CN110289637A - A kind of joint island detection method that region multi-inverter is grid-connected - Google Patents
A kind of joint island detection method that region multi-inverter is grid-connected Download PDFInfo
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- CN110289637A CN110289637A CN201910639555.3A CN201910639555A CN110289637A CN 110289637 A CN110289637 A CN 110289637A CN 201910639555 A CN201910639555 A CN 201910639555A CN 110289637 A CN110289637 A CN 110289637A
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- 238000001514 detection method Methods 0.000 title claims abstract description 49
- 238000007689 inspection Methods 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims description 16
- 230000008859 change Effects 0.000 description 5
- 238000004088 simulation Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000010248 power generation Methods 0.000 description 4
- 230000009183 running Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000005611 electricity Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
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- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
-
- H02J3/385—
-
- 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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
-
- 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
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
-
- 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
Abstract
The invention belongs to grid-connected technical field of relay protection; in particular a kind of joint island detection method that region multi-inverter is grid-connected, comprising the following steps: S1: the solution combined with the local island detection method based on voltage positive feedback is detected using the long-range isolated island based on carrier signal；S2: a carrier signal generating device is added in substation, a carrier wave AM access module is integrated in each single-phase photovoltaic inverter；S3: remote carrier sending device constantly sends power carrier signal in the distribution line into region when power grid has；S4: when power grid breaks down, carrier wave reception device cannot receive carrier signal, and the inverter in region can all start the isolated island inspection policies based on voltage positive feedback, reduce active output electric current, and from grid entry point voltage is lowered, trigger voltage crosses limit protection.High reliablity of the present invention, can accurate detection isolated island voltage magnitude, so as to preferably be detected to isolated island.
Description
Technical field
The present invention relates to grid-connected technical field of relay protection more particularly to a kind of joints that region multi-inverter is grid-connected
Island detection method.
Background technique
People increasingly pay close attention to enhancement of environment and clean energy resource application aspect, and distributed photovoltaic power generation technology obtains
More and more applications, national help-the-poor policy are also combined with distributed photovoltaic power generation, increase distributed photovoltaic power generation
Using scale.Photovoltaic DC-to-AC converter is the vital electrical electronic equipment in distributed photovoltaic power generation system.For the peace of power grid entirety
Row for the national games, one of them important criteria is exactly to have the function of isolated island detection in photovoltaic inverter grid-connected standard.Namely exist
In the case that distribution network systems failure is not powered, photovoltaic DC-to-AC converter is required to the state for preparing to detect power distribution network, and stops
It only powers to load, prevents from damaging load and maintenance personal.
The isolated island detection technique of present isolated island be divided into passively with actively two kinds, passively load and inverter just
With when, can not correctly detect.Active detection technique is that certain disturbance is actively added in power grid, be can solve above-mentioned
Problem.But a large amount of harmonic wave can be injected to power grid.Moreover, injecting similar disturbance to power grid simultaneously for multiple generator units
The influence correctly detected further research not yet for isolated island.Distributed generation system is mostly completed simultaneously in single-phase form
Net, for the case where multiple single-phase photovoltaic inverter parallel runnings, how to reduce active island detection method in a region
Influence to power quality, while improving isolated island Detection accuracy there are no good methods.
Therefore we have proposed a kind of joint island detection methods that region multi-inverter is grid-connected for solving the above problems.
Summary of the invention
The purpose of the present invention is to solve disadvantages existing in the prior art, and a kind of region multi-inverter proposed is simultaneously
The joint island detection method of net.
To achieve the goals above, present invention employs following technical solutions: a kind of joint that region multi-inverter is grid-connected
Island detection method, including S1: using the long-range isolated island detection based on carrier signal and the local isolated island based on voltage positive feedback
The solution that detection method combines；
S2: a carrier signal generating device is added in substation, a load is integrated in each single-phase photovoltaic inverter
Wave AM access module；
S3: remote carrier sending device constantly sends electric power in the distribution line into region when power grid has
Carrier signal；
S4: when power grid breaks down, carrier wave reception device cannot receive carrier signal, and the inverter in region can all open
The dynamic isolated island inspection policies based on voltage positive feedback, reduce active output electric current, and from grid entry point voltage is lowered, trigger voltage crosses limit
Protection；
S5: using a kind of voltage positive feedback method of variable coefficient；Inverter when executing isolated island inspection policies, watt current
It is given below shown in formula:
Compared with prior art, the beneficial effects of the present invention are:
It is remotely combined with local island detection method, local active isolated island detection algorithm is not within the whole service time
All start, only start in the case where carrier signal is lost, this mode is significantly less based on voltage positive feedback control
Influence of the active island detection method to photovoltaic inverter grid-connected power stability, be more advantageous to MPPT algorithm normal work,
Improve the utilization efficiency of solar energy resources；
In the case where carrier equipment dropout, distributed photovoltaic inverter be will start based on voltage-controlled positive feedback
Isolated island inspection policies, this strategy are much smaller compared to influence of the strategy to power supply line's power quality based on frequency disturbance, and
And it is easier to practical realization, detection voltage magnitude accuracy is high, it is easier to the accurate judgement of isolated island situation；
Since the normal working condition of inverter is usually MPPT state, i.e. maximal power tracing state, so inverter
Active given value tend to the maximum value of photovoltaic panel generated output, so the direction that the active power of voltage positive feedback disturbs is unified
Be established as the direction of active power reduction, the mechanism of the isolated island detection actual effect of multi-inverter parallel system be perturbation direction difference from
And disturb and cancel out each other, isolated island detection failure is caused, using the inverter controlled based on voltage positive feedback in more parallel runnings
Shi Ze can be very good to avoid the generation of such case；
High reliablity of the present invention, can accurate detection isolated island voltage magnitude, so as to preferably be detected to isolated island.
Detailed description of the invention
Fig. 1 is that a kind of region of the grid-connected joint island detection method of region multi-inverter proposed by the present invention is multiple single-phase
Photovoltaic DC-to-AC converter alone island detection system structure chart；
Fig. 2 is a kind of region multi-inverter of the grid-connected joint island detection method of region multi-inverter proposed by the present invention
Joint isolated island detects work flow diagram；
Fig. 3 is a kind of single-phase inverter electricity of the grid-connected joint island detection method of region multi-inverter proposed by the present invention
Positive pressure feeds back island detection method voltage, current waveform；
Fig. 4 is a kind of single-phase inverter electricity of the grid-connected joint island detection method of region multi-inverter proposed by the present invention
Positive pressure feeds back island detection method voltage change.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
Embodiment
With reference to Fig. 1-4, a kind of joint island detection method that region multi-inverter is grid-connected is proposed in the present embodiment, remotely
Carrier sending device constantly sends power carrier signal in the distribution line into region when power grid has；It is integrated in
Carrier receiving module in single-phase photovoltaic inverter equipment is attached by the controller of one I/O mouthfuls and inverter, and I/O mouthfuls
State output control can be carried out by carrier receiving module, by inverter controller receive.What carrier sending device was sent
The frequency of carrier signal can select 100kHz~450kHz, amplitude 1mV~10mV of carrier signal, and baud rate can be chosen
500bit/s or 200bit/s, such high-frequency, the carrier signal of low amplitude value influence very the power quality of distribution line
Small, the multiple single-phase photovoltaic inverter alone island detection system structures in region are as shown in Figure 1；
The co-ordination process that long-range isolated island detection is detected with the local isolated island based on voltage positive feedback is as shown in Fig. 2, fortune
The carrier signal sending device of journey and the direct interactive information of protective relaying device in this distribution network systems region, obtain regional power grid
Fault message.In bulk power grid, there is no when failure, carrier sending device can the continual distribution wire to this region
Road sends specific power line carrier signal, and the integrated carrier wave reception device in inverter can receive carrier signal, and
Information is communicated to inverter by I/O port.In distribution network systems, carrier wave reception device will can not collect carrier sending device
The information of carrier signal is communicated to inverter.If power grid breaks down, output power, frequency and the load of inverter can not
Matching well, then exception can occur rapidly in the voltage magnitude of grid entry point or frequency, triggers the protection mechanism of photovoltaic DC-to-AC converter,
Implement isolated island protection, stops working.If power grid breaks down, the output power of inverter, frequency can be matched with load, then
Voltage, electric current are normal, and at this time since carrier wave reception device cannot receive carrier signal, the inverter in region can all be opened
The dynamic isolated island inspection policies based on voltage positive feedback, reduce active output electric current, and from grid entry point voltage is lowered, trigger voltage crosses limit
Protection, carrier signal is lost once in a while, inverter startup isolated island inspection policies, but since the presence of power grid has voltage
Very strong stabilization, so the active disturbance that photovoltaic DC-to-AC converter is added not will cause the variation of grid entry point voltage.Photovoltaic inversion
Device is after isolated island inspection policies run 2S, if grid entry point voltage does not change still, judgement is that carrier signal is lost, and restores to be not added
Enter the normal mode of operation of isolated island inspection policies；
The specific embodiment of single-phase inverter voltage positive feedback island detection method is as follows: the method for voltage positive feedback is logical
The current control for crossing inverter is disturbed to grid entry point Injection Current, the hair of observation grid entry point voltage changed to judge isolated island situation
Raw, the method is smaller compared to the influence of the methods of frequency disturbance method, reactive power disturbance method to power quality.Although comparing frequency
Influence with reactive disturbance method to electric flux is small, but voltage positive feedback can have an impact watt current, the work to MPPT
Effect, if longtime running and voltage positive feedback mode will cause the utilization efficiency reduction to solar energy.By long-range lonely
The method that single detection is combined with local lonely detection, can largely reduce local active island detection method for inversion
The influence of device normal operation effect；
The specific implementation step that voltage positive feedback island detection method is applied to single-phase photovoltaic DC-to-AC converter is as follows, with common
5KW single-phase photovoltaic grid-connected inverter for be illustrated；
It is firstly added the disturbance to inverter output current amplitude, general photovoltaic DC-to-AC converter work is in MPPT maximum power point tracking
(MPPT) operating mode, so generalling use the perturbation scheme for reducing inverter power output；
Then the variation for observing photovoltaic DC-to-AC converter PCC point voltage magnitude, whether determining that isolated island occurs, according to GB50052-
2009 " Code for design of electric power supply systems " answer the regulation of electrical equipment end voltage deviation permissible value, the size deviation of voltage magnitude
Within positive and negative the 5% of voltage rating, the qualified supply voltage of 220V power supply system voltage should be 209V~231V.In determination
To prevent from malfunctioning when isolated island occurs, the voltage limitation that isolated island occurs for judgement is positioned lower than 180V or is higher than 255V；
The voltage positive feedback method of currently used fixed coefficient will fail when inverter output power is larger, mention
The voltage positive feedback method of a kind of variable coefficient out, solves this problem.Inverter is when executing isolated island inspection policies, watt current
Be given below shown in formula:
Wherein, Iisland (t) is the defeated of the watt current given using inverter after voltage positive feedback island detection method
It instructs out；Δ U (t) is the variation of grid entry point voltage between two control periods；Iref (t) is that island detection method is not added
It is the given watt current output order of inverter, this instruction is generally calculated by MPPT maximum power point tracking algorithm (MPPT)
It arrives；Kr is voltage positive feedback direct proportion adjustment factor, this coefficient is generally provided in program debugging, not with different controls
Mechanical periodicity processed；K (t) is the positive and negative feedforward coefficient of voltage positive feedback island detection method, this coefficient and a upper inverter control
The voltage value U (t-1) for the grid entry point that the given value of current value Iref (t-1) in period processed and a upper inverter control cycle detection are arrived
Ratio direct proportionality；Feedforward coefficient each control period positive and negative in this way can change, when can prevent feedback factor from determining,
Isolated island is caused to detect actual effect if inverter output power is larger.Such as if inverter output power increases, Iref (t-1)
Increase, the feedback factor k (t) in corresponding next control period also increases, and thus can solve power and increases detection failure
Problem；
Single-phase inverter is using the simulation waveform of voltage positive feedback island detection method as shown in figure 3, single-phase inverter
Output power is 5KW, and it is contrast simulation waveform that kr, which takes simulation waveform above 0.1, Fig. 3, for proving that the load parameter of emulation is set
It sets rationally, i.e., if isolated island inspection policies are not added, the resonance frequency of load can be matched with the frequency that inverter exports,
It still will form isolated island continuous service when bulk power grid failure (0.5S moment, bulk power grid failure removal), charge distribution line, make
At danger, following simulation waveform was the simulation result that the detection of voltage positive feedback isolated island is added in Fig. 3, it can be seen that at 0.5 second
In 0.5S (namely whole process is less than 1S time point) after grid collapses, grid-connected voltage is just more than under-voltage protection value
The correct detection to island state may be implemented in (180V)；
Grid entry point voltage change waveform after inverter isolated island occurs is as shown in Figure 4.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
Anyone skilled in the art in the technical scope disclosed by the present invention, according to the technique and scheme of the present invention and its
Inventive concept is subject to equivalent substitution or change, should be covered by the protection scope of the present invention.
Claims (1)
1. a kind of joint island detection method that region multi-inverter is grid-connected, which comprises the following steps:
S1: it is combined using the long-range isolated island detection based on carrier signal with the local island detection method based on voltage positive feedback
Solution；
S2: a carrier signal generating device is added in substation, a carrier wave is integrated in each single-phase photovoltaic inverter and is connect
Enter module；
S3: remote carrier sending device constantly sends power carrier in the distribution line into region when power grid has
Signal；
S4: when power grid breaks down, carrier wave reception device cannot receive carrier signal, and the inverter in region can all start base
In the isolated island inspection policies of voltage positive feedback, active output electric current is reduced, from grid entry point voltage is lowered, trigger voltage is crossed limit and protected
Shield；
S5: using a kind of voltage positive feedback method of variable coefficient, when executing isolated island inspection policies, watt current gives inverter
It is shown below:
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102412592A (en) * | 2011-10-09 | 2012-04-11 | 山亿新能源股份有限公司 | Island detection method and system of photovoltaic grid-connected generation system |
| CN104569696A (en) * | 2015-01-30 | 2015-04-29 | 闫朝阳 | Island detection method based on dq conversion and used for voltage per unit value positive feedback |
| CN105606921A (en) * | 2015-11-26 | 2016-05-25 | 国家电网公司 | Negative sequence voltage positive feedback-based islanding detection system and method |
| US20170077703A1 (en) * | 2015-07-16 | 2017-03-16 | Michael Ropp | Subharmonic power line carrier based island detection systems and methods |
| CN108918996A (en) * | 2018-06-19 | 2018-11-30 | 中国科学院电工研究所 | Island detection method for distributed photovoltaic power generation system |
-
2019
- 2019-07-16 CN CN201910639555.3A patent/CN110289637A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102412592A (en) * | 2011-10-09 | 2012-04-11 | 山亿新能源股份有限公司 | Island detection method and system of photovoltaic grid-connected generation system |
| CN104569696A (en) * | 2015-01-30 | 2015-04-29 | 闫朝阳 | Island detection method based on dq conversion and used for voltage per unit value positive feedback |
| US20170077703A1 (en) * | 2015-07-16 | 2017-03-16 | Michael Ropp | Subharmonic power line carrier based island detection systems and methods |
| CN105606921A (en) * | 2015-11-26 | 2016-05-25 | 国家电网公司 | Negative sequence voltage positive feedback-based islanding detection system and method |
| CN108918996A (en) * | 2018-06-19 | 2018-11-30 | 中国科学院电工研究所 | Island detection method for distributed photovoltaic power generation system |
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Application publication date: 20190927 |