CN108599153A - A kind of off-network for low pressure flexibility supplying power allocation system turns grid-connected Phase angle control method - Google Patents

A kind of off-network for low pressure flexibility supplying power allocation system turns grid-connected Phase angle control method Download PDF

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Publication number
CN108599153A
CN108599153A CN201810443604.1A CN201810443604A CN108599153A CN 108599153 A CN108599153 A CN 108599153A CN 201810443604 A CN201810443604 A CN 201810443604A CN 108599153 A CN108599153 A CN 108599153A
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bus
grid
power
phase angle
network
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尹春丽
李颖
贺中桥
陈颖
滕松
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State Grid Corp of China SGCC
Xuzhou Power Supply Co of Jiangsu Electric Power Co Ltd
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State Grid Corp of China SGCC
Xuzhou Power Supply Co of Jiangsu Electric Power Co Ltd
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Priority to CN201810443604.1A priority Critical patent/CN108599153A/en
Publication of CN108599153A publication Critical patent/CN108599153A/en
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/383
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/40Synchronising a generator for connection to a network or to another generator
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The present invention provides one kind being used for low pressure flexibility supplying power allocation system coordination control method, the operating mode being incorporated into the power networks is transferred to from off-grid operation for current transformer under different operational modes, using the no phase-locked loop Phase angle control technology of synchronous rotating angle, power grid three-phase voltage is coordinately transformed under inverter synchronous rotating frame under off-network state, obtain its q shaft voltage component, angular frequency deviation amount is obtained through angular frequency adjuster, the angular frequency of the off-network that is added to pattern generates link, to adjust the phase angle of inverter, it is set to fast implement synchronous with power grid phase angle, judge to determine whether same period success through the same period, reach grid-connected without impacting.Control method of the present invention is not necessarily to network voltage locking phase, even entire control system is not necessarily to phaselocked loop completely under VF patterns and VSG patterns, avoid the uncertain influence such as locking phase operation complicated in Phase angle control and its delay brought, parameter applicability, the load factor of controller is reduced, control efficiency is improved.

Description

A kind of off-network for low pressure flexibility supplying power allocation system turns grid-connected Phase angle control method
Technical field
The invention belongs to flexible transmission technical fields, more particularly to a kind of off-network for low pressure flexibility supplying power allocation system Turn grid-connected Phase angle control method.
Background technology
Flexible DC power transmission is introduced into the intensive urban distribution network of electricity consumption due to its distinctive technical advantage, using it The problems such as the characteristics of quick controllability, solves to power present in urban electricity supply difficult, and of high cost and trend is difficult to control, Also had broad application prospects in city power distribution, first flexible DC power transmission conveying active power can fast and flexible control System, the trend between power distribution network difference circuit carry out effective and feasible allotment;Secondly, flexible DC power transmission dynamic compensation is handed over The reactive power for flowing busbar, is conducive to the distributed generation resource grid integration of power electronics interface, and again, flexible DC power transmission can be with It realizes the Electromagnetic coupling of different distribution lines, improves power supply reliability.
Energy-storage system is an important composition in " Cai-hair-defeated-with-use-storage " six big links in power production process Part, can be effectively performed peak clipping Pinggu, and smooth load promotes the application of regenerative resource;Electricity can be improved with peak-frequency regulation Force system operation stability;Power equipment can be more effectively utilized, power supply cost is reduced.Energy-storage system builds intelligent grid Setting tool has important supporting role.It is non-linear, impact load largely to connect with the continuous improvement of distributed generation resource permeability Enter and the lasting increase of load peak-valley difference, bringing bi-directional current to power distribution network is difficult to control, and voltage fluctuation is big, and harmonic wave is dirty Dye is serious, the problems such as peak regulation difficulty, and energy-storage system can make power distribution network have certain " flexibility ", in conjunction with the control of power electronics Technology is capable of the carry out power regulation of fast and flexible.Energy-storage system can give full play to peak clipping Pinggu in urban distribution network application, Smooth load promotes regenerative resource access, the functions such as emergency service, while entire distribution system power supply reliability can be improved.
Typical community in urban areas distribution network figure is as shown in figure 3, traditional distribution is usually closed loop design, open loop operation, The load of the respective low-voltage bus bar of transformer belt, bus connection switch are separated under normal circumstances.Only in certain road inlet wire dead electricity or main transformer event When barrier, mother just can automatically be closed by prepared auto restart.There are following problems for conventional electrical distribution network:1) certain section of load is lighter The corresponding main transformer of busbar (such as workaday daytime) is operated in underloading or light condition, less efficient;2) as two sections of low pressure mothers When the total load of line is more than separate unit main transformer capacity, at this time since certain road inlet wire dead electricity or main transformer failure cause bus connection switch to close, Separate unit main transformer overload even overcurrent tripping is easily caused, failure propagation is caused;3) with the increase of city electric car quantity, newly Increase more charging pile or charger, power is all in 50kW or more, the high-power impact load in short-term such as charging pile or charger Input easily cause distribution transforming overload.4) with the development of distributed energy, the access of community building or villa roof photovoltaic can give The existing capacity of distribution and the power quality of distribution bring new challenge.
Invention content
To solve the problems, such as present on, the present invention applies in the power distribution network of existing community in urban areas, is not increasing distribution transforming Under conditions of capacity, by the transformation to existing switchgear house, increases soft straight and energy storage device, more power supplys are realized by flexible direct current Between mutual support, form the Electromagnetic coupling of more power supplys, while the energy storage of certain capacity is configured on DC bus, promotion is matched The distributed photovoltaic of the power supply capacity and power supply reliability of electric system, later stage access can be realized in DC bus direct grid-connected The light of photovoltaic energy storage complementation stores up combined hybrid system, and proposes that the off-network of the system turns grid-connected Phase angle control method.
The present invention is specially a kind of grid-connected Phase angle control method of off-network for low pressure flexibility supplying power allocation system turn, described Low pressure flexibility supplying power allocation system, which includes 4 station power distribution transformer T1~T4, transformer T1, has high side switch S1 and low-pressure side There is high side switch S2 and low-side switch CB2, transformer T3 to have high side switch S3 and low by switch CB1, transformer T2 Press side switch CB3, transformer T4 that there is high side switch S4 and low-side switch CB4;The system also includes 4 sections of 400V low pressure Ac bus, ac bus 1 are connected to transformer T1 by low-side switch CB1, and ac bus 2 passes through low-side switch CB2 It is connected to transformer T2, ac bus 3 is connected to transformer T3 by low-side switch CB3, and ac bus 4 is opened by low-pressure side It closes CB4 and is connected to transformer T4, every section of ac bus is respectively connected with AC load;4 sections of 400V low-voltage alternating-current busbares pass through mother Switch connection, bus connection switch CF1 are connected between ac bus 1 and ac bus 2, and bus connection switch CF2 is connected to ac bus 2 Between ac bus 3, bus connection switch CF3 is connected between ac bus 3 and ac bus 4;It is soft the system also includes 4 Straight transverter;Soft one end straight transverter C1 is connected to ac bus 1, and the other end is connected to DC bus;Soft straight transverter C2 mono- End is connected to ac bus 2, and the other end is connected to DC bus;Soft one end straight transverter C3 is connected to ac bus 3, the other end It is connected to DC bus;Soft one end straight transverter C4 is connected to ac bus 4, and the other end is connected to DC bus;The system Further include energy storage transverter C5 and photovoltaic converter C6;The one end energy storage transverter C5 is connected to DC bus, and the other end is connected to Energy-storage battery;The one end photovoltaic converter C6 is connected to DC bus, and the other end is connected to photovoltaic generating module;
There are following four patterns for the operating condition of the system:Single channel is into ray mode, when load is less than 1 distribution transforming for a long time When power, it is at this time single channel electric power incoming line pattern, is defined as M1 patterns, puts into situation for distribution transforming high-pressure side to distinguish submodule Formula, referred to as M11 patterns, the position of S1, CB1 conjunction at this time, T1 operations, T2, T3, T4 stop transport when S1 is put into, and CF1, CF2, CF3 close position; Two-way uses double loop power supply into ray mode at this time into ray mode when load is higher than 1 for a long time but matches Variable power less than 2, fixed Justice be M2 patterns, by distribution transforming high-pressure side electrification situation distinguish, S1, S3 electrification when be defined as M21 patterns, at this time S1, CB1, S3, CB3 closes position, and T2 and T4 stop transport, and mother CF1, CF3 closes position, transverter C1 and C3 normal operation, and transverter C2 and C4 are in and wait for Machine state;Three roads use three-way power inlet wire at this time into ray mode when load is higher than 2 for a long time but matches Variable power less than 3 Pattern is defined as M3 patterns, by distribution transforming high-pressure side electrification situation distinguish, S1S2S3 charge when be defined as M31 patterns, at this time S1, CB1, S2, CB3, S3, CB3 close position, and T4 stops transport, and mother CF3 closes position;Four roads are into ray mode, when load is higher than 3 distribution transformings for a long time It when power, uses four-way power supply into ray mode at this time, is defined as M4 patterns, under the pattern, 4 distribution transformings are all put into, and mother is opened It closes CF1-CF3 and is dividing position, C1-C4 is in operating status;
The grid-connected Phase angle control method of the off-network turn is transferred to for current transformer under different operational modes from off-grid operation grid-connected The operating mode of operation, using the no phase-locked loop Phase angle control technology of synchronous rotating angle, the power grid three-phase electricity under off-network state It is pressed under inverter synchronous rotating frame and is coordinately transformed, obtain its q shaft voltage component, angle is obtained through angular frequency adjuster Frequency offset, the angular frequency of the off-network that is added to pattern generates link, to adjust the phase angle of inverter, make its fast implement with Power grid phase angle synchronizes, and judges to determine whether same period success through the same period, reaches grid-connected without impacting.
The off-network turns grid-connected Phase angle control method and specifically comprises the following steps:
Under step (1), off-network state, grid side three-phase voltage uga、ugb、ugcAfter coordinate transform, it is obtained in inverter D, q axis component u under synchronous rotating framegd、ugq
Step (2), ugqThe angular frequency deviation amount Δ ω of phase angle adjusting is obtained through angular frequency adjuster;
Step (3), Δ ω be added to off-grid operation pattern angular frequency generate link;
Step (4) generates inverter angular frequency by " model selection ", and inverter phase angle is obtained using integral element;
Step (5), ugd、ugqObtaining same period outlet by " same period judgement " allows grid-connected signal;
Under step (6) and net state, Δ ω is forced to 0, and the inverter for the pattern that is incorporated into the power networks is generated by " model selection " Angular frequency, and then integrated obtain inverter phase angle.
Grid side voltage u in the step (1)ga、ugb、ugcIt is obtained by sensor sample, grid side voltage is through CLARK After transformation, phase angle theta is exported using inverterINVPARK transformation is carried out, to obtain it under inverter synchronous rotating frame ugd、ugq
Angular frequency adjuster is pi regulator or PID regulator in the step (2).
Off-grid operation pattern includes at least electric voltage frequency VF patterns and virtual synchronous machine VSG patterns in the step (4), " model selection " off-network, it is grid-connected when select respectively associative mode generate angular frequency:Electric voltage frequency VF patterns are selected when off-network Or virtual synchronous machine VSG patterns, select virtual synchronous machine VSG patterns or active reactive to control PQ patterns when grid-connected.
" same period judges " is judges network voltage d, q axis component u in the step (5)gd、ugqU corresponding to inverter voltageid、 uiqBetween error:The same period is not allowed to export if being more than " same to duration value ", if " same period delay " less than limit value by setting The same period is allowed to export afterwards.
This control method is not necessarily to network voltage locking phase, and even entire control system is complete under VF patterns and VSG patterns Without phaselocked loop, the uncertainties such as locking phase operation complicated in Phase angle control and its delay brought, parameter applicability are avoided It influences, reduces the load factor of controller, improve control efficiency.
Description of the drawings
Fig. 1 is that current transformer off-network of the present invention turns grid-connected Phase angle control method schematic diagram;
Fig. 2 is the structural schematic diagram of low pressure flexibility supplying power allocation system of the present invention;
Fig. 3 is typical urban community distribution system structural schematic diagram;
Fig. 4 be low pressure flexibility supplying power allocation system of the present invention work in single channel into ray mode schematic diagram;
Fig. 5 be low pressure flexibility supplying power allocation system of the present invention work in two-way into ray mode schematic diagram;
Fig. 6 be low pressure flexibility supplying power allocation system of the present invention work in three roads into ray mode schematic diagram.
Specific implementation mode
Grid-connected Phase angle control is turned to a kind of off-network for low pressure flexibility supplying power allocation system of the invention below in conjunction with the accompanying drawings The specific implementation mode of method elaborates.
Based on the supplying power allocation system traditional by Xuzhou star arm of lake cell, it is as follows to be transformed design.
1, bus connection switch designs
4 station power distribution transformers (distribution transforming) are defined as T1~T4, and distribution transforming high side switch is respectively defined as S1~S4, with being lower Pressure side switch is defined as CB1~CB4;4 sections of 400V low-voltage alternating-current busbares are coupled by bus connection switch;Before improvement and design, star lake The power supply system structure chart of gulf cell power distribution room is as shown in Figure 3.
When cell load is low, in order to realize that is matched four sections of bus runs of variable speed, needs in ac bus 2 and hand over A bus connection switch is added between stream busbar 3, bus connection switch is sequentially defined as CF1~CF3, as shown in Figure 2.
2, distributed photovoltaic system designs
Distributed photovoltaic uses direct current access scheme, photovoltaic string formation real by photovoltaic DC/DC transverters in this power supply system Existing multichannel MPPT, boosting access DC bus.
Consider that the illumination of cell roof generally existing in urban distribution network is blocked, inclination angle is inconsistent, component count in this system The actual conditions such as mismatch, transverter selects multichannel independence MPPT to track, single-machine capacity is small, the flexible string type change of current of configuration Device.Transverter single machine 40kW, 3 tunnel independence MPPT, using non-isolated BOOST topologys.
3, energy-storage system designs
Energy-storage system by:Energy storage device, energy storage transverter, Energy Management System composition.Energy storage device preferably uses in distribution It configures flexibly, using ripe battery energy storage scheme.The direct current of battery output is transformed into alternating current through energy storage bi-directional inverter It is connected to the grid.Energy storage uses direct current access scheme, energy-storage battery to be connect by energy storage DC/DC bi-directional inverters in this combined hybrid system Enter DC bus, realizes the charge and discharge control of energy-storage battery.
Cell important load is not more than 300kW in this system, considers light-preserved system islet operation 1 hour after electric network fault, And the demand that electricity stores more than photovoltaic generation, comprehensive selected energy-storage battery capacity is 300kW/340kWh.Energy storage DC/DC transverters Power 300kW, input side are matched with cell voltage, and outlet side matches with rectilinear generatrix voltage, using non-isolated BUCK/ BOOST topologys.
When peak load shifting is run, this transverter is operated in invariable power (constant power, CP) pattern;Light stores up isolated island fortune When row, this transverter is operated in permanent DC bus-bar voltage (constant voltage, CV) pattern.
4, soft straight inverter design
This system realizes the interconnection of a plurality of circuit of distribution by soft straight transverter, realizes that the power between circuit turns for branch It helps, after certain distribution line failure disconnects, soft straight transverter on-load islet operation can be passed through.And it can four-quadrant using soft lineal system The characteristic of operation reduces the investment of of no help compensation equipment.Meanwhile realizing and interconnecting in DC link with photovoltaic, energy storage, form light storage With soft straight combined hybrid system.
To reduce inverter output voltage, current harmonics to the greatest extent, more level block transverters are preferably used.Since this system connects Enter 400V electric designs, it is contemplated that cost and equipment complexity select three-level converter that can meet application demand.
The capacity of 4 distribution lines is 800kVA in this system, considers that power equalization maximum turns for load about 50% The demand of (400kW) and the demand of island with power important load 300kW, 4 soft straight transverter capacity of design are respectively 500kW, the maximum idle fan-out capability of separate unit are not less than 200kVar.
And under net state, this transverter needs to support permanent DC bus-bar voltage (CV) pattern, invariable power (CP) pattern;Isolated island Under state, need to support electric voltage frequency (VF) pattern, sagging (Droop) pattern.
5, intelligent coordination control device designs
This system configure intelligent coordination control device (CCU), realize combined hybrid system inside important node signal measurement and The start-up and shut-down control of each unit, power dispatching, pattern setting, carrier synchronization.
To realize the rapidity of system intelligent coordination control, using the substation towards general object based on fiber optic network Event (GOOSE) rapid communication mechanism realizes that the transmitting-receiving of signal high speed, system communication delay are less than 1ms.
CCU using it is high can property embedded equipment framework, can flexible expansion DSP, analog quantity, on-off model acquisition etc. it is each Kind function type board.CCU monitors voltage, current signal and each main position of the switch state of system of 4 road inlet wires, simultaneously Controllable service entrance switch, bus connection switch point/close a floodgate.CCU and each transverter real-time communication, obtain each transverter operating status, and Control each transverter start and stop, operational mode, operation power.
6, DC voltage designs
The object that common low-voltage direct-current system standard is directed to is the following systems of voltage class 1000V, in order to minimum Transform part realizes the connection with distribution 400V AC networks, needs to be designed DC voltage lower limit.
Due to the limitation of DC voltage utilization rate, for meet when transverter SPWM modulation ratios are 1 minimum voltage requirement (for Zero sequence circulation between inhibition transverter, is not superimposed residual voltage), consider the shadow of the factors such as line drop, element pressure drop, the dead zones IGBT It rings, further considers that 400V distribution systems allow ± 10% fluctuation, when extreme case+10% fluctuates, minimum DC bus electricity The requirement of pressure:Therefore, the scope of design of DC voltage is 718~1000V.By The running wastage (voltage is higher, and IGBT switching losses are bigger) of transverter is also affected simultaneously in DC voltage and system is exhausted Edge designs (voltage is higher, and insulating requirements are higher), considers above each factor, it is 720V that this programme, which designs DC bus-bar voltage,.
Photovoltaic DC/DC Energy storage DC/DC Soft straight transverter
Power/kW 40 300 500
Input voltage/V 300~720 (DC) 420~600 (DC) 720(DC)
Output voltage/V 720(DC) 720(DC) 400(AC)
Topological structure BOOST BUCK/BOOST Three level
Operating mode MPPT CP/CV CP/CV/VF/Droop
Converter power direction defines in this system, it is specified that it is just to flow into DC bus power on the basis of DC bus. 4 soft straight transverters are defined as C1-C4, and energy storage transverter is defined as C5, and photovoltaic converter is defined as C6.It is set in conjunction with above system Meter scheme, when the distribution transforming quantity difference actually put into, there are following several modes for the operating condition of system
1) single channel is into ray mode
It is at this time single channel electric power incoming line pattern when load is less than 1 for a long time matches Variable power, defined herein as M1 patterns, Situation is put into for distribution transforming high-pressure side to distinguish subpattern, such as:S1 is put into, referred to as M11 patterns, and so on have M11, M12, M13, M14 totally four kinds of patterns.Below with the control strategy of M11 mode declaration pattern specification single channel electric power incoming lines.
M11 patterns:S1, CB1 close position, T1 operations, and T2, T3, T4 stop transport, and CF1, CF2, CF3 close position.As shown in Figure 4. CCU judges which kind of pattern is system be in by mother, the distribution low-voltage side position of the switch, ac bus voltage.Lower of M1 patterns Separate unit DC/AC transverters are needed to run, 4 any of transverters each may participate in, and CCU according to transverter state specify wherein One work, the transverter of the acquiescence input same busbar of electric power incoming line, such as M11 patterns, acquiescence input C1.The change of current of not running Device is in standby blocking, and photovoltaic transverter C6 operates in MPPT working methods always.
2) two-way is into ray mode
When load is higher than 1 for a long time but matches Variable power less than 2, use double loop power supply into ray mode at this time, it is fixed herein Justice is M2 patterns, is put into for different inlet wires to distinguish, accidental conditions, only considers that CF2 is combined in the inlet wire for dividing position, presses Distribution transforming high-pressure side electrification situation is divided into S1S3 electrifications, S1S4 electrifications, S2S3 electrifications, S2S4 electrifications, is respectively defined as M21-M24.
It is described below by taking M21 patterns as an example:
M21 patterns:S1, CB1, S3, CB3 close position, and T2 and T4 stop transport, and mother CF1, CF3 closes position, as shown in Figure 5.M21 Pattern, to realize that idle control function transverter C1 and C3 need normal operation, transverter C2 and C4 to be in standby.Pass through CCU specifies C1 to be operated in CV, and C3 is operated in PQ control modes.
Relative to single channel into ray mode under the pattern:Increase division power to turn for function, when distribution transforming T1 or T3 power is more than When limitation, there can be power regulation to carry out power support by C3.When one inlet wire has a power failure, another inlet wire and light-preserved system can be passed through It is used as power supply together, through soft straight isolated island VF patterns, continues to power to load.
3) three roads are into ray mode
When load is higher than 2 for a long time but matches Variable power less than 3, use three-way power into ray mode at this time, it is fixed herein Justice is M3 patterns.It is divided into S1S2S3 electrifications, S1S2S4 electrifications, S1S3S4 electrifications, S2S3S4 bands by distribution transforming high-pressure side electrification situation Electric four kinds of patterns, are respectively defined as M31, M32, M33, M34 patterns
It is described below by taking M31 patterns as an example:
M31 patterns:S1, CB1, S2, CB3, S3, CB3 close position, and T4 stops transport, and mother CF3 closes position, as shown in Figure 6.
4) four roads are into ray mode
When load is higher than 3 for a long time matches Variable power, use four-way power supply into ray mode at this time, defined herein as M4 moulds Formula.Under the pattern, 4 distribution transformings are all put into, and bus connection switch CF1-CF3 is dividing position, and C1-C4 is in operating status, such as Fig. 2 institutes Show.
It is designed according to system above, improved supplying power allocation system forms alternating current-direct current using flexible DC transmission technology and mixes Distribution system is closed, the two-way controllable function of flexible current transformer, activeization is made full use of to control the Rational flow of power, is formed mostly electric Mutual support between source;It is equipped with energy storage and the photovoltaic of certain capacity on DC bus, realizes the on-site elimination of clean energy resource, together When energy-storage system can flexible charge and discharge, the charge control of the realization of activeization to the power support and battery of power supply system;Change Power supply system after making realizes flexible Electromagnetic coupling, the operating status of intelligent coordination control device real-time monitoring system, when certain power supply When power supply or equipment etc. break down, intelligent coordinated control system operational mode variation ensures power supply reliability.
This system is according to payload difference, and the fault condition for occurring under different operational modes and this pattern (open by mother Close failure, inlet wire failure, PCS failures), this results in system, and there are different operating conditions.The characteristics of according to different operating modes, intelligence Energy tuning controller is ensured not by switching the orders such as control and the operational mode switching of PCS, coordination whole system stable operation With the reliability powered under operating mode.
The control method for coordinating of this system is introduced from M11, M21, M31, M4 these four typical modules below.
M11 patterns
1. bus connection switch CF1 failures
The equal dead electricity of busbar II, III, CCU confirm that CF1, CB2, CB3, CB4 are dividing position, start any unsteady flow of C2, C3, C4 Device powers to the corresponding bus load of C2, C3, C4, and is operated in VF control modes simultaneously.
Petri Nets:It waits for CF1 fault recoveries, judges the both sides CF1 voltage, CCU completes synchronization function, after meeting condition Close CF1.
2. bus connection switch CF2 failures
Busbar III, IV dead electricity, CCU confirm that CF2, CB3, CB4 are dividing position, start any current transformer of C3, C4, give C3, C4 Corresponding bus load is powered simultaneously, is operated in VF control modes.
Petri Nets:It waits for CF2 fault recoveries, judges the both sides CF2 voltage, CCU completes synchronization function, after meeting condition Close CF2.
3. bus connection switch CF3 failures
Busbar IV dead electricity, CCU confirm that CF3, CB4 are dividing position, start C4 current transformers, give C4 corresponding bus load power supplies, C4 is operated in VF control modes.
Petri Nets:It waits for CF3 fault recoveries, judges the both sides CF3 voltage, CCU completes synchronization function, after meeting condition Close CF3.
4.S1 electric power incoming line dead electricity
It is initially switched off CB1 switches at this time, judges whether the load before dead electricity is less than 300kW (maximum power of energy-storage system), If more than 300kW, then current transformer C1 lockings;If being less than 300kW, system switches to off-network state:C5 is switched to DC controlling parties Formula, C1 are switched in VF modes, power of battery 300kW.
Petri Nets:Wait for that incoming power restores failure, CB1 voltages suitable for reading restore, and C1 is adjusted and restored same with power grid Phase closes CB1 after meeting condition, and after CB1 closes, C1 is switched to DC control models, and C5 is switched to power control mode.
5.C1 failures
Since C1 controls DC bus voltage, C1 failures need any current transformer switch mode in other C2, C3, C4 It is controlled for DC.
6.C5 failures
Energy accumulation current converter is out of service, to ensure power supply reliability and continuity, needs to prompt to overhaul as early as possible or be switched to Two-way electric power incoming line operating mode.
7.C6 failures
Photovoltaic system exits, on whole control without influence.
Wherein, the control mode of other three kinds of operating conditions M12, M13, M14 are similar with M11, do not repeat.
M21 patterns
1. bus connection switch CF1 failures
Busbar II dead electricity confirms that CF1, CB2 are dividing position, starts C2, C2 is operated in VF operating modes;
Petri Nets:It waits for CF1 fault recoveries, closes CF1, judge that the both sides CF1 voltage, CCU complete synchronization function, meet CF1 is closed after condition.
2. bus connection switch CF3 failures
Busbar IV dead electricity confirms that CF3, CB4 are dividing position, starts C4, C4 is operated in VF operating modes;
Petri Nets:It waits for CF3 fault recoveries, closes CF3, judge that the both sides CF3 voltage, CCU complete synchronization function, meet CF3 is closed after condition.
3.S1 inlet wire failure
C3 is switched to DC control modes, and CCU disconnects CB1 switches, confirms that CB1, CB2 are dividing position, the VF controls that C1 is switched to Mode, due to losing power supply all the way, system net capability is 800+300=1100kW, energy-storage system power control Target is the power limit by power supply S3 in 800kW or less.
Petri Nets:Wait for that S1 fault recoveries, CB1 voltages suitable for reading restore, C1 is adjusted and restored and the power grid same period, satisfaction CB1 is closed after condition, after CB1 closes, C1 is switched to PQ control models.
4.S3 inlet wire failure
CCU disconnects CB3 switches, confirms that CB3, CB4 are dividing position, C3 by PQ control mode switchings to VF control modes, due to Power supply all the way is lost, system net capability is 800+300=1100kW, and energy-storage system power control target is will be electric The power limit of source S1 is in 800kW or less.
Petri Nets:Wait for that S3 restores failure, CB3 voltages suitable for reading restore, and C3 is adjusted and restored and the power grid same period, satisfaction CB3 is closed after condition, after CB3 closes, C1 is switched to PQ control models.
5.C1 failures
C3 is switched to DC control modes, starts C2 and is operated in PQ modes.
6.C3 failures
Start C4, and is operated in PQ control modes.
7.C2, C4 failure
Do not influence system operation
8.C5 failures
Energy accumulation current converter is out of service, to ensure reliability, needs to prompt to overhaul or be switched to two-way electric power incoming line as early as possible Operating mode.
9.C6 failures
Photovoltaic system exits, on whole control without influence.
Wherein, the control mode of other three kinds of operating conditions M22, M23, M24 are similar with M21, do not repeat.
M31 patterns
1. mother CF3 failures
CCU confirms that CF3 and CB4 is dividing position, starts C4, is operated in VF control modes;
Petri Nets:It waits for that CF3 restores failure, judges the both sides CF3 voltage, CCU completes synchronization function, after meeting condition Close CF3.
2.S3 inlet wire failure
CCU confirms that CB3, CF2, CB4 are dividing position, C3 to be switched to VF control modes, and C2 is operated in PQ control modes, the control of C2 Target processed is identical as accidental conditions.If Ps1+Ps2 at this time>1600kW, the urgent power support of energy-storage system.
Petri Nets:It waits for that S3 restores failure, closes CB3 and charged to busbar, the same period is carried out by C3 when closing CB3.
3.S2 inlet wire failure
CCU confirms that CB2, CF2, CF1 are dividing position, C2 to be switched to VF control modes, and C3 is operated in PQ control modes, the control of C3 Target processed becomes limiting the power of S1 and S3 respectively in 800kW or less.If Ps1+Ps3 at this time>1600kW, the urgent work(of energy-storage system Rate supports.
Petri Nets:It waits for that S3 restores failure, closes CB2 and charged to busbar, the same period is carried out by C2 when closing CB2.
4.S1 inlet wire failure
CCU confirms that CB1, CF1 are dividing position, C1 to be switched to DC control modes by DC control mode switching VF control modes, C2, C3 is operated in PQ control modes, and C3 control targes become limiting the power of S2 and S3 respectively in 800kW or less.If Ps2+ at this time Ps3>1600kW, the urgent power support of energy-storage system.
Petri Nets:It waits for that S1 restores failure, closes CB1 and charged to busbar, the same period is carried out by C1 when closing CB1.
5.C1 failures
C2 is switched to DC control modes, and the control targe of C3 becomes limiting the power of S2 and S3 respectively in 800kW or less.This If when Ps2+Ps3>1600kW, the urgent power support of energy-storage system.
6.C2 failures
C1 still operates in DC control modes, the control targe of C3 become limiting respectively the power of S1 and S3 800kW with Under.If Ps1+Ps3 at this time>1600kW, the urgent power support of energy-storage system.
7.C3 failures
C1 still operates in DC control modes, starts C4, and control mode is identical with normal operation
8.C4 failures
System operation is without influence
9.C5 failures
Energy accumulation current converter is out of service, to ensure reliability, needs to prompt to overhaul or be switched to two-way electric power incoming line as early as possible Operating mode.
10.C6 failures
Photovoltaic system exits, on whole control without influence.
Wherein, the control mode of other three kinds of operating conditions M32, M33, M34 are similar with M31, do not repeat.
M4 patterns
1.S1 inlet wire failure
CCU confirms that CB1 and CF1 is dividing position, C1 to be switched to VF control modes, and C2 is switched to DC control modes, and C3 controls mesh Mark limitation S2, respectively in 800kW hereinafter, C4 control targes limitation S2+S3 power is less than 1600kW, S4 power is less than S3 power 800kW.C5 control targes limit value S2+S3+S4 power is less than 2400kW at this time.
Petri Nets:Restore inlet wire S1 power supplies, closes CB1 and charged to busbar, the same period is carried out by C1 when closing CB1.
2.S2 inlet wire failure
CCU confirms that CB2 and CF1 is dividing position, C2 to be switched to V-F control modes, and the control targe of C3 limits S1, S3 power point Not in 800kW hereinafter, C4 control targes limitation S1+S3 power is less than 1600kW, S4 power is less than 800kW.C5 controls mesh at this time It marks limit value S1+S3+S4 power and is less than 2400kW.
Petri Nets:Restore inlet wire S2 power supplies, closes CB2 and charged to busbar, the same period is carried out by C2 when closing CB2.
3.S3 inlet wire failure
CCU confirms that CB3, CF2, CF3 are dividing position, C3 to be switched to V-F control modes, and the control targe of C2 limits S1, S2 work( For rate respectively in 800kW hereinafter, C4 control targes limitation S1+S2 power is less than 1600kW, S4 power is less than 800kW.C5 is controlled at this time Target limit value S1+S2+S4 power processed is less than 2400kW.
Petri Nets:Restore inlet wire S3 power supplies, closes CB3 and charged to busbar, the same period is carried out by C3 when closing CB3.
4.S4 inlet wire failure
CCU confirms that CB4 and CF3 is dividing position, C4 to be switched to V-F control modes, and the control targe of C2 limits S1, S2 power point Not in 800kW hereinafter, C3 control targes limitation S1+S2 power is less than 1600kW, S3 power is less than 800kW.C5 controls mesh at this time It marks limit value S1+S2+S3 power and is less than 2400kW.
Petri Nets:Restore inlet wire S4 power supplies, closes CB4 and charged to busbar, the same period is carried out by C4 when closing CB4.
5.C1 failures
C2 is switched to DC control modes, and C3 control targes limit S2, and S3 power is respectively in 800kW hereinafter, C4 control targes It limits S2+S3 power and is less than 1600kW, S4 power is less than 800kW.C5 control targes limit value S2+S3+S4 power is less than at this time 2400kW。
6.C2 failures
C3 control targes limit S1, and S3 power is respectively in 800kW hereinafter, C4 control targes limitation S1+S3 power is less than 1600kW, S4 power are less than 800kW.C5 control targes limit value S1+S3+S4 power is less than 2400kW at this time.
7.C3 failures
C2 control targes limit S1, and S2 power is respectively in 800kW hereinafter, C4 control targes limitation S1+S2 power is less than 1600kW, S4 power are less than 800kW.C5 control targes limit value S1+S2+S4 power is less than 2400kW at this time.
8.C4 failures
C2 control targes limit S1, and S2 power is respectively in 800kW hereinafter, C3 control targes limitation S1+S2 power is less than 1600kW, S3 power are less than 800kW.C5 control targes limit value S1+S2+S3 power is less than 2400kW at this time.
9.C5 failures
Energy accumulation current converter is out of service, to ensure reliability, needs to prompt to overhaul or be switched to two-way electric power incoming line as early as possible Operating mode.
10.C6 failures
Photovoltaic system exits, on whole control without influence.
The control of above-mentioned different operating conditions during, repeatedly there is current transformer and be transferred to from off-grid operation to be incorporated into the power networks Operating mode.Current transformer is run under off-network pattern in a manner of voltage source, and system is given birth to automatically in order to control for output voltage amplitude, frequency At, therefore its output voltage amplitude, frequency, phase angle may there are errors with external electrical network, if the situation big in application condition Under be converted directly into and be incorporated into the power networks, instantaneous power, rush of current or even overcurrent protection tripping may be caused.Therefore in off-network It needs to control the phase angle of inverter when turning grid-connected, is allowed to synchronous with external electrical network, reconvert is to simultaneously after same period success Network operation.
Conventional scheme is detected to the amplitude, frequency, phase angle of network voltage, and inverter is gradually adjusted to and power grid It is transferred to after voltage synchronous grid-connected.Wherein frequency and phase-angle detection need to use complicated locking phase operation, not only increase controller Load factor, and there are a variety of adverse effect factors such as delay, parameter matching, system disturbance in phase locked algorithm.
The no phase-locked loop Phase angle control technology of this control method sample-synchronous rotating coordinate transformation, the power grid under off-network state Three-phase voltage is coordinately transformed under inverter synchronous rotating frame, its q shaft voltage component is obtained, through angular frequency adjuster Angular frequency deviation amount is obtained, the angular frequency of the off-network that is added to pattern generates link, to adjust the phase angle of inverter, makes it quickly Realization is synchronous with power grid phase angle, judges to determine whether same period success through the same period, reaches grid-connected without impacting.This control method without pair Network voltage locking phase, even entire control system is not necessarily to phaselocked loop completely under VF patterns and VSG patterns, avoids Phase angle control The locking phase operation of middle complexity and its delay brought, parameter applicability etc. are uncertain to be influenced, and is reduced the load factor of controller, is carried High control efficiency.
Control method is as shown in Figure 1, specifically include following steps:
Under off-network state, grid side three-phase voltage uga,gb,gcAfter coordinate transform, obtains it and sat in inverter synchronous rotary D, q axis component u under mark systemgd,gq
ugqThe angular frequency deviation amount Δ ω of phase angle adjusting is obtained through " angular frequency adjuster ";
Δ ω be added to off-grid operation pattern angular frequency generate link;
Inverter angular frequency is generated by " model selection ", inverter phase angle is obtained using integral element;
ugd,gqObtaining same period outlet by " same period judgement " allows grid-connected signal;
And under net state, Δ ω is forced to 0, and the inverter angular frequency for the pattern that is incorporated into the power networks is generated by " model selection ", It is integrated in turn to obtain inverter phase angle.
Wherein, grid side voltage uga,gb,gcIt is obtained for sensor sample, grid side voltage is after CLARK is converted, using inverse Become device and exports phase angle thetaINVPARK transformation is carried out, to obtain its u under inverter synchronous rotating framegd,gq;" angular frequency Adjuster " is pi regulator or PID regulator;Off-grid operation pattern includes at least VF patterns and VSG patterns;" model selection " exists Off-network, it is grid-connected when select respectively associative mode generate angular frequency:When off-network select VF or VSG patterns, when grid-connected select VSG or PQ patterns;" same period judges " is judges network voltage d, q axis component ugd,gqU corresponding to inverter voltageid,iqBetween error:If super Crossing " same to duration value " does not then allow the same period to export, if less than the permission same period exports after " same period delay " set if limit value.
Finally it should be noted that only illustrating technical scheme of the present invention rather than its limitations in conjunction with above-described embodiment.Institute The those of ordinary skill in category field is it is to be understood that those skilled in the art can repair the specific implementation mode of the present invention Change or equivalent replacement, but these modifications or change are among applying for pending claims.

Claims (6)

1. a kind of off-network for low pressure flexibility supplying power allocation system turns grid-connected Phase angle control method, which is characterized in that described low The flexible supplying power allocation system of pressure includes 4 station power distribution transformer T1~T4, transformer T1, and there is high side switch S1 and low-pressure side to open CB1 is closed, there is transformer T2 high side switch S2 and low-side switch CB2, transformer T3 to have high side switch S3 and low pressure Side switch CB3, transformer T4 have high side switch S4 and low-side switch CB4;The system also includes 4 sections of 400V low pressure to hand over Busbar is flowed, ac bus 1 is connected to transformer T1 by low-side switch CB1, and ac bus 2 is connected by low-side switch CB2 It is connected to transformer T2, ac bus 3 is connected to transformer T3 by low-side switch CB3, and ac bus 4 passes through low-side switch CB4 is connected to transformer T4, and every section of ac bus is respectively connected with AC load;4 sections of 400V low-voltage alternating-current busbares are opened by mother Connection connects, and bus connection switch CF1 is connected between ac bus 1 and ac bus 2, and bus connection switch CF2 is connected to 2 He of ac bus Between ac bus 3, bus connection switch CF3 is connected between ac bus 3 and ac bus 4;It is soft straight the system also includes 4 Transverter;Soft one end straight transverter C1 is connected to ac bus 1, and the other end is connected to DC bus;Soft one end straight transverter C2 It is connected to ac bus 2, the other end is connected to DC bus;Soft one end straight transverter C3 is connected to ac bus 3, and the other end connects It is connected to DC bus;Soft one end straight transverter C4 is connected to ac bus 4, and the other end is connected to DC bus;The system is also Including energy storage transverter C5 and photovoltaic converter C6;The one end energy storage transverter C5 is connected to DC bus, and the other end is connected to storage It can battery;The one end photovoltaic converter C6 is connected to DC bus, and the other end is connected to photovoltaic generating module;
There are following four patterns for the operating condition of the system:Single channel matches Variable power into ray mode, when load is less than 1 for a long time When, it is at this time single channel electric power incoming line pattern, is defined as M1 patterns, puts into situation for distribution transforming high-pressure side to distinguish subpattern, S1 Referred to as M11 patterns, the position of S1, CB1 conjunction at this time, T1 operations, T2, T3, T4 stop transport when input, and CF1, CF2, CF3 close position;Two-way into Ray mode uses double loop power supply into ray mode, is defined as M2 at this time when load is higher than 1 for a long time but matches Variable power less than 2 Pattern is distinguished by distribution transforming high-pressure side electrification situation, and S1, S3 are defined as M21 patterns when charging, and S1, CB1, S3, CB3 are closed at this time Position, T2 and T4 stop transport, and mother CF1, CF3 closes position, and transverter C1 and C3 normal operation, transverter C2 and C4 are in standby; Three roads use three-way power into ray mode at this time into ray mode when load is higher than 2 for a long time but matches Variable power less than 3, fixed Justice be M3 patterns, by distribution transforming high-pressure side electrification situation distinguish, S1S2S3 electrification when be defined as M31 patterns, at this time S1, CB1, S2, CB3, S3, CB3 close position, and T4 stops transport, and mother CF3 closes position;Four roads are into ray mode, when load is higher than 3 for a long time matches Variable power, It uses four-way power supply into ray mode at this time, is defined as M4 patterns, under the pattern, 4 distribution transformings are all put into, bus connection switch CF1- CF3 is dividing position, and C1-C4 is in operating status;
The grid-connected Phase angle control method of the off-network turn is transferred to from off-grid operation for current transformer under different operational modes and is incorporated into the power networks Operating mode, using the no phase-locked loop Phase angle control technology of synchronous rotating angle, power grid three-phase voltage exists under off-network state It is coordinately transformed under inverter synchronous rotating frame, obtains its q shaft voltage component, angular frequency is obtained through angular frequency adjuster Offset, the angular frequency of the off-network that is added to pattern generates link, to adjust the phase angle of inverter, it is made to fast implement and power grid Phase angle synchronizes, and judges to determine whether same period success through the same period, reaches grid-connected without impacting.
2. a kind of off-network for low pressure flexibility supplying power allocation system according to claim 1 turns grid-connected Phase angle control side Method, which is characterized in that the off-network turns grid-connected Phase angle control method and specifically comprises the following steps:
Under step (1), off-network state, grid side three-phase voltage uga、ugb、ugcAfter coordinate transform, obtains it and synchronized in inverter D, q axis component u under rotating coordinate systemgd、ugq
Step (2), ugqThe angular frequency deviation amount Δ ω of phase angle adjusting is obtained through angular frequency adjuster;
Step (3), Δ ω be added to off-grid operation pattern angular frequency generate link;
Step (4) generates inverter angular frequency by " model selection ", and inverter phase angle is obtained using integral element;
Step (5), ugd、ugqObtaining same period outlet by " same period judgement " allows grid-connected signal;
Under step (6) and net state, Δ ω is forced to 0, and the inverter angular frequency for the pattern that is incorporated into the power networks is generated by " model selection " Rate, and then integrated obtain inverter phase angle.
3. a kind of off-network for low pressure flexibility supplying power allocation system according to claim 2 turns grid-connected Phase angle control side Method, which is characterized in that grid side voltage u in the step (1)ga、ugb、ugcIt is obtained by sensor sample, grid side voltage warp After CLARK transformation, phase angle theta is exported using inverterINVPARK transformation is carried out, to obtain it in inverter synchronously rotating reference frame U under systemgd、ugq
4. a kind of off-network for low pressure flexibility supplying power allocation system according to claim 2 turns grid-connected Phase angle control side Method, which is characterized in that angular frequency adjuster is pi regulator or PID regulator in the step (2).
5. a kind of off-network for low pressure flexibility supplying power allocation system according to claim 2 turns grid-connected Phase angle control side Method, which is characterized in that off-grid operation pattern includes at least electric voltage frequency VF patterns and virtual synchronous machine VSG in the step (4) Pattern, " model selection " off-network, it is grid-connected when select respectively associative mode generate angular frequency:Electric voltage frequency VF is selected when off-network Pattern or virtual synchronous machine VSG patterns select virtual synchronous machine VSG patterns or active reactive to control PQ patterns when grid-connected.
6. a kind of off-network for low pressure flexibility supplying power allocation system according to claim 2 turns grid-connected Phase angle control side Method, which is characterized in that " same period judges " is judges network voltage d, q axis component u in the step (5)gd、ugqWith inverter voltage Corresponding uid、uiqBetween error:The same period is not allowed to export if being more than " same to duration value ", if less than limit value by the " same of setting Phase is delayed " allow the same period to export afterwards.
CN201810443604.1A 2018-05-10 2018-05-10 A kind of off-network for low pressure flexibility supplying power allocation system turns grid-connected Phase angle control method Pending CN108599153A (en)

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