CN111983348A - Island detection method and device and island detection equipment - Google Patents
Island detection method and device and island detection equipment Download PDFInfo
- Publication number
- CN111983348A CN111983348A CN202010791055.4A CN202010791055A CN111983348A CN 111983348 A CN111983348 A CN 111983348A CN 202010791055 A CN202010791055 A CN 202010791055A CN 111983348 A CN111983348 A CN 111983348A
- Authority
- CN
- China
- Prior art keywords
- current signal
- island
- voltage
- voltage frequency
- reactive disturbance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
The embodiment of the invention relates to an island detection method, an island detection device and island detection equipment, wherein the island detection method comprises the following steps: controlling a grid-connected inverter to output a reactive disturbance current signal, wherein the reactive disturbance current signal is a periodic square wave signal comprising at least two modes in any period, and the reactive disturbance current signals corresponding to adjacent modes are different; acquiring a difference value of voltage frequencies of common connection points corresponding to adjacent modes; and triggering the island protection if the continuously acquired difference value meets the preset condition. Through the mode, the influence on the quality of the output current is small, and the implementation is simple.
Description
Technical Field
The invention relates to the technical field of power systems, in particular to an island detection method, an island detection device and island detection equipment.
Background
Distributed power generation is now increasingly being used in the power generation market. Under the normal condition of a power grid, the power grid and the distributed power supply jointly supply power to surrounding loads, under the condition that the power grid is disconnected from the loads due to overhauling or faults and the like, the distributed power supply still supplies power to the loads, and the distributed power supply and the loads form an island which cannot be controlled by a power company.
Load equipment can be damaged by abnormal load voltage and frequency in an island state, the personal safety of electric power maintenance personnel can be damaged by electrification of a load end, and when a power grid is reclosed, the power grid and electric equipment are damaged due to the fact that voltage, frequency and phase on the load are different from those of the power grid and large impact current is generated during closing.
The existing active island detection method comprises an active frequency deviation method, a sliding mode frequency deviation method and the like, but the method has a large influence on the quality of output current by applying disturbance to the frequency of the output current, or directly detects electrical parameters such as voltage harmonic, sequence impedance and the like of a public connection point of a power grid, when the voltage harmonic and the sequence impedance exceed set thresholds, island protection is triggered, the calculation amount is large, the requirement on a controller is high, and the implementation is complex.
Disclosure of Invention
The embodiment of the invention mainly solves the technical problem of providing an island detection method, an island detection device and island detection equipment, which have small influence on the quality of output current and are simple to implement.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions: in a first aspect, an islanding detection method is provided, where the method includes:
controlling a grid-connected inverter to output a reactive disturbance current signal, wherein the reactive disturbance current signal is a periodic square wave signal comprising at least two modes in any period, and the reactive disturbance current signals corresponding to adjacent modes are different;
acquiring a difference value of voltage frequencies of common connection points corresponding to adjacent modes;
and triggering the island protection if the continuously acquired difference value meets a preset condition.
In an optional manner, the obtaining a difference between voltage frequencies of common connection points corresponding to adjacent modes includes:
acquiring the voltage frequency of the common connection point;
and if the variation trend of the amplitude of the voltage frequency is consistent with the variation trend of the reactive disturbance current, acquiring the difference value of the voltage frequency of the public connection points corresponding to the adjacent modes.
In an optional manner, the triggering an islanding protection if the continuously obtained difference value meets a preset condition includes:
respectively acquiring the voltage frequency f corresponding to the Nth mode and the N-1 th modeN、fN-1And calculating the voltage frequency difference value delta f [ N ] corresponding to the Nth mode]Wherein, Δ f [ N ]]＝fN-fN-1；
Obtaining an active current signal output by the grid-connected inverter, and calculating a voltage frequency change value delta f corresponding to the Nth mode based on the active current signal and the reactive disturbance current signalN；
And triggering the island protection if the voltage frequency difference value and the voltage frequency change value meet preset conditions.
In an optional manner, the active current signal output by the grid-connected inverter is obtained, and the voltage frequency change value Δ f corresponding to the nth mode is calculated based on the active current signal and the reactive disturbance current signalNThe method comprises the following steps:
acquiring the voltage frequency of a common connection point when no island occurs;
calculating a first ratio of the reactive disturbance current signal and the active current signal corresponding to the Nth mode;
calculating a second ratio of the voltage frequency of the common connection point when the islanding does not occur to the 2 times quality factor;
calculating the product of the second ratio and the first ratio, and recording as the voltage frequency change value delta f corresponding to the Nth modeN。
In an optional manner, if the voltage-frequency difference and the voltage-frequency variation satisfy a preset condition, triggering an islanding protection includes:
within a preset time period, when delta f [ N ]]When the pressure is higher than 0, the pressure is higher,
and when Δ f [ N ]]When the ratio is less than 0, the reaction mixture is,
and triggering the island protection at the moment when the preset time length is finished.
In an optional manner, the reactive disturbance current signal is a periodic square wave signal including four modes, and the currents corresponding to the four modes are respectively: iq1, 0, Iq2 and 0, wherein Iq2<0< Iq 1.
In an alternative form of the method according to the invention,
in a second aspect, an islanding detection apparatus is provided, the apparatus comprising:
the control module is used for controlling the grid-connected inverter to output a reactive disturbance current signal, wherein the reactive disturbance current signal is a periodic square wave signal comprising at least two modes in any period;
the acquisition module is used for acquiring the difference value of the voltage frequencies of the common connection points corresponding to two adjacent modes;
and the judging module is used for judging whether the continuously acquired difference value meets a preset condition or not, and if so, triggering the island protection.
In a third aspect, an islanding detection device is provided, the device comprising:
at least one processor and a memory communicatively coupled to the at least one processor, the memory storing instructions executable by the at least one processor to enable the at least one processor to perform a method as described above.
In a fourth aspect, a grid-connected power generation system is provided, where the grid-connected power generation system includes the island detection device and the distributed power supply.
In a fifth aspect, a non-transitory computer-readable storage medium is provided, the computer-readable storage medium storing computer-executable instructions that, when executed by an islanding detection device, cause the islanding detection device to perform the method as described above.
According to the island detection method, the device and the equipment, the grid-connected inverter is controlled to output the reactive disturbance current signal to detect the island, the reactive disturbance current signal is a periodic square wave signal comprising at least two modes in any period, the reactive disturbance current signal has small influence on the quality of the grid-connected current under the condition of grid connection, when the island occurs, only the frequency of a load end needs to be detected, and the condition for triggering island protection can be obtained through calculation.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
Fig. 1 is a schematic flowchart of an island detection method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a reactive disturbance current signal provided by an embodiment of the present invention;
FIG. 3 is a schematic diagram of another reactive disturbance current signal provided by an embodiment of the present invention;
FIG. 4 is a schematic diagram of a further reactive disturbance current signal provided by an embodiment of the present invention;
fig. 5 is a schematic diagram of a disturbance reactive current signal and a voltage frequency signal before and after an islanding is generated according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of an island operation of a photovoltaic power generation system provided by an embodiment of the invention;
fig. 7 is a flowchart illustrating a calculation process of triggering islanding protection according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of an island detection device according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a computer device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the application provides an island detection method, which superimposes a smaller reactive disturbance current on an output current of an inverter, has less influence on the quality of grid-connected current under the condition of grid connection, performs island detection and island protection based on the variation relation between a load and the disturbance current, and can obtain more complete and accurate data compared with the prior art.
The island detection method provided by the embodiment of the invention is configured in island detection equipment. Optionally, the islanding detection device includes a central processing unit, a memory, an input device, and an output device, and integrates one or more of an embedded computation, a control technology, a signal construction technology, and the like to implement functions such as signal construction and information processing.
The types of the islanding detection equipment are many and can be selected according to application requirements, for example: desktop, tablet, embedded device, etc.
Referring to fig. 1, fig. 1 is a schematic flow chart of an island detection method according to an embodiment of the present invention, which specifically includes:
11: and controlling the grid-connected inverter to output a reactive disturbance current signal, wherein the reactive disturbance current signal is a periodic square wave signal comprising at least two modes in any period, and the reactive disturbance current signals corresponding to adjacent modes are different.
The reactive disturbance current signal may have various forms, which are not limited herein, such as the reactive disturbance current signal L1a shown in fig. 2, the reactive disturbance current signal L1b shown in fig. 3, and the reactive disturbance current signal L1c shown in fig. 4; the number of modes in one period of each reactive disturbance current signal is only two or more, for example, in one period, the reactive disturbance current signal L1a has exactly two modes and the reactive disturbance current signal L1c has four modes. The reactive disturbance is disturbance of reactive power output by an alternating current port of the grid-connected inverter so as to change the frequency of alternating current output by the alternating current port of the grid-connected inverter. The reactive current is a current 90 degrees out of phase with the voltage.
Optionally, the reactive disturbance current signal is L1d as shown in fig. 5, where the reactive disturbance current signal L1d includes 4 modes, i.e., mode 1, mode 2, mode 3, and mode 4, and the current corresponding to each mode is Iq1, 0, Iq3, and 0, respectively, where Iq3<0< Iq 1.
12: and acquiring the difference of the voltage frequencies of the common connection points corresponding to the adjacent modes.
In an embodiment, the voltage frequency of the common connection point is obtained first, and if the variation trend of the amplitude of the voltage frequency is consistent with the variation trend of the reactive disturbance current, the difference value of the voltage frequencies of the common connection points corresponding to adjacent modes is obtained.
Specifically, L2 is the voltage frequency curve of the common connection point. When the islanding phenomenon does not occur, namely before the islanding, the voltage frequency of the public connection point cannot be disturbed and biased, the public connection point is in a stable state and is close to a straight line, namely the amplitude change value of the voltage frequency of the public connection point is small, the change trend of the voltage frequency of the public connection point is completely different from that of reactive disturbance current, and therefore the islanding can be accurately detected.
After the islanding, the voltage frequency of the common connection point is disturbed and biased, L2 is an actually detected frequency curve, and the actually detected frequency curve lags behind the phase of the reactive disturbance current by a mode, so that the variation trend of the amplitude of the voltage frequency is substantially consistent with the variation trend of the reactive disturbance current, that is, the amplitude of the voltage frequency increases with the increase of the reactive disturbance current and decreases with the decrease of the reactive disturbance current, so that the islanding can be accurately detected accordingly. After the occurrence of the island is determined, the difference between the voltage frequencies corresponding to each two modes is calculated and recorded.
In practical application, how to detect an island is explained by using a schematic structural diagram of the island operation of the photovoltaic power generation system provided by the embodiment of the invention shown in fig. 6, in the system, a resonant simulation load circuit is used to explain the actual influence condition of disturbance reactive current on the quality of grid-connected current, an inverter U, a resistor R, an inductor L, a capacitor C and a power grid Ug exist in the system, in practical application, the inverter U is controlled to generate disturbance reactive current, that is, active current and reactive current exist in an output current signal of the inverter U, a resonant circuit is formed between the inductor L and the capacitor C at a load end, the resonant frequency of the inductor L and the capacitor C at the load end is power frequency 50HZ, and the active power output by the inverter is completely matched with the active power at the load end.
Then, for the load side, the active power P satisfies the equation (1): p is U1 2R, wherein U1Is the output voltage of the inverter U; the reactive power Q satisfies the equation (2): q ═ U1 2(1/ω L- ω C); the resonant frequency of the inductor L and the capacitor C is set to f0I.e. the frequency when no island is sent is f0And satisfies the formula (3):
quality factor QfSatisfies the following formula (4):
wherein, ω is0Is a and f0A corresponding angular frequency; formula (5) can be obtained by combining formula (1), formula (2), formula (3) and formula (4):
wherein f is the actual frequency; solving equation (5) yields equation (6):
and for the inverter, the active power P satisfies the equation (7): p1.5 UIdIn which IdOutputting active current for the inverter; the reactive power Q satisfies the equation (8): q ═ 1.5UIqIn which IqOutputting reactive current for the inverter; the formula (6), the formula (7) and the formula (8) are combinedThe resultant obtainable formula (9):
setting k as Iq/IdUnder normal operating conditions, the power factor approaches 1 and k<<1; the quality factor is determined by the load, and is generally not less than 1 in engineering, so that
And
equation (9) can be simplified to equation (10):
therefore, as can be seen from the above calculation process, the quality factor QfThe amount of change in frequency in the determined case
Is determined entirely by the coefficient k, which is only related to the active current IdAnd a reactive current IqAnd after the islanding is determined, calculating and recording the difference value between the voltage frequencies corresponding to each two modes.
It will be appreciated that in steady state, i.e. when islanding is not being sent, the inverter power factor is assumed to be 0.05 with k set
It can be seen that under the condition of grid connection, the influence of reactive disturbance current on the quality of grid-connected current is small.
13: and triggering the island protection if the continuously acquired difference value meets a preset condition.
In one embodiment, how to trigger islanding protection is described using the steps shown in fig. 7, which include:
131: is divided intoRespectively acquiring the voltage frequency f corresponding to the Nth mode and the N-1 th modeN、fN-1And calculating a first voltage frequency difference value delta f [ N ] corresponding to the Nth mode]Wherein, Δ f [ N ]]＝fN-fN-1。
132: obtaining an active current signal output by the grid-connected inverter, and calculating a voltage frequency change value delta f corresponding to the Nth mode based on the active current signal and the reactive disturbance current signalN。
Wherein the voltage frequency difference value delta f [ N ]]Is a value directly detected by an instrument or equipment, and the voltage frequency change value deltafNIs a theoretical value calculated based on theory. For example, the voltage frequencies f corresponding to the 2 nd mode and the 1 st mode are respectively obtained2And f1Then, the corresponding voltage frequency difference Δ f [2 ] on the 2 nd mode can be obtained]＝f2-f1Then, the voltage frequency variation value delta f corresponding to the 2 nd mode is calculated2，Δf2Is calculated from the active current signal and the reactive disturbance current signal, if delta f 2]And Δ f2If the preset condition is satisfied, the island protection is triggered, such as delta f 2]And Δ f2Satisfy a magnitude relation or a multiple relation, etc.
Optionally, the voltage frequency of the common connection point when no islanding occurs is denoted as f0Obtaining the quality factor of the load end, and recording the quality factor as QfRespectively recording the reactive disturbance current signal and the active current signal corresponding to the Nth mode as IqnAnd IdnThen the reactive disturbance current signal I corresponding to the Nth modeqnWith active current signal IdnHas a first ratio of
The second ratio of the voltage frequency of the common connection point to the 2 times quality factor when no island occurs is
The voltage frequency variation value corresponding to the Nth mode is the product of the second ratio and the first ratioComprises the following steps:
frequency f of voltage at point of common connection0When no island occurs, the island is kept in a stable state, which can be regarded as a fixed value, and the quality factor Q at the load endfUnder the determined condition, the voltage frequency change value delta f corresponding to the Nth modenIs totally made of
And (4) determining.
133: and triggering the island protection if the voltage frequency difference value and the voltage frequency change value meet preset conditions.
Optionally, within a preset time period, when Δ f [ N ]]When > 0,. DELTA.f [ N ]]＞(ΔfN-1-ΔfN-2) 2, and when Δ f [ N ]]When <0,. DELTA.f [ N ]]＜(ΔfN-1-ΔfN-2) And/2, triggering the island protection at the moment when the preset time length is finished.
As can be seen from the above, the voltage frequency variation Δ f corresponding to the nth modenIs totally made of
Determined, that is to say when islanding occurs,. DELTA.fnAnd IqnOne-to-one correspondence, and the symbols are also consistent,
if is Iqn>Δ f when equal to 0n>If 0, if Iqn<Δ f 0n<0, when Δ f [ N ]]The following are the cases > 0:
if Δ fN-1>ΔfN-2>0, then
If Δ fN-1>0>ΔfN-2Then, then
If 0>ΔfN-1>ΔfN-2Then, then
When Δ f [ N ] <0, there are the following cases:
if Δ fN-2>ΔfN-1>0, then
If Δ fN-2>0>ΔfN-1Then, then
If 0>ΔfN-2>ΔfN-1Then, then
It can be understood that there are various ways to set a preset duration, which is not limited herein, for example, an island fault counter may be used, and when the count reaches a preset threshold, that is, the timing time is up, island protection is triggered. The islanding protection mode may specifically be that ac power output through an ac port of the grid-connected inverter is stopped, and of course, islanding protection may also be performed in other modes, which is not limited in this application.
For ease of understanding, the above-described islanding detection method is exemplified below with reference to fig. 5.
As shown in fig. 5, each period of the reactive disturbance current signal L1d has a total of 4 modes, i.e., mode 1, mode 2, mode 3, and mode 4, and the current corresponding to each mode is Iq1, 0, Iq3, and 0, where Iq3<0< Iq 1.
When the islanding phenomenon occurs, the islanding phenomenon is caused by Iq3<0<Iq1, setting the voltage frequency change values corresponding to 1-4 modes as delta f1、Δf2、Δf3And Δ f4Calculating delta f according to the reactive disturbance current and the active current3<0<Δf1And Δ f2＝Δf4Due to the letter being 0The number is a periodic signal, so that if the previous mode to mode 1 is mode 4, then it can be obtained from the above equation:
based on the voltage frequency signal L2 of the point of common connection after islanding and the reactive disturbance current signal L1d in FIG. 5, it can be determined that Δ f [1 ]]＝f1-f4；Δf[2]＝f2-f1；Δf[3]＝f3-f2；Δf[4]＝f4-f3. When the islanding phenomenon occurs, the voltage frequency signal L2 of the common node changes along with the change of the reactive disturbance current signal L1d, and the voltage frequency f at the common node is assumed to be0The frequency of the voltage superposed on each other is Deltaf11、Δf21、Δf31、Δf41Likewise,. DELTA.f21＝Δf 410, so Δ f is not shown in the figure21And Δ f41. Then combining L1d with L2 yields Δ f [1 ]]＝f1-f4＝|Δf31|；Δf[2]＝f2-f1＝Δf11；Δf[3]＝f3-f2＝-Δf11；Δf[4]＝f4-f3＝-|Δf31|。
Theoretically, the frequency difference calculated by the reactive disturbance current and the active current is the same as the actually detected frequency difference, i.e. Δ f1＝Δf11；Δf2＝Δf21；Δf3＝Δf31；Δf4＝Δf41Further, by combining the above 8 equations, it can be seen that the following equation is satisfied at the same time when the islanding occurs:
due to Δ f2＝Δf4If 0, the judgment condition can be simplified as:
(Δf[1]>|Δf3|/2)&&(Δf[2]>Δf1/2)&&(Δf[3]<-Δf1/2)&&(Δf[4]<-Δf3and/2) when the condition is detected to be met, timing is started, and when the timing time is up, the islanding protection is triggered, namely within the preset time length, the condition can be met all the time, and when the end time of the preset time length is up, the islanding protection is triggered.
It is understood that there are various ways of timing, which are not limited herein, for example, an islanding fault counter may be used, and when a preset threshold is counted, even if the time is up, islanding protection is triggered.
The embodiment of the invention further discloses an island detection device, which is applied to island detection equipment, and as shown in fig. 8, the island detection device comprises:
a control module 81, an acquisition module 82, and a determination module 83.
Specifically, the control module 81 is configured to control the grid-connected inverter to output a reactive disturbance current signal, where the reactive disturbance current signal is a periodic square wave signal including at least two modes in any period, and for example, as shown in fig. 2, the reactive disturbance current signal L1a changes twice in one period, I isq1And 0, then the current remains Iq1This segment is denoted as one mode, and the segment in which the current remains 0 is denoted as the other mode.
The obtaining module 82 is configured to obtain a difference between voltage and frequency of a common connection point corresponding to two adjacent modes, where the difference between the voltage and frequency of the common connection point corresponding to the two adjacent modes changes due to the existence of the reactive disturbance current signal after the islanding occurs, and is greatly different from the difference between the voltage and frequency of the common connection point before the islanding occurs.
The determining module 83 is configured to determine whether the continuously obtained difference value meets a preset condition, and trigger islanding protection if the continuously obtained difference value meets the preset condition. When the islanding phenomenon does not occur, the frequency of the public connection point is kept in a stable state, the islanding phenomenon can be judged to not occur, if the islanding phenomenon occurs, the frequency of the public connection point can be changed due to the influence of the reactive disturbance current signal, and whether the islanding exists or not and when the islanding protection is triggered can be judged according to the frequency of the public connection point along with the change condition of the reactive disturbance current signal.
It should be noted that, since the device embodiment and the method embodiment of the present invention are based on the same inventive concept, and the technical content in the method embodiment is also applicable to the device embodiment, the technical content in the device embodiment that is the same as that in the method embodiment is not described herein again.
In order to better achieve the above object, as shown in fig. 9, an embodiment of the present invention further provides an island detection device 900, where the island detection device 900 stores executable instructions, and the executable instructions may execute the island detection method in any method embodiment described above.
Fig. 9 is a schematic structural diagram of an island detection device 900 according to an embodiment of the present invention, and as shown in fig. 9, the island detection device 900 includes: one or more processors 901 and a memory 902, where one processor 901 is taken as an example in fig. 9.
The processor 901 and the memory 902 may be connected by a bus or other means, and fig. 9 illustrates the connection by a bus as an example.
The memory 902, which is a non-volatile computer-readable storage medium, may be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as program instructions/modules (e.g., the modules shown in fig. 8) corresponding to the islanding detection method in the embodiment of the present invention. The processor 901 executes various functional applications and data processing of the islanding detection apparatus by running nonvolatile software programs, instructions, and modules stored in the memory 902, that is, the functions of the islanding detection method of the above method embodiment and the various modules of the above apparatus embodiment are implemented.
The memory 902 may include high speed random access memory and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some embodiments, the memory 902 may optionally include memory located remotely from the processor 901, which may be connected to the processor 901 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The program instructions/modules stored in the memory 902, when executed by the one or more processors 901, perform the islanding detection method in any of the method embodiments described above, e.g., performing the various steps shown in fig. 1 and 7 described above; the various modules described in fig. 8 may also be implemented.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.
Claims (10)
1. An islanding detection method, the method comprising:
controlling a grid-connected inverter to output a reactive disturbance current signal, wherein the reactive disturbance current signal is a periodic square wave signal comprising at least two modes in any period, and the reactive disturbance current signals corresponding to adjacent modes are different;
acquiring a difference value of voltage frequencies of common connection points corresponding to adjacent modes;
and triggering the island protection if the continuously acquired difference value meets a preset condition.
2. The islanding detection method according to claim 1, wherein the obtaining a difference between voltage frequencies of the common connection points corresponding to adjacent modes comprises:
acquiring the voltage frequency of the common connection point;
and if the variation trend of the amplitude of the voltage frequency is consistent with the variation trend of the reactive disturbance current, acquiring the difference value of the voltage frequency of the public connection points corresponding to the adjacent modes.
3. The island detection method according to claim 1, wherein triggering island protection if the continuously obtained difference value meets a preset condition comprises:
respectively acquiring the voltage frequency f corresponding to the Nth mode and the (N-1) th modeN、fN-1And calculating the voltage frequency difference value delta f [ N ] corresponding to the Nth mode]Wherein, Δ f [ N ]]＝fN-fN-1；
Obtaining an active current signal output by the grid-connected inverter, and calculating a voltage frequency change value delta f corresponding to the Nth mode based on the active current signal and the reactive disturbance current signalN；
And triggering the island protection if the voltage frequency difference value and the voltage frequency change value meet preset conditions.
4. The island detection method according to claim 3, wherein the active current signal output by the grid-connected inverter is obtained, and the voltage frequency change value Δ f corresponding to the Nth mode is calculated based on the active current signal and the reactive disturbance current signalNThe method comprises the following steps:
acquiring the voltage frequency of a common connection point when no island occurs;
calculating a first ratio of the reactive disturbance current signal and the active current signal corresponding to the Nth mode;
calculating a second ratio of the voltage frequency of the common connection point when the islanding does not occur to the 2 times quality factor;
calculating the product of the second ratio and the first ratio, and recording as the voltage frequency change value delta f corresponding to the Nth modeN。
5. The islanding detection method according to claim 4, wherein the triggering an islanding protection if the voltage-frequency difference value and the voltage-frequency variation value satisfy a preset condition includes:
within a preset time period, when delta f [ N ]]When the pressure is higher than 0, the pressure is higher,
and when Δ f [ N ]]When the ratio is less than 0, the reaction mixture is,
and triggering the island protection at the moment when the preset time length is finished.
6. The islanding detection method according to any of claims 1-5,
the reactive disturbance current signal is a periodic square wave signal comprising four modes, and the currents corresponding to the four modes are respectively: iq1, 0, Iq3 and 0, wherein Iq3<0< Iq 1.
7. An islanding detection apparatus, the apparatus comprising:
the control module is used for controlling the grid-connected inverter to output a reactive disturbance current signal, wherein the reactive disturbance current signal is a periodic square wave signal comprising at least two modes in any period;
the acquisition module is used for acquiring the difference value of the voltage frequencies of the common connection points corresponding to two adjacent modes;
and the judging module is used for judging whether the continuously acquired difference value meets a preset condition or not, and if so, triggering the island protection.
8. An islanding detection device, the device comprising:
at least one processor and a memory communicatively coupled to the at least one processor, the memory storing instructions executable by the at least one processor to enable the at least one processor to perform the method of any of claims 1-6.
9. A grid-connected power generation system, characterized in that the grid-connected power generation system comprises an island detection device according to claim 8 and a distributed power supply.
10. A non-transitory computer-readable storage medium having stored thereon computer-executable instructions that, when executed by an islanding detection device, cause the islanding detection device to perform the method of any of claims 1-6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010791055.4A CN111983348B (en) | 2020-08-07 | 2020-08-07 | Island detection method and device and island detection equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010791055.4A CN111983348B (en) | 2020-08-07 | 2020-08-07 | Island detection method and device and island detection equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111983348A true CN111983348A (en) | 2020-11-24 |
| CN111983348B CN111983348B (en) | 2022-05-13 |
Family
ID=73445696
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010791055.4A Active CN111983348B (en) | 2020-08-07 | 2020-08-07 | Island detection method and device and island detection equipment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111983348B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114301267A (en) * | 2022-03-09 | 2022-04-08 | 深圳市首航新能源股份有限公司 | Driving method and device of switch tube and inverter |
| CN114498760A (en) * | 2022-03-11 | 2022-05-13 | 深圳市首航新能源股份有限公司 | Island detection method and device and electronic equipment thereof |
| CN116047212A (en) * | 2023-03-27 | 2023-05-02 | 华中科技大学 | Island detection method and device based on reactive power disturbance |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060146582A1 (en) * | 2004-12-31 | 2006-07-06 | Pao-Chuan Lin | Islanding detection method |
| CN103064035A (en) * | 2013-01-08 | 2013-04-24 | 天津大学 | Active island detection method of multi-distributed power supply tied-grid |
| US20130116947A1 (en) * | 2011-11-09 | 2013-05-09 | Zafer Sahinoglu | Method and System for Detecting Unbalance in Power Grids |
| CN104155555A (en) * | 2014-08-27 | 2014-11-19 | 阳光电源股份有限公司 | Active island detection method and device |
| CN104730396A (en) * | 2015-04-07 | 2015-06-24 | 国家电网公司 | Island detection method and device for electric power system |
| CN104865479A (en) * | 2015-06-15 | 2015-08-26 | 江苏方天电力技术有限公司 | Islanding detecting method |
| CN106199235A (en) * | 2016-06-21 | 2016-12-07 | 江苏大学 | A kind of island detection method based on fundamental frequency with switching frequency time impedance |
-
2020
- 2020-08-07 CN CN202010791055.4A patent/CN111983348B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060146582A1 (en) * | 2004-12-31 | 2006-07-06 | Pao-Chuan Lin | Islanding detection method |
| US20130116947A1 (en) * | 2011-11-09 | 2013-05-09 | Zafer Sahinoglu | Method and System for Detecting Unbalance in Power Grids |
| CN103064035A (en) * | 2013-01-08 | 2013-04-24 | 天津大学 | Active island detection method of multi-distributed power supply tied-grid |
| CN104155555A (en) * | 2014-08-27 | 2014-11-19 | 阳光电源股份有限公司 | Active island detection method and device |
| CN104730396A (en) * | 2015-04-07 | 2015-06-24 | 国家电网公司 | Island detection method and device for electric power system |
| CN104865479A (en) * | 2015-06-15 | 2015-08-26 | 江苏方天电力技术有限公司 | Islanding detecting method |
| CN106199235A (en) * | 2016-06-21 | 2016-12-07 | 江苏大学 | A kind of island detection method based on fundamental frequency with switching frequency time impedance |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114301267A (en) * | 2022-03-09 | 2022-04-08 | 深圳市首航新能源股份有限公司 | Driving method and device of switch tube and inverter |
| CN114498760A (en) * | 2022-03-11 | 2022-05-13 | 深圳市首航新能源股份有限公司 | Island detection method and device and electronic equipment thereof |
| CN116047212A (en) * | 2023-03-27 | 2023-05-02 | 华中科技大学 | Island detection method and device based on reactive power disturbance |
| CN116047212B (en) * | 2023-03-27 | 2023-06-02 | 华中科技大学 | Island detection method and device based on reactive power disturbance |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111983348B (en) | 2022-05-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111983348B (en) | Island detection method and device and island detection equipment | |
| Khan et al. | On the stability of the power electronics-dominated grid: A new energy paradigm | |
| Sahoo et al. | On detection of false data in cooperative DC microgrids—A discordant element approach | |
| Gkavanoudis et al. | A combined fault ride-through and power smoothing control method for full-converter wind turbines employing supercapacitor energy storage system | |
| Salimin et al. | Simulation analysis of DVR performance for voltage sag mitigation | |
| RU2471274C2 (en) | Method and device for quick unlocking of remote protection in case of power oscillation in power system | |
| Chiang et al. | Active islanding detection method for inverter-based distribution generation power system | |
| CN108599241A (en) | Photovoltaic virtual synchronous machine primary frequency modulation control method and equipment | |
| US10935588B2 (en) | Systems and methods for islanding detection | |
| US20180348308A1 (en) | Systems and methods for islanding detection | |
| Malla et al. | Online learning control for harmonics reduction based on current controlled voltage source power inverters | |
| Emadi et al. | A reference current perturbation method for islanding detection of a multi-inverter system | |
| Liu et al. | Phase locked-loop with decaying DC transient removal for three-phase grids | |
| CN107769247B (en) | RLC load simulation system for anti-islanding detection and control method thereof | |
| Azim et al. | A fuzzy logic based dynamic voltage restorer for voltage sag and swell mitigation for industrial induction motor loads | |
| US20190190254A1 (en) | A method for phase controlled energizing of power transformer | |
| Elyasichamazkoti et al. | Digital filter‐based grid synchronization for autonomous microgrids | |
| CN113972634A (en) | Micro-grid differential protection method for self-adaptive zero-sequence energy injection | |
| Lin et al. | Adaptive fault ride through control of VSM Grid-forming converters | |
| Sharma et al. | Affine projection sign algorithm based control for mitigation of distribution side power quality problems | |
| CN112583050A (en) | Control method and system for multi-VSG inverter loop current suppression and fault handling | |
| CN103944158B (en) | A kind of online Poewr control method based on small interference stability risk supervision and system | |
| JP2021013207A (en) | Converter control device and converter control method for simulating virtual impedance | |
| Pires et al. | Phase-locked loop topology based on a synchronous reference frame and sliding mode approach for DVR applications | |
| CN107147138B (en) | Three-phase and four-line power distribution network compensates equipment DC capacitor detection method, apparatus and system |
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 | ||
| CB02 | Change of applicant information | ||
| CB02 | Change of applicant information |
Address after: 518000 building 401, building 4, Antongda industrial plant, zone 68, Xingdong community, Xin'an street, Bao'an District, Shenzhen City, Guangdong Province Applicant after: Shenzhen Shouhang new energy Co.,Ltd. Address before: 518000 building 401, building 4, Antongda industrial plant, zone 68, Xingdong community, Xin'an street, Bao'an District, Shenzhen City, Guangdong Province Applicant before: SHENZHEN SOFARSOLAR Co.,Ltd. |
|
| GR01 | Patent grant | ||
| GR01 | Patent grant |