CN113437733A - Photovoltaic power generation grid-connected tie line pilot protection method and system based on comprehensive impedance - Google Patents
Photovoltaic power generation grid-connected tie line pilot protection method and system based on comprehensive impedance Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—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
- H02H7/263—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 involving transmissions of measured values
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0092—Details of emergency protective circuit arrangements concerning the data processing means, e.g. expert systems, neural networks
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Abstract
本发明公开了一种基于综合阻抗的光伏发电并网联络线纵联保护方法及系统，方法包括：在启动元件动作后，基于纵联保护装置分别提取光伏发电并网联络线两侧的三相电压采样值和电流采样值，通过快速傅里叶算法分别提取三相电压工频相量和三相电流工频相量，并按相计算差动电压相量和差动电流相量；基于差动电压相量和差动电流相量，计算并网联络线中的三相综合阻抗，并分别取其虚部绝对值；将三相综合阻抗的虚部绝对值分别与保护整定门槛值作比较；基于比较结果执行相对应的保护动作。实现了能够在不受光伏逆变控制策略影响下，进行判别区内外故障，具有较强的抗过渡电阻能力，可靠性和灵敏性高。
The invention discloses a method and a system for the longitudinal protection of photovoltaic power generation grid-connected tie lines based on comprehensive impedance. The method includes: after a start-up element is actuated, based on a longitudinal protection device, three-phase protection devices on both sides of the photovoltaic power generation grid-connected tie lines are respectively extracted. Voltage sampling value and current sampling value, extract three-phase voltage power-frequency phasor and three-phase current power-frequency phasor respectively through fast Fourier algorithm, and calculate differential voltage phasor and differential current phasor by phase; The dynamic voltage phasor and the differential current phasor are used to calculate the three-phase comprehensive impedance in the grid-connected tie line, and take the absolute value of its imaginary part respectively; compare the absolute value of the imaginary part of the three-phase comprehensive impedance with the protection setting threshold value. ; Execute the corresponding protection action based on the comparison result. It is realized that the faults inside and outside the zone can be discriminated without being affected by the photovoltaic inverter control strategy, and it has strong anti-transition resistance ability, high reliability and sensitivity.
Description
Technical Field
The invention belongs to the technical field of power system relay protection, and particularly relates to a photovoltaic power generation grid-connected tie line pilot protection method and system based on comprehensive impedance.
Background
With the development of renewable energy and the implementation of sustainable energy development strategies, photovoltaics have unique advantages and become hot spots for the development of new energy at present, and meanwhile, the access of a photovoltaic system also brings a lot of influences on the protection of the current power grid. The random fluctuation of the output of the photovoltaic power supply and the influence of a control structure and a control strategy in the grid-connected inversion process cause the fault characteristics of the photovoltaic system to be more complex, and a relay protection principle formed based on the fault characteristic analysis of the traditional synchronous machine system can not adapt to the change of the system fault characteristics after the photovoltaic power supply is connected, so that the protection performance is reduced, even misoperation or failure is caused.
A feasible new protection scheme needs to be researched to guarantee safe and stable operation of a power grid and further promote development of the photovoltaic industry.
Disclosure of Invention
The invention aims to provide a comprehensive impedance-based pilot protection method and system for a photovoltaic power generation grid-connected tie line, and solves the problem that the sensitivity of the existing line pilot current differential protection is reduced and even the existing line pilot current differential protection is rejected in the photovoltaic grid-connected tie line.
In a first aspect, the invention provides a comprehensive impedance-based pilot protection method for a photovoltaic power generation grid-connected tie line, which comprises the following steps: step 1, after a starting element acts, respectively extracting three-phase voltage sampling values and current sampling values on two sides of a photovoltaic power generation grid-connected tie line based on a pilot protection device, respectively extracting three-phase voltage power frequency phasor and three-phase current power frequency phasor through a fast Fourier algorithm, and calculating differential voltage phasor according to phases
And differential current phasor
(ii) a Step 2, based on the differential voltage phasor
And said differential current phasor
Calculating the three-phase comprehensive impedance in the grid-connected tie line
、
、
And taking the absolute values of their imaginary parts
、
、
(ii) a Step 3, the imaginary part absolute value of the three-phase comprehensive impedance is obtained
、
、
Respectively setting threshold value with protection
Making a comparison, wherein the protection setting threshold value
In the formula (I), wherein,
，
is the equivalent capacitive reactance of each phase of the line,
is a capacitance value per unit length of a grid-connected tie line,
for the length of the grid-connected tie-line,
the angular frequency is the power frequency; and 4, executing corresponding protection actions based on the comparison result, wherein the protection actions specifically comprise: if the absolute value of the imaginary part of a certain phase of comprehensive impedance in the grid-connected tie line is less than
And judging the single-phase fault in the photovoltaic power generation grid-connected tie line areaProtecting the action jump fault phase; if the imaginary part absolute value of a certain two-phase comprehensive impedance or three-phase comprehensive impedance in the grid-connected tie line is less than
Judging that two-phase faults or three-phase faults exist in the photovoltaic power generation grid-connected tie line area, and protecting the action to jump to three phases; if the absolute values of the imaginary parts of the three-phase comprehensive impedance in the grid-connected tie line are all larger than
And if the photovoltaic power generation grid-connected tie line is not in fault, the protection does not act.
In a second aspect, the present invention provides a comprehensive impedance-based pilot protection system for a photovoltaic power generation grid-connected tie line, comprising: the first calculation module is configured to extract three-phase voltage sampling values and current sampling values on two sides of the photovoltaic power generation grid-connected tie line respectively based on the pilot protection device after the starting element acts, extract three-phase voltage power frequency phasor and three-phase current power frequency phasor respectively through a fast Fourier algorithm, and calculate differential voltage phasor according to phases
And differential current phasor
(ii) a A second calculation module configured to calculate phasor based on the differential voltage
And said differential current phasor
Calculating the three-phase comprehensive impedance in the grid-connected tie line
、
、
And taking the absolute values of their imaginary parts
、
、
；
A judging module configured to determine an absolute value of an imaginary part of the three-phase synthesized impedance
、
、
Respectively setting threshold value with protection
Making a comparison, wherein the protection setting threshold value
In the formula (I), wherein,
，
is the equivalent capacitive reactance of each phase of the line,
is a capacitance value per unit length of a grid-connected tie line,
for the length of the grid-connected tie-line,
the angular frequency is the power frequency; an execution module configured to execute a corresponding protection action based on the comparison result, wherein the execution module specifically includes: if the absolute value of the imaginary part of a certain phase of comprehensive impedance in the grid-connected tie line is less than
Judging that the single-phase fault exists in the photovoltaic power generation grid-connected tie line area, and protecting the action from jumping the fault phase; if the imaginary part absolute value of a certain two-phase comprehensive impedance or three-phase comprehensive impedance in the grid-connected tie line is less than
Judging that two-phase faults or three-phase faults exist in the photovoltaic power generation grid-connected tie line area, and protecting the action to jump to three phases; if the absolute values of the imaginary parts of the three-phase comprehensive impedance in the grid-connected tie line are all larger than
And if the photovoltaic power generation grid-connected tie line is not in fault, the protection does not act.
In a third aspect, an electronic device is provided, comprising: the protection method comprises at least one processor and a memory which is in communication connection with the at least one processor, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the steps of the comprehensive impedance-based pv grid tie pilot protection method according to any embodiment of the invention.
In a fourth aspect, the present invention also provides a computer readable storage medium having stored thereon a computer program comprising program instructions which, when executed by a computer, cause the computer to perform the steps of the integrated impedance based pv grid tie pilot protection method according to any of the embodiments of the present invention.
According to the photovoltaic power generation grid-connected tie line pilot protection method and system based on the comprehensive impedance, the comprehensive impedance is formed by utilizing the differential voltage phase difference current phasor ratio at two ends of a line, the faults inside and outside the area and the fault types are judged according to the absolute value of the imaginary part of the comprehensive impedance, the faults inside and outside the area can be judged without being influenced by a photovoltaic inversion control strategy, the fault types can be identified according to the phase action, the method and system have strong transition resistance capability, and the reliability and the sensitivity are high.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a flowchart of a method for pilot protection of a photovoltaic power generation grid-connected tie line based on comprehensive impedance according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a photovoltaic power generation grid-connected system according to an embodiment of the present invention;
fig. 3 is an equivalent circuit diagram of the photovoltaic power generation grid-connected tie line provided by an embodiment of the present invention when an external fault occurs;
fig. 4 is an equivalent circuit diagram of a fault in the photovoltaic power generation grid-connected tie line area according to an embodiment of the present invention;
fig. 5 is a network diagram of a fault component when a fault occurs in a photovoltaic power generation grid-connected tie line area according to an embodiment of the present invention;
fig. 6 is a schematic diagram illustrating a fault simulation of a photovoltaic power generation grid-connected system according to an embodiment of the present invention;
fig. 7 is a block diagram of a comprehensive impedance-based pilot protection system of a photovoltaic power generation grid-connected tie line according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of an electronic 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 invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. 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.
Referring to fig. 1, a flowchart of a method for pilot protection of a photovoltaic power generation grid-connected tie line based on comprehensive impedance according to the present application is shown.
As shown in fig. 1, in step 1, after the start component is operated, three-phase voltage sampling values and current sampling values at two sides of the photovoltaic power generation grid-connected tie line are respectively extracted based on the pilot protection device, three-phase voltage power frequency phasor and three-phase current power frequency phasor are respectively extracted through a fast fourier algorithm, and differential voltage phasor is calculated according to phases
And differential current phasor
；
In step 2, phasor is calculated based on the differential voltage
And said differential current phasor
Calculating the three-phase comprehensive impedance in the grid-connected tie line
、
、
And taking the absolute values of their imaginary parts
、
、
；
In step 3, the imaginary part absolute value of the three-phase synthetic impedance is calculated
、
、
Respectively setting threshold value with protection
Making a comparison, wherein the protection setting threshold value
In the formula (I), wherein,
，
is the equivalent capacitive reactance of each phase of the line,
is a capacitance value per unit length of a grid-connected tie line,
for the length of the grid-connected tie-line,
the angular frequency is the power frequency;
and 4, executing corresponding protection actions based on the comparison result, wherein the protection actions specifically comprise:
if the absolute value of the imaginary part of a certain phase of comprehensive impedance in the grid-connected tie line is less than
Judging that the single-phase fault exists in the photovoltaic power generation grid-connected tie line area, and protecting the action from jumping the fault phase;
if the imaginary part absolute value of a certain two-phase comprehensive impedance or three-phase comprehensive impedance in the grid-connected tie line is less than
Judging that two-phase faults or three-phase faults exist in the photovoltaic power generation grid-connected tie line area, and protecting the action to jump to three phases;
if the absolute values of the imaginary parts of the three-phase comprehensive impedance in the grid-connected tie line are all larger than
And if the photovoltaic power generation grid-connected tie line is not in fault, the protection does not act.
In summary, the method of the embodiment collects three-phase voltage phasor and three-phase current phasor at the photovoltaic side and the system side of the grid-connected tie line and transmits the collected data to the opposite end, performs fourier transform on the three-phase voltage current at the two ends of the obtained tie line, extracts three-phase voltage current power frequency phasor, calculates differential voltage phasor and differential current phasor in a split-phase manner, forms a comprehensive impedance based on the ratio of the differential voltage phasor and the differential current phasor at the two ends of the line, takes the absolute value of the imaginary part of the comprehensive impedance, and uses the obtained absolute value of the imaginary part of the three-phase comprehensive impedance of the grid-connected tie line as a criterion to distinguish the internal fault and the external fault and the fault type of the area.
Fig. 2 is a schematic structural diagram of a photovoltaic power generation grid-connected system. A centralized grid-connected structure is adopted, and photovoltaic modules are connected in series, boosted, connected in parallel and expanded and then are connected into a power grid through a DC/AC inverter. Photovoltaic inversion control is vector control based on grid voltage orientation, a synchronous rotation dq coordinate system and a grid voltage vector rotate synchronously, three-phase intersection flow is converted into direct current quantity under a positive and reverse dq coordinate system through positive and negative sequence separation and coordinate transformation, and positive and negative sequence components are respectively controlled under the positive and reverse dq coordinate system.
Fig. 3 is an equivalent circuit diagram of the photovoltaic power generation grid-connected tie line when a fault occurs outside the area. Line adoption
A model-equivalent model of the model,
as regards the impedance of the line, it is,
the equivalent capacitive reactance of each phase of the line is obtained;
respectively the voltage and the current of the photovoltaic side busbar P,
the voltage and the current of a system side bus S are respectively;
respectively are capacitance current at two ends of a photovoltaic side bus P and capacitance current at two ends of a system side bus S;
is a fault point transition resistance.
Differential current at both ends of the tie line
And differential voltage
As shown in formula (1):
the line comprehensive impedance is shown as the formula (2):
in the formula (I), the compound is shown in the specification,
the phase difference of the A phase, the phase difference of the B phase or the phase difference of the C phase,
in order to be the phasor for the differential voltage,
is the differential current phasor.
From fig. 3, when the outside of the tie line fails:
the comprehensive impedance of the connecting line is as follows:
. Therefore, when a fault occurs outside the grid-connected line area, the comprehensive impedance of the line is equal to the capacitive reactance of the line, the imaginary part of the capacitive reactance is a negative number, and the absolute value of the imaginary part is larger.
Fig. 4 is an equivalent circuit diagram of a fault in the photovoltaic power generation grid-connected tie line region.
System impedances for the photovoltaic side and the system, respectively;
line resistance respectively between fault point and two sides of photovoltaic side bus PThe impedance and the line impedance of the fault point from the two sides of the system side bus S,
the equivalent capacitive reactance of each phase of the line is obtained;
respectively photovoltaic side bus P voltage and photovoltaic side bus P current;
respectively representing the voltage S of a system side bus and the current S of the system side bus;
respectively are the capacitance current to ground at two ends of a photovoltaic side bus P and the capacitance current to ground at two ends of a system side bus S,
in order to be a fault point transition resistance,
a current flows into the fault point.
Fig. 5 is a network diagram of a fault component when a fault occurs in a photovoltaic power generation grid-connected tie line region.
In order to be a component of the fault current,
is a fault voltage component.
The differential current at the two ends of the grid-connected tie line is as follows:
in formula (4):
as can be seen from fig. 5, neglecting the influence of the line capacitance to ground, the fault point current is:
further, it is possible to obtain:
in general, when a line has a metallic fault, the line capacitance current can be approximately ignored. Because of the fact that
Related to the voltage before the fault, and can be expressed as a multiple of the voltage across the terminals, i.e.
The integrated impedance can now be expressed as:
in the formula (I), the compound is shown in the specification,
the phase difference of phase A, phase difference of phase B or phase difference of phase C.
When the transition resistor is grounded, the capacitance effect needs to be considered, and the comprehensive impedance can be expressed as:
in the formula (I), the compound is shown in the specification,
the phase difference of phase A, phase difference of phase B or phase difference of phase C.
As can be seen from equations (8) and (9), the fault line composite impedance is related to the two-terminal system impedance and the line impedance, and is affected by the transition resistance. In the formula (9), the reaction mixture is,
then, then
The absolute value of its imaginary part is generally much smaller than the line capacitive reactance.
When the grid-connected tie line has an external fault, the comprehensive impedance is equal to the line capacitive reactance, the imaginary part is negative and the absolute value is larger; when an in-zone fault occurs, the absolute value of the imaginary part of the synthetic impedance is calculated to be far smaller than that of the synthetic impedance when an out-of-zone fault occurs. Therefore, the fault can be judged by taking the magnitude of the absolute value of the imaginary part of the comprehensive impedance obtained during the faults inside and outside the area as a criterion.
The following describes in detail the implementation process and effect of the method according to a specific embodiment, as shown in fig. 6, a PSCAD/EMTDC simulation software is used to build a photovoltaic grid-connected system fault simulation circuit, a photovoltaic power station is boosted and then merged into the system through a grid-connected tie line, the rated capacity of the photovoltaic power station is 150MW, a main transformer adopts Ynd wiring, the rated voltage is 35kV/220kV, and the rated capacity is 160 MW. The length of a grid-connected connecting line is 40km, the unit positive sequence impedance is 0.076+ j0.338 omega/km, and the unit zero sequence impedance is 0.284+ j0.824 omega/km. The equivalent positive sequence impedance of the system side is 0.4+ j12.568 omega, and the equivalent zero sequence impedance is 0.6+18.849 omega. And the protection devices on the P side of the photovoltaic side bus and the S side of the system side bus acquire data on the local side and transmit the data to the opposite end in real time, and the protection devices calculate absolute values of imaginary parts of the comprehensive impedance values to judge faults and start to make instructions.
In order to have a fault outside the photovoltaic side region,
for the failure of the inner outlet of the photovoltaic side area,
in order to have a fault at the midpoint of the tie line,
in order to have a fault at the outlet in the side area of the system,
is a system side out-of-range fault. The simulation time length is 3s, and the sampling frequency is 2.5 kHz. Table 1 shows simulation results of different types of faults occurring at different positions of the tie line; table 2 shows simulation results of phase a transition resistance ground faults at different fault positions of the tie line; table 3 shows the tie line midpoints under different photovoltaic power generation output conditions
And generating simulation results of different types of faults.
Simulation results in tables 1, 2 and 3 show that the comprehensive impedance-based pilot protection method for the photovoltaic power generation grid-connected tie line can reliably judge different types of faults at different positions on the photovoltaic power generation grid-connected tie line, is not influenced by the magnitude of the output of photovoltaic power generation, and has strong transition resistance capability, high sensitivity and high reliability.
In summary, the invention provides a comprehensive impedance-based pilot protection method for a photovoltaic power generation grid-connected tie line, which can reliably judge faults inside and outside a region according to the absolute value of the imaginary part of the comprehensive impedance of the grid-connected tie line, can be well applied to the photovoltaic power generation grid-connected tie line, and is simple and effective in protection method and convenient for engineering application.
Referring to fig. 7, a block diagram of a comprehensive impedance-based pilot protection system for a photovoltaic power generation grid-connected tie line according to the present application is shown.
As shown in fig. 7, the pv grid-connected tie-line pilot protection system 100 includes a first calculating module 110, a second calculating module 120, a determining module 130, and an executing module 140.
The first calculation module 110 is configured to extract three-phase voltage sampling values and current sampling values on two sides of the photovoltaic power generation grid-connected tie line based on the pilot protection device after the starting element acts, extract three-phase voltage power frequency phasor and three-phase current power frequency phasor through a fast Fourier algorithm, and calculate differential voltage phasor according to phases
And differential current phasor
；
A second calculation module 120 configured to calculate phasors based on the differential voltage
And said differential current phasor
Calculating the three-phase comprehensive impedance in the grid-connected tie line
、
、
And taking the absolute values of their imaginary parts
、
、
；
A judging module 130 configured to determine an absolute value of an imaginary part of the three-phase synthesized impedance
、
、
Respectively setting threshold value with protection
Making a comparison, wherein the protection setting threshold value
In the formula (I), wherein,
，
is the equivalent capacitive reactance of each phase of the line,
is a capacitance value per unit length of a grid-connected tie line,
for the length of the grid-connected tie-line,
the angular frequency is the power frequency;
the execution module 140 is configured to execute a corresponding protection action based on the comparison result, where:
if the absolute value of the imaginary part of a certain phase of comprehensive impedance in the grid-connected tie line is less than
Judging that the single-phase fault exists in the photovoltaic power generation grid-connected tie line area, and protecting the action from jumping the fault phase;
if the imaginary part absolute value of a certain two-phase comprehensive impedance or three-phase comprehensive impedance in the grid-connected tie line is less than
Judging that two-phase faults or three-phase faults exist in the photovoltaic power generation grid-connected tie line area, and protecting the action to jump to three phases;
if the absolute values of the imaginary parts of the three-phase comprehensive impedance in the grid-connected tie line are all larger than
And if the photovoltaic power generation grid-connected tie line is not in fault, the protection does not act.
It should be understood that the modules recited in fig. 7 correspond to various steps in the method described with reference to fig. 1. Thus, the operations and features described above for the method and the corresponding technical effects are also applicable to the modules in fig. 7, and are not described again here.
In other embodiments, the present invention further provides a computer-readable storage medium, where computer-executable instructions are stored, where the computer-executable instructions may execute the comprehensive impedance-based pilot protection method for a photovoltaic power generation grid-connected tie line in any of the above method embodiments;
as one embodiment, the computer-readable storage medium of the present invention stores computer-executable instructions configured to:
after the starting element acts, based on the pilot protection device respectivelyExtracting three-phase voltage sampling values and current sampling values at two sides of a photovoltaic power generation grid-connected tie line, respectively extracting three-phase voltage power frequency phasor and three-phase current power frequency phasor through a fast Fourier algorithm, and calculating differential voltage phasor according to phases
And differential current phasor
；
Based on the differential voltage phasor
And said differential current phasor
Calculating the three-phase comprehensive impedance in the grid-connected tie line
、
、
And taking the absolute values of their imaginary parts
、
、
；
The imaginary part absolute value of the three-phase comprehensive impedance
、
、
Respectively setting threshold value with protection
Comparing;
and executing corresponding protection actions based on the comparison result.
The computer-readable storage medium may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created from use of the photovoltaic power generation grid-connected tie line pilot protection system based on the synthetic impedance, and the like. Further, the computer-readable storage medium may include high speed random access memory, and may also include 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 computer readable storage medium optionally includes memory remotely located from the processor, and the remote memory may be connected to the integrated impedance based pv grid tie pilot protection system 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.
Fig. 8 is a schematic structural diagram of an electronic device according to an embodiment of the present invention, and as shown in fig. 8, the electronic device includes: a processor 210 and a memory 220. The electronic device may further include: an input device 230 and an output device 240. The processor 210, the memory 220, the input device 230, and the output device 240 may be connected by a bus or other means, and fig. 8 illustrates an example of a bus connection. The memory 220 is the computer-readable storage medium described above. The processor 210 executes various functional applications and data processing of the server by running the nonvolatile software program, instructions and modules stored in the memory 220, that is, the method for pilot protection of the photovoltaic power generation grid-connected tie line based on the synthetic impedance in the above method embodiment is realized. The input device 230 may receive input numeric or character information and generate key signal inputs related to user settings and function control of the integrated impedance based pv grid tie pilot protection system. The output device 240 may include a display device such as a display screen.
The electronic device can execute the method provided by the embodiment of the invention, and has the corresponding functional modules and beneficial effects of the execution method. For technical details that are not described in detail in this embodiment, reference may be made to the method provided by the embodiment of the present invention.
As an embodiment, the electronic device is applied to a comprehensive impedance-based pilot protection system of a photovoltaic power generation grid-connected tie line, and used for a client, and includes: at least one processor; and a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to cause the at least one processor to:
after the starting element acts, three-phase voltage sampling values and current sampling values on two sides of a photovoltaic power generation grid-connected tie line are respectively extracted based on a pilot protection device, three-phase voltage power frequency phasor and three-phase current power frequency phasor are respectively extracted through a fast Fourier algorithm, and differential voltage phasor is calculated according to phases
And differential current phasor
；
Based on the differential voltage phasor
And said differential current phasor
Calculating the three-phase comprehensive impedance in the grid-connected tie line
、
、
And taking the absolute values of their imaginary parts
、
、
；
The imaginary part absolute value of the three-phase comprehensive impedance
、
、
Respectively setting threshold value with protection
Comparing;
and executing corresponding protection actions based on the comparison result.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
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; 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 such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A comprehensive impedance-based pilot protection method for a photovoltaic power generation grid-connected tie line is characterized by comprising the following steps:
step 1, after a starting element acts, respectively extracting three-phase voltage sampling values and current sampling values on two sides of a photovoltaic power generation grid-connected tie line based on a pilot protection device, respectively extracting three-phase voltage power frequency phasor and three-phase current power frequency phasor through a fast Fourier algorithm, and calculating differential voltage phasor according to phases
And differential current phasor
；
Step 2, based on the differential voltage phasor
And said differential current phasor
Calculating the three-phase comprehensive impedance in the grid-connected tie line
、
、
And taking the absolute values of their imaginary parts
、
、
；
Step 3, the imaginary part absolute value of the three-phase comprehensive impedance is obtained
、
、
Respectively setting threshold value with protection
Making a comparison, wherein the protection setting threshold value
In the formula (I), wherein,
，
is the equivalent capacitive reactance of each phase of the line,
is a capacitance value per unit length of a grid-connected tie line,
for the length of the grid-connected tie-line,
the angular frequency is the power frequency;
and 4, executing corresponding protection actions based on the comparison result, wherein the protection actions specifically comprise:
if the absolute value of the imaginary part of a certain phase of comprehensive impedance in the grid-connected tie line is less than
Judging that the single-phase fault exists in the photovoltaic power generation grid-connected tie line area, and protecting the action from jumping the fault phase;
if the imaginary part absolute value of a certain two-phase comprehensive impedance or three-phase comprehensive impedance in the grid-connected tie line is less than
Judging that two-phase faults or three-phase faults exist in the photovoltaic power generation grid-connected tie line area, and protecting the action to jump to three phases;
if the absolute values of the imaginary parts of the three-phase comprehensive impedance in the grid-connected tie line are all larger than
And if the photovoltaic power generation grid-connected tie line is not in fault, the protection does not act.
2. The integrated impedance-based grid-connected tie line pilot protection method for photovoltaic power generation according to claim 1, wherein before step 1, the method further comprises:
and longitudinal protection devices are arranged on two sides of the photovoltaic power generation grid-connected tie line, and three-phase voltage and three-phase current on two sides are respectively collected.
3. The integrated impedance-based pilot protection method for the photovoltaic power generation grid-connected tie line according to claim 1, wherein the method comprises the steps ofIn step 1, the differential voltage phasor
The expression of (a) is:
，
in the formula (I), the compound is shown in the specification,
is the voltage of the photovoltaic side busbar P,
is the voltage of the system side bus S.
4. The integrated impedance-based grid-connected tie line pilot protection method for photovoltaic power generation according to claim 1, wherein in step 1, the differential current phasor
The expression of (a) is:
，
in the formula (I), the compound is shown in the specification,
is the current of the photovoltaic side busbar P,
is the current of the system side bus S.
5. The integrated impedance-based pilot protection method for the photovoltaic power generation grid-connected tie line according to claim 1, wherein in step 2, the integrated impedance of a certain phase in the grid-connected tie line is:
，
in the formula (I), the compound is shown in the specification,
the phase difference of the A phase, the phase difference of the B phase or the phase difference of the C phase,
in order to be the phasor for the differential voltage,
is the differential current phasor.
6. The utility model provides a photovoltaic power generation tie-in line pilot protection system that is incorporated into power networks based on synthesize impedance which characterized in that includes:
the first calculation module is configured to extract three-phase voltage sampling values and current sampling values on two sides of the photovoltaic power generation grid-connected tie line respectively based on the pilot protection device after the starting element acts, extract three-phase voltage power frequency phasor and three-phase current power frequency phasor respectively through a fast Fourier algorithm, and calculate differential voltage phasor according to phases
And differential current phasor
；
A second calculation module configured to calculate phasor based on the differential voltage
And said differential current phasor
Calculating the three-phase comprehensive impedance in the grid-connected tie line
、
、
And taking the absolute values of their imaginary parts
、
、
；
A judging module configured to determine an absolute value of an imaginary part of the three-phase synthesized impedance
、
、
Respectively setting threshold value with protection
Making a comparison, wherein the protection setting threshold value
In the formula (I), wherein,
，
is the equivalent capacitive reactance of each phase of the line,
is a capacitance value per unit length of a grid-connected tie line,
for the length of the grid-connected tie-line,
the angular frequency is the power frequency;
an execution module configured to execute a corresponding protection action based on the comparison result, wherein the execution module specifically includes:
if the absolute value of the imaginary part of a certain phase of comprehensive impedance in the grid-connected tie line is less than
Judging that the single-phase fault exists in the photovoltaic power generation grid-connected tie line area, and protecting the action from jumping the fault phase;
if the imaginary part absolute value of a certain two-phase comprehensive impedance or three-phase comprehensive impedance in the grid-connected tie line is less than
Judging that two-phase faults or three-phase faults exist in the photovoltaic power generation grid-connected tie line area, and protecting the action to jump to three phases;
if the absolute values of the imaginary parts of the three-phase comprehensive impedance in the grid-connected tie line are all larger than
And if the photovoltaic power generation grid-connected tie line is not in fault, the protection does not act.
7. An electronic device, comprising: at least one processor, and a memory communicatively coupled to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any of claims 1 to 5.
8. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the method of any one of claims 1 to 5.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115296319A (en) * | 2022-06-27 | 2022-11-04 | 清华大学 | Phasor dynamic modeling method and device for electrochemical energy storage grid-connected system |
| CN119253551A (en) * | 2024-12-05 | 2025-01-03 | 浙江省送变电工程有限公司 | A longitudinal protection method for lines connected to a photovoltaic power station taking into account the charging and discharging characteristics of energy storage |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2352891A (en) * | 1999-08-03 | 2001-02-07 | Alstom Uk Ltd | Fault protection in multi-phase power systems |
| US6829544B1 (en) * | 2000-04-10 | 2004-12-07 | General Electric Company | Line current differential protective relaying method and relay for in-zone tapped transformers |
| CN101227084A (en) * | 2008-01-08 | 2008-07-23 | 西安交通大学 | A judging method for longitudinal protection of high-voltage transmission lines in power systems |
| CN101320911A (en) * | 2008-01-25 | 2008-12-10 | 烟台东方电子信息产业股份有限公司 | A Judgment Method for Transmission Line Pilot Protection Based on Synthetic Impedance |
| CN103795042A (en) * | 2014-02-21 | 2014-05-14 | 华北电力大学 | Pilot protection system and method based on virtual transition impedance |
| CN111480275A (en) * | 2017-12-20 | 2020-07-31 | Abb电网瑞士股份公司 | Zero sequence current based differential protection for power transmission lines |
-
2021
- 2021-08-30 CN CN202111002453.4A patent/CN113437733A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2352891A (en) * | 1999-08-03 | 2001-02-07 | Alstom Uk Ltd | Fault protection in multi-phase power systems |
| US6829544B1 (en) * | 2000-04-10 | 2004-12-07 | General Electric Company | Line current differential protective relaying method and relay for in-zone tapped transformers |
| CN101227084A (en) * | 2008-01-08 | 2008-07-23 | 西安交通大学 | A judging method for longitudinal protection of high-voltage transmission lines in power systems |
| CN101320911A (en) * | 2008-01-25 | 2008-12-10 | 烟台东方电子信息产业股份有限公司 | A Judgment Method for Transmission Line Pilot Protection Based on Synthetic Impedance |
| CN103795042A (en) * | 2014-02-21 | 2014-05-14 | 华北电力大学 | Pilot protection system and method based on virtual transition impedance |
| CN111480275A (en) * | 2017-12-20 | 2020-07-31 | Abb电网瑞士股份公司 | Zero sequence current based differential protection for power transmission lines |
Non-Patent Citations (1)
| Title |
|---|
| 索南加乐等: "输电线路综合阻抗纵联保护新原理", 《电力系统自动化》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115296319A (en) * | 2022-06-27 | 2022-11-04 | 清华大学 | Phasor dynamic modeling method and device for electrochemical energy storage grid-connected system |
| CN119253551A (en) * | 2024-12-05 | 2025-01-03 | 浙江省送变电工程有限公司 | A longitudinal protection method for lines connected to a photovoltaic power station taking into account the charging and discharging characteristics of energy storage |
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