CN113162111A - Method and system for reducing reactive impact in power plant grid connection process - Google Patents
Method and system for reducing reactive impact in power plant grid connection process Download PDFInfo
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- CN113162111A CN113162111A CN202110341475.7A CN202110341475A CN113162111A CN 113162111 A CN113162111 A CN 113162111A CN 202110341475 A CN202110341475 A CN 202110341475A CN 113162111 A CN113162111 A CN 113162111A
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- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
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- 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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/28—The renewable source being wind energy
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- 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
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Abstract
A method and a system for reducing reactive power impact in the grid-connected process of a power plant comprise the following steps: acquiring homologous nuclear phase information of a plurality of power devices to be connected to the grid; if the plurality of power devices to be connected to the grid have completed the homologous phase checking, gear information is judged; if the plurality of power devices to be connected to the grid do not complete the homologous nuclear phase, performing a homologous nuclear phase test and finishing the operation information judgment; and if the gear judgment or the operation information judgment is passed, setting closing parameters, namely pressure difference judgment is carried out, and if the pressure difference judgment is passed, sending a grid connection permission signal to the synchronous device. The method for reducing the reactive power impact in the grid-connected process of the power plant effectively solves the problem of large reactive power impact caused by design errors, installation errors, manual operation errors and the like, reduces the damage to power generation equipment, and simultaneously enables the grid-connected process to be more stable.
Description
Technical Field
The invention belongs to the technical field of information, and particularly relates to a method and a system for reducing reactive power impact in a power plant grid connection process.
Background
Along with the construction of domestic large-scale power plant, extra-high voltage electric wire netting accelerates, the further deepening of national foreign electric power engineering, power equipment is also more and more, has consequently also appeared some problems in use and debugging process: when the generator is connected to the grid, a main transformer has larger transient forward reactive impact on a system, the reactive impact value is far larger than the reactive output rated value of a generator-transformer set and the reactive amount in a given load of dispatching, meanwhile, transient reactive impact and voltage fluctuation also occur to a near-end load and a factory power supply of an adjacent unit, excitation alarm can easily occur under extreme conditions, and even overvoltage amplitude limiting action is caused; in this case, the grid connection of the generator may cause voltage oscillation to the adjacent units or loads. Meanwhile, in foreign debugging projects, due to the difference of relevant national electric power specifications, design specifications and application scenes, reactive reverse absorption of partial small and medium-sized unit generators is caused, voltage oscillation-shaped fluctuation of a small power grid is easily caused, and even an event that the adjacent unit trips due to fluctuation occurs.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a method for reducing reactive power impact in the grid-connected process of a power plant, and the method for reducing the reactive power impact in the grid-connected process of the power plant solves the problem of large reactive power impact when a power plant is connected to the grid. The invention also provides a system for reducing reactive power impact in the grid-connected process of the power plant.
According to the embodiment of the first aspect of the invention, the method for reducing the reactive power impact in the grid-connected process of the power plant comprises the following steps:
acquiring homologous nuclear phase information of a plurality of power devices to be connected to the grid;
if the plurality of electric devices to be connected to the grid have completed homologous nuclear phase, judging whether the gear information of the plurality of electric devices to be connected to the grid is consistent with a preset gear setting value, if so, performing closing parameter setting, and if not, stopping connecting to the grid and sending alarm information;
if the plurality of to-be-grid-connected power devices do not complete the same source nuclear phase, performing a same source nuclear phase test, calculating a first difference between the operation information of each to-be-grid-connected power device and preset operation setting information, if the first differences are all within a preset first error allowable range, performing closing parameter setting, and if the first differences exceed the first error allowable range, stopping grid connection and sending alarm information;
the closing parameter setting comprises the following steps: and obtaining second difference values among the actually measured voltage values of the power devices to be connected to the grid, if the second difference values are smaller than a preset second error allowable range, sending a signal allowing the grid connection to the synchronous device, and if the second difference values exceed the second error allowable range, stopping the grid connection and sending alarm information.
The method for reducing reactive power impact in the grid-connected process of the power plant according to the embodiment of the invention at least has the following technical effects: by judging whether homologous nuclear phase is carried out or not, reactive power impact caused by wrong selection of the working mode of the power device to be connected to the grid can be avoided. By carrying out the homologous nuclear phase test, the problem that the voltage level is inconsistent with the design value can be avoided, namely the problem that the type selection of the transformer is wrong or the actual installation is wrong is mainly solved. By judging the gear information, the gear information change caused by human errors can be avoided, and the power device to be connected in parallel for a long time and to be connected in parallel can be prevented from generating larger reactive impact due to the gear information change. Through the setting of the closing parameters, the pressure difference interference of a part of power devices to be connected to the grid, which do not have gear information or cannot send the gear information, can be eliminated. The method for reducing the reactive power impact in the grid-connected process of the power plant effectively solves the problem of large reactive power impact caused by design errors, installation errors, manual operation errors and the like, reduces the damage to power generation equipment, and simultaneously enables the grid-connected process to be more stable.
According to some embodiments of the invention, before entering the closing parameter tuning, the method further comprises the following steps:
acquiring N times of closing time of the power device to be connected to the grid before the current closing, wherein N is larger than a preset time fine-tuning numerical value;
and adjusting a preset closing time setting value according to the closing time of N-1 times before the last closing.
According to some embodiments of the present invention, after the adjusting the preset closing time setting value according to the N-1 closing times before the last closing, the method further comprises the following steps:
calculating a third difference value between the closing time when the last closing is carried out and the adjusted closing time setting value;
and if the third difference is larger than a preset third error allowable range, stopping grid connection and sending alarm information.
According to some embodiments of the invention, the closing parameter tuning further comprises the steps of:
acquiring N reactive impact data corresponding to N times of closing time;
and calculating the reactive impact data with the minimum numerical value in the N reactive impact data, acquiring corresponding voltage data, current data and phase angle data, and adjusting the excitation of the power device to be connected to the grid according to the voltage data, the current data and the phase angle data.
According to some embodiments of the invention, the closing parameter tuning further comprises the steps of:
and obtaining angle difference data, voltage data and current data of each power device to be connected to the grid during the last closing of the power device to be connected to the grid, comparing the angle difference data, the voltage data and the current data of the power device to be connected to the grid during the same-source phase checking, obtaining a fourth difference value, and if the fourth difference value exceeds a preset fourth error allowable range, sending alarm information.
According to a second aspect of the present invention, a system for reducing reactive power impact during grid connection of a power plant includes:
the system comprises a homologous information acquisition module, a phase synchronization module and a phase synchronization module, wherein the homologous information acquisition module is used for acquiring homologous nuclear phase information of a plurality of power devices to be connected to the grid;
the homologous nuclear phase judging module is connected with the homologous information acquiring module and used for judging whether the plurality of electric devices to be connected to the grid complete homologous nuclear phases or not;
the gear information judging module is connected with the homologous kernel phase judging module and is used for judging whether the gear information of the power devices to be connected to the grid is consistent with a preset gear setting value or not;
the test module is connected with the homologous nuclear phase judgment module and is used for carrying out homologous nuclear phase tests on the plurality of to-be-grid-connected electric power devices;
the first fixed value comparison module is connected with the test module and used for calculating a first difference value between the operation information of each power device to be connected to the grid and preset operation setting information and judging whether each first difference value is within a preset first error allowable range or not;
and the closing parameter setting module is respectively connected with the first fixed value comparison module and the gear information judgment module and is used for acquiring second difference values among the actually measured voltage values of the power devices to be connected to the grid and judging whether each second difference value is within a preset second error allowable range.
The system for reducing reactive power impact in the grid-connected process of the power plant, provided by the embodiment of the invention, at least has the following technical effects: whether homologous nuclear phase is performed or not is judged by the homologous nuclear phase judging module, and reactive power impact caused by selection error of a working mode of the power device to be connected to the grid can be avoided. The problem that the voltage grade is inconsistent with the design value can be avoided by performing a homologous nuclear phase test through the test module and the first fixed value comparison module, namely the problem that the type selection error or the actual installation error of the transformer is mainly eliminated. The gear information is judged by the gear information judging module, so that gear information change caused by human errors can be avoided, and large reactive impact on long-term parallel power devices to be connected to the grid due to the gear information change can be avoided. The closing parameter setting module is used for setting closing parameters, so that differential pressure interference existing in a part of power devices to be connected to the grid, which do not have gear information or cannot send gear information, can be eliminated. The system for reducing the reactive power impact in the grid-connected process of the power plant effectively solves the problem of large reactive power impact caused by design errors, installation errors, manual operation errors and the like, reduces the damage to power generation equipment, and simultaneously enables the grid-connected process to be more stable.
According to some embodiments of the invention, the gear information judgment module is further configured to adjust a preset closing time setting value according to N closing times of the power device to be connected to the grid before the current closing; n is larger than a preset time fine-tuning numerical value.
According to some embodiments of the present invention, the gear information determining module is further configured to calculate a third difference between the closing time at the last closing and the adjusted setting value of the closing time, and determine whether to stop grid connection according to the third difference and a preset third error allowable range.
According to some embodiments of the invention, the closing parameter setting module is further configured to compare the angular difference data, the voltage data, and the current data of each to-be-connected grid power device during the last closing with the angular difference data, the voltage data, and the current data of each to-be-connected grid power device during the homologous phase checking, and send alarm information according to the comparison result.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a simplified flow diagram of a method for reducing reactive power surges during grid-connection of a power plant according to an embodiment of the present invention;
FIG. 2 is a block diagram of a data acquisition and processing system according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the directional descriptions, such as the directions of upper, lower, front, rear, left, right, etc., are referred to only for convenience of describing the present invention and for simplicity of description, and are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
A method for reducing reactive power shock during grid connection of a power plant according to an embodiment of the first aspect of the present invention is described below with reference to fig. 1 to 2.
The method for reducing the reactive power impact in the grid-connected process of the power plant comprises the following steps:
acquiring homologous nuclear phase information of a plurality of power devices to be connected to the grid;
if the plurality of electric devices to be connected to the grid have completed homologous nuclear phase, judging whether the gear information of the plurality of electric devices to be connected to the grid is consistent with a preset gear setting value, if so, performing closing parameter setting, and if not, stopping connecting to the grid and sending alarm information;
if the plurality of power devices to be connected to the grid do not complete the same source phase checking, performing a same source phase checking test, calculating a first difference between the operation information of each power device to be connected to the grid and preset operation setting information, if the first differences are within a preset first error allowable range, setting closing parameters, and if the first differences exceed the first error allowable range, stopping the grid connection and sending alarm information;
the closing parameter setting comprises the following steps: and obtaining second difference values among the actually measured voltage values of the plurality of power devices to be connected to the grid, if the second difference values are smaller than a preset second error allowable range, sending a signal allowing the grid to be connected to the synchronous device, and if the second difference values exceed the second error allowable range, stopping the grid connection and sending alarm information.
Referring to fig. 1 and 2, before performing homologous nuclear phase judgment, each power device to be grid-connected is subjected to self-inspection, so that whether a fault of the power device to be grid-connected exists can be eliminated first, and the situation that an error warning signal is sent out due to the fault of the power device to be grid-connected in the following process and the fault elimination in the following process are not facilitated is avoided.
After the self-checking is finished, the homologous nuclear phase conditions of the power devices to be connected to the grid are firstly confirmed, if homologous nuclear phase is performed between the power devices to be connected to the grid, the homologous nuclear phase is not required to be performed again, and if the homologous nuclear phase is not performed, the homologous nuclear phase test is required to be performed.
If the homologous nuclear phase is carried out, gear detection is carried out, in practical engineering, after grid connection is finished every time, errors of operators can occur, and the problem that gears are moved is caused. Therefore, after the homologous phase checking, the gear information of each power device to be grid-connected needs to be compared with a preset gear setting value, and grid connection can be performed only if the gear information of all the power devices to be grid-connected is consistent. If the detected gear information is inconsistent with the gear setting value, the grid connection is stopped, meanwhile, the alarm information is transmitted to the monitoring terminal, and the monitoring terminal can inform an operator to reset the gear after receiving the alarm information, or the gear setting value is modified and the gear information of the power device to be grid connected is synchronously adjusted according to the actual engineering condition, and finally the gear information of all the power devices to be grid connected is adjusted to be consistent with the gear setting value.
If the homologous nuclear phase test is not carried out, the homologous nuclear phase test needs to be carried out again, and after the homologous nuclear phase test, the operation information of the power device to be connected to the grid needs to be compared with preset operation setting information, wherein the comparison of the operation data mainly refers to comparison of voltage data. Comparing the voltage value of each phase of each electric power device to be grid-connected with a setting value on the premise of homology, and if the first difference value generated by all the electric power devices to be grid-connected in the process is within a preset first error allowable range, indicating that the electric power devices to be grid-connected have no connection error, type selection error and installation error, wherein the problem of a transformer is mainly solved: 1. the specific difference of the transformer and the PT equipment is out of tolerance; 2. the transformer design transformation ratio is inconsistent with the synchronous protection design transformation ratio; 3. the type selection of the transformer is wrong or the arrival is not consistent with the design. In some embodiments of the present invention, 2% is selected within the first error allowable range, which may allow less reactive impact and may not increase grid-connection difficulty too much.
After the above steps are completed, the closing parameter setting will be entered, and mainly the differential pressure comparison is performed here. In actual engineering, the problem that part of the power devices to be connected to the grid cannot send gear information or have no gear information exists, the pressure difference comparison is carried out before the last step before grid connection, at the moment, all the power devices to be connected to the grid, which need to be connected to the grid, are in an electrified state, therefore, the pressure difference comparison can be directly carried out on a plurality of power devices to be connected to the grid, which need to be directly connected to the last time, and the second difference is within the second error allowable range, so that the final confirmation can be completed, and at the moment, a grid connection allowable signal can be sent to the synchronous device. After multiple times of grid connection, when the second voltage difference is compared, the second voltage difference can be compared with historical data switching-on voltage data to actively find whether gear change problems exist, for example: the current switching-on voltage value is much larger than the historical switching-on voltage value, so that the obvious problem can be deduced, and at the moment, alarm information is mainly sent out to stop grid connection.
According to the method for reducing the reactive power impact in the grid-connected process of the power plant, whether homologous nuclear phasing is carried out or not is judged, and the reactive power impact caused by the wrong selection of the working mode of the power device to be connected to the grid can be avoided. By carrying out the homologous nuclear phase test, the problem that the voltage level is inconsistent with the design value can be avoided, namely the problem that the type selection of the transformer is wrong or the actual installation is wrong is mainly solved. By judging the gear information, the gear information change caused by human errors can be avoided, and the power device to be connected in parallel for a long time and to be connected in parallel can be prevented from generating larger reactive impact due to the gear information change. Through the setting of the closing parameters, the pressure difference interference of a part of power devices to be connected to the grid, which do not have gear information or cannot send the gear information, can be eliminated. The method for reducing the reactive power impact in the grid-connected process of the power plant effectively solves the problem of large reactive power impact caused by design errors, installation errors, manual operation errors and the like, reduces the damage to power generation equipment, and simultaneously enables the grid-connected process to be more stable.
In some embodiments of the present invention, before entering the closing parameter setting, the method further includes the following steps:
acquiring N times of closing time of the power device to be connected to the grid before the current closing, wherein N is larger than a preset time fine-tuning numerical value;
and adjusting a preset closing time setting value according to N-1 closing times before the last closing.
The initial value of the closing time setting value is set based on theoretical design, but in actual grid-connected work, the closing time may deviate due to various reasons, such as equipment aging, loose wiring and the like. At this time, the switching time setting value needs to be properly adjusted to ensure that the reactive impact is not increased due to the switching time deviation. And adjusting the switching-on time setting value is mainly based on historical switching-on time data, N times of switching-on time of the power device to be connected to the grid before the current switching-on is obtained, further, an average switching-on time value can be calculated by utilizing N-1 times of switching-on time before the last switching-on time, then, the average switching-on time setting value is utilized to carry out fine adjustment, and the average switching-on time value can be directly utilized to replace the switching-on time setting value. The average value of the closing time is calculated without adding the last closing time, and the main reason is that: the switching time can only be obtained after one switching is finished, so that once the last switching time has an error, the calculated average value has an error. The value of N needs to be as reasonable as possible, and cannot be too small, and too small calculated average value loses meaning, where N is generally guaranteed to be more than 5 times, preferably about 20 times is selected to be appropriate, and too large results in excessive calculation.
In some embodiments of the present invention, after adjusting the preset closing time setting value according to N-1 times of the closing time before the last closing, the method further includes the following steps:
calculating a third difference value between the closing time of the last closing and the adjusted closing time setting value;
and if the third difference is larger than a preset third error allowable range, stopping grid connection and sending alarm information.
The reason why the last closing time is not added to the closing time setting value fine adjustment has been described above, but the last closing time is not meaningless. The last closing time can be used for checking whether a fault exists in the power device to be connected to the grid, for example: if the deviation between the last closing time and the closing time setting value after fine adjustment is large, it can be shown that the last closing of the power device to be connected to the grid absolutely has a problem, an alarm needs to be given, manual check is carried out, and the grid connection is not put into use any more. The method of the real-time embodiment of the invention is implemented before the synchronous device works, so that the judgment of overlarge change of the closing time and fault removal cannot be carried out by utilizing the closing time of the time, and the subsequent risks are avoided by skillfully utilizing the closing time of the last time. In some embodiments of the present invention, the average closing time calculated by the closing time of N-1 times may also be used for comparison, so as to effectively prevent the closing time from changing too much. In some embodiments of the present invention, the amount of change in the closing time that is too large is 15%, and the change can be determined to be too large as long as the change exceeds 15%.
In some embodiments of the present invention, the tuning of the closing parameter further comprises the steps of:
acquiring N reactive impact data corresponding to N times of closing time;
and calculating the reactive impact data with the minimum numerical value in the N reactive impact data, acquiring corresponding voltage data, current data and phase angle data, and adjusting the excitation of the power device to be connected to the grid according to the voltage data, the current data and the phase angle data.
The closing time is an important factor influencing reactive shock, but the voltage and the angle during closing are not aligned, so that large reactive shock can be generated, and the optimal closing voltage and angle can be found through historical data. Every time of closing, closing time and non-functional impact data exist, so that after the optimal closing time is known, corresponding non-functional impact data and specific closing time can be confirmed, historical data can be inquired, data such as voltage data, current data and phase angle data corresponding to the moment can be obtained, and then excitation of a grid-connected power device can be adjusted by utilizing the data, so that the closing time, the closing voltage and the closing angle can be close to the optimal value. The selection of the minimum reactive impact data also needs more data as a support, and fewer samples do not have representativeness, but errors are easily introduced. In addition, in some embodiments of the invention, it is also considered that if the situation that the reactive impact is large still exists after excitation optimization is carried out for multiple times, an alarm is needed so as to carry out analysis manually.
In some embodiments of the present invention, the tuning of the closing parameter further comprises the steps of:
and obtaining angle difference data, voltage data and current data of each power device to be connected to the grid during the last closing of the power device to be connected to the grid, comparing the angle difference data, the voltage data and the current data of the power device to be connected to the grid during the same-source core phase, obtaining a fourth difference value, and sending alarm information if the fourth difference value exceeds a preset fourth error allowable range.
All power equipment after putting into operation, the difficult circumstances such as can appear ageing that avoid, and appear ageing after, voltage data, current data, the poor data of PT secondary all can appear changing, consequently, before every combined floodgate, the fourth difference between the data when can comparing last combined floodgate and the data when carrying out the homologous nuclear phase at first, as long as the fourth difference of any one has exceeded fourth error allowable range, it is serious to explain ageing, need send alarm information, let the manual work investigate. In some embodiments of the present invention, the fourth allowable error range is selected to be 2%, and the error is within this range, so that excessive reactive shock is not generated.
The system for reducing the reactive power impact in the power plant grid-connected process comprises a homologous information acquisition module, a homologous nuclear phase judgment module, a gear information judgment module, a test module, a first fixed value comparison module and a closing parameter setting module.
The system comprises a homologous information acquisition module, a phase synchronization module and a phase synchronization module, wherein the homologous information acquisition module is used for acquiring homologous nuclear phase information of a plurality of power devices to be connected to the grid;
the homologous nuclear phase judging module is connected with the homologous information acquiring module and is used for judging whether the plurality of power devices to be connected to the grid complete homologous nuclear phases or not;
the gear information judging module is connected with the homologous kernel phase judging module and is used for judging whether the gear information of the plurality of power devices to be connected to the grid is consistent with a preset gear setting value or not;
the test module is connected with the homologous nuclear phase judgment module and is used for carrying out homologous nuclear phase tests on the plurality of power devices to be connected to the grid;
the first fixed value comparison module is connected with the test module and used for calculating a first difference value between the operation information of each power device to be connected to the grid and preset operation setting information and judging whether each first difference value is within a preset first error allowable range or not;
and the closing parameter setting module is respectively connected with the first fixed value comparison module and the gear information judgment module and is used for acquiring second difference values among the actually measured voltage values of the plurality of power devices to be connected to the grid and judging whether each second difference value is within a preset second error allowable range.
Referring to fig. 1 and 2, before performing homologous nuclear phase judgment, each power device to be grid-connected is subjected to self-inspection, so that whether a fault of the power device to be grid-connected exists can be eliminated first, and the situation that an error warning signal is sent out due to the fault of the power device to be grid-connected in the following process and the fault elimination in the following process are not facilitated is avoided.
After the self-checking is finished, firstly, the homologous nuclear phase judgment module is used for confirming the homologous nuclear phase conditions of the power devices to be connected to the grid, if homologous nuclear phase is performed between the power devices to be connected to the grid, the homologous nuclear phase is not needed to be performed again, and if the homologous nuclear phase is not performed, the homologous nuclear phase test is needed to be performed through the test module.
And if the homologous nuclear phase is already carried out, gear detection is carried out through the gear information judging module. In practical engineering, after grid connection is finished every time, errors of operators can occur, so that the problem that gears are shifted is caused, and at the moment, if grid connection is directly performed, the problem that pressure difference is too large can occur, and reactive power impact is large due to the fact that pressure difference is too large synchronously. Therefore, after the homologous phase checking, the gear information of each power device to be grid-connected needs to be compared with a preset gear setting value, and grid connection can be performed only if the gear information of all the power devices to be grid-connected is consistent. If the detected gear information is inconsistent with the gear setting value, the grid connection is stopped, meanwhile, the alarm information is transmitted to the monitoring terminal, and the monitoring terminal can inform an operator to reset the gear after receiving the alarm information, or the gear setting value is modified and the gear information of the power device to be grid connected is synchronously adjusted according to the actual engineering condition, and finally the gear information of all the power devices to be grid connected is adjusted to be consistent with the gear setting value. First constant value comparison module
If the homogeneous nuclear phase test is not carried out, the homogeneous nuclear phase test needs to be carried out again through the test module, and after the homogeneous nuclear phase test, the operation information of the power device to be connected to the grid needs to be compared with preset operation setting information through the first fixed value comparison module, wherein the comparison of the operation data mainly comprises comparison of voltage data. Comparing the voltage value of each phase of each electric power device to be grid-connected with a setting value on the premise of homology, and if the first difference value generated by all the electric power devices to be grid-connected in the process is within a preset first error allowable range, indicating that the electric power devices to be grid-connected have no connection error, type selection error and installation error, wherein the problem of a transformer is mainly solved: 1. the specific difference of the transformer and the PT equipment is out of tolerance; 2. the transformer design transformation ratio is inconsistent with the synchronous protection design transformation ratio; 3. the type selection of the transformer is wrong or the arrival is not consistent with the design. In some embodiments of the present invention, 2% is selected within the first error allowable range, which may allow less reactive impact and may not increase grid-connection difficulty too much.
After the steps are completed, the differential pressure comparison is carried out through the closing parameter setting module. In actual engineering, the problem that part of the power devices to be connected to the grid cannot send gear information or have no gear information exists, the pressure difference comparison is carried out before the last step before grid connection, at the moment, all the power devices to be connected to the grid, which need to be connected to the grid, are in an electrified state, therefore, the pressure difference comparison can be directly carried out on a plurality of power devices to be connected to the grid, which need to be directly connected to the last time, the difference values are within a second error allowable range, the final confirmation can be completed, and at the moment, a grid connection allowable signal can be sent to the same-period device. In addition, after multiple times of grid connection are carried out, the voltage difference can be compared with historical data switching-on voltage data during comparison, and whether gear change problems exist or not can be actively found, for example: the current switching-on voltage value is much larger than the historical switching-on voltage value, so that the obvious problem can be deduced, and at the moment, alarm information is mainly sent out to stop grid connection.
According to the system for reducing the reactive power impact in the grid-connected process of the power plant, whether the homologous nuclear phase is performed or not is judged by the homologous nuclear phase judging module, and the reactive power impact caused by the wrong selection of the working mode of the power device to be connected to the grid can be avoided. The problem that the voltage grade is inconsistent with the design value can be avoided by performing a homologous nuclear phase test through the test module and the first fixed value comparison module, namely the problem that the type selection error or the actual installation error of the transformer is mainly eliminated. The gear information is judged by the gear information judging module, so that gear information change caused by human errors can be avoided, and large reactive impact on long-term parallel power devices to be connected to the grid due to the gear information change can be avoided. The closing parameter setting module is used for setting closing parameters, so that differential pressure interference existing in a part of power devices to be connected to the grid, which do not have gear information or cannot send gear information, can be eliminated. The system for reducing the reactive power impact in the grid-connected process of the power plant effectively solves the problem of large reactive power impact caused by design errors, installation errors, manual operation errors and the like, reduces the damage to power generation equipment, and simultaneously enables the grid-connected process to be more stable.
In some embodiments of the present invention, the gear information determining module is further configured to adjust a preset closing time setting value according to N closing times of the power device to be connected to the grid before the current closing; n is larger than a preset time fine-tuning numerical value.
The initial value of the closing time setting value is set based on theoretical design, but in actual grid-connected work, the closing time may deviate due to various reasons, such as equipment aging, loose wiring and the like. At this time, the gear information judgment module needs to properly adjust the closing time setting value, so as to ensure that the reactive impact is not increased due to the deviation of the closing time. And adjusting the switching-on time setting value is mainly based on historical switching-on time data, N times of switching-on time of the power device to be connected to the grid before the current switching-on is obtained, further, an average switching-on time value can be calculated by utilizing N-1 times of switching-on time before the last switching-on time, then, the average switching-on time setting value is utilized to carry out fine adjustment, and the average switching-on time value can be directly utilized to replace the switching-on time setting value. The average value of the closing time is calculated without adding the last closing time, and the main reason is that: the switching time can only be obtained after one switching is finished, so that once the last switching time has an error, the calculated average value has an error. The value of N needs to be as reasonable as possible, and cannot be too small, and too small calculated average value loses meaning, where N is generally guaranteed to be more than 5 times, preferably about 20 times is selected to be appropriate, and too large results in excessive calculation.
In some embodiments of the present invention, the gear information determining module is further configured to calculate a third difference between a closing time at the last closing and the adjusted closing time setting value, and determine whether to stop grid connection according to the third difference and a preset third error allowable range.
The reason why the last closing time is not added to the closing time setting value fine adjustment has been described above, but the last closing time is not meaningless. The gear information judgment module can check whether the power device to be connected to the grid has a fault by using the last closing time, for example: if the deviation between the last closing time and the closing time setting value after fine adjustment is large, it can be shown that the last closing of the power device to be connected to the grid absolutely has a problem, an alarm needs to be given, manual check is carried out, and the grid connection is not put into use any more. In consideration of the fact that the system of the real-time embodiment of the invention works before the synchronous device, the fault removal with overlarge change of the closing time cannot be carried out by utilizing the closing time of the time, and the subsequent risks are avoided by skillfully utilizing the closing time of the last time. In some embodiments of the present invention, the average closing time calculated by the closing time of N-1 times may also be used for comparison, so as to effectively prevent the closing time from changing too much. In some embodiments of the present invention, the amount of change in the closing time that is too large is 15%, and the change can be determined to be too large as long as the change exceeds 15%.
In some embodiments of the present invention, the closing parameter setting module is further configured to compare the angular difference data, the voltage data, and the current data of each to-be-connected grid power device during the last closing with the angular difference data, the voltage data, and the current data of each to-be-connected grid power device during the homologous phase checking, and send an alarm message according to the comparison result.
After all power equipment is put into use, the situations such as aging and the like are difficult to avoid, and after aging occurs, voltage data, current data and PT secondary poor data are changed, so that before switching on each time, a switching-on parameter setting module compares the data of the last switching-on and the data of the same-source nuclear phase, if any fourth difference exceeds a fourth error allowable range, the aging is serious, alarm information needs to be sent out, and manual troubleshooting is carried out. In some embodiments of the present invention, the fourth allowable error range is selected to be 2%, and the error is within this range, so that excessive reactive shock is not generated.
It should be further noted that the method and system of embodiments of the present invention uses a plurality of data, and a brief description of the data acquisition and processing system for obtaining such data is provided herein. Referring to fig. 2, the data collection and processing system includes an analog sampling module, a switching value sampling module, a data sampling and recording analysis module, and a plurality of functional modules. The analog quantity sampling module and the switching value sampling module are used for collecting real-time data of a plurality of power devices to be connected to the grid, and the real-time data comprises voltage, current, phase, gear, opening and closing, alarm signals and the like. The data sampling and recording analysis module is mainly used for storing and recording the data, so that the data can be conveniently used for analysis in the subsequent process. The plurality of functional modules are mainly used for preprocessing data in the data sampling, recording and analyzing module aiming at the functions of switching-on time adjustment, gear information judgment, operation mode judgment, excitation adjustment and the like so as to reduce the time for executing the method of the embodiment of the invention once.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to the embodiments, and those skilled in the art will understand that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (9)
1. A method for reducing reactive power impact in a power plant grid connection process is characterized by comprising the following steps:
acquiring homologous nuclear phase information of a plurality of power devices to be connected to the grid;
if the plurality of electric devices to be connected to the grid have completed homologous nuclear phase, judging whether the gear information of the plurality of electric devices to be connected to the grid is consistent with a preset gear setting value, if so, performing closing parameter setting, and if not, stopping connecting to the grid and sending alarm information;
if the plurality of to-be-grid-connected power devices do not complete the same source nuclear phase, performing a same source nuclear phase test, calculating a first difference between the operation information of each to-be-grid-connected power device and preset operation setting information, if the first differences are all within a preset first error allowable range, performing closing parameter setting, and if the first differences exceed the first error allowable range, stopping grid connection and sending alarm information;
the closing parameter setting comprises the following steps: and obtaining second difference values among the actually measured voltage values of the power devices to be connected to the grid, if the second difference values are smaller than a preset second error allowable range, sending a signal allowing the grid connection to the synchronous device, and if the second difference values exceed the second error allowable range, stopping the grid connection and sending alarm information.
2. The method for reducing reactive power impact in the power plant grid-connection process according to claim 1, further comprising the following steps before entering the closing parameter setting:
acquiring N times of closing time of the power device to be connected to the grid before the current closing, wherein N is larger than a preset time fine-tuning numerical value;
and adjusting a preset closing time setting value according to the closing time of N-1 times before the last closing.
3. The method for reducing reactive power impact in the power plant grid-connected process according to claim 2, wherein after the preset closing time setting value is adjusted according to the closing time N-1 times before the last closing, the method further comprises the following steps:
calculating a third difference value between the closing time when the last closing is carried out and the adjusted closing time setting value;
and if the third difference is larger than a preset third error allowable range, stopping grid connection and sending alarm information.
4. The method for reducing reactive power impact in the power plant grid-connection process according to claim 2, wherein the setting of the closing parameter further comprises the following steps:
acquiring N reactive impact data corresponding to N times of closing time;
and calculating the reactive impact data with the minimum numerical value in the N reactive impact data, acquiring corresponding voltage data, current data and phase angle data, and adjusting the excitation of the power device to be connected to the grid according to the voltage data, the current data and the phase angle data.
5. The method for reducing reactive power impact in the power plant grid-connection process according to claim 1, wherein the setting of the closing parameter further comprises the following steps:
and obtaining angle difference data, voltage data and current data of each power device to be connected to the grid during the last closing of the power device to be connected to the grid, comparing the angle difference data, the voltage data and the current data of the power device to be connected to the grid during the same-source phase checking, obtaining a fourth difference value, and if the fourth difference value exceeds a preset fourth error allowable range, sending alarm information.
6. A system for reducing reactive power impact in a power plant grid-connected process is characterized by comprising:
the system comprises a homologous information acquisition module, a phase synchronization module and a phase synchronization module, wherein the homologous information acquisition module is used for acquiring homologous nuclear phase information of a plurality of power devices to be connected to the grid;
the homologous nuclear phase judging module is connected with the homologous information acquiring module and used for judging whether the plurality of electric devices to be connected to the grid complete homologous nuclear phases or not;
the gear information judging module is connected with the homologous kernel phase judging module and is used for judging whether the gear information of the power devices to be connected to the grid is consistent with a preset gear setting value or not;
the test module is connected with the homologous nuclear phase judgment module and is used for carrying out homologous nuclear phase tests on the plurality of to-be-grid-connected electric power devices;
the first fixed value comparison module is connected with the test module and used for calculating a first difference value between the operation information of each power device to be connected to the grid and preset operation setting information and judging whether each first difference value is within a preset first error allowable range or not;
and the closing parameter setting module is respectively connected with the first fixed value comparison module and the gear information judgment module and is used for acquiring second difference values among the actually measured voltage values of the power devices to be connected to the grid and judging whether each second difference value is within a preset second error allowable range.
7. The system for reducing reactive power impact in the power plant grid-connected process according to claim 6, wherein the gear information judgment module is further configured to adjust a preset switching-on time setting value according to N switching-on times of the power device to be grid-connected before the current switching-on; n is larger than a preset time fine-tuning numerical value.
8. The system for reducing reactive power impact in the power plant grid-connection process according to claim 7, wherein the gear information determination module is further configured to calculate a third difference between the closing time at the last closing time and the adjusted setting value of the closing time, and determine whether to stop grid connection according to the third difference and a preset third error allowable range.
9. The system for reducing reactive power impact in the power plant grid-connected process according to claim 7, wherein the closing parameter setting module is further configured to compare the angular difference data, the voltage data, and the current data of each to-be-connected power device during the last closing with the angular difference data, the voltage data, and the current data during the homologous phase checking, and send out an alarm message according to the comparison result.
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