CN115912291A - Generalized lateral difference protection method for 400V photovoltaic platform area power generation unit - Google Patents
Generalized lateral difference protection method for 400V photovoltaic platform area power generation unit Download PDFInfo
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- CN115912291A CN115912291A CN202211644836.6A CN202211644836A CN115912291A CN 115912291 A CN115912291 A CN 115912291A CN 202211644836 A CN202211644836 A CN 202211644836A CN 115912291 A CN115912291 A CN 115912291A
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Abstract
The invention discloses generalized lateral difference protection aiming at a 400V photovoltaic platform area power generation unit, which comprises the following steps: collecting information data of detected electrical quantity; judging the state of the acquired data; and executing corresponding operation according to different state conditions. The generalized lateral difference protection for the 400V photovoltaic power generation unit provided by the invention can judge potential faults or electrical short-circuit faults, and different protection measures are respectively adopted. The method has low dependence on communication and high adaptivity, and is suitable for the requirement of a low-cost scheme of a 400V station area. And a communication online self-checking mode is adopted, and a self-adaptive method is adopted for the power generation unit with abnormal communication, so that corresponding data is removed, and locking protection is performed.
Description
Technical Field
The invention relates to the technical field of relay protection, in particular to a generalized lateral difference protection method for a 400V photovoltaic power generation unit.
Background
With the increasing prominence of energy problems and environmental problems, the construction of novel power grids is gradually scheduled, and a large number of photovoltaic power supplies are connected into the power grids. The conventional power distribution network has a tree shape, a radial shape and a ring network shape, a relatively simple grid connection structure is a radial shape, and the power distribution network has better performance in the aspects of wiring, protection, constant volume, capacity expansion and the like. In such distribution networks, photovoltaic power stations are added and, in the overall structure, protective breaking devices limiting the overcurrent and breaking devices automatically reclosing can be fitted.
Information interaction and reliable transmission between the photovoltaic power station and the regulation and control master station must be realized by means of a communication system, and appointments, rules and protocols of data transmission formats necessary for starting and maintaining communication are formulated in advance. The photovoltaic power station is provided with a large amount of measurement and control, protection and other automation equipment for collecting the operation and state information of the photovoltaic array and the boosting equipment and transmitting the collected information to the background monitoring computer and the regulation and control mechanism. The control master station sends the control command to the measurement and control equipment through a data transmission channel by means of automation equipment such as a telecontrol communication workstation and the like, and control over the photovoltaic power station is achieved. At present, most of photovoltaic power stations adopt a wired communication system, wherein the application of optical fiber communication is the most common.
Current protection, overload protection and the like are adopted in traditional power distribution network protection, but with the access of a large number of photovoltaic power supplies, the structure of the power distribution network is greatly changed, traditional relay protection measures are possibly not applicable any more, and higher requirements are provided for relay protection. Under the condition of good communication, a new protection measure can be provided.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and title of the application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The present invention has been made in view of the above-mentioned problems.
Therefore, the technical problem solved by the invention is as follows: if a certain photovoltaic unit has the potential failure possibility, the power generation unit can be cut off in a long time delay, so that the influence of internal failure on other power generation units as backup protection is avoided; after an electrical short-circuit fault occurs in the 400V line, the minimum photovoltaic units can be selectively cut off and used as main protection. The method has low dependence on communication and high self-adaptability, and is suitable for the requirement of a low-cost scheme in a 400V distribution room.
In order to solve the technical problems, the invention provides the following technical scheme: a generalized lateral difference protection method for a photovoltaic platform area power generation unit comprises the following steps:
collecting information data of detected electrical quantity;
judging the state of the acquired data;
and executing corresponding operation according to different state conditions.
As a preferable scheme of the generalized lateral difference protection method for the photovoltaic power generation unit, the generalized lateral difference protection method is characterized by comprising the following steps:
when one photovoltaic unit has relatively concentrated or dispersed photovoltaic power generation units and the potential failure possibility or abnormality is found, the power generation units are cut off after long time delay;
for photovoltaic power generation units which are relatively dispersed and are single-phase, the harmonic spectrum characteristics of the power generation units are the same;
for the photovoltaic power generation units which are relatively concentrated and are three-phase, the three-phase power is symmetrical, and the three-phase harmonic spectrum characteristics are the same;
if the above conditions are not met, the abnormal state is determined;
when an electrical short-circuit fault occurs in the 400V line, the minimum photovoltaic units can be selectively cut off, and the high cost and low efficiency of longitudinal differential protection are avoided.
As a preferable solution of the generalized lateral difference protection method for a 400V photovoltaic platform power generation unit in the present invention, wherein: the collection of information data of the detected electric quantity is to detect the electric quantities such as current, voltage, power, harmonic waves and the like at the outlet of each power generation unit
As a preferable scheme of the generalized lateral difference protection method for the 400V photovoltaic platform area power generation unit, according to the present invention, wherein: the abnormal state judgment is to provide a generalized lateral difference protection according to the photovoltaic power generation unit or the three phases under the condition of meeting the communication condition to compare information data, and the abnormal state of the power generation unit can be judged according to the statistical law of faults;
as a preferable solution of the generalized lateral difference protection method for a 400V photovoltaic platform power generation unit in the present invention, wherein: and the corresponding operation is to send the detection data to the manager, the manager judges that data of one power generation unit is abnormal, can judge that the state of the power generation unit is abnormal according to the statistical rule of the fault, send an alarm to the control center and send a trip instruction to an outlet switch of the power generation unit after long time delay.
As a preferable scheme of the generalized lateral difference protection method for the 400V photovoltaic platform area power generation unit, the method is characterized in that: the 400V distribution area of the photovoltaic power generation unit is in a radiation type network structure from a distribution outlet to the photovoltaic power generation unit or the load equipment.
As a preferable scheme of the generalized lateral difference protection method for the 400V photovoltaic platform area power generation unit, the method is characterized in that: when the electrical short-circuit fault of a line occurs at the upstream of the branch box, the output currents and directions of all the photovoltaic inverters with the same type at the downstream of the branch box are the same, and the manager judges that the fault occurs at the upstream of the branch box after receiving the signal, so that the switches of the branch box and all the equipment switches trip;
when an outgoing line at the downstream of the branch box is electrically short-circuited, the output currents and directions of all the photovoltaic inverters with the same type at the downstream of the branch box have larger difference, and the manager judges that the fault occurs at the downstream of the branch box after receiving the signal, so that the corresponding equipment switch trips, the cutting range can be reduced, the fault cutting selectivity is improved, and in order to prevent the judgment fault and the distribution current protection, the trip is carried out after short delay.
As a preferable scheme of the generalized lateral difference protection method for the 400V photovoltaic platform area power generation unit, the method is characterized in that: the transverse differential protection is applied to parallel circuits, the action depends on the unbalanced distribution of current among the circuits, and the communication unit is used for digitizing and sharing voltage and current data from the secondary sides of the voltage and current transformers and the current transformers so as to provide short-circuit voltage and current data for the protection device.
As a preferable scheme of the generalized lateral difference protection method for the 400V photovoltaic platform area power generation unit, the communication condition is characterized in that: and a communication online self-checking mode is adopted, and a self-adaptive method is adopted for the power generation unit with abnormal communication, so that corresponding data is removed and locked for protection.
As a preferable scheme of the generalized lateral difference protection method for the 400V photovoltaic platform power generation unit, the generalized lateral difference protection method is characterized in that: the generalized meaning is: the relevance with specific topological structure and distribution position is low, and the adopted data is dynamic regardless of the quantity.
The invention has the beneficial effects that: the generalized lateral difference protection method for the 400V photovoltaic platform area power generation unit can achieve the following steps: and judging whether the fault is a potential fault or an electrical short-circuit fault, and respectively taking different protective measures: if a certain photovoltaic unit has the potential failure possibility, the power generation unit can be cut off in a long time delay manner; if the 400V line has an electrical short-circuit fault, the minimum photovoltaic units can be selectively cut off and used as main protection. The method has low dependence on communication and high adaptivity, and is suitable for the requirement of a low-cost scheme of a 400V station area. And a communication online self-checking mode is adopted, and a self-adaptive method is adopted for the power generation unit with abnormal communication, so that corresponding data is removed and locked for protection.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor. Wherein:
fig. 1 is an overall flowchart of a generalized lateral difference protection method for a photovoltaic power generation unit according to a first embodiment of the present invention;
fig. 2 is a structural diagram of a generalized lateral difference protection method for a photovoltaic power generation unit according to a first embodiment of the present invention;
fig. 3 is a schematic diagram illustrating normal operation and external short circuit of a generalized lateral difference protection method for a photovoltaic power generation unit according to a second embodiment of the present invention;
fig. 4 is an intra-area D of a generalized lateral difference protection method for a photovoltaic power generation unit according to a second embodiment of the present invention 1 And (5) demonstrating a schematic diagram of the point short circuit.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures of the present invention are described in detail below, and it is apparent that the described embodiments are a part, not all or all of the embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as specifically described herein, and it will be appreciated by those skilled in the art that the present invention may be practiced without departing from the spirit and scope of the present invention and that the present invention is not limited by the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
The present invention will be described in detail with reference to the drawings, wherein the cross-sectional views illustrating the structure of the device are not enlarged partially in general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected" and "connected" in the present invention are to be construed broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected; they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
For one embodiment of the invention, a computing platform load balancing method based on a particle swarm genetic algorithm is provided, which comprises the following steps:
s1: collecting information data of detected electrical quantity;
for a potential fault or anomaly, for a relatively concentrated photovoltaic power generation unit (typically three-phase), it is characterized by: under the condition of meeting the communication condition, a generalized lateral difference protection is provided, the electric quantities such as current, voltage, power, harmonic wave and the like at the outlet of each power generation unit are detected,
further, for a potential fault or anomaly, for a relatively dispersed photovoltaic power generation unit (typically a single phase), it is characterized by: under the condition of meeting the communication condition, a generalized lateral difference protection is provided, the electric quantities such as current, voltage, power, harmonic wave and the like at the outlet of each power generation unit are detected,
s2: judging the state of the acquired data;
for relatively dispersed, usually single-phase, photovoltaic power generation units, the harmonic spectrum characteristics of these power generation units are similar;
for a relatively concentrated, usually three-phase, photovoltaic power generation unit, the three-phase power should be substantially symmetrical, and the three-phase harmonic spectral characteristics should be similar;
under the same illumination and meteorological conditions, if the conditions are met,
furthermore, for the photovoltaic power generation units with the same or similar models and relatively dispersed, under the same illumination and meteorological conditions, if the conditions are not met, the detection data are sent to the manager, and the manager judges that data of one power generation unit are abnormal;
s3: executing corresponding operation according to different state conditions;
according to the statistical rule of the fault, the abnormal state of the power generation unit is judged, an alarm can be sent to a control center, and a tripping command is sent to an outlet switch of the power generation unit after long-time delay, and the tripping command is equivalent to backup protection;
furthermore, when an electrical short-circuit fault occurs on the upstream of the branch box, the output currents and the directions of the photovoltaic inverters of the same type on the downstream of the branch box are the same, and the manager judges that the fault occurs on the upstream of the branch box after receiving the signal, so that the branch box switch and all equipment switches trip, and the island is prevented from occurring. When an outgoing line at the downstream of the branch box is electrically short-circuited, the output currents and directions of the photovoltaic inverters of the same type at the downstream of the branch box have large differences, and the manager judges that a fault occurs at the downstream of the branch box after receiving a signal, so that a corresponding equipment switch trips. Therefore, the cutting range can be reduced, and the fault cutting selectivity is improved. In order to prevent misjudgment, the power distribution current is protected and is tripped after short time delay;
furthermore, the transverse differential protection device is arranged at the equipment end of the photovoltaic unit, the load port and the branch box, and the communication unit is used for digitizing and sharing voltage and current data from the secondary side of the voltage and current transformer so as to provide short-circuit voltage and current data for a plurality of protection devices.
It should be noted that, a communication online self-checking mode is adopted, and for a power generation unit with abnormal communication, a self-adaptive method is adopted to remove corresponding data and lock the power generation unit for protection.
It should be further explained that the lateral difference protection principle of the photovoltaic power generation unit:
the transverse differential protection is a relay protection device which reflects the magnitude and direction of the homonymous phase difference current of parallel operation lines so as to selectively remove fault lines. The transverse differential directional protection is used for reacting to an internal fault of the parallel line and not reacting to an external fault of the parallel line, and the action current of the transverse differential directional protection is larger than the maximum unbalanced current caused in the differential current loop when a penetrating fault occurs.
It should be noted that "broad" of broad lateral differential protection means: the relevance with specific topological structure and distribution position is low, and the quantity is irrelevant. The data employed is dynamic.
Example 2
Referring to fig. 3 and 4, an embodiment of the present invention provides a single-phase lateral difference protection principle, taking lateral difference protection of a single-side power load as an example, and scientific demonstration is performed through economic benefit calculation and simulation experiments to verify the beneficial effects of the present invention.
When the parallel lines are in normal operation or the external D point is in short circuit, the fault currents flowing through the parallel lines are equal in magnitude and same in direction. Setting the transformation ratio of the current transformer to n ct The differential current flowing into the lateral differential protection startup element LJ is:
the lateral difference protection does not act.
When the first line D 1 When short circuit occurs in the point generating area, the fault currents flowing through the parallel lines are equal in magnitude and opposite in direction. The differential current flowing into the startup element LJ is:
and when the differential current reaches or exceeds the transverse differential protection setting value, the transverse differential protection acts on the jump wire circuit breaker. Similarly, when the B line is short-circuited in the area, the protection action jumps the B line.
In order to prevent the transverse differential protection from being mistakenly operated when an external fault occurs during the operation of a single line, the protected direct-current power supply is serially locked through the normally open auxiliary contacts of the two switches of the parallel line, and the protection is only acted when the two switches are simultaneously connected.
Claims (10)
1. A generalized lateral difference protection method for a 400V photovoltaic platform area power generation unit is characterized by comprising the following steps:
collecting information data of detected electrical quantity;
judging the abnormal state of the acquired data;
and executing corresponding operation according to different state conditions.
2. The generalized lateral difference protection method for a 400V photovoltaic block power generation unit of claim 1, further comprising:
when one photovoltaic unit is provided with relatively concentrated or dispersed photovoltaic power generation units and potential failure possibility or abnormity is discovered, the power generation units are cut off after long time delay;
for photovoltaic power generation units which are relatively dispersed and are single-phase, the harmonic spectrum characteristics of the power generation units are the same;
for the photovoltaic power generation units which are relatively concentrated and are three-phase, the three-phase power is symmetrical, and the three-phase harmonic spectrum characteristics are the same;
if the above conditions are not met, the abnormal state is determined;
when an electrical short-circuit fault occurs in the 400V line, the minimum photovoltaic units can be selectively cut off, and the high cost and low efficiency of longitudinal differential protection are avoided.
3. The generalized lateral difference protection method for a 400V photovoltaic platform power generation unit according to claim 1, wherein: the collection of information data of the detected electrical quantity is to detect the electrical quantity of current, voltage, power and harmonic at the outlet of each power generation unit.
4. The generalized lateral difference protection method for a 400V photovoltaic platform power generation unit according to claim 1, characterized in that: the abnormal state judgment is that according to the photovoltaic power generation unit or the three phases, under the condition of meeting the communication condition, a generalized lateral difference protection is provided to compare information data, and according to the statistical law of faults, the abnormal state of the power generation unit can be judged.
5. The generalized lateral difference protection method for a 400V photovoltaic platform power generation unit according to claim 1, characterized in that: and the corresponding operation is to send the detection data to the manager, the manager judges that data of one power generation unit is abnormal, can judge that the state of the power generation unit is abnormal according to the statistical rule of the fault, sends an alarm to a control center, and sends a tripping command to an outlet switch of the power generation unit after long time delay.
6. The generalized lateral difference protection method for a 400V photovoltaic platform power generation unit according to any one of claims 1 to 5, characterized by: the photovoltaic power generation unit is in a radiation type network structure from a 400V distribution area to a photovoltaic power generation unit or load equipment.
7. The generalized lateral difference protection method for a 400V photovoltaic platform power generation unit according to claim 2, wherein: when the electrical short-circuit fault of a circuit occurs at the upstream of the branch box, the output current and the direction of each photovoltaic inverter with the same model at the downstream of the branch box are the same, and the manager judges that the fault occurs at the upstream of the branch box after receiving the signal, so that a branch box switch and all equipment switches trip;
when an outlet line at the downstream of the branch box is electrically short-circuited, the output currents and directions of all the photovoltaic inverters of the same type at the downstream of the branch box have larger difference, and the manager judges that the fault occurs at the downstream of the branch box after receiving the signal, so that the corresponding equipment switch trips, the cutting range can be reduced, the fault cutting selectivity is improved, and the tripping operation is carried out after short delay in order to prevent the judgment of fault and distribution current protection.
8. The generalized lateral difference protection method for a 400V photovoltaic platform power generation unit according to any one of claims 1 to 7, characterized by: the transverse differential protection is applied to parallel circuits, the action depends on unbalanced distribution of current among the circuits, and voltage and current data from the secondary side of a voltage transformer and a current transformer are digitized and shared through a communication unit, so that short-circuit voltage and current data are provided for a protection device.
9. The generalized lateral difference protection method for a 400V photovoltaic platform power generation unit according to claim 4, wherein: the communication conditions comprise that a communication online self-checking mode is adopted, a self-adaptive method is adopted for power generation units with abnormal communication, corresponding data are removed, and locking protection is carried out.
10. The generalized lateral difference protection method for a 400V photovoltaic platform power generation unit according to any one of claims 1 to 9, wherein: the broad sense means: the relevance with the specific topological structure and the distribution position is low, the data is dynamic regardless of the quantity.
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