CN114498586B - Power grid current protection setting method and device for high-proportion fluctuating power supply - Google Patents
Power grid current protection setting method and device for high-proportion fluctuating power supply Download PDFInfo
- Publication number
- CN114498586B CN114498586B CN202210110487.3A CN202210110487A CN114498586B CN 114498586 B CN114498586 B CN 114498586B CN 202210110487 A CN202210110487 A CN 202210110487A CN 114498586 B CN114498586 B CN 114498586B
- Authority
- CN
- China
- Prior art keywords
- current
- power supply
- value
- section
- protection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 46
- 230000009471 action Effects 0.000 claims description 59
- 230000035945 sensitivity Effects 0.000 claims description 14
- 230000001360 synchronised effect Effects 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000001514 detection method Methods 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 2
- 238000010248 power generation Methods 0.000 abstract description 12
- 230000007547 defect Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 12
- 238000004590 computer program Methods 0.000 description 7
- 230000006870 function Effects 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 230000004044 response Effects 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
Images
Classifications
-
- 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
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/006—Calibration or setting of parameters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
-
- 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
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
Landscapes
- Inverter Devices (AREA)
Abstract
The invention provides a power grid current protection setting method and device for a high-proportion fluctuating power supply, aiming at the defect that the existing power grid current protection is difficult to adapt to the high-proportion new energy power generation power supply at the power supply side. In the power grid oriented to the future high-proportion new energy power generation power supply, the relay protection function with good performance is realized, and the engineering practicability is high.
Description
Technical Field
The invention relates to a power grid current protection setting method and device for a high-proportion fluctuating power supply, and belongs to the technical field of relay protection.
Background
With the development of renewable energy, a large number of inverter power supplies based on renewable energy power generation are connected to a power grid, and the proportion of the inverter power supplies in the power grid is continuously increased. The traditional rotary generator outputs current by means of self inertia after fault, the fault current can reach 20-50 times of rated current in a short time, and the fault current and the equivalent impedance of a fault loop present a linear relation, so that sufficient fault information can be obtained.
Compared with the traditional rotating electric machine, the inverter power supply has small equivalent impedance and high response speed, and can bear smaller fault current which is only 1.0-2.0 times of rated current, so that when the inverter power supply fails, the output of the power device can be quickly locked due to the limitation of the structure of the inverter power supply and the internal power electronic devices, and sufficient fault information cannot be output. The current limiting control of a plurality of related inverters after the power grid is short-circuited comprehensively influences, so that the power grid short-circuit current has smaller amplitude and stronger nonlinear characteristic, the selectivity and sensitivity of the traditional power grid current protection are influenced, and the applicability of the traditional current protection is seriously influenced.
The power grid structure completely applying the traditional power supply based on the rotating synchronous motor is shown in figure 1, the traditional rotating generator outputs current by means of self inertia after fault, the fault current can reach 20-50 times of rated current in short time, and the fault current can be measured at fault current I k Sufficient fault information is obtained, faults can be quickly and effectively eliminated through traditional sectional type current protection, and protection actions are completed.
As shown in fig. 2, the power grid structure completely applying the inverter-based high-proportion new energy power generation power supply has the advantages that the inverter power supply has small equivalent impedance and high response speed, and can bear small fault current which is only 1.0 to 2.0 times of rated current, so that when the inverter power supply fails, the output of a power device of the inverter power supply can be quickly locked due to the limitation of the structure of the inverter power supply and internal power electronic devices, and sufficient fault information cannot be output. The current limiting control of a plurality of related inverters after the power grid is short-circuited comprehensively influences, so that the power grid short-circuit current has smaller amplitude and stronger nonlinear characteristic, the selectivity and sensitivity of the traditional power grid current protection are influenced, and the applicability of the traditional current protection is seriously influenced.
With the gradual depletion of mineral deposits and fossil resources and the rapid development of renewable energy sources, inverter power sources based on renewable energy source power generation are largely connected into a power grid, and the proportion of the inverter power sources in the power grid power sources is continuously increased. Due to the self-limitation of the inverter power supply, when short-circuit fault occurs, the output can be automatically limited or locked, when the inverter power supply in the power grid has a high proportion, fault current cannot output enough fault information, the original current protection loses selectivity, and accurate action cannot be realized.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, provides a power grid current protection setting method for a high-proportion fluctuation power supply, and improves the power grid current protection selectivity and sensitivity of an inverter power supply.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a power grid current protection setting method for a high-ratio fluctuating power supply, including the following steps:
step 1: identifying and acquiring the power composition ratio of the power grid on line; the power grid at least comprises a traditional synchronous motor power supply and an inverter power supply;
and 2, step: collecting actually measured short-circuit current information;
and step 3: converting the actually measured short-circuit current information into a corresponding equivalent fault current value according to the power supply composition ratio;
and 4, step 4: and judging the fault section according to the converted short-circuit current value, and carrying out sectional type current protection setting according to the fault section.
Further, the method for converting the measured short-circuit current information into a corresponding short-circuit current value according to the power supply composition ratio comprises the following steps:
step 1: calculating and obtaining the limit current I output after the inverter power supply fails according to the following formula k2 ：
I k2 ＝kI N ；
In the formula I N Rated output current of the inverter power supply is obtained, and k is a proportionality coefficient;
step 2: according to the power supply composition ratio, the inverter power supply is equivalently replaced by the traditional rotary power supply with the same capacity, and the equivalent fault current I obtained after the traditional rotary power supply with the same capacity is used for replacing the inverter power supply in the power grid is calculated k2 ′；
And step 3: calculating to obtain an equivalent fault current value I obtained after the inverter power supply is replaced according to the following formula k ′；
I k '＝(I k -I k2 )+I k2 '
In the formula I k ' is an equivalent fault current value, I k The measured short-circuit current information is obtained.
Furthermore, the method for judging the fault section according to the converted short-circuit current value and carrying out sectional type current protection setting according to the fault section comprises the following steps:
according to equivalent fault current value I k Comparing the current I section action current setting value with the current II section action current setting value, judging a section where a fault occurs, and performing corresponding protection action, wherein the method specifically comprises the following steps:
step 1: judging whether the protection is started or not, if so, judging the equivalent fault current value I k Whether the current is larger than the I section of current or not, if not, returning to read the power supply to form an on-line identification result of the proportion;
step 2: protection of start-up, if equivalent fault current value I k ' greater than current I section action current setting value and at delta t Ⅰ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent out, and if the relation is not kept, the actual measured value of the reading current is directly returned;
and step 3: if equivalent fault current value I k If the current is not greater than the I-section action current setting value of the current, judging the equivalent fault current value I k Whether the current is larger than the setting value of the current II section action current or not, if so, the current is larger than and at delta t Ⅱ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent, and if the relation is not kept, the actual measured value of the reading current is directly returned;
and 4, step 4: if equivalent fault current value I k If the current is not greater than the setting value of the current II section action current, judging whether the protection is started again, if so, skipping to read the measured value of the current, and if not, returning to read the power supply to form an on-line comparison identification result.
Further, the setting value of the current I-stage action current is calculated by an operation mode of constructing a power grid by taking the maximum total power capacity and the minimum historically measured inverter power ratio as boundaries, and the operation mode is as follows:
wherein,
in order to protect the I section of the current of the protection 2 to act on the current setting value,
for reliability factor, E' is the phase potential of the system equivalent power supply, Z S.min Is the minimum equivalent internal impedance of the system, Z AB Is the line impedance between the busbars A, B, E' and Z S.min It is obtained after on-line identification.
Further, the setting value of the current II-stage action current is calculated by an operation mode of constructing a power grid according to the minimum total power supply capacity and the maximum historically measured inverter power supply ratio boundary, and is as follows:
wherein,
in order to protect the II-section action current setting value of the current of the protection 2,
in order to be a reliable factor,
in order to protect the I section action current setting value of the current 1,
in order to protect the I section action time limit of the current of 1, delta t is the time limit difference;
according to the equivalent short-circuit current value when the two-phase metal at the tail end of the line is short-circuited in the 'minimum operation mode' of the system
Checking, wherein a checking formula is as follows:
wherein, K sen Is sensitivity.
Further, a fault current I flowing through the short-circuit point k Rated output current I of inverter power supply N Measured directly by existing measuring devices.
In a second aspect, the present invention provides a grid current protection setting apparatus for a high-proportion fluctuating power supply, the apparatus comprising:
an acquisition module: the power supply composition ratio for online identification and acquisition of the power grid is obtained; the power grid at least comprises a traditional synchronous motor power supply and an inverter power supply;
a notch module: the short-circuit current detection device is used for collecting actually-measured short-circuit current information;
a conversion module: the short-circuit current measuring device is used for converting the actually measured short-circuit current information into a corresponding equivalent fault current value according to the power supply composition ratio;
a region judgment module: and the sectional type current protection setting device is used for judging a fault section according to the converted short circuit current value and performing sectional type current protection setting according to the fault section.
Further, the method for converting the actually measured short-circuit current information into the corresponding short-circuit current value by the conversion module according to the power supply configuration ratio comprises:
calculating and obtaining the limit current I output after the inverter power supply fails according to the following formula k2 ：
I k2 ＝kI N ；
In the formula I N Is the inverse ofRated output current of the converter power supply, wherein k is a proportionality coefficient;
according to the power supply composition ratio, equivalently replacing the inverter power supply with the traditional rotary power supply with the same capacity, and calculating the equivalent fault current I obtained after replacing the inverter power supply in the power grid with the traditional rotary power supply with the same capacity k2 ′；
Calculating to obtain an equivalent fault current value I obtained after the inverter power supply is replaced according to the following formula k ′；
I k '＝(I k -I k2 )+I k2 '
In the formula I k ' is an equivalent fault current value, I k Is the measured short circuit current information.
Further, the method for judging the fault section by the area judgment module according to the converted short circuit current value and performing sectional type current protection setting according to the fault section comprises the following steps:
according to equivalent fault current value I k Comparing the current I section action current setting value with the current II section action current setting value, judging a section where a fault occurs, and performing corresponding protection action, wherein the method specifically comprises the following steps:
judging whether the protection is started or not, if so, judging the equivalent fault current value I k Whether the current is larger than the I section of the current or not is judged, and if not, the power supply is returned to be read to form a ratio on-line identification result;
protection starting, if the equivalent fault current value I k ' greater than current I section action current setting value and at delta t Ⅰ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent, and if the relation is not kept, the actual measured value of the reading current is directly returned;
if equivalent fault current value I k If the current is not greater than the I-section action current setting value of the current, judging the equivalent fault current value I k Whether the current is larger than the setting value of the current II section action current or not, if so, the current is larger than and at delta t Ⅱ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent, and if the relation is not kept, the actual measured value of the reading current is directly returned;
if equivalent fault current value I k If the current is not greater than the setting value of the current II section action current, judging whether the protection is started again, if so, skipping to read the measured value of the current, and if not, returning to read the power supply to form an on-line comparison identification result.
In a third aspect, the invention provides a power grid current protection setting device for a high-proportion fluctuating power supply, which comprises a processor and a storage medium, wherein the processor is used for processing a power grid current;
the storage medium is used for storing instructions;
the processor is configured to operate in accordance with the instructions to perform the steps of the method according to the first aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) Aiming at the problems that the amplitude of the short-circuit current of the power grid is small and the power grid has strong nonlinear characteristics caused by the comprehensive influence of the current-limiting control of a plurality of related inverters after the power grid is short-circuited in the power grid containing a high-proportion inverter power supply, the virtual short-circuit current value amplified by comparing with the actually-measured short-circuit current value is converted, and meanwhile, the virtual short-circuit current value is approximately linearized.
(2) The method overcomes the defect that the current protection of the existing power grid is difficult to adapt to the high-proportion new energy power generation power supply at the power supply side, and the improved power grid current protection setting method fully considers the sensitivity requirement. The sensitivity problem of the traditional power grid is mainly considered for the starting condition of the synchronous generator (difference of maximum and minimum operation modes), and the grid connection condition of a fluctuating power supply in the novel power grid cannot be expressed by the traditional size mode. The invention provides a novel setting and checking method, and sectional type current protection setting is carried out according to the method, so that the sensitivity requirement is met.
(3) The power grid current protection setting method for the high-proportion fluctuating power supply can utilize the original power grid current protection device, does not need to change a circuit structure, has certain self-adaptive capacity and has higher engineering practicability.
Drawings
Fig. 1 is a schematic diagram of a power grid architecture fully utilizing a conventional power supply based on a rotating synchronous machine;
FIG. 2 is a schematic diagram of a power grid architecture fully utilizing an inverter-based high-ratio new energy power generation source;
FIG. 3 is a conversion diagram of a power grid structure in which a conventional power supply based on a rotating synchronous motor is mixed with a high-proportion new energy power generation power supply based on an inverter and a power grid structure after equivalent replacement of the power supply;
FIG. 4 is a schematic diagram of power composition ratio online identification;
fig. 5 is a flow of a grid current protection operation for a high-ratio fluctuating power supply.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The first embodiment is as follows:
based on the defect that the existing power grid current protection is difficult to adapt to a high-proportion new energy power generation power supply on the power supply side, the embodiment provides the power grid current protection setting method for the high-proportion fluctuating power supply, and the method has high engineering practicability for realizing a relay protection function with good performance in a power grid facing the future high-proportion new energy power generation power supply.
The specific method of the power grid current protection setting method for the high-proportion fluctuating power supply is that according to the measured power supply proportions of different types before the occurrence of the short-circuit fault, an inverter power supply is equivalently replaced by a traditional rotating power supply with the same capacity, so that a virtual power supply end is constructed, namely, the power supply side only comprises a rotating motor from the viewpoint of protection installation, and the virtual power supply end is further used for steady-state analysis and calculation. And acquiring actual short-circuit current information after short circuit occurs, modifying the actual short-circuit current information into virtual short-circuit current corresponding to the virtual power end, namely replacing an inverter power supply at the power supply side in an imagination, wherein the replacement principle is to keep the total capacity of the power supply unchanged, completely converting the power supply components into a traditional rotating motor, and then calculating a corresponding short-circuit current value measured value. And judging the section of the fault according to the converted short-circuit current value (meeting the selectivity requirement), and carrying out sectional type current protection setting according to the section of the fault (meeting the sensitivity requirement).
The mathematical calculation steps are as follows:
step one, measuring fault current I flowing through a short-circuit point after a short-circuit fault occurs in a power grid k ；
Step two, calculating to obtain the limiting current I output after the inverter power supply fails k2 From the inverter power supply characteristics, I k2 ＝kI N (ii) a In the formula I N For rated output current of an inverter power supply, k is a proportionality coefficient and can be 1.0-2.0 (determined by the overcurrent capacity of a power electronic switch device);
step three, calculating equivalent fault current I obtained after replacing an inverter power supply in the power grid with a traditional rotary power supply with the same capacity k2 '；
Step five, calculating to obtain an equivalent fault current value I obtained after the inverter power supply is replaced k ', wherein, I k '＝(I k -I k2 )+I k2 '；
Step six, according to the equivalent fault current value I obtained by calculation k ', based on the equivalent fault current value I k Comparing with the current sectional type protection setting value, judging the section where the fault occurs, and performing corresponding protection action.
Wherein a fault current I flowing through the short-circuit point k Rated output current I of inverter power supply N Can be directly measured by the existing measuring device.
The present invention will be further described with reference to the accompanying drawings.
The power grid structure of the hybrid power generation of the conventional rotating electric machine and the inverter power supply is shown in the upper half part of fig. 3, the inverter power supply in the power grid is replaced by the conventional rotating power supply with the same capacity (shown in the lower half part of fig. 3), and the equivalent fault current value I obtained after the inverter power supply is replaced is calculated k ' thereafter, a segmented grid current protection may be performed on the grid.
The following setting values are set according to a power grid of the inverter power supply replaced by a rotating motor power supply with the same capacity, wherein the power grid of the high-proportion fluctuating power supply is greatly different from a traditional power grid in a maximum (minimum) operation mode, the traditional power grid power supply is composed of rotating generators and meets load requirements, and therefore the time period of the maximum (minimum) operation mode of the power supply is fixed. In the power grid of the high-proportion fluctuating power supply, the maximum (minimum) operation state of the power supply needs to adapt to different states of inverters related to new energy power generation at different places and different time periods, and basic data needed by a setting process needs to be obtained through online identification and statistical induction.
The basic principle of setting is as follows: constructing the maximum operation mode according to the boundary of the maximum total power capacity and the minimum historically measured inverter power occupation ratio, calculating a corresponding short-circuit current value for setting current protection, ensuring that the current protection does not generate misoperation under the condition that an online identification module is not updated timely, and meeting the selective requirement; and constructing the minimum operation mode according to the minimum total power capacity and the maximum historically measured inverter power occupation ratio boundary, and calculating the minimum short-circuit current for checking the protection performance and meeting the sensitivity requirement.
In order to ensure the selectivity of the current quick-break (current I section) protection action, for the protection 2, the protection 2 is No. 2 protection installed in the lower half part of the attached drawing 3, and when the action current is kept away from the system in a maximum operation mode, namely the head end (B) of the next line, the tail end of the line is in three-phase short circuit, the equivalent maximum short-circuit current flowing through the protection
Setting, namely:
wherein,
current I to protect 2The setting value of the segment action current is set,
for reliability factor (specific values are accumulated by engineering experience), E' is the phase electromotive force of the equivalent power supply of the system, Z S.min Is the minimum equivalent internal impedance of the system, Z AB Is the line impedance between the busbars A, B, E' and Z S.min It is obtained after on-line identification.
The protection pass action value
The setting meets the selectivity, but the whole length of the line cannot be protected, and only a part of the head end of the line can be protected.
The time-limited current quick-break (current II section) protection requires the whole length of the circuit, and the protection range of the circuit necessarily extends to the next circuit and is overlapped with the current protection range of the next circuit. When the outlet of the next line is short-circuited, the current I section of the protection 1 and the current II section of the protection 2 are started simultaneously, in order to ensure selectivity and reduce the action time of the protection, the current II section and the current I section of the next line are matched and set, and the protection range is required to be smaller than the protection range of the current I section of the next line and the action time limit is required
The current I section protection of the next line is larger than the current I section protection of the next line by a time limit grade delta t, namely:
wherein,
in order to protect the II-section action current setting value of the current of the 2,
for the reliability factor (the specific values are accumulated with engineering experience),
in order to protect the I section of the current of the 1 to act on the current setting value,
the current I section for protection 1 is in action time limit (the action of the current I section protection is fast and is approximate to 0), and delta t is time limit step difference (specific values are accumulated by engineering experience).
The sensitivity of the time-limited current quick-break (current II section) protection is calculated according to the minimum equivalent short-circuit current of the protection when the end of the protected line is short-circuited, namely according to the equivalent short-circuit current value when the two-phase metallic short-circuit at the end of the line is short-circuited in the minimum operation mode of the system
Checking, wherein a checking formula is as follows:
wherein, K sen For sensitivity (there is a range of values required, specific values to be accumulated with engineering experience).
If the sensitivity does not meet the requirement, the time-limited current quick-break protection (current II section) protection is matched and set with the current II section of the next line:
Wherein, K rel For reliable coefficients (specific values are to be accumulated by engineering experience),
in order to protect the setting value of the current II section action current of the 1,
in order to protect the current II section action time limit of 1,
in order to protect the action time limit of the current II section of 2, delta t is the time limit step difference (the specific numerical value is accumulated by engineering experience).
The basic principle of the online measurement and identification of the power capacity ratio is as follows:
the method of the embodiment is based on an online measurement identification procedure of the capacity ratio of the traditional rotating electric machine and the inverter power supply in the power grid, and the identification of the capacity ratio of the two power supplies on the power supply side of the power grid is already completed.
The principle of the identification method is as follows: the proportions of the components in the direction of the power supply (side) are continuously identified on-line by means of a corresponding busbar voltage measuring circuit at the protective installation and a current measuring circuit of the line to be protected and stored in the protective device. The identification model is shown in fig. 4, the disturbance source is a large load fluctuation or a short-circuit fault on the line side, and therefore the identification method has certain time-varying tracking performance.
In general, a conventional rotating electrical machine can be regarded as a voltage source, an inverter power source can be regarded as a controlled current source, and after a certain disturbance signal (such as switching of high-power equipment on a load side) is given to the system due to different response characteristics of the voltage source and the current source, voltage/current response information of a protection installation position can also be different along with different occupation ratios of power source components, so that the respective occupation ratios of the inverter power source and the conventional rotating electrical generator in a power grid at the moment can be obtained. The actual power supply equipment on the power supply side is numerous, but the synchronous machine is basically a constant voltage source, and the inverter basically meets the characteristic of current control, so the model structure can be regarded as an equivalent power supply obtained by equivalently combining the traditional rotating electric machine and the inverter power supply (by utilizing the Thevenin theorem, the Noton theorem and the like).
Example two:
the present embodiment provides a power grid current protection setting device for a high-ratio fluctuating power supply, where the device includes:
an acquisition module: the power supply composition ratio is used for identifying and acquiring the power supply composition ratio of the power grid on line; the power grid at least comprises a traditional synchronous motor power supply and an inverter power supply;
a notch module: the short-circuit current acquisition module is used for acquiring actually measured short-circuit current information;
a conversion module: the short-circuit current detection device is used for converting the actually measured short-circuit current information into a corresponding equivalent fault current value according to the power supply composition ratio;
a region judgment module: and the fault section is judged according to the converted short-circuit current value, and sectional type current protection setting is carried out according to the fault section.
Further, the method for converting the actually measured short-circuit current information into the corresponding short-circuit current value by the conversion module according to the power supply configuration ratio comprises:
calculating and obtaining the limit current I output after the inverter power supply fails according to the following formula k2 ：
I k2 ＝kI N ；
In the formula I N Rated output current is the inverter power supply, and k is a proportionality coefficient;
according to the power supply composition ratio, the inverter power supply is equivalently replaced by the traditional rotary power supply with the same capacity, and the equivalent fault current I obtained after the traditional rotary power supply with the same capacity is used for replacing the inverter power supply in the power grid is calculated k2 ′；
Calculating to obtain an equivalent fault current value I obtained after the inverter power supply is replaced according to the following formula k ′；
I k '＝(I k -I k2 )+I k2 '
In the formula I k ' is an equivalent fault current value, I k Is the measured short circuit current information.
Further, the method for judging the fault section by the area judgment module according to the converted short circuit current value and performing sectional current protection setting according to the fault section comprises the following steps:
according to equivalent fault current value I k Comparing the current I section action current setting value with the current II section action current setting value, judging a fault occurring section, and performing corresponding protection action, wherein the method specifically comprises the following steps of:
judging whether the protection is started or not, if so, judging an equivalent fault current value I k Whether the current is larger than the I section of current or not, if not, returning to read the power supply to form an on-line identification result of the proportion;
protection of start-up, if equivalent fault current value I k ' greater than current I section action current setting value and at delta t Ⅰ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent out, and if the relation is not kept, the actual measured value of the reading current is directly returned;
if equivalent fault current value I k If the current is not greater than the I-section action current setting value of the current, judging the equivalent fault current value I k Whether the current is larger than the setting value of the current II section action current or not, if so, the current is larger than and at delta t Ⅱ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent, and if the relation is not kept, the actual measured value of the reading current is directly returned;
if the equivalent fault current value I k If the current is not greater than the setting value of the current II section action current, judging whether the protection is started again, if so, skipping to read the measured value of the current, and if not, returning to read the power supply to form an on-line comparison identification result.
The apparatus of this embodiment can be used to implement the method described in the first embodiment.
Example three:
the embodiment of the invention also provides a power grid current protection setting device for the high-proportion fluctuating power supply, which comprises a processor and a storage medium;
the storage medium is used for storing instructions;
the processor is configured to operate in accordance with the instructions to implement the steps of the method.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (6)
1. A power grid current protection setting method for a high-proportion fluctuating power supply is characterized by comprising the following steps:
identifying and acquiring the power composition ratio of the power grid on line; the power grid at least comprises a traditional synchronous motor power supply and an inverter power supply;
collecting actually measured short-circuit current information;
converting the actually measured short-circuit current information into a corresponding equivalent fault current value according to the power supply composition ratio;
judging a fault section according to the converted short circuit current value, and carrying out sectional type current protection setting according to the fault section;
the method for converting the actually measured short-circuit current information into the corresponding short-circuit current value according to the power supply composition ratio comprises the following steps:
calculating and obtaining the limit current I output after the inverter power supply fails according to the following formula k2 ：
I k2 ＝kI N ；
In the formula I N Rated output current of the inverter power supply is obtained, and k is a proportionality coefficient;
according to the power supply composition ratio, equivalently replacing the inverter power supply with the traditional rotary power supply with the same capacity, and calculating the equivalent fault current I obtained after replacing the inverter power supply in the power grid with the traditional rotary power supply with the same capacity k2 ′；
Calculating to obtain an equivalent fault current value I obtained after the inverter power supply is replaced according to the following formula k ′；
I k '＝(I k -I k2 )+I k2 '
In the formula I k ' is an equivalent fault current value, I k The information is actually measured short-circuit current information;
the method for judging the fault section according to the converted short-circuit current value and carrying out sectional type current protection setting according to the fault section comprises the following steps:
according to equivalent fault current value I k ' ratio to Current I-segment action Current setting value and Current II-segment action Current setting valueAnd judging the section with the fault, and performing corresponding protection actions, wherein the method specifically comprises the following steps:
judging whether the protection is started or not, if so, judging the equivalent fault current value I k Whether the current is larger than the I section of current or not, if not, returning to read the power supply to form an on-line identification result of the proportion;
protection is started if the equivalent fault current value I k ' greater than current I section action current setting value and at delta t Ⅰ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent out, and if the relation is not kept, the actual measured value of the reading current is directly returned;
if the equivalent fault current value I k If the current is not greater than the I-section action current setting value of the current, judging the equivalent fault current value I k Whether the current is greater than the setting value of the current II section action current, if so, the current is greater than the setting value of the current II section action current and is delta t Ⅱ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent out, and if the relation is not kept, the actual measured value of the reading current is directly returned;
if equivalent fault current value I k If the current is not greater than the setting value of the current II section action current, judging whether the protection is started again, if so, skipping to read the current measured value, and if not, returning to read the power supply to form an on-line identification result of the ratio.
2. The grid current protection setting method according to claim 1, wherein the current i-stage action current setting value is calculated by an operation mode of constructing a grid based on a boundary that a total power supply capacity is maximum and a historically measured inverter power supply duty ratio is minimum, and the operation mode is as follows:
wherein,
in order to protect the I section of the current of the protection 2 to act on the current setting value,
for reliability factor, E' is the phase potential of the system equivalent power supply, Z S.min Is the minimum equivalent internal impedance of the system, Z AB Is the line impedance between the busbars A, B, E' and Z S.min It is obtained after on-line identification.
3. The grid current protection setting method according to claim 1, wherein the current ii-stage operating current setting value is calculated by an operating mode of constructing a grid according to a boundary that a total power supply capacity is minimum and a historically measured inverter power supply ratio is maximum, and is as follows:
wherein,
in order to protect the II-section action current setting value of the current of the protection 2,
in order to be a reliable factor,
in order to protect the I section of the current of the 1 to act on the current setting value,
in order to protect the I section action time limit of the current of 1, delta t is the time limit difference;
according to the equivalent short-circuit current value when the two-phase metal at the tail end of the line is short-circuited in the 'minimum operation mode' of the system
Checking, wherein a checking formula is as follows:
wherein, K sen Is sensitivity.
4. The grid current protection setting method according to claim 1, wherein a fault current I flowing through the short-circuit point k Inverter power source rated output current I N Measured directly by the measuring device.
5. A grid current protection setting device for a high-proportion fluctuating power supply, the device comprising:
an acquisition module: the power supply composition ratio is used for identifying and acquiring the power supply composition ratio of the power grid on line; the power grid at least comprises a traditional synchronous motor power supply and an inverter power supply;
a notch module: the short-circuit current detection device is used for collecting actually-measured short-circuit current information;
a conversion module: the short-circuit current measuring device is used for converting the actually measured short-circuit current information into a corresponding equivalent fault current value according to the power supply composition ratio;
a region judgment module: the system is used for judging a fault section according to the converted short circuit current value and carrying out sectional type current protection setting according to the fault section;
the method for converting the actually measured short-circuit current information into the corresponding short-circuit current value by the conversion module according to the power supply constitution ratio comprises the following steps:
calculating and obtaining the limit current I output after the inverter power supply fails according to the following formula k2 ：
I k2 ＝kI N ；
In the formula I N Rated output current of the inverter power supply is obtained, and k is a proportionality coefficient;
according to the power supply composition ratio, equivalently replacing the inverter power supply with the traditional rotary power supply with the same capacity, and calculating the equivalent fault current I obtained after replacing the inverter power supply in the power grid with the traditional rotary power supply with the same capacity k2 ′；
Calculating to obtain an equivalent fault current value I obtained after the inverter power supply is replaced according to the following formula k ′；
I k '＝(I k -I k2 )+I k2 '
In the formula I k ' is an equivalent fault current value, I k The information is actually measured short-circuit current information;
the method for judging the fault section by the area judgment module according to the converted short circuit current value and carrying out sectional type current protection setting according to the fault section comprises the following steps:
according to equivalent fault current value I k Comparing the current I section action current setting value with the current II section action current setting value, judging a section where a fault occurs, and performing corresponding protection action, wherein the method specifically comprises the following steps:
judging whether the protection is started or not, if so, judging the equivalent fault current value I k Whether the current is larger than the I section of the current or not is judged, and if not, the power supply is returned to be read to form a ratio on-line identification result;
protection is started if the equivalent fault current value I k ' greater than current I section action current setting value and at delta t Ⅰ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent out, and if the relation is not kept, the actual measured value of the reading current is directly returned;
if the equivalent fault current value I k If the current is not greater than the I-section action current setting value of the current, judging the equivalent fault current value I k Whether the current is larger than the setting value of the current II section action current or not, if so, the current is larger than and at delta t Ⅱ If the relation is kept, the actual measured value of the reading current is returned after a tripping command is sent out, and if the relation is not kept, the actual measured value of the reading current is directly returned;
if the equivalent fault current value I k If the current is not greater than the setting value of the current II section action current, judging whether the protection is started again, if so, skipping to read the measured value of the current, and if not, returning to read the power supply to form an on-line comparison identification result.
6. A power grid current protection setting device for a high-proportion fluctuating power supply is characterized by comprising a processor and a storage medium;
the storage medium is to store instructions;
the processor is configured to operate in accordance with the instructions to perform the steps of the method according to any one of claims 1 to 4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210110487.3A CN114498586B (en) | 2022-01-29 | 2022-01-29 | Power grid current protection setting method and device for high-proportion fluctuating power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210110487.3A CN114498586B (en) | 2022-01-29 | 2022-01-29 | Power grid current protection setting method and device for high-proportion fluctuating power supply |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114498586A CN114498586A (en) | 2022-05-13 |
| CN114498586B true CN114498586B (en) | 2022-11-29 |
Family
ID=81478207
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210110487.3A Active CN114498586B (en) | 2022-01-29 | 2022-01-29 | Power grid current protection setting method and device for high-proportion fluctuating power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114498586B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103956717A (en) * | 2014-05-27 | 2014-07-30 | 国家电网公司 | Self-adaption microgrid overcurrent protection method |
| CN104218549A (en) * | 2014-08-28 | 2014-12-17 | 天津大学 | Inter-phase short circuit protecting method for inverter-based distributed generation (IBDG) power distribution network |
| CN105186468A (en) * | 2015-08-13 | 2015-12-23 | 广东电网有限责任公司佛山供电局 | Power distribution network direction over-current protection online setting method and system for access of distributed power supply |
| WO2018129842A1 (en) * | 2017-01-10 | 2018-07-19 | 华北电力大学 | Pilot protection method for transmission line of new energy station based on current waveform similarity |
-
2022
- 2022-01-29 CN CN202210110487.3A patent/CN114498586B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103956717A (en) * | 2014-05-27 | 2014-07-30 | 国家电网公司 | Self-adaption microgrid overcurrent protection method |
| CN104218549A (en) * | 2014-08-28 | 2014-12-17 | 天津大学 | Inter-phase short circuit protecting method for inverter-based distributed generation (IBDG) power distribution network |
| CN105186468A (en) * | 2015-08-13 | 2015-12-23 | 广东电网有限责任公司佛山供电局 | Power distribution network direction over-current protection online setting method and system for access of distributed power supply |
| WO2018129842A1 (en) * | 2017-01-10 | 2018-07-19 | 华北电力大学 | Pilot protection method for transmission line of new energy station based on current waveform similarity |
Non-Patent Citations (1)
| Title |
|---|
| 考虑逆变电源控制策略的电流保护整定计算;金甚达等;《电网技术》;20210930;第45卷(第9期);第3690-3698页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114498586A (en) | 2022-05-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113433419A (en) | Intelligent alarm method and system based on polymorphic data coprocessing | |
| Piskunov et al. | Power transformer relay protection with its condition monitoring function | |
| Zainan et al. | A fast pilot protection for DC distribution networks considering the whole fault process | |
| Chen et al. | Time–frequency characteristics analysis and diagnosis of rotating rectifier faults in multiphase annular brushless system | |
| Laadjal et al. | An integrated strategy for the real-time detection and discrimination of stator inter-turn short-circuits and converter faults in asymmetrical six-phase induction motors | |
| Zare et al. | A new relaying scheme for protection of transmission lines connected to DFIG‐based wind farms | |
| CN114498586B (en) | Power grid current protection setting method and device for high-proportion fluctuating power supply | |
| Shahriyari et al. | Fast prediction of angle stability using support vector machine and fault duration data | |
| D'Aversa et al. | Challenges and solutions of protecting variable speed drive motors | |
| Ni et al. | A real-time fault diagnosis method for grid-side overcurrent in train traction system using signal time series feature pattern recognition | |
| Dawood et al. | An Efficient Protection Scheme Against Single-Phasing Fault for Three-Phase Induction Motor | |
| CN109557398B (en) | Power distribution network fault diagnosis method and device | |
| CN109245049A (en) | A kind of AC excitation synchronous electric motor rotor winding overcurrent protection method and device | |
| CN114400640B (en) | Power grid distance protection method and device based on power supply constitution proportion online identification | |
| Guerrero et al. | AC ground fault location for DC–AC inverters based on a grounding resistor voltage analysis | |
| CN112595932A (en) | Single-pole fault line selection method suitable for medium-voltage direct-current power distribution network | |
| Bianchini et al. | Stator fault diagnosis by reactive power in dual three-phase reluctance motors | |
| Postal et al. | Locus-based fault indicators and a cumulative sum algorithm to detect induction machine stator interturn short-circuit faults | |
| Sadeghkhani | A single-end reactor voltage based protection scheme for meshed VSC-interfaced HVDC grids | |
| Sravani et al. | Improvement of Power System Stability Using SFCL in Electric Power Grid under Voltage Unbalance conditions | |
| Kazeminia et al. | A Novel Islanding Detection Method Based on a Hybrid Algorithm in DC Microgrids | |
| CN113917249B (en) | Wind turbine generator high-low voltage fault ride through monitoring method and system | |
| Barros et al. | Analysis of Turn-to-Ground and Turn-to-Turn Stator Faults in Permanent Magnet Synchronous Machine | |
| Liu et al. | Primary admittance based fault detection for inter-turn short circuit in 3-phase power transformers | |
| Lv et al. | Node Voltage Sag Severity Evaluation Based on Improved Energy Index |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |