WO2019148391A1 - 具有分布式能源的电网故障检测方法和装置 - Google Patents

具有分布式能源的电网故障检测方法和装置 Download PDF

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Publication number
WO2019148391A1
WO2019148391A1 PCT/CN2018/074814 CN2018074814W WO2019148391A1 WO 2019148391 A1 WO2019148391 A1 WO 2019148391A1 CN 2018074814 W CN2018074814 W CN 2018074814W WO 2019148391 A1 WO2019148391 A1 WO 2019148391A1
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WIPO (PCT)
Prior art keywords
parallel
current
fault
protection device
collection point
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PCT/CN2018/074814
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English (en)
French (fr)
Inventor
杜峰
陈维刚
刘臻
卓越
Original Assignee
西门子公司
杜峰
陈维刚
刘臻
卓越
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Application filed by 西门子公司, 杜峰, 陈维刚, 刘臻, 卓越 filed Critical 西门子公司
Priority to PCT/CN2018/074814 priority Critical patent/WO2019148391A1/zh
Priority to US16/965,383 priority patent/US11831158B2/en
Priority to CN201880079211.5A priority patent/CN111433992B/zh
Priority to DE112018006983.4T priority patent/DE112018006983T5/de
Publication of WO2019148391A1 publication Critical patent/WO2019148391A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
    • H02J3/0012—Contingency detection
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B23/00—Testing or monitoring of control systems or parts thereof
    • G05B23/02—Electric testing or monitoring
    • G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
    • G05B23/0218—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults
    • G05B23/0221—Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00002—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by monitoring
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Definitions

  • the present invention relates to power grids, and more particularly to fault detection methods and apparatus for power grids having distributed energy sources.
  • the fault current can only come from the AC power source, so it can be easily judged whether the power grid has failed by judging whether multiple protection devices in the power grid exceed the fault current threshold. Once the protection device in the power grid exceeds the fault current threshold, it can be triggered.
  • the disconnection circuit cuts off the power supply of the AC power supply of the public power grid to prevent accidents.
  • the public power grid provides an AC power source UG 11 , and the AC power source UG 11 is sequentially connected with a protection device PD 11 , a fuse device F 11 , and a protection device PD 12 .
  • the protection device PD 12 is connected with a parallel circuit.
  • the parallel circuit includes a plurality of branches, wherein one branch protection device PD 13 , cable C 11 , and load L 11 are connected in series, and the other branch protection device PD 14 , cable C 12 , and load L 12 are connected in series.
  • another branch protection device PD 15 , a cable C 13 , and a load L 13 are connected in series, and a branch protection device PD 16 , a cable C 14 , and a load L 14 are connected in series.
  • a branch protection device PD 16 , a cable C 14 , and a load L 14 are connected in series.
  • the branch in turn connected in series with a fuse F 12, the cable C 15,
  • the protection device P11 should first be triggered.
  • the protection device PD 15 should first be triggered.
  • the fuse F 12 is first triggered.
  • the protection device is preset with a fault current threshold, and the protection device can be triggered only when the fault current flowing through the protection device exceeds the fault current threshold, thereby protecting the entire line.
  • the DC load of the user terminal is often provided with other DC power sources, such as a solar power source. Therefore, the other branches in the entire power system circuit will also shunt the fault current, so the fault current flowing through the protection device cannot reach the fault current threshold, and the protection device cannot be triggered, and cannot function as a circuit for protecting the power system.
  • a first aspect of the present invention provides a power grid fault detection method with distributed energy sources, the power grid including at least one AC power source provided by a public power grid, the AC power source coupled to a plurality of parallel parallel circuits, each of the parallel The circuit includes a plurality of parallel branches connected to a load and/or a DC power source, wherein the grid fault detection method with distributed energy includes the following steps: the AC power source and the parallel Selecting a first collection point between the plurality of parallel circuits, collecting the current value of the first collection point and the current direction thereof; comparing the output current and the input current of the first collection point, if the input current is greater than the output current, then It is judged that the plurality of parallel circuits in parallel are faulty.
  • I in I PDgrid + ⁇ Ibranchi ,
  • IP Dgrid is a current output from the AC power source to the first collection point
  • ⁇ I branchi is a current output from the parallel parallel circuit to the first collection point in the same direction as the IP Dgrid , i For natural numbers.
  • ⁇ I branchi is the current output from the parallel parallel circuit of the parallel to the I PDgrid to the first collection point, i is a natural number.
  • a plurality of second collection points are set in the parallel plurality of parallel circuit regions, and the plurality of current values of the plurality of second collection points are collected, and the plurality of current values of the plurality of second collection points are the smallest If the value is greater than the first fault current threshold, the fault is determined to be a blind spot fault.
  • the following steps are further performed: when the current value of any of the second collection points is greater than the second fault current threshold, triggering the second protection device of the parallel branch where the second collection point is located, wherein The second fault current threshold is less than the first fault current threshold.
  • a second aspect of the present invention provides a power grid fault detecting apparatus having a distributed energy source, the power grid including at least one AC power source provided by a public power grid, the AC power source being coupled to a plurality of parallel parallel circuits, each of the parallel circuits
  • the circuit includes a plurality of parallel branches, the parallel branches are respectively connected with a load and/or a DC power source
  • the grid fault detecting device with distributed energy includes: a first protection device connected to the AC power source and the Between the plurality of parallel circuits in parallel, wherein a first collection point is selected between the alternating current power source and the plurality of parallel parallel circuits, and the first protection device collects the first collection point.
  • the current value and its current direction are compared, and the output current and the input current of the first collection point are compared. If the input current is greater than the output current, it is determined that the parallel multiple parallel circuits are faulty.
  • the grid fault detecting device with distributed energy further includes a plurality of second protection devices connected on a branch of the parallel plurality of parallel circuits, wherein in the parallel multiple parallel circuit regions Setting a plurality of second collection points, the second protection device collecting a plurality of current values of the plurality of second collection points, wherein a minimum value of the plurality of current values of the plurality of second collection points is greater than the first failure The current threshold, the second protection device determines that the fault is a blind spot fault.
  • the second protection device is triggered, wherein the second fault current threshold is less than the first fault current threshold.
  • the first protection device communicates with a plurality of second protection devices, and the plurality of second protection devices communicate with each other.
  • the grid fault detecting apparatus with distributed energy sources further includes a plurality of voltage and current detecting modules connected on a branch of the parallel plurality of parallel circuits, wherein in the parallel multiple parallel circuit regions Setting a plurality of second collection points, the second protection device collecting a plurality of current values of the plurality of second collection points, wherein a minimum value of the plurality of current values of the plurality of second collection points is greater than the first failure
  • the current threshold the voltage current detecting module determines that the fault is a blind spot fault, wherein a voltage current detecting module is also disposed in the first protection device.
  • the voltage current detection module triggers the second protection device of the parallel branch where the second collection point is located, where The second fault current threshold is less than the first fault current threshold.
  • the first protection device communicates with a plurality of the voltage and current detection modules, respectively.
  • a third aspect of the present invention also provides a power grid fault detecting apparatus having a distributed energy source, the power grid including at least one AC power source provided by a public power grid, the AC power source being coupled to a plurality of parallel parallel circuits, each of the The parallel circuit includes a plurality of parallel branches, the parallel branches are respectively connected with a load and/or a DC power source, wherein the grid fault detecting device with distributed energy includes: a first protection device connected to the AC power source and Between the plurality of parallel circuits connected in parallel; a controller connected to the first protection device, wherein a first acquisition is further selected between the alternating current power source and the plurality of parallel parallel circuits Point, the first protection device collects the current value of the first collection point and its current direction and sends the current direction to the controller, and the controller compares the output current and the input current of the first collection point, if the input current is greater than the output The current determines that the plurality of parallel circuits in parallel are faulty.
  • the grid fault detecting device with distributed energy further includes a plurality of second protection devices connected on a branch of the parallel plurality of parallel circuits, wherein the controller is further connected to the first a second protection device, wherein a plurality of second collection points are disposed in the parallel plurality of parallel circuit regions, and the second protection device collects a plurality of current values of the plurality of second collection points and sends the plurality of current values to the controller When the minimum value of the plurality of current values of the plurality of second collection points is greater than the first fault current threshold, the controller determines that the fault is a blind spot fault.
  • the controller when the current value of any of the second collection points is greater than the second fault current threshold, the controller triggers a second protection device of the parallel branch where the second collection point is located, wherein the The second fault current threshold is less than the first fault current threshold.
  • controller communicates with the first protection device and the plurality of second protection devices, respectively.
  • the invention can set a plurality of collection points according to the line connection of the power grid with distributed energy to check the fault, and determine whether the fault is a blind spot fault and trigger the protection device, thereby avoiding the misjudgment of the blind spot fault.
  • FIG. 1 is a circuit connection diagram of a prior art power system without a distributed power source
  • FIG. 2 is a circuit connection diagram of a power system having a distributed power source according to an embodiment of the present invention
  • FIG. 3 is a circuit connection diagram of fault current detection of a power system having a distributed power source according to an embodiment of the present invention
  • FIG. 4 is a schematic diagram of a communication connection of a power system having a distributed power source, in accordance with an embodiment of the present invention.
  • the power system shown in FIG. 2 is a cell power supply system, and the AC power supply 21 supplies AC power to four subscribers of one unit.
  • the AC power source UG 21 is connected in turn with a protection device PD 21 , a fuse device F 21 , and a protection device PD 22 , and the protection device PD 22 is connected to a parallel circuit.
  • the parallel circuit includes four parallel branches, four parallel branches being four users from one unit, respectively.
  • the first parallel branch routing protection device PD 23 , the cable C 11 , and the photovoltaic converter PV are connected in series.
  • the second parallel branch routing protection device PD 24 , the cable C 22 , and the battery B are connected in series.
  • the third parallel branch protection device PD 25 , the cable C 23 , and the first load L 21 are connected in series.
  • the fourth parallel branch routing protection device PD 26 , the cable C 24 , and the second load L 22 are connected in series.
  • the photovoltaic converter PV and the battery B are distributed power sources in the power system, which are in particular DC power sources. Therefore, the module in area A in FIG. 2 is a nanogrid (distributed power grid), and its fault current can be from the AC power source UG 21 or from the photovoltaic converter PV and/or the battery B.
  • the series branch is also a series branch between the first fuse F 21 and the first protection device PD 21 , and the series branch indicates that the cell includes other units in addition to one unit of the four user terminals.
  • the series branch is connected in turn with a second fuse F 22 and a fifth cable.
  • the first protection device PD 21 and the second protection device PD 22 should be triggered first.
  • the second protection device PD 22 should be triggered in preference to the third protection device PD 23 and the fourth protection device PD 24 , and the second protection device PD 22 is defined as an open circuit between the AC power source UG 21 and the nanogrid.
  • the first protection device PD 21 should not have a protection blind spot throughout the line.
  • the fifth protection device PD 25 should be triggered first.
  • the fuse F 22 should be triggered first.
  • the fault current I consists of two parts, one part being supplied by the AC power source UG 21 and the other part being provided by the photovoltaic converter PV and/or the battery B.
  • the fault current provided by the AC power source UG 21 is I 1 in the counterclockwise direction
  • the fault current threshold set by the first protection device PD 21 is 1000 A
  • the current flowing through the first protection device PD 21 will trigger and open once it exceeds 1000 A.
  • a first protection device 31 is connected to the PD 31 UG AC power
  • a first protection means coupling the PD 31
  • Each parallel circuit represents a distributed grid (nanogrid) or distributed power supply in a distributed grid.
  • a second protection device PD 32 is connected between the first parallel circuit and the first protection device PD 31.
  • the three parallel branches of the first parallel circuit are respectively connected with the first load L 31 and the second load L 32 .
  • a third load L 33 is provided.
  • a third protection device PD 33 is connected between the second parallel circuit and the first protection device PD 31.
  • the three parallel branches of the first parallel circuit are respectively connected with a fourth load L 34 , a first DC power source D 31 and The second DC power source D 32 .
  • a fourth protection device PD 34 is connected between the third parallel circuit and the first protection device PD 31.
  • the three parallel branches of the third parallel circuit are respectively connected with a sixth load L 36 , a third DC power source D 33 and a third Two DC power supplies D 32 .
  • a fifth protection device PD 35 is connected between the fourth parallel circuit and the first protection device PD 31 , and the three parallel branches of the fourth parallel circuit are respectively connected with a seventh load L 37 , an eighth load L 38 and a ninth Load L 39 .
  • a first aspect of the present invention provides a power grid fault detection method with distributed energy. Among them, the following steps are included:
  • step S1 is performed, and a first collection point is selected between the alternating current power source and the parallel plurality of parallel circuits, and the current value of the first collection point and the current direction thereof are collected.
  • a first acquisition point b 3 is selected between an alternating current source UG31 having a grid 300 having a distributed power source and a plurality of parallel parallel circuits, i.e. said first collection point b 3 It is installed between the public power grid UG 31 and a plurality of parallel circuits before the home.
  • the current flowing through the first collection point b 3 includes a current supplied from the alternating current power source UG 31 and a current supplied from each of the distributed power sources of the four parallel circuits, wherein the current direction provided by the alternating current power source UG 31 should be
  • the flow from the AC power source UG 22 to the first collection point b 3 is the top-down direction shown in FIG. 3 and is the input current of the first collection point b 3 .
  • Current power supply should be distributed from one or more parallel circuits to a first collection point b 3, the direction from the bottom up is shown in Figure 3, is the output current of the first collection point b 3. The two are in opposite directions.
  • the invention needs to collect the current value of the input current and the output current flowing through the first collection point b 3 and the current direction thereof.
  • the second protection device PD 32 and the fourth protection device PD 34 corresponding to the first parallel circuit and the fourth parallel circuit respectively The current flowing is from top to bottom.
  • the second parallel circuit and the third parallel circuit are respectively provided with the first DC power source D 31 and the second DC power source D 32 and the third DC power source D 33 , so the second parallel circuit and the third parallel circuit correspond to each other.
  • the current flowing through the second protection device PD 32 and the fourth protection device PD 34 is from bottom to top.
  • step S2 is performed to compare the output current and the input current of the first collection point. If the input current is greater than the output current, it is determined that the parallel multiple parallel circuits are faulty.
  • the input current of the first collection point is:
  • I PDgrid is a current output from the AC power source to the first collection point
  • ⁇ I branchi is a current outputted from the parallel parallel circuit of the parallel to the I PDgrid to the first collection point, i
  • the output from the AC power supply to the first direction of the current collection point I PDgrid should output a plurality of parallel circuit and parallel to the first collection point from the current I branchi opposite direction.
  • the input of the first collection point it is the current I in and output from the AC power supply output to the first direction of the current I PDgrid collection point from a plurality of parallel circuits connected in parallel to the first sum of the current I branchi the collection point.
  • the output current of the first collection point is:
  • ⁇ I branchi is the current output from the parallel parallel circuit of the parallel to the I PDgrid to the first collection point, i is a natural number. If I input >I output , then there is a fault in this area of the line.
  • the embodiment specifically includes four parallel circuits, and four parallel circuits are respectively connected to four clients.
  • the invention also needs to collect the current value and the direction through which the four parallel circuits respectively flow, that is, the first collection point c 3 , the first collection point d 3 , the first in the power grid 300 with distributed power as shown in FIG. 3 .
  • the current value and the direction through which the point e 3 and the first collection point f 3 respectively flow are collected.
  • a second collection point c 3 , a second collection point d 3 , a second collection point e 3 , and a second collection point f 3 are also disposed in the power grid 30 having the distributed power source.
  • the current output from the AC power source UG 31 to the first collection point b 3 , the current flowing through the second collection point c 3 , and the current flowing through the second collection point f 3 are all illustrated from top to bottom.
  • the input current I in30 of the first collection point b 3 is I PD30 +I c3 +I f3 , wherein the branch of the third parallel circuit is provided because the first DC power source D 31 is disposed in the branch of the second parallel circuit.
  • I in3> I out3 it is determined that a plurality of parallel circuits connected in parallel to the first area A 3 failure.
  • a second collection point c 4 , a second collection point d 4 , a second collection point e 4 , and a second collection point f 4 are also disposed in the power grid 40 having the distributed power source.
  • the first power supply device UG 41 is connected to the first protection device PD 41 , and the first protection device PD 41 is connected with four parallel parallel circuits, which are a first parallel circuit nano 41 , a second parallel circuit nano 42 , and a third parallel circuit nano 43 .
  • the fourth parallel circuit nano 44 is connected.
  • a second protection device PD 42 is connected between the second connection point c 4 and the first parallel circuit nano 41
  • a third protection device PD is connected between the second connection point d 4 and the second parallel circuit nano 42 .
  • a fourth protection device PD 44 is connected between the second connection point e 4 and the third parallel circuit nano 43
  • a fifth protection device PD 45 is connected between the second connection point f 4 and the fourth parallel circuit nano 44 .
  • the current output from the AC power source UG 41 to the first collection point b 4 , the current flowing through the second collection point c 3 , and the current flowing through the second collection point f 4 are all illustrated from top to bottom.
  • the input current I in40 of the first acquisition point b 4 is I PD41 +I c4 +I f4 .
  • the current flowing through the second collection points d 4 and e 4 should be the bottom-up direction and the output current. Therefore, the output current I out4 of the first acquisition point b 4 is I d4 +I e4 .
  • a second collection point c 5 , a second collection point d 5 , a second collection point e 5 , and a second collection point f 5 are also disposed in the power grid 50 having the distributed power source.
  • the first power supply device UG 51 is connected to the first protection device PD 51 , and the first protection device PD 51 is connected with four parallel parallel circuits, which are a first parallel circuit nano 51 , a second parallel circuit nano 52 , and a third parallel circuit nano 53 .
  • the fourth parallel circuit nano 54 is connected between the second connection point c 5 and the first parallel circuit nano 51
  • a third protection device PD 53 is connected between the second connection point 54 and the second parallel circuit nano 52 .
  • a fourth protection device PD 54 is connected between the second connection point 54 and the third parallel circuit nano 53
  • a fifth protection device PD 55 is connected between the second connection point f 4 and the fourth parallel circuit nano 54 .
  • the current output from the AC power source UG 51 to the first collection point b 5 and the current flowing through the second collection point f 5 are all input currents from the top to the bottom. Therefore, the input current I in50 of the first acquisition point b 5 is I PD51 +I f5 .
  • the current flowing through the second collection points d 5 , e 5 and c 5 should be the bottom-up direction and the output current. Therefore, the output current I out5 of the first acquisition point b 4 is I c5 + I d5 + I e5 .
  • I in3> I out3 A 5 is determined first region of a plurality of parallel circuits connected in parallel fails.
  • step S3 a plurality of second collection points are set in the parallel plurality of parallel circuit regions, and a plurality of current values of the plurality of second collection points are collected, when the plurality of second collection points are plural If the minimum value of the current values is greater than the first fault current threshold, it is determined that the fault is a blind spot fault.
  • the second fault current threshold is less than the first fault current threshold.
  • a point at which a fault current may occur on a parallel circuit of the power grid 300 having a distributed power source includes a second collection point c 3 , a second collection point d 3 , a second collection point e 3 , a second collection point f 3 , and a second The acquisition point g 3 , the second collection point h 3 , the second collection point i 3 , the collection point j 3 , and the second collection point k 3 . If the minimum current value flowing through the second collection point are fault current exceeds a first threshold value, it can be determined the first region A 3 blind spot failure occurs.
  • current collection at the second collection point described above can be accomplished by a protection device.
  • step S4 when the current value of any of the second collection points is greater than the second fault current threshold, the protection device of the parallel branch where the second collection point is located is triggered, wherein the second fault current threshold Less than the first fault current threshold.
  • the fault current is not shunted on the parallel branch, so the protection device with the fault current near the first collection point can reach the first fault current threshold and thus be triggered. Completely solve the blind spot problem of the line.
  • I max I PD31 + I d3 + I e3 - I c3 .
  • I max I PD41 + I nano42 + I nano43 -I nano44 .
  • the second collection point c 5 the second collection point d 5 , the second collection point e 5 , the second collection point f 5 , the second collection point g 5 , The second collection point h 5 , the second collection point i 5 , and the second collection point k 5 .
  • the maximum current is assumed that I nano51> I nano52, the maximum current value of the collection points occurs at the second collection point k 5, k 5 of the second collection point appears:
  • I max I PD51 + I nano1 + I nano3 -I nano2 -I nano4 ;
  • I max I PD51 +I nano3 -I nano4
  • the maximum current appearing in the plurality of second collection points is determined by the circuit connection, structure and fault current of the parallel circuit.
  • the first fault current threshold is a threshold of the first protection devices PD 31 , PD 41 , PD 51 , and a blind spot fault occurs.
  • FIG. 4 is a schematic diagram of a communication connection of a power system having a distributed power source, in accordance with an embodiment of the present invention.
  • the communication portion of the present invention can be realized by a protection device between an AC power source and a plurality of parallel parallel circuits and a protection device in each distributed power grid, or in an AC power source and a plurality of parallel devices.
  • the protection device between the parallel circuits and the multiple voltage and current detection modules are respectively arranged in each distributed power grid, and can also be realized by setting an additional controller.
  • a second aspect of the present invention provides a power grid fault detecting apparatus having a distributed energy source, the power grid 60 including at least one AC power supply UG 61 provided by a public power grid, the AC power source UG 61 being coupled to a plurality of parallel parallel circuits Nano 1 , Nano 2 ... Nano n , each of the parallel circuits includes a plurality of parallel branches, the parallel branches are respectively connected with a load and/or a DC power source, wherein the grid fault detecting device with distributed energy includes a protection device PD 61 connected between the alternating current power source UG 61 and the parallel plurality of parallel circuits Nano 1 , Nano 2 ...
  • Nano n wherein the alternating current power source UG 61 and the parallel A first collection point is also selected between the plurality of parallel circuits Nano 1 , Nano 2 ... Nano n , and the first protection device PD 61 collects the current value of the first collection point and its current direction, and compares the current The output current and the input current of the first collection point are judged to be faulty if the input parallel current is greater than the output current.
  • the grid fault detecting device with distributed energy sources further includes a plurality of second protection devices PD 62 , PD 63 . . . PD 6 n connected to the branches of the parallel plurality of parallel circuits, wherein a plurality of second collection points are disposed in a plurality of parallel circuit regions in parallel, and the second protection devices PD 62 , PD 63 , ... PD 6 n collect a plurality of current values of the plurality of second collection points, when The minimum of the plurality of current values of the plurality of second collection points is greater than the first fault current threshold, and the second protection device PD 62 , PD 63 . . . PD 6 n determines that the fault is a blind spot fault.
  • the second protection devices PD 62 , PD 63 . . . PD 6 n are triggered, wherein the second fault current threshold is less than The first fault current threshold is described.
  • the first protection device PD 61 communicates with a plurality of second protection devices PD 62 , PD 63 . . . PD 6 n , respectively, and the plurality of second protection devices PD 62 , PD 63 ... PD 6n communicates with each other.
  • the communication line is shown by a broken line in the drawing.
  • the grid fault detection device with distributed energy sources further comprises a plurality of connections connected on the branches of the plurality of parallel circuits connected in parallel a second voltage current detecting module S 2 , S 3 , S 4 . . . S n , wherein a plurality of second collecting points are disposed in the parallel plurality of parallel circuit regions, and the second protection device PD 62 PD 63 ??
  • PD 6n collecting the plurality of current values of the second plurality of collection points, when a plurality of current values of said plurality of second collection point in a first fault current is greater than the minimum threshold, the voltage and current detecting The module then determines that the fault is a blind spot fault, wherein a first voltage current detecting module S 1 is also disposed in the first protection device.
  • the second voltage current detection module S 2, S 3, S 4 ?? S n triggers the second collection point a second protection device of the parallel branch, wherein the second fault current threshold is less than the first fault current threshold.
  • first voltage current detecting module S 1 of the first protection device and the plurality of the second voltage current detecting modules S 2 , S 3 , S 4 . . . , S n communicate with each other. Among them, the communication line is shown by a broken line in the drawing.
  • a third aspect of the present invention also provides a power grid fault detecting apparatus having a distributed energy source, the power grid 80 including at least one AC power supply UG 81 provided by a public power grid, the AC power source UG 81 being coupled to a plurality of parallel parallel circuits Nano 1 , Nano 2 ... Nano n , each of the parallel circuits includes a plurality of parallel branches, the parallel branches being respectively connected with a load and/or a DC power source, wherein the grid fault detecting device with distributed energy includes a first protection device PD 81 connected between the AC power source UG 81 and the parallel plurality of parallel circuits Nano 1 , Nano 2 ...
  • controller C 1 respectively, and a first protection means PD 81 respectively and a plurality of second protection device PD 82, mutual communication PD 83 ?? PD 8n.
  • the invention can set a plurality of collection points according to the line connection of the power grid with distributed energy to check the fault, and determine whether the fault is a blind spot fault and trigger the protection device, thereby avoiding the misjudgment of the blind spot fault.

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Abstract

具有分布式能源的电网故障检测方法和装置，电网(300)包括至少一个公共电网提供的交流电源(UG 31)，交流电源耦合于并联的复数个并联电路，每个并联电路包括复数个并联支路，并联支路分别连接有负载和/或直流电源，其中，具有分布式能源的电网故障检测方法包括如下步骤：在交流电源和并联的复数个并联电路之间选定一个第一采集点(b 3)，采集该第一采集点的电流值及其电流方向；比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断并联的复数个并联电路出现故障。该电网故障检测方法和装置能够根据具有分布式能源的电网的线路连接来设置多个采集点来排查故障，并判断该故障是否为盲点故障从而触发保护装置，从而避免盲点故障的误判。

Description

具有分布式能源的电网故障检测方法和装置 技术领域
本发明涉及电网，尤其涉及具有分布式能源的电网的故障检测方法和装置。
背景技术
在传统的没有分布式电源的电力系统中，所有的负载都依靠公共电网提供交流电源供电。在这样的电力系统中，故障电流只能从交流电源中来，因此可以简单通过判断电网中多个保护装置是否超过故障电流阈值来判断电网是否发生故障。电网中的保护装置一旦超过故障电流阈值即可触发，断开电路切断公共电网交流电源的供电，以防止发生事故。
图1是现有技术的不具备分布式电源的电力系统。如图1所示，公共电网提供了一个交流电源UG 11，交流电源UG 11依次连接有保护装置PD 11、保险装置F 11、保护装置PD 12，所述保护装置PD 12连接有一个并联电路。其中，所述并联电路包括多个支路，其中一个支路由保护装置PD 13、电缆C 11、负载L 11串联而成，另一个支路由保护装置PD 14、电缆C 12、负载L 12串联而成，其他一个支路由保护装置PD 15、电缆C 13、负载L 13串联而成，还有一个支路由保护装置PD 16、电缆C 14、负载L 14串联而成。在保护装置PD 11和保险装置F 11之间还连接有一个串联支路，所述串联支路依次连接有保险装置F 12、电缆C 15、
因此，当故障处a 11发生故障时，则保护装置P11应当首先触发。当电缆C 14发生故障时，则保护装置PD 15应当首先触发。当电缆C 15发生故障时，则保险装置F 12首先触发。
其中，保护装置都是预先设定一个故障电流阈值，只有当流过保护装置的故障电流超过故障电流阈值时保护装置才能够被触发，起到保护整个线路作用。然而，在具有分布式电源的电力系统中，由于公共电网提供交流电源供电并非是唯一的电源，用户端的负载处还往往设置有其他直流电源，例如太阳能电源等。因此，整个电力系统的线路中其他支路还会分流故障电流， 因此流过保护装置的故障电流没办法达到故障电流阈值，保护装置就无法触发，无法起到保护电力系统的电路的作用。
发明内容
本发明第一方面提供了一种具有分布式能源的电网故障检测方法，所述电网包括至少一个公共电网提供的交流电源，所述交流电源耦合于并联的复数个并联电路，每个所述并联电路包括复数个并联支路，所述并联支路分别连接有负载和/或直流电源，其中，所述具有分布式能源的电网故障检测方法包括如下步骤：在所述交流电源和所述并联的复数个并联电路之间选定一个第一采集点，采集该第一采集点的电流值及其电流方向；比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路出现故障。
进一步地，所述第一采集点的输入电流：
I in＝I PDgrid+∑ Ibranchi，
其中，IP Dgrid为从所述交流电源输出至该第一采集点的电流，∑I branchi为方向与所述IP Dgrid相同的从并联的复数个并联电路输出至该第一采集点的电流，i为自然数。
进一步地，所述第一采集点的输出电流：
Iout＝∑I branchi
其中，∑I branchi为方向与所述I PDgrid相反的从并联的复数个并联电路输出至该第一采集点的电流，i为自然数。
进一步地，在比较判断之后还如下步骤：
在所述并联的复数个并联电路区域中设置复数个第二采集点，采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，则判断所述故障为盲点故障。
进一步地，在采集判断之后还如下步骤：当任一所述第二采集点的电流值大于第二故障电流阈值时，则触发该第二采集点所在的并联支路的第二保护装置，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
本发明第二方面提供了一种具有分布式能源的电网故障检测装置，所述电网包括至少一个公共电网提供的交流电源，所述交流电源耦合于并联的复数个并联电路，每个所述并联电路包括复数个并联支路，所述并联支路分别 连接有负载和/或直流电源，其中，具有分布式能源的电网故障检测装置包括：第一保护装置，其连接于所述交流电源和所述并联的复数个并联电路之间，其中，在所述交流电源和所述并联的复数个并联电路之间还选定有一个第一采集点，所述第一保护装置采集该第一采集点的电流值及其电流方向，并比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路出现故障。
进一步地，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路的支路上连接的复数个第二保护装置，其中，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述第二保护装置则判断所述故障为盲点故障。
进一步地，当任一所述第二采集点的电流值大于第二故障电流阈值时，第二保护装置则触发，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
进一步地，所述第一保护装置分别和复数个第二保护装置相互通信，所述复数个第二保护装置之间相互通信。
进一步地，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路的支路上连接的复数个电压电流检测模块，其中，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述电压电流检测模块则判断所述故障为盲点故障，其中，在所述第一保护装置中也设置有电压电流检测模块。
进一步地，当任一所述第二采集点的电流值大于第二故障电流阈值时，所述电压电流检测模块则触发该第二采集点所在的并联支路的第二保护装置，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
进一步地，所述第一保护装置分别和复数个所述电压电流检测模块相互通信。
本发明第三方面还提供了一种具有分布式能源的电网故障检测装置，所述电网包括至少一个公共电网提供的交流电源，所述交流电源耦合于并联的 复数个并联电路，每个所述并联电路包括复数个并联支路，所述并联支路分别连接有负载和/或直流电源，其中，具有分布式能源的电网故障检测装置包括：第一保护装置，其连接于所述交流电源和所述并联的复数个并联电路之间；控制器，其连接于所述第一保护装置，其中，在所述交流电源和所述并联的复数个并联电路之间还选定有一个第一采集点，所述第一保护装置采集该第一采集点的电流值及其电流方向并发送给所述控制器，控制器比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路出现故障。
进一步地，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路的支路上连接的复数个第二保护装置，其中，所述控制器还分别连接于所述第二保护装置，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置采集所述复数个第二采集点的复数个电流值并发送给所述控制器，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述控制器则判断所述故障为盲点故障。
进一步地，当任一所述第二采集点的电流值大于第二故障电流阈值时，所述控制器则触发该第二采集点所在的并联支路的第二保护装置，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
进一步地，所述控制器分别和第一保护装置分别以及复数个第二保护装置相互通信。
本发明能够根据具有分布式能源的电网的线路连接来设置多个采集点来排查故障，并判断该故障是否为盲点故障从而触发保护装置，从而避免盲点故障的误判。
附图说明
图1是现有技术的不具备分布式电源的电力系统的线路连接图；
图2是根据本发明一个具体实施例的具备分布式电源的电力系统的线路连接图；
图3是根据本发明一个具体实施例的具备分布式电源的电力系统的故障电流检测的线路连接图；
图4是根据本发明一个具体实施例的具备分布式电源的电力系统的通信连接示意图。
具体实施方式
以下结合附图，对本发明的具体实施方式进行说明。
如图2所示，在一个具备分布式电源的电力系统中，除了包括公共电网提供交流电源供电，还具有其他直流电源。假设图2所示的电力系统是一个小区供电系统，交流电源供电21为一个单元的四个用户端提供交流电。交流电源UG 21依次连接有保护装置PD 21、保险装置F 21、保护装置PD 22，所述保护装置PD 22连接有一个并联电路。所述并联电路包括四个并联支路，四个并联支路分别是来自一个单元的四个用户。第一并联支路由保护装置PD 23、电缆C 11、光伏转换器PV串联而成。第二并联支路由保护装置PD 24、电缆C 22、电池B串联而成。第三并联支路保护装置PD 25、电缆C 23、第一负载L 21串联而成。第四并联支路由保护装置PD 26、电缆C 24、第二负载L 22串联而成。其中，光伏转换器PV和电池B就是该电力系统中的分布式电源，其特别地为直流电源。因此，图2中区域A中的模块即是nanogrid(分布式电网)，其故障电流即可以从交流电源UG 21中来，也可以从光伏转换器PV和/或电池B中来。其中，第一保险装置F 21和第一保护装置PD 21之间还具有一个串联支路，串联支路表示该小区除了四个用户端的一个单元以外还包括其他单元。该串联支路依次连接有第二保险装置F 22、第五电缆。
因此，如图2所示，当故障a 21处发生故障时，第一保护装置PD 21和第二保护装置PD 22应当首先触发。其中，第二保护装置PD 22应当优先于第三保护装置PD 23和第四保护装置PD 24触发，第二保护装置PD 22被定义为交流电源UG 21和nanogrid之间的断路。同时，第一保护装置PD 21在整个线路中不应当具有保护盲点。当电缆C 23发生故障时，第五保护装置PD 25应当首先触发。同样，当第五电缆C 25发生故障时，保险装置F 22应当首先触发。
然而，当故障发生在a 21处时，在故障点a 21上会流过一个较大的故障电流I。故障电流I包括两部分，一部分是由交流电源UG 21提供，另一部分则是由光伏转换器PV和/或电池B提供。其中，交流电源UG 21提供的故障电流为逆时针方向的I 1，光伏转换器PV和/或电池B提供的故障电流为顺时针方向的I 2，因此I＝I 1+I 2。假设第一保护装置PD 21设置的故障电流阈值为1000A，第一保护装置PD 21流过的电流一旦超过1000A就会触发并断路。而光伏转换器PV和/或电池B提供的故障电流I 2为100A，假设此时故障电流I刚好为 1000A，因此第一保护装置PD 21流过的故障电流I 1＝I-I 2＝800A。由于第一保护装置PD 21设置的故障电流阈值为1000A，则第一保护装置PD 21不会判断为故障电流而触发，这样就会产生整个线路中的保护盲点。
如图3所示，在具有分布式电源的电网300中设置了一个由公共电网提供的交流电源UG 31，交流电源UG 31上连接有一个第一保护装置PD 31，第一保护装置PD 31耦合至4个并联的并联电路，每个并联电路包括3个并联支路，其中，每个并联支路分别连接有负载和/或直流电源。每个并联电路代表一个分布式电网(nanogrid)，在分布式电网中或设置有分布式电源。具体地，第一并联电路和第一保护装置PD 31之间连接有一个第二保护装置PD 32，第一并联电路的三个并联支路分别连接有第一负载L 31、第二负载L 32和第三负载L 33。第二并联电路和第一保护装置PD 31之间连接有一个第三保护装置PD 33，第一并联电路的三个并联支路分别连接有第四负载L 34、第一直流电源D 31和第二直流电源D 32。第三并联电路和第一保护装置PD 31之间连接有一个第四保护装置PD 34，第三并联电路的三个并联支路分别连接有第六负载L 36、第三直流电源D 33和第二直流电源D 32。第四并联电路和第一保护装置PD 31之间连接有一个第五保护装置PD 35，第四并联电路的三个并联支路分别连接有第七负载L 37、第八负载L 38和第九负载L 39。
本发明第一方面提供了一种具有分布式能源的电网故障检测方法。其中，包括如下步骤：
首先执行步骤S1，在所述交流电源和所述并联的复数个并联电路之间选定一个第一采集点，采集该第一采集点的电流值及其电流方向。根据本发明的一个优选实施例，在具有具有分布式电源的电网300中的交流电源UG31和并联的复数个并联电路之间选择一个第一采集点b 3，即所述第一采集点b 3设置在公共电网提供交流电源UG 31和入户以前的复数个并联电路之间。该第一采集点b 3流过的电流包括从交流电源UG 31提供的电流以及从四个并联电路构成的各支路分布式电源提供的电流，其中，交流电源UG 31提供的电流方向应当是从交流电源UG 22流向第一采集点b 3，是图3所示的自上向下方向，是第一采集点b 3的输入电流。分布式电源提供的电流应当是从一个或多个并联电路到第一采集点b 3，是图3所示的自下向上方向，是第一采集点b 3的输出电流。两者方向相反。本发明需要采集第一采集点b 3流过的输入电流和输出电流的电流值及其电流方向。如图3所示，由于第一并联电路和第四并联电 路未设置分布式直流电源，因此，第一并联电路和第四并联电路分别对应的第二保护装置PD 32和第四保护装置PD 34流过的电流都是自上向下的。其中，由于第二并联电路和第三并联电路的分别设置有第一直流电源D 31以及第二直流电源D 32和第三直流电源D 33，因此第二并联电路和第三并联电路对应的第二保护装置PD 32和第四保护装置PD 34流过的电流是自下向上的。
然后执行步骤S2，比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路出现故障。其中，第一采集点的输入电流为：
I in＝I PDgrid+∑I branchi(i＝1,…n),
其中，I PDgrid为从所述交流电源输出至该第一采集点的电流，∑I branchi为方向与所述I PDgrid相同的从并联的复数个并联电路输出至该第一采集点的电流，i为自然数。在一般情况下，从所述交流电源输出至该第一采集点的电流I PDgrid的方向应当和从并联的复数个并联电路输出至该第一采集点的电流I branchi方向相反。但是从所述交流电源输出至该第一采集点的电流I PDgrid的方向应当和从并联的复数个并联电路输出至该第一采集点的电流I branchi方向相同时，则第一采集点的输入电流I in为从所述交流电源输出至该第一采集点的电流I PDgrid的方向应当和从并联的复数个并联电路输出至该第一采集点的电流I branchi之总和。进一步地，第一采集点的输出电流为：
I out＝∑I branchi(i＝1,…n)
其中，∑I branchi为方向与所述I PDgrid相反的从并联的复数个并联电路输出至该第一采集点的电流，i为自然数。如果I input>I output，则说明线路该区域出现了故障。
其中，本实施例特别地包括四个并联电路，四个并联电路分别连接至四个客户端。本发明还需要采集四个并联电路分别流过的电流值及其方向，即如图3所示的具有分布式电源的电网300中第一采集点c 3、第一采集点d 3、第一采集点e 3、第一采集点f 3分别流过的电流值及其方向。
特别地，电流采集由交流电源UG 31和四个并联电路之间的第一保护装置PD 31来完成。其中，盲点问题仅在系统电源高于Un的80％时发生，这意味着故障电流总是在第一保护装置PD 31的长时间保护区域中。因此，对线路的通信速度的要求并不高。
例如，在具有分布式电源的电网30中还设置有第二采集点c 3、第二采集 点d 3、第二采集点e 3、第二采集点f 3。其中，从所述交流电源UG 31输出至该第一采集点b 3的电流、第二采集点c 3流过的电流和第二采集点f 3流过的电流都是图示从上往下的，为输入电流。因此，第一采集点b 3的输入电流I in30＝I PD32+I c3+I f3，其中，由于第二并联电路的支路中设置有第一直流电源D 31，第三并联电路的支路中分别设置有第三直流电源D 33和第二直流电源D 32，因此第二采集点d 3和e 3流过的电流都应当是自下而上的方向，是输出电流。因此，第一采集点b 3的输出电流I out30＝I d3+I e3。当I in3>I out3，则判断并联的复数个并联电路的第一区域A 3出现故障。
例如，在具有分布式电源的电网40中还设置有第二采集点c 4、第二采集点d 4、第二采集点e 4、第二采集点f 4。交流电源UG 41连接有第一保护装置PD 41，第一保护装置PD 41连接有四个并联的并联电路，分别为第一并联电路nano 41、第二并联电路nano 42、第三并联电路nano 43和第四并联电路nano 44。其中，所述第二连接点c 4和第一并联电路nano 41之间连接有第二保护装置PD 42，第二连接点d 4和第二并联电路nano 42之间连接有第三保护装置PD 43，第二连接点e 4和第三并联电路nano 43之间连接有第四保护装置PD 44，第二连接点f 4和第四并联电路nano 44之间连接有第五保护装置PD 45。
其中，从所述交流电源UG 41输出至该第一采集点b 4的电流、第二采集点c 3流过的电流和第二采集点f 4流过的电流都是图示从上往下的，为输入电流。因此，第一采集点b 4的输入电流I in40＝I PD41+I c4+I f4。其中，第二采集点d 4和e 4流过的电流都应当是自下而上的方向，是输出电流。因此，第一采集点b 4的输出电流I out4＝I d4+I e4。当I in3>I out3，则判断并联的复数个并联电路的第一区域A 4出现故障。
例如，在具有分布式电源的电网50中还设置有第二采集点c 5、第二采集点d 5、第二采集点e 5、第二采集点f 5。交流电源UG 51连接有第一保护装置PD 51，第一保护装置PD 51连接有四个并联的并联电路，分别为第一并联电路nano 51、第二并联电路nano 52、第三并联电路nano 53和第四并联电路nano 54。其中，所述第二连接点c 5和第一并联电路nano 51之间连接有第二保护装置PD 42，第二连接点 54和第二并联电路nano 52之间连接有第三保护装置PD 53，第二连接点 54和第三并联电路nano 53之间连接有第四保护装置PD 54，第二连接点f 4和第四并联电路nano 54之间连接有第五保护装置PD 55。
其中，从所述交流电源UG 51输出至该第一采集点b 5的电流和第二采集点f 5 流过的电流都是图示从上往下的，为输入电流。因此，第一采集点b 5的输入电流I in50＝I PD51+I f5。其中，第二采集点d 5、e 5和c 5流过的电流都应当是自下而上的方向，是输出电流。因此，第一采集点b 4的输出电流I out5＝I c5+I d5+I e5。当I in3>I out3，则判断并联的复数个并联电路的第一区域A 5出现故障。
然后执行步骤S3，在所述并联的复数个并联电路区域中设置复数个第二采集点，采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，则判断所述故障为盲点故障。其中，所述第二故障电流阈值小于所述第一故障电流阈值。经过步骤S2，我们只能判断一个或多个并联电路所在的第一区域出现故障，但是无法定位具体故障的具体位置，也无从得知故障的具体类型，特别是需要判断是否是盲点故障，并排除由盲点故障带来的风险。由于并联电路的支路连接是固定的，本发明能够确定并联电路所有可能出现故障的点并采集电流。
例如，具有分布式电源的电网300的并联电路上可能出现故障电流的点包括第二采集点c 3、第二采集点d 3、第二采集点e 3、第二采集点f 3、第二采集点g 3、第二采集点h 3、第二采集点i 3、采集点j 3、第二采集点k 3。如果上述第二采集点流过的电流值的最小值都超过第一故障电流阈值，则可以判断第一区域A 3发生盲点故障。典型地，上述第二采集点的电流采集可由保护装置来完成。
最后执行步骤S4，当任一所述第二采集点的电流值大于第二故障电流阈值时，则触发该第二采集点所在的并联支路的保护装置，其中，所述第二故障电流阈值小于所述第一故障电流阈值。当所有发生盲点故障的并联支路的保护装置触发并断路以后，则故障电流在并联支路上没有分流，所以故障电流在第一采集点附近的保护装置能够达到第一故障电流阈值，从而被触发彻底解决线路的盲点故障问题。
具体地，在具有分布式电源的电网300中，假设在第二采集点c 3、第二采集点d 3、第二采集点e 3、第二采集点f 3、第二采集点g 3、第二采集点h 3、第二采集点i 3、采集点j 3、第二采集点k 3中的最大电流值出现在第二采集点i 3，第二采集点i 3出现的最大电流值：
I max＝I PD31+I d3+I e3-I c3。
具体地，在具有分布式电源的电网400中，假设在第二采集点c 4、第二采集点d 4、第二采集点e 4、第二采集点f 4、第二采集点g 4、第二采集点h 4、 第二采集点i 4、采集点j 4、第二采集点k 4中的最大电流值出现在第二采集点j 4，第二采集点j 4出现的最大电流值：
I max＝I PD41+I nano42+I nano43-I nano44。
具体地，在具有分布式电源的电网500中，设置有第二采集点c 5、第二采集点d 5、第二采集点e 5、第二采集点f 5、第二采集点g 5、第二采集点h 5、第二采集点i 5、第二采集点k 5。假设I nano51>I nano52，上述采集点中的最大电流值出现在第二采集点k 5，则第二采集点k 5出现的最大电流值为：
I max＝I PD51+I nano1+I nano3-I nano2-I nano4；
假设I nano51<I nano52，上述采集点中的最大电流值出现在第二采集点g 5，则第二采集点g 5出现的最大电流值为：
I max＝I PD51+I nano3-I nano4
因此，由上述分析可知，在复数个第二采集点中出现的电流最大值是由并联电路的电路连接、结构和故障电流来互相决定的。
因此，从第一采集点b 3、b 4、b 5附近的第一保护装置PD 31、PD 41、PD 51来看，当I max大于第一故障电流阈值，IPD 31或IPD 41或IPD 51小于第一故障电流阈值，并且所述第一故障电流阈值为第一保护装置PD 31、PD 41、PD 51的阈值，盲点故障才会发生。
而从并联电路的保护装置来看，当I max大于第二故障电流阈值时，并且第二故障电流阈值小于第一故障电流阈值，其中，第二故障电流阈值为具有分布式电源的支路保护装置的阈值时，盲点故障才会发生。
图4是根据本发明一个具体实施例的具备分布式电源的电力系统的通信连接示意图。如图4所示，本发明的通信部分可以通过交流电源和复数个并联的并联电路之间的保护装置以及每个分布式电网中的保护装置来实现，也可以在交流电源和复数个并联的并联电路之间的保护装置以及每个分布式电网中分别设置多个电压电流检测模块来实现，还可以通过设置额外的控制器来实现。
本发明第二方面提供了一种具有分布式能源的电网故障检测装置，所述电网60包括至少一个公共电网提供的交流电源UG 61，所述交流电源UG 61耦合于并联的复数个并联电路Nano 1、Nano 2……Nano n，每个所述并联电路包括复数个并联支路，所述并联支路分别连接有负载和/或直流电源，其中，具有分布式能源的电网故障检测装置包括第一保护装置PD 61，其连接于所述交流 电源UG 61和所述并联的复数个并联电路Nano 1、Nano 2……Nano n之间，其中，在所述交流电源UG 61和所述并联的复数个并联电路Nano 1、Nano 2……Nano n之间还选定有一个第一采集点，所述第一保护装置PD 61采集该第一采集点的电流值及其电流方向，并比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路出现故障。
进一步地，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路的支路上连接的复数个第二保护装置PD 62、PD 63……PD 6n，其中，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置PD 62、PD 63……PD 6n采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述第二保护装置PD 62、PD 63……PD 6n则判断所述故障为盲点故障。
进一步地，当任一所述第二采集点的电流值大于第二故障电流阈值时，第二保护装置PD 62、PD 63……PD 6n则触发，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
进一步地，如图4所示，所述第一保护装置PD 61分别和复数个第二保护装置PD 62、PD 63……PD 6n相互通信，所述复数个第二保护装置PD 62、PD 63……PD 6n之间相互通信。其中，通信线路是以附图中的虚线示出的。
根据本发明的上述实施例的一个变化例，在具有分布式能源的电网70中，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路的支路上连接的复数个第二电压电流检测模块S 2、S 3、S 4……S n，其中，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置PD 62、PD 63……PD 6n采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述电压电流检测模块则判断所述故障为盲点故障，其中，在所述第一保护装置中也设置有第一电压电流检测模块S 1。
进一步地，当任一所述第二采集点的电流值大于第二故障电流阈值时，所述第二电压电流检测模块S 2、S 3、S 4……S n则触发该第二采集点所在的并联支路的第二保护装置，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
进一步地，所述第一保护装置的第一电压电流检测模块S 1分别和复数个所述第二电压电流检测模块S 2、S 3、S 4……S n相互通信。其中，通信线路是 以附图中的虚线示出的。
本发明第三方面还提供了一种具有分布式能源的电网故障检测装置，所述电网80包括至少一个公共电网提供的交流电源UG 81，所述交流电源UG 81耦合于并联的复数个并联电路Nano 1、Nano 2……Nano n，每个所述并联电路包括复数个并联支路，所述并联支路分别连接有负载和/或直流电源，其中，具有分布式能源的电网故障检测装置包括：第一保护装置PD 81，其连接于所述交流电源UG 81和所述并联的复数个并联电路Nano 1、Nano 2……Nano n之间；控制器C 1，其连接于所述第一保护装置PD 81，其中，在所述交流电源UG 81和所述并联的复数个并联电路Nano 1、Nano 2……Nano n之间还选定有一个第一采集点，所述第一保护装置PD 81采集该第一采集点的电流值及其电流方向并发送给所述控制器C 1，控制器C 1比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路Nano 1、Nano 2……Nano n出现故障。
进一步地，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路Nano 1、Nano 2……Nano n的支路上连接的复数个第二保护装置PD 82、PD 83……PD 8n，其中，所述控制器C 1还分别连接于所述第二保护装置PD 82、PD 83……PD 8n，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置采集所述复数个第二采集点的复数个电流值并发送给所述控制器C 1，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述控制器C 1则判断所述故障为盲点故障。
进一步地，当任一所述第二采集点的电流值大于第二故障电流阈值时，所述控制器C 1则触发该第二采集点所在的并联支路的第二保护装置PD 82、PD 83……PD 8n，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
进一步地，所述控制器C 1分别和第一保护装置PD 81分别以及复数个第二保护装置PD 82、PD 83……PD 8n相互通信。
本发明能够根据具有分布式能源的电网的线路连接来设置多个采集点来排查故障，并判断该故障是否为盲点故障从而触发保护装置，从而避免盲点故障的误判。
尽管本发明的内容已经通过上述优选实施例作了详细介绍，但应当认识到上述的描述不应被认为是对本发明的限制。在本领域技术人员阅读了上述内容后，对于本发明的多种修改和替代都将是显而易见的。因此，本发明的 保护范围应由所附的权利要求来限定。此外，不应将权利要求中的任何附图标记视为限制所涉及的权利要求；“包括”一词不排除其它权利要求或说明书中未列出的装置或步骤；“第一”、“第二”等词语仅用来表示名称，而并不表示任何特定的顺序。

Claims (16)

  1. 具有分布式能源的电网故障检测方法，所述电网包括至少一个公共电网提供的交流电源，所述交流电源耦合于并联的复数个并联电路，每个所述并联电路包括复数个并联支路，所述并联支路分别连接有负载和/或直流电源，其中，所述具有分布式能源的电网故障检测方法包括如下步骤：
    在所述交流电源和所述并联的复数个并联电路之间选定一个第一采集点，采集该第一采集点的电流值及其电流方向；
    比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路出现故障。
  2. 根据权利要求1所述的具有分布式能源的电网故障检测方法，其特征在于，所述第一采集点的输入电流：
    I in＝I PDgrid+∑I branchi，
    其中，I PDgrid为从所述交流电源输出至该第一采集点的电流，∑I branchi为方向与所述I PDgrid相同的从并联的复数个并联电路输出至该第一采集点的电流，i为自然数。
  3. 根据权利要求2所述的具有分布式能源的电网故障检测方法，其特征在于，所述第一采集点的输出电流：
    I out＝∑I branchi，
    其中，∑I branchi为方向与所述I PDgrid相反的从并联的复数个并联电路输出至该第一采集点的电流，i为自然数。
  4. 根据权利要求3所述的具有分布式能源的电网故障检测方法，其特征在于，在比较判断之后还如下步骤：
    在所述并联的复数个并联电路区域中设置复数个第二采集点，采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，则判断所述故障为盲点故障。
  5. 根据权利要求4所述的具有分布式能源的电网故障检测方法，其特征在于，在采集判断之后还如下步骤：
    当任一所述第二采集点的电流值大于第二故障电流阈值时，则触发该第二采集点所在的并联支路的第二保护装置，
    其中，所述第二故障电流阈值小于所述第一故障电流阈值。
  6. 具有分布式能源的电网故障检测装置，所述电网包括至少一个公共电网提供的交流电源，所述交流电源耦合于并联的复数个并联电路，每个所述并联电路包括复数个并联支路，所述并联支路分别连接有负载和/或直流电源，其中，具有分布式能源的电网故障检测装置包括：
    第一保护装置，其连接于所述交流电源和所述并联的复数个并联电路之间，其中，在所述交流电源和所述并联的复数个并联电路之间还选定有一个第一采集点，所述第一保护装置采集该第一采集点的电流值及其电流方向，并比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路出现故障。
  7. 根据权利要求6所述的具有分布式能源的电网故障检测装置，其特征在于，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路的支路上连接的复数个第二保护装置，其中，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述第二保护装置则判断所述故障为盲点故障。
  8. 根据权利要求7所述的具有分布式能源的电网故障检测装置，其特征在于，当任一所述第二采集点的电流值大于第二故障电流阈值时，第二保护装置则触发，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
  9. 根据权利要求8所述的具有分布式能源的电网故障检测装置，其特征在于，所述第一保护装置分别和复数个第二保护装置相互通信，所述复数个第二保护装置之间相互通信。
  10. 根据权利要求6所述的具有分布式能源的电网故障检测装置，其特征在于，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路的支路上连接的复数个第二电压电流检测模块，其中，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置采集所述复数个第二采集点的复数个电流值，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述电压电流检测模块则判断所述故障为盲点故障，其中，在所述第一保护装置中也设置有第一电压电流检测模块。
  11. 根据权利要求10所述的具有分布式能源的电网故障检测装置，其特征在于，当任一所述第二采集点的电流值大于第二故障电流阈值时，所述电 压第二电流检测模块则触发该第二采集点所在的并联支路的第二保护装置，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
  12. 根据权利要求8所述的具有分布式能源的电网故障检测装置，其特征在于，所述第一保护装置中的第一电压电流检测模块分别和复数个所述第二电压电流检测模块相互通信。
  13. 具有分布式能源的电网故障检测装置，所述电网包括至少一个公共电网提供的交流电源，所述交流电源耦合于并联的复数个并联电路，每个所述并联电路包括复数个并联支路，所述并联支路分别连接有负载和/或直流电源，其中，具有分布式能源的电网故障检测装置包括：
    第一保护装置，其连接于所述交流电源和所述并联的复数个并联电路之间；
    控制器，其连接于所述第一保护装置，
    其中，在所述交流电源和所述并联的复数个并联电路之间还选定有一个第一采集点，所述第一保护装置采集该第一采集点的电流值及其电流方向并发送给所述控制器，控制器比较该第一采集点的输出电流和输入电流，如果其输入电流大于输出电流，则判断所述并联的复数个并联电路出现故障。
  14. 根据权利要求13所述的具有分布式能源的电网故障检测装置，其特征在于，所述具有分布式能源的电网故障检测装置还包括在所述并联的复数个并联电路的支路上连接的复数个第二保护装置，其中，所述控制器还分别连接于所述第二保护装置，在所述并联的复数个并联电路区域中设置复数个第二采集点，所述第二保护装置采集所述复数个第二采集点的复数个电流值并发送给所述控制器，当所述复数个第二采集点的复数个电流值中最小值大于第一故障电流阈值，所述控制器则判断所述故障为盲点故障。
  15. 根据权利要求14所述的具有分布式能源的电网故障检测装置，其特征在于，当任一所述第二采集点的电流值大于第二故障电流阈值时，所述控制器则触发该第二采集点所在的并联支路的第二保护装置，其中，所述第二故障电流阈值小于所述第一故障电流阈值。
  16. 根据权利要求15所述的电网的故障检测方法，其特征在于，所述控制器分别和第一保护装置分别以及复数个第二保护装置相互通信。
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