each phase of any two contactors can be collected, and the voltage of each phase of the other contactor can be calculated. In another preferred embodiment of the present invention, the alarm signal may be generated based on time, such as by automatically cross-connecting the first contactor, the second contactor, and the third contactor at regular intervals. In other preferred embodiments of the present invention, the alert signal may also be generated based on other conditions.
In a preferred embodiment of the present invention, the step S2 further includes: s2a, opening the first contactor to transfer load current to the second contactor and the third contactor based on the alarm signal; opening the second contactor to transfer the load current to the third contactor; opening the third contactor to generate an arc discharge on the third contactor to clean the third contactor; s2b, opening the second contactor again to transfer the load current to the first contactor and the third contactor; re-opening the third contactor to divert load current to the first contactor; re-opening the first contactor to generate an arc discharge on the first contactor to clean the first contactor; s2c, opening the third contactor again to transfer the load current to the first contactor and the second contactor; re-opening the first contactor to divert load current to the second contactor; and opening the second contactor again to generate arc discharge on the second contactor so as to clean the second contactor.
In the invention, the first contactor can be disconnected first, the second contactor can be disconnected after the first contactor is disconnected, the third contactor can be disconnected after the second contactor is disconnected, and the main contact of the third contactor is cleaned by electric arc because the load current is finally disconnected by the third contactor. And then, the second contactor is switched off firstly, the third contactor is switched off after the second contactor is switched off, the first contactor is switched off after the third contactor is switched off, and the main contact of the first contactor is cleaned by electric arc because the load current is finally switched off by the first contactor. And finally, the third contactor is switched off firstly, the first contactor is switched off after the third contactor is switched off, the second contactor is switched off after the first contactor is switched off, and the main contact of the second contactor is cleaned by electric arc because the load current is switched off finally by the second contactor. The purpose of cleaning a plurality of parallel contact main contacts can be achieved by breaking load current by a plurality of parallel contacts in turn, and the problems of premature aging and failure of insulation caused by abnormal resistance change of the contacts are avoided.
Also, in order to ensure that the breaking is successful, the cleaning of the first contactor, the second contactor and the third contactor may be performed with reference to the embodiment shown in fig. 3-4.
The cleaning of the third contactor may include: s2a1, sampling the stator current of the wind energy converter; s2a2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2a3, otherwise, returning to the step S2a 1; s2a3, canceling the driving signal of the first contactor to transfer the load current to the second contactor and the third contactor; s2a4, detecting whether the state of a feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S2a5, otherwise, continuing the detection; s2a5, canceling the driving signal of the second contactor to transfer the load current to the third contactor; s2a6, detecting whether the state of a feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S2a7, otherwise, continuing the detection; s2a7, canceling the driving signal of the third contactor to generate arc discharge on the third contactor so as to clean the third contactor; and S2a8, detecting whether the state of the feedback contact of the third contactor changes, if so, judging that the breaking is successful and cleaning the first contactor is carried out, otherwise, continuously detecting.
The cleaning of the first contactor may include: s2b1, sampling the stator current of the wind energy converter; s2b2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2b3, otherwise, returning to the step S2b 1; s2b3, canceling the driving signal of the second contactor to transfer the load current to the first contactor and the third contactor; s2b4, detecting whether the state of a feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S2b5, otherwise, continuing the detection; s2b5, canceling the driving signal of the third contactor to transfer the load current to the first contactor; s2b6, detecting whether the state of a feedback contact of the third contactor changes, if so, judging that the breaking is successful, and executing the step S2b7, otherwise, continuing the detection; s2b7, canceling the driving signal of the first contactor to generate arc discharge on the first contactor so as to clean the first contactor; s2b8, detecting whether the state of the feedback contact of the first contactor changes, if so, judging that the breaking is successful and cleaning the second contactor is carried out, otherwise, continuously detecting.
Cleaning of the second contactor may comprise S2c1, sampling the stator current of the wind energy converter; s2c2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2c3, otherwise, returning to the step S2c 1; s2c3, canceling a driving signal of the third contactor to transfer load current to the first contactor and the second contactor; s2c4, detecting whether the state of a feedback contact of the third contactor changes, if so, judging that the breaking is successful, and executing the step S2c5, otherwise, continuing the detection; s2c5, canceling the driving signal of the first contactor to transfer the load current to the second contactor; s2c6, detecting whether the state of a feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S2c7, otherwise, continuing the detection; s2c7, canceling the driving signal of the second contactor to generate arc discharge on the second contactor so as to clean the second contactor; and S2c8, detecting whether the state of the feedback contact of the second contactor changes, if so, judging that the breaking is successful, and cleaning the third contactor, otherwise, continuously detecting.
It is known to those skilled in the art that, throughout the present application, the first, second and third contactors are only used for distinguishing contactors, and are not particularly limited to a certain contactor, and the arrangement positions of the first, second and third contactors may be changed as needed as long as they are connected in parallel.
By implementing the contactor protection method of the wind energy converter, the parallel contactors are switched off in a time-sharing manner, so that the main contacts of the contactors are cleaned by utilizing the generated electric arc, and the condition that the main contacts of the contactors are heated seriously due to the abnormal resistance of the main contacts of the contactors caused by dust deposition, and the insulators are overheated and aged in advance can be avoided. Further, the contactor protection method of the wind energy converter can be applied to the condition that two or more contactors are connected in parallel.
Fig. 6 is a schematic circuit diagram of a first exemplary embodiment of a contactor protection circuit of a wind energy converter according to the present invention. As shown in fig. 6, the contactor protection circuit of the wind power converter of the present invention includes: the system comprises a grid-connected switch 10, a generator 20, a rotor-side module 30, a grid-side module 40, a main contactor module 50, at least two contactors KM101 and KM102 connected in parallel between the generator 20 and the grid-connected switch 10, and a control module 70 for controlling the at least two contactors, which are sequentially connected in series. In the preferred embodiment shown in fig. 6, a suppression reactor 60 is provided between the generator 20 and the rotor side module 30, and a filter module LCL is provided between the grid side module 40 and the main contactor module 50. It will be appreciated by those skilled in the art that the grid-tie switch 10, the generator 20, the rotor-side module 30, the grid-side module 40, the main contactor module 50, the suppression reactor 60 and the filter module LCL may be any module, device and circuit configuration known in the art and will not be described in detail herein. In the present embodiment, the control module 70 stores a computer program, and the computer program, when executed by the control module 70, implements any one of the methods for protecting a contactor of a wind energy converter described in fig. 1 to 5 and the corresponding text of the specification.
The contactor protection circuit of the wind energy converter is implemented to divide the parallel contactors in a time-sharing way, so that the main contacts of the contactors are cleaned by the generated electric arcs, and the condition that the main contacts of the contactors are heated seriously due to the abnormal resistance of the main contacts of the contactors caused by dust deposition, and the insulators are overheated and aged in advance can be avoided. Further, the contactor protection circuit of the wind energy converter can be applied to the condition that two or more contactors are connected in parallel.
Accordingly, the present invention can be realized in hardware, software, or a combination of hardware and software. The present invention can be realized in a centralized fashion in at least one computer system, or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods of the present invention is suited. A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein.
The present invention may also be implemented by a computer program product, comprising all the features enabling the implementation of the methods of the invention, when loaded in a computer system. The computer program in this document refers to: any expression, in any programming language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to other languages, codes or symbols; b) reproduced in a different format.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (11)
1. A contactor protection method of a wind energy converter is characterized by comprising the following steps:
s1, connecting at least two contactors in parallel between a generator of a wind energy converter and a grid-connected switch;
s2, cross-disconnecting a first contactor and a second contactor of the two contactors based on the alarm signal to clean the first contactor and the second contactor.
2. The contactor protection method for the wind power converter according to claim 1, wherein the step S2 further comprises:
s21, opening the first contactor to transfer the load current to the second contactor based on the alarm signal; opening the second contactor to generate an arc discharge on the second contactor to clean the second contactor;
s22, opening the second contactor again to transfer the load current to the first contactor; and opening the first contactor again to generate arc discharge on the first contactor so as to clean the first contactor.
3. The contactor protection method of a wind power converter according to claim 2, wherein said step S2 further comprises, before performing step S21, performing step S20: and comparing the sampling current value of the first contactor with a first design current value and/or comparing the sampling current value of the second contactor with a second design current value, and outputting a normal operation signal or the alarm signal based on the comparison result.
4. The contactor protection method of a wind power converter according to claim 2, wherein said step S21 further comprises:
s211, sampling the stator current of the wind energy converter;
s212, judging whether the stator current is smaller than a preset current value, if so, executing a step S213, otherwise, returning to the step S211;
s213, canceling the driving signal of the first contactor to transfer the load current to the second contactor;
s214, detecting whether the state of a feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S215, otherwise, continuously detecting;
s215, canceling a driving signal of the second contactor to generate arc discharge on the second contactor so as to clean the second contactor;
s216, detecting whether the state of the feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S22, otherwise, continuing the detection.
5. The contactor protection method of a wind power converter according to claim 2, wherein said step S22 further comprises:
s221, sampling the stator current of the wind energy converter;
s222, judging whether the stator current is smaller than a preset current value, if so, executing the step S223, otherwise, returning to the step S221;
s223, canceling a driving signal of the second contactor to transfer load current to the first contactor;
s224, detecting whether the state of a feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S225, otherwise, continuously detecting;
s225, canceling a driving signal of the first contactor to generate arc discharge on the first contactor so as to clean the first contactor;
s226, detecting whether the state of the feedback contact of the first contactor changes, if so, judging that the breaking is successful, returning to the step S21, and if not, continuing the detection.
6. The contactor protection method of the wind power converter according to claim 1, wherein in step S1, three contactors are connected in parallel between the generator and the grid-connected switch of the wind power converter; in the step S2, a first contactor, a second contactor, and a third contactor are alternately opened to clean the first contactor, the second contactor, and the third contactor based on an alarm signal.
7. The contactor protection method for the wind power converter according to claim 6, wherein the step S2 further comprises:
s2a, opening the first contactor to transfer load current to the second contactor and the third contactor based on the alarm signal; opening the second contactor to transfer the load current to the third contactor; opening the third contactor to generate an arc discharge on the third contactor to clean the third contactor;
s2b, opening the second contactor again to transfer the load current to the first contactor and the third contactor; re-opening the third contactor to divert load current to the first contactor; re-opening the first contactor to generate an arc discharge on the first contactor to clean the first contactor;
s2c, opening the third contactor again to transfer the load current to the first contactor and the second contactor; re-opening the first contactor to divert load current to the second contactor; and opening the second contactor again to generate arc discharge on the second contactor so as to clean the second contactor.
8. The contactor protection method for the wind power converter according to claim 7, wherein the step S2a further comprises:
s2a1, sampling the stator current of the wind energy converter;
s2a2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2a3, otherwise, returning to the step S2a 1;
s2a3, canceling the driving signal of the first contactor to transfer the load current to the second contactor and the third contactor;
s2a4, detecting whether the state of a feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S2a5, otherwise, continuing the detection;
s2a5, canceling the driving signal of the second contactor to transfer the load current to the third contactor;
s2a6, detecting whether the state of a feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S2a7, otherwise, continuing the detection;
s2a7, canceling the driving signal of the third contactor to generate arc discharge on the third contactor so as to clean the third contactor;
s2a8, detecting whether the state of the feedback contact of the third contactor changes, if so, judging that the breaking is successful, and executing the step S2b, otherwise, continuing the detection.
9. The contactor protection method for the wind power converter according to claim 7, wherein the step S2b further comprises:
s2b1, sampling the stator current of the wind energy converter;
s2b2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2b3, otherwise, returning to the step S2b 1;
s2b3, canceling the driving signal of the second contactor to transfer the load current to the first contactor and the third contactor;
s2b4, detecting whether the state of a feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S2b5, otherwise, continuing the detection;
s2b5, canceling the driving signal of the third contactor to transfer the load current to the first contactor;
s2b6, detecting whether the state of a feedback contact of the third contactor changes, if so, judging that the breaking is successful, and executing the step S2b7, otherwise, continuing the detection;
s2b7, canceling the driving signal of the first contactor to generate arc discharge on the first contactor so as to clean the first contactor;
s2b8, detecting whether the state of the feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S2c, otherwise, continuing the detection.
10. The contactor protection method for the wind power converter according to claim 7, wherein the step S2c further comprises:
s2c1, sampling the stator current of the wind energy converter;
s2c2, judging whether the stator current is smaller than a preset current value, if so, executing a step S2c3, otherwise, returning to the step S2c 1;
s2c3, canceling a driving signal of the third contactor to transfer load current to the first contactor and the second contactor;
s2c4, detecting whether the state of a feedback contact of the third contactor changes, if so, judging that the breaking is successful, and executing the step S2c5, otherwise, continuing the detection;
s2c5, canceling the driving signal of the first contactor to transfer the load current to the second contactor;
s2c6, detecting whether the state of a feedback contact of the first contactor changes, if so, judging that the breaking is successful, and executing the step S2c7, otherwise, continuing the detection;
s2c7, canceling the driving signal of the second contactor to generate arc discharge on the second contactor so as to clean the second contactor;
s2c8, detecting whether the state of the feedback contact of the second contactor changes, if so, judging that the breaking is successful, and executing the step S2a, otherwise, continuing the detection.
11. A contactor protection circuit for a wind power converter, comprising: a grid-connected switch, a generator, a rotor side module, a grid side module, a main contactor module, and at least two contactors connected in parallel between the generator and the grid-connected switch, which are connected in series in sequence, and further comprising a control module for controlling the at least two contactors, wherein the control module stores a computer program thereon, and the computer program is executed by the control module to implement the contactor protection method of the wind energy converter according to any one of claims 1-10.
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| CN201811339266.3A CN111181137B (en) | 2018-11-12 | 2018-11-12 | Contactor protection method and circuit of wind energy converter |
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| CN201811339266.3A CN111181137B (en) | 2018-11-12 | 2018-11-12 | Contactor protection method and circuit of wind energy converter |
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| CN103855725A (en) * | 2012-12-04 | 2014-06-11 | 浙江海得新能源有限公司 | Converter topology and control method |
| CN105589348A (en) * | 2014-11-06 | 2016-05-18 | 洛克威尔自动控制技术股份有限公司 | Single-pole, single current path switching system and method |
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| US20010036047A1 (en) * | 2000-02-03 | 2001-11-01 | Macbeth Bruce F. | AFCI which detects and interrupts line side arcing |
| US20140028094A1 (en) * | 2012-07-25 | 2014-01-30 | Hamilton Sundstrand Corporation | Power management and distribution with auxiliary dc bus |
| CN103855725A (en) * | 2012-12-04 | 2014-06-11 | 浙江海得新能源有限公司 | Converter topology and control method |
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