CN102810872B - Power compensation method and power compensation system for power distribution network - Google Patents
Power compensation method and power compensation system for power distribution network Download PDFInfo
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- CN102810872B CN102810872B CN201210300878.8A CN201210300878A CN102810872B CN 102810872 B CN102810872 B CN 102810872B CN 201210300878 A CN201210300878 A CN 201210300878A CN 102810872 B CN102810872 B CN 102810872B
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- 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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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- 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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The invention provides a power compensation method for a power distribution network. The power compensation method comprises the steps of: sampling three-phase load current of the power distribution network; converting the three-phase load current of the power distribution network from analog signals into digital signals; acquiring reactive current required to be compensated, harmonic compensation instructional current and reactive compensation instructional current according to the three-phase load current of the power distribution network after the three-phase load current is converted into the digital signals; performing harmonic compensation for the power distribution network according to the harmonic compensation instructional current; stopping reactive compensation when the change rate of the reactive compensation instructional current is greater than a preset value; and performing reactive compensation according to reactive current required to be compensated and the reactive compensation instructional current when the change rate of the reactive compensation instructional current is smaller than the preset value. The invention also provides a power compensation system for the power distribution network, and the stability and the reliability of the power distribution network can be improved.
Description
Technical field
The present invention relates to distribution network security control field, particularly relate to a kind of power compensating method and system of power distribution network.
Background technology
Instantly the subject matter that system for distribution network of power faces is how for user provides safety, reliable, high-quality, economic electric energy.Along with the development of modern industrial technology, power electronic equipment is increasingly extensive is applied to electric power system, and the harm of idle deficiency and harmonic wave becomes increasingly conspicuous.Therefore reactive power compensation and harmonics restraint just seem particularly important for realizing appeal target.In traditional electric power system, reactive power compensation and harmonic compensation two kinds of equipment independent operating separately, between reactive power compensation and harmonic compensation without mutually intercommunication and data fusion.Its shortcoming is remarkable, as: the impact that the impulse current that dynamic reactive compensator switched capacitor brings brings Active Power Filter-APF; Dynamic reactive compensator low-response, Active Power Filter-APF response is fast.
Therefore, reactive power compensation and harmonic wave compensation integration need be got up use, but in current method, by both simple parallel runnings, there is the situations such as frequent switching capacitor in dynamic reactive compensator, easily there is vibration in such system, show as Active Power Filter-APF and occur overcurrent suddenly, stability is not high; Easily shorten equipment life in addition, severe one causes other equipment in power distribution station to occur catastrophic effect, and reliability is not high.
Summary of the invention
The object of the invention is to the power compensating method and the system that propose a kind of power distribution network, stability and the reliability of power distribution network can be improved.
In order to achieve the above object, the technical scheme adopted is:
A power compensating method for power distribution network, comprises step:
The threephase load electric current of sampling power distribution network;
By the threephase load electric current of described power distribution network, analog signal is had to convert digital signal to;
Threephase load electric current according to converting the described power distribution network after digital signal to obtains reactive current, harmonic compensation instruction current and the reactive power compensation command current that need compensate;
According to described harmonic compensation instruction current, harmonic compensation is carried out to power distribution network;
When the rate of change of described reactive power compensation command current is greater than default value, do not carry out reactive power compensation; When the rate of change of described reactive power compensation command current is less than described default value, carry out reactive power compensation according to the described reactive current that need compensate and described reactive power compensation command current;
When the described rate of change when reactive power compensation command current is less than described default value, the step of carrying out reactive power compensation according to the described reactive current that need compensate and described reactive power compensation command current is specially:
To the sequence that the described reactive current that need compensate is carried out from small to large;
Determine the one-to-one relationship that the described reactive current that need compensate and dynamic reactive compensator switching combine;
If I
j<I
lq<I
j+1, and when the rate of change of described reactive power compensation command current is less than described default value, drop into described I
jcorresponding dynamic reactive compensator switching combination upgrades the switching state of Capacitor banks, and update mode is: by controller, drops into and excise capacitor until I
lqconvergence is 0; Wherein, I
jfor the reactive current that need compensate; I
lqfor described reactive power compensation command current.
And a kind of power compensating system of power distribution network, comprising: current sampling circuit, analog to digital converter, digital signal processor, harmonic compensation circuit, reactive power compensation circuits for triggering and reactive power compensation circuit;
Wherein, described current sampling circuit connects described analog to digital converter; Described analog to digital converter connects described digital signal processor; Described digital signal processor connects described harmonic compensation circuit and described reactive power compensation circuits for triggering; One end of described reactive power compensation circuits for triggering, described harmonic compensation circuit connects described reactive power compensation circuit respectively; The other end of described harmonic compensation circuit connects distribution network system side;
The threephase load electric current of described sampling circuit samples power distribution network;
Described analog to digital converter, by the threephase load electric current of the power distribution network of described sampling circuit samples, converts digital signal to by analog signal;
Described digital signal processor obtains reactive current, harmonic compensation instruction current and the reactive power compensation command current that need compensate according to the threephase load electric current converting the described power distribution network after digital signal to;
Described harmonic compensation circuit carries out harmonic compensation according to described harmonic compensation instruction current to power distribution network;
When described reactive power compensation circuits for triggering judge that the rate of change of described reactive power compensation command current is greater than default value, described reactive power compensation circuit does not carry out reactive power compensation;
When described reactive power compensation circuits for triggering judge that the rate of change of described reactive power compensation command current is less than described default value, described reactive power compensation circuit carries out sequence from small to large to the described reactive current that need compensate; Determine the one-to-one relationship that the described reactive current that need compensate and dynamic reactive compensator switching combine; If I
j<I
lq<I
j+1, and when the rate of change of described reactive power compensation command current is less than described default value, then drop into described I
jcorresponding dynamic reactive compensator switching combination upgrades the switching state of Capacitor banks, and update mode is: by controller, drops into and excise capacitor until I
lqconvergence is 0; Wherein, I
jfor the reactive current that need compensate; I
lqfor described reactive power compensation command current.
The present invention samples power distribution network threephase load electric current, then utilizes idle theory calculate to go out the reactive current that need compensate, and according to threephase load Current calculation harmonic compensation instruction current and reactive power compensation command current; Harmonic compensation is carried out according to harmonic compensation instruction current; Before carrying out reactive power compensation, also need the rate of change considering reactive power compensation command current whether to meet the value preset, if meet just input Capacitor banks to carry out reactive power compensation, make that the stability of a system is good, reliability is high like this.
Accompanying drawing explanation
Fig. 1 is an embodiment flow chart of the inventive method;
Fig. 2 is a structural representation of present system;
Fig. 3 is an application schematic diagram of present system.
Embodiment
For ease of understanding the present invention, be described below in conjunction with accompanying drawing.
The present invention proposes a kind of power compensating method of power distribution network, please refer to Fig. 1, comprises step:
The threephase load electric current of S101, sampling power distribution network;
S102, by the threephase load electric current of power distribution network, convert digital signal to by analog signal;
The threephase load electric current of the power distribution network after S103, basis convert digital signal to obtains reactive current, harmonic compensation instruction current and the reactive power compensation command current that need compensate;
S104, according to harmonic compensation instruction current, harmonic compensation is carried out to power distribution network;
S105, when the rate of change of reactive power compensation command current is greater than default value, do not carry out reactive power compensation; When the rate of change of reactive power compensation command current is less than default value, carry out reactive power compensation according to the reactive current that need compensate and reactive power compensation command current.
The present invention samples power distribution network threephase load electric current, then utilizes idle theory calculate to go out the reactive current that need compensate, and according to threephase load Current calculation harmonic compensation instruction current and reactive power compensation command current; Harmonic compensation is carried out according to harmonic compensation instruction current; Before carrying out reactive power compensation, also need the rate of change considering reactive power compensation command current whether to meet the value preset, if meet just input Capacitor banks to carry out reactive power compensation, make that the stability of a system is good, reliability is high like this.
For a better understanding of the present invention, will set forth from following steps the present invention:
One, the threephase load electric current of sampling power distribution network;
The threephase load electric current of sampling power distribution network, obtains three-phase current and is respectively i
a, i
band i
c.
Two, by the threephase load electric current of power distribution network, digital signal is converted to by analog signal;
Three, according to the threephase load electric current after digital translation, harmonic compensation instruction current is calculated;
Circular can be undertaken by general computational methods, repeats no more concrete computational process herein.
Four, according to the threephase load electric current after digital translation, the reactive current and reactive power compensation command current that need compensate is calculated;
A, according to the threephase load electric current after digital translation, calculate the reactive current that need compensate, can calculate according to Instantaneous Power Theory, repeat no more concrete computational process herein;
B, according to the threephase load electric current after digital translation, calculate reactive power compensation command current time, can carry out in the following manner:
Following formulae discovery is utilized to obtain instantaneous reactive power;
Wherein, i
qfor instantaneous reactive power; i
pfor instantaneous active power; i
a, i
band i
cfor threephase load electric current; i
qfor instantaneous reactive power comprises First Harmonic Reactive Power and harmonic wave reactive power; Therefore need to carry out harmonic process to instantaneous reactive power, low pass filter can be used realize, can fundamental reactive current be obtained after low-pass filtering; Concrete, the processing mode of low-pass filtering is: use following equation to carry out process y (n+1)=(1-f) y (n)+x (n) f;
Wherein, y (n+1) is the current output of low pass filter, that is, current fundamental reactive current value; Y (n) is fundamental reactive current value corresponding to a sampled point on low pass filter; X (n) is current instantaneous reactive power i
q, f is the characteristic value of cut-off frequency.Can choose cut-off frequency is 2Hz, namely weighs cut-off frequency f=0.001.When system voltage one timing,
represent the reactive current effective value of load, the reactive current effective value of this load is required reactive power compensation command current.
Wherein, step 3 and step 4, without sequencing, can be carried out simultaneously.
Five, according to harmonic compensation instruction current, harmonic compensation is carried out to power distribution network;
Harmonic compensation mode by conventional harmonic compensation mode, can repeat no more herein.
Six, reactive power compensation is carried out according to reactive power compensation command current.
(1) the rate of change dI of reactive power compensation command current is asked for
lq/ dt;
(2) rate of change of reactive power compensation command current and the size of the value preset is compared;
(3) when the rate of change of reactive power compensation command current is greater than default value, reactive power compensation is not carried out;
(4) when the rate of change of reactive power compensation command current is less than default value, reactive power compensation is carried out according to the reactive current that need compensate and reactive power compensation command current.For convenience of understanding, be described with an object lesson below: suppose there are 3 group capacitors.The reactive compensation capacity that 3 group capacitors can realize has 8 kinds of combinations, by the reactive current compensated by compiling from small to large as I
0, I
1i
7.
Determine the mapping relations one by one of reactive compensation capacity and switching combination, i.e. I
0, I
1i
7corresponding switching combination C respectively
0, C
1c
7.Work as I
lqmeet I
j<I
lq<I
j+1, and dI
lqduring/dt> Δ, wherein, Δ is default value, and represent that reactive load is in transient process, the switching state now maintaining Capacitor banks is constant;
Work as I
lqmeet I
j<I
lq<I
j+1, and dI
lqduring/dt< Δ, select switching combination C
j(j=1,2 ..., 7) the switching state of Capacitor banks is upgraded.Concrete update mode is, by controller, drops into and excise capacitor until I
lqconvergence is 0.
The invention allows for a kind of power compensating system of power distribution network, with reference to figure 2, comprising: current sampling circuit 201, analog to digital converter 202, digital signal processor 203, harmonic compensation circuit 204, reactive power compensation circuits for triggering 205 and reactive power compensation circuit 206;
Wherein, current sampling circuit 201 connection mode number converter 202; Analog to digital converter 202 linking number word signal processor 203; Digital signal processor 203 connects harmonic compensation circuit 204 and reactive power compensation circuits for triggering 205; One end of reactive power compensation circuits for triggering 205, harmonic compensation circuit 204 connects reactive power compensation circuit 206 respectively; The other end of harmonic compensation circuit 204 connects distribution network system side;
Sample circuit 201 is sampled the threephase load electric current of power distribution network;
Analog to digital converter 202, by the threephase load electric current of the power distribution network of sampling circuit samples, converts digital signal to by analog signal;
Digital signal processor 203 obtains reactive current, harmonic compensation instruction current and the reactive power compensation command current that need compensate according to the threephase load electric current converting the power distribution network after digital signal to;
Harmonic compensation circuit 204 carries out harmonic compensation according to harmonic compensation instruction current to power distribution network;
When reactive power compensation circuits for triggering 205 judge that the rate of change of reactive power compensation command current is greater than default value, reactive power compensation circuit 206 does not carry out reactive power compensation;
When reactive power compensation circuits for triggering 205 judge that the rate of change of reactive power compensation command current is less than default value, reactive power compensation circuit 206 carries out reactive power compensation according to the reactive current that need compensate and reactive power compensation command current.
As an embody rule example of the present invention, refer to Fig. 3, the threephase load electric current that the current transformer 207 that current sampling circuit 201 gathers power distribution network load-side is responded to; The electric current of sampling is after analog to digital converter 202 is changed, and give digital signal processor 203 and process, concrete processing mode comprises:
Instantaneous Power Theory is utilized to calculate harmonic compensation instruction current;
Following formulae discovery is utilized to obtain instantaneous reactive power;
Wherein, i
qfor instantaneous reactive power; i
pfor instantaneous active power; i
a, i
band i
cfor threephase load electric current; And harmonic process is carried out to instantaneous reactive power, obtain fundamental reactive current; Reactive power compensation command current is obtained according to fundamental reactive current.
When carrying out harmonic compensation, harmonic compensation circuit 204 provides harmonic power to compensate according to harmonic compensation instruction current to distribution network system side;
When triggering reactive power compensation, reactive power compensation circuit 206 carries out sequence from small to large to the reactive current that need compensate;
Determine the one-to-one relationship that the reactive current that need compensate and dynamic reactive compensator switching combine;
If I
j<I
lq<I
j+1, and when the rate of change of reactive power compensation command current is less than default value, then drop into I
jcorresponding dynamic reactive compensator switching combination; Wherein, I
jfor the reactive current that need compensate; I
lqfor reactive power compensation command current.
Wherein, reactive power compensation circuit 206 comprises: controller 302, bidirectional triode thyristor 301 and Capacitor banks 303; Controller 302 connects reactive power compensation circuits for triggering 205; Controller 302 connects the control end of bidirectional triode thyristor 301; The other end of bidirectional triode thyristor 301 connects harmonic compensation circuit 204; The other end of bidirectional triode thyristor 301 connects one end of Capacitor banks 303; The other end ground connection of Capacitor banks 303.
The above embodiment only have expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.
Claims (3)
1. a power compensating method for power distribution network, is characterized in that, comprises step:
The threephase load electric current of sampling power distribution network;
By the threephase load electric current of described power distribution network, convert digital signal to by analog signal;
Threephase load electric current according to converting the described power distribution network after digital signal to obtains reactive current, harmonic compensation instruction current and the reactive power compensation command current that need compensate;
According to described harmonic compensation instruction current, harmonic compensation is carried out to power distribution network;
When the rate of change of described reactive power compensation command current is greater than default value, do not carry out reactive power compensation; When the rate of change of described reactive power compensation command current is less than described default value, carry out reactive power compensation according to the described reactive current that need compensate and described reactive power compensation command current;
When the described rate of change when reactive power compensation command current is less than described default value, the step of carrying out reactive power compensation according to the described reactive current that need compensate and described reactive power compensation command current is specially:
To the sequence that the described reactive current that need compensate is carried out from small to large;
Determine the one-to-one relationship that the described reactive current that need compensate and dynamic reactive compensator switching combine;
If I
j<I
lq<I
j+1, and when the rate of change of described reactive power compensation command current is less than described default value, drop into described I
jcorresponding dynamic reactive compensator switching combination upgrades the switching state of Capacitor banks, and update mode is: by controller, drops into and excise capacitor until I
lqconvergence is 0; Wherein, I
jfor the reactive current that need compensate; I
lqfor described reactive power compensation command current;
The step that the described threephase load electric current according to power distribution network obtains reactive power compensation command current is specially:
Following formulae discovery is utilized to obtain instantaneous reactive power;
Wherein, i
qfor instantaneous reactive power; i
pfor instantaneous active power; i
a, i
band i
cfor described threephase load electric current;
Harmonic process is carried out to described instantaneous reactive power, obtains fundamental reactive current;
Described reactive power compensation command current is obtained according to described fundamental reactive current.
2. a power compensating system for power distribution network, is characterized in that, comprising: current sampling circuit, analog to digital converter, digital signal processor, harmonic compensation circuit, reactive power compensation circuits for triggering and reactive power compensation circuit;
Wherein, described current sampling circuit connects described analog to digital converter; Described analog to digital converter connects described digital signal processor; Described digital signal processor connects described harmonic compensation circuit and described reactive power compensation circuits for triggering; One end of described reactive power compensation circuits for triggering, described harmonic compensation circuit connects described reactive power compensation circuit respectively; The other end of described harmonic compensation circuit connects distribution network system side;
The threephase load electric current of described sampling circuit samples power distribution network;
Described analog to digital converter, by the threephase load electric current of the power distribution network of described sampling circuit samples, converts digital signal to by analog signal;
Described digital signal processor obtains reactive current, harmonic compensation instruction current and the reactive power compensation command current that need compensate according to the threephase load electric current converting the described power distribution network after digital signal to;
Described harmonic compensation circuit carries out harmonic compensation according to described harmonic compensation instruction current to power distribution network;
When described reactive power compensation circuits for triggering judge that the rate of change of described reactive power compensation command current is greater than default value, described reactive power compensation circuit does not carry out reactive power compensation;
When described reactive power compensation circuits for triggering judge that the rate of change of described reactive power compensation command current is less than described default value, described reactive power compensation circuit carries out sequence from small to large to the described reactive current that need compensate; Determine the one-to-one relationship that the described reactive current that need compensate and dynamic reactive compensator switching combine; If I
j<I
lq<I
j+1, and when the rate of change of described reactive power compensation command current is less than described default value, then drop into described I
jcorresponding dynamic reactive compensator switching combination upgrades the switching state of Capacitor banks, and update mode is: by controller, drops into and excise capacitor until I
lqconvergence is 0; Wherein, I
jfor the reactive current that need compensate; I
lqfor described reactive power compensation command current;
The following formulae discovery of described digital signal processor obtains instantaneous reactive power;
Wherein, i
qfor instantaneous reactive power; i
pfor instantaneous active power; i
a, i
band i
cfor described threephase load electric current;
And harmonic process is carried out to described instantaneous reactive power, obtain fundamental reactive current;
Described reactive power compensation command current is obtained according to described fundamental reactive current.
3. the power compensating system of power distribution network according to claim 2, is characterized in that,
Described reactive power compensation circuit comprises controller, bidirectional triode thyristor and Capacitor banks; Described controller connects described reactive power compensation circuits for triggering; Described controller connects the control end of described bidirectional triode thyristor; One end of described bidirectional triode thyristor connects described harmonic compensation circuit; The other end of described bidirectional triode thyristor connects one end of described Capacitor banks; The other end ground connection of described Capacitor banks.
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| CN103091525B (en) * | 2012-12-28 | 2015-03-25 | 上海贝岭股份有限公司 | Electric energy measuring chip three phase wattful power measurement and crosstalk compensation method |
| CN106374478A (en) * | 2015-07-24 | 2017-02-01 | 利思电气（上海）有限公司 | Outdoor active power filter device with reactive power dispatch function |
| CN105490274B (en) * | 2015-12-28 | 2018-12-14 | 国网山东省电力公司青岛供电公司 | Electric power supply system for subway utility power quality control system and method |
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| CN101741093A (en) * | 2010-03-11 | 2010-06-16 | 哈尔滨工业大学 | Reactive power compensation and harmonic governance system and control method for realizing power compensation and harmonic governance by using the same |
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| CN101741093A (en) * | 2010-03-11 | 2010-06-16 | 哈尔滨工业大学 | Reactive power compensation and harmonic governance system and control method for realizing power compensation and harmonic governance by using the same |
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