CN110401182A - A kind of modified self-adaptation nonlinear droop control method for direct-current grid - Google Patents
A kind of modified self-adaptation nonlinear droop control method for direct-current grid Download PDFInfo
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- CN110401182A CN110401182A CN201910374127.2A CN201910374127A CN110401182A CN 110401182 A CN110401182 A CN 110401182A CN 201910374127 A CN201910374127 A CN 201910374127A CN 110401182 A CN110401182 A CN 110401182A
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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
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
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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
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/14—Balancing the load in a network
Abstract
The invention discloses a kind of modified self-adaptation nonlinear droop control methods for direct-current grid, are related to DC distribution network control running technology, belong to the technical field of power generation, power transformation or distribution.The sagging control of tradition aiming at the problem that multiple distributed power supply module parallel running Shi Junliu precision and busbar voltage regulation are difficult to optimize simultaneously, micro- source output electric current is divided into light loading district by payload size and the heavily loaded area source Hou Duiwei carries out Discrete control, and the self-adaptation nonlinear sagging curve that precision and busbar voltage regulation are flowed with realization adjust automatically being fitted according to the sagging curve characteristic of not same district, preferentially improve the busbar voltage regulation of light loading district in light loading district, preferentially guarantee that current sharing can be so that further improve busbar voltage regulation in heavily loaded area, sagging control non-linear compared to existing multinomial, additional compensation is not needed, avoid waypoint problem out of control, control is simple.
Description
Technical field
The invention discloses a kind of modified self-adaptation nonlinear droop control method for DC distribution net, it is related to straight
It flows power distribution network and controls running technology, belong to the technical field of power generation, power transformation or distribution.
Background technique
With the large-scale grid connection and industrial load of distribution type renewable energy, DC data center, direct-current charging post
With increasing for LED illumination System, traditional electric network composition, power equipment and coordinated operation strategy are not able to satisfy wanting for stability
It asks.Direct-current grid is not required to consider idle and frequency influence, improves the power supply efficiency and power quality of system, therefore, directly
The main control target of stream micro-capacitance sensor is to stablize the power of busbar voltage and each distributed generation resource of distribution.
Due between distributed generation resource each in direct-current grid and DC bus there are line impedance, direct-current micro-grid
There are load current uneven phenomenon between each distributed power supply module in system, there are certain deviations for busbar voltage.Tradition is sagging
Control is difficult to meet simultaneously the requirement for flowing precision and busbar voltage regulation, is usually mentioned by increasing busbar voltage regulation
The current sharing energy of high system.Existing modified droop control method realizes that steady state voltage is inclined using adaptive dynamic programming method
Difference control and multi-source load sharing control improve rated load area and heavily loaded sound zone system current sharing by the sagging emphasis of multi slope
Energy and busbar voltage deviation, need compensation tache, have the defects that algorithm is complicated and control process is complicated.The application is intended to mention
One kind is simple out and can meet the adaptive sagging control that mostly micro- source direct current system flows precision and busbar voltage regulation simultaneously
Method processed.
Summary of the invention
The invention proposes a kind of modified self-adaptation nonlinear droop control method for direct-flow distribution system, fittings
Light loading district and the sagging curve in heavily loaded area are obtained to improve and be loaded under busbar voltage regulation and case of heavy load in the case of being lightly loaded
The self-adaptation nonlinear sagging curve for flowing effect, avoids waypoint out-of-control phenomenon, solves tradition to control simple scheme
Sagging control cannot meet the technical issues of electric current flows precision and busbar voltage regulation simultaneously.
Used technical solution is the present invention for achieving the above object: a kind of modified for direct-current grid
Self-adaptation nonlinear droop control method, in underloading, load stream precision it is small will not cause converter excess work, it is excellent
First guarantee busbar voltage regulation；Under case of heavy load, non-uniform load distribution will lead to part distributed generation resource quota work
Work can not adjust, and busbar voltage is accelerated to fall, therefore precision is flowed in preferential proof load, to further improve busbar voltage tune
Whole rate.In both cases, sagging virtual impedance parameter is separately designed, mother can not be met simultaneously by solving the sagging control methods of tradition
The problem of accuracy requirement is flowed in line voltage regulation and load.
This method specifically includes following three steps.
Step 1: precision is flowed for electric current existing for the sagging control of tradition and busbar voltage regulation is conflicting asks
Topic, proposes the sagging control of segmented, carries out subregion according to size to the load in direct current micro-grid system, is divided into heavily loaded area and light
Area is carried, if the critical current of heavily loaded area and light loading district is Is, according to the constraint condition of DC bus-bar voltage deviation, adopting at light load
With the sagging control of the lesser once linear of sagging coefficient to improve busbar voltage regulation, using sagging coefficient larger when overloaded
The sagging control of cubic non-linearity to improve system power flow precision, segmented sagging curve expression formula and corresponding virtual resistance
It is anti-to be respectively as follows:
In formula (1), UdciFor the output voltage of i-th of converter, IoiFor the output electric current of i-th of converter, p1And p2Point
Not Wei once linear sagging curve and cubic non-linearity sagging curve coefficient, UNFor specified busbar voltage, INFor nominal load electricity
Stream, Rdi_LAnd Rdi_HRespectively indicate the virtual impedance of light loading district and heavily loaded area, IimaxFor the maximum allowable output of i-th of converter
Electric current.
Step 2: work as Rdi_L=Rdi_HWhen, segmented current value I can be found outs, then [0, Is] it is light loading district, [Is, IN] attach most importance to
Area is carried, in light loading district, | Rdi_L| > | Rdi_H|, in heavily loaded area, | Rdi_L| < | Rdi_H|。
Step 3: since there are waypoint out-of-control phenomenons in the sagging control of segmented, and in case of heavy load Down Highway electricity
Press deviation excessive, it usually needs voltage compensation obtains good busbar voltage regulation, keeps control complicated, passes through least square
Method by step 1 segmented sagging curve and line impedance RLiIt is fitted to obtain under a kind of modified self-adaptation nonlinear
Hang down controlling curve:
In formula (2), ni(i=1,3,5) are the coefficient value that least square method obtains.
Beneficial effect
Using technical solution provided by the invention, compared with existing well-known technique, there is following remarkable result: the present invention
The load current of each micro- source converter is divided into light loading district and the heavily loaded area region Liang Ge according to load condition, and according to not same district
Sagging curve characteristic, which is fitted to obtain, can be realized adjust automatically and flows the adaptive non-thread of precision and busbar voltage regulation
Property sagging curve, preferentially improve busbar voltage regulation in light loading district, heavily loaded area preferentially guarantee current sharing can to further
Improve busbar voltage regulation, sagging control non-linear compared to existing multinomial does not need additional compensation, avoids waypoint
Problem out of control, control are simple.
Detailed description of the invention
Fig. 1 (a) is double DC-DC converter parallel system topology knots applied by the sagging control of modified self-adaptation nonlinear
Structure, Fig. 1 (b) are the equivalent circuits for the direct current system that two DC-DC converters are constituted.
Fig. 2 is using the sagging controlling curve of different sagging transformation of coefficient device tradition.
Fig. 3 is that once linear sagging curve, cubic non-linearity sagging curve, segmented sagging curve and multinomial are non-linear
Sagging controlling curve.
Fig. 4 is the sagging controlling curve of modified self-adaptation nonlinear.
Fig. 5 (a), Fig. 5 (b) are underloading situation downconverter output voltage Uo1、Uo2With busbar voltage UBusIt is defeated with converter
Electric current I outo1、Io2、IoWaveform.
Fig. 6 (a), Fig. 6 (b) are case of heavy load downconverter output voltage Uo1、Uo2With busbar voltage UBusIt is defeated with converter
Electric current I outo1、Io2、IoWaveform.
Figure label explanation: L1、L2For the energy storage inductor of Boost, Q1、Q2、Q3、Q4For first, second, third,
4th power tube, C1、C2For the filter capacitor of Boost, RL1、RL2For line impedance equivalence value, resistance RCPLAnd current source
iCPLIt is equivalent to constant power load.
Specific embodiment
The technical solution of invention is described in detail with reference to the accompanying drawing.
Modified self-adaptation nonlinear droop control method for direct-current grid of the invention, using current characteristics
(U-I) the sagging control strategy of DC voltage solves electric current existing for the sagging control of tradition and flows precision and busbar voltage tune
The conflicting problem of whole rate improves busbar voltage regulation while improving electric current and flowing precision.Based on overloaded partition
Load current is divided into the area Liang Ge according to the size of load by modified self-adaptation nonlinear droop control method: light loading district and
Heavily loaded area configures lesser sagging coefficient in underloading then by the sagging controlling curve of modified self-adaptation nonlinear
To improve busbar voltage regulation, biggish sagging coefficient is configured under case of heavy load to improve electric current and flow precision and bus electricity
Press regulation.
The present invention carries out the detailed process of the sagging control of modified self-adaptation nonlinear of direct-current grid are as follows: using different
The sagging controlling curve of sagging transformation of coefficient device tradition is as shown in Fig. 2, whip under once linear sagging curve, cubic non-linearity
Line, segmented sagging curve and the non-linear sagging controlling curve of multinomial are as shown in Figure 3.For electricity existing for the sagging control of tradition
Stream stream precision and the conflicting problem of busbar voltage regulation, propose the sagging control of segmented, to Fig. 1 (a), Fig. 1 (b)
Load in shown direct current micro-grid system carries out subregion according to size, is divided into heavily loaded area and light loading district, if heavily loaded area and light loading district
Critical current be Is.According to the constraint condition of DC bus-bar voltage deviation, using sagging coefficient lesser primary at light load
Linear sagging control is using the sagging control of the biggish cubic non-linearity of sagging coefficient to improve busbar voltage regulation when overloaded
Precision is flowed to improve system power.Segmented sagging curve expression formula and corresponding virtual impedance are respectively as follows:
In formula (1), UdciFor the output voltage of i-th of converter, IoiFor the output electric current of i-th of converter, p1And p2Point
Not Wei once linear sagging curve and cubic non-linearity sagging curve coefficient, UNFor specified busbar voltage, INFor nominal load electricity
Stream, Rdi_LAnd Rdi_HThe respectively virtual impedance of light loading district and heavily loaded area, IimaxFor the maximum allowable output electricity of i-th of converter
Stream.
Work as Rdi_L=Rdi_HWhen, segmented current value I can be found outs, then [0, Is] it is light loading district, [Is, IN] it is heavily loaded area.In
Light loading district, | Rdi_L| > | Rdi_H|；In heavily loaded area, | Rdi_L| < | Rdi_H|。
Since there are waypoint out-of-control phenomenons in the sagging control of segmented, and in case of heavy load Down Highway voltage deviation mistake
Greatly, it usually needs voltage compensation obtains good busbar voltage regulation, keeps control complicated, will be above-mentioned by least square method
Segmented sagging curve and linear impedance RLiIt is fitted to obtain a kind of sagging controlling curve of modified self-adaptation nonlinear:
In formula (2), ni(i=1,3,5) are the coefficient value that least square method obtains.
The modified self-adaptation nonlinear droop control method of proposition, does not need voltage compensation link, can be in heavily loaded feelings
Good busbar voltage regulation is obtained under condition and electric current flows precision.Modified self-adaptation nonlinear sagging curve such as Fig. 4 institute
Show
Fig. 5 is by taking double DC-DC converter parallel-connection structures as an example, the comparative analysis non-linear sagging control of multinomial and modified
Control effect of the sagging control of self-adaptation nonlinear in busbar voltage deviation and equal stream error, is arranged main circuit parameter such as table 1
It is shown.Fig. 5 (a), Fig. 5 (b) are that load power is the voltage U that 200W works when being lightly loaded situationo1、Uo2、UBusWith electric current Io1、
Io2、IoWaveform, system dc busbar voltage deviation are 0.42%, and each distributed power supply module output electric current is smaller, to system
Current sharing can be of less demanding；Fig. 6 (a), Fig. 6 (b) are that load power is the voltage U that 500W works in case of heavy loado1、Uo2、
UBusWith electric current Io1、Io2、IoWaveform, system busbar voltage deviation are 1.2%, and equal stream error is 4.5%, be ensure that preferable equal
The requirement of busbar voltage is met while fluidity energy.
1 simulation parameter of table
| Parameter | Value |
| Switching frequency fs/kHz | 50 |
| Cable impedance R1、R2/Ω | 0.3、0.35 |
| Maximum output current Imax/A | 6 |
| DC bus lateral capacitance C/uF | 800 |
| Input side voltage V1、V2/V | 36 |
| n1、n3、n5 | 0.022866804、0.00188899、-0.00012553 |
| Rated output voltage UN/V | 48 |
Claims (4)
1. a kind of modified self-adaptation nonlinear droop control method for direct-current grid, which is characterized in that according to load
The output electric current of micro- source converter each in DC micro-electric network control system is divided into light loading district and heavily loaded area by the size of electric current, is adopted
Micro- source that light loading district is worked in the control of once linear sagging curve works in heavy duty using the control of cubic non-linearity sagging curve
Micro- source in area, output voltage of the micro- source of simultaneous in light loading district and heavily loaded area obtains segmented sagging curve, using least square method
Fitting segmented sagging curve and line impedance obtain self-adaptation nonlinear sagging curve, by self-adaptation nonlinear sagging curve control
Make each micro- source.
2. a kind of modified self-adaptation nonlinear droop control method for direct-current grid according to claim 1,
It is characterized in that, the self-adaptation nonlinear sagging curve are as follows:UdciFor i-th micro- source
Output voltage, IoiFor the output electric current in i-th of micro- source, UNFor specified busbar voltage, n1、n3、n5It is for what least square method obtained
Numerical value.
3. a kind of modified self-adaptation nonlinear droop control method for direct-current grid according to claim 1 or claim 2,
It is characterized in that, the segmented sagging curve are as follows:UdciFor i-th micro- source
Output voltage, IoiFor the output electric current in i-th of micro- source, p1And p2Respectively once linear sagging curve and cubic non-linearity are sagging
The coefficient of curve, UNFor specified busbar voltage, INFor nominal load current, IsFor the critical current in heavily loaded area and light loading district.
4. a kind of modified self-adaptation nonlinear droop control method for direct-current grid according to claim 3,
It is characterized in that, the critical current in heavy duty area and light loading district is determined in the case of heavily loaded area and equal light loading district virtual impedance,Rdi_LAnd Rdi_HRespectively light loading district and heavily loaded area
Virtual impedance, IimaxFor the maximum allowable output electric current in i-th of micro- source.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110912110A (en) * | 2019-11-15 | 2020-03-24 | 东南大学 | Dynamic self-adaptive droop control method for direct-current micro-grid |
| CN111555258A (en) * | 2020-06-08 | 2020-08-18 | 南京工程学院 | Improved self-adaptive droop control method for direct-current micro-grid |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110912110A (en) * | 2019-11-15 | 2020-03-24 | 东南大学 | Dynamic self-adaptive droop control method for direct-current micro-grid |
| CN111555258A (en) * | 2020-06-08 | 2020-08-18 | 南京工程学院 | Improved self-adaptive droop control method for direct-current micro-grid |
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