CN109787254A - A kind of switchover policy of three-phase load unbalance regulating cycle - Google Patents
A kind of switchover policy of three-phase load unbalance regulating cycle Download PDFInfo
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Abstract
A kind of switchover policy of three-phase load unbalance regulating cycle is related to the calculation method of action cycle, especially controls the switchover policy of three-phase load unbalance regulating cycle, be related to the improving environment of substation, platform area power supply quality.Three-Dimensional Dynamic regression algorithm is used in determine three-phase load unbalance regulating cycle.The present invention weighs the factors such as load factor, the tri-phase unbalance factor of power grid, under the premise of guaranteeing power supply quality, the period of three-phase imbalance is adjusted according to route real time status switching at runtime, scientifically and rationally plans regulating time, the action frequency for reducing relay, extends the service life of relay.It is realized by following formula:*K+T。
Description
Technical field
The present invention relates to the calculation methods of action cycle, especially control the switching plan of three-phase load unbalance regulating cycle
Slightly, it is related to the improving environment of substation, platform area power supply quality.
Background technique
The low-voltage electricity transmission line of China is mostly three-phase four-wire power supply network, with the raising of national economy level, electric power
Net load sharply increases, especially the continuous growth of impact, nonlinear-load capacity, so that power grid generation voltage waveform is abnormal
The power quality problems such as change, voltage fluctuation, flickering and three-phase load unbalance.The wherein variation of load, three-phase load unbalance
The problems such as cause electrical network negative phase-sequence voltage and negative-sequence current, seriously affect power supply quality, and then increase line loss, reducing power supply can
By property.
Low-voltage circuit radius of electricity supply is long at present, with electrodispersion, single-phase lighting consumer and the mashed up electricity consumption of three-phase power user
Situation causes threephase load extremely uneven, and line end low-voltage is serious.
In order to promote power distribution station power supply quality, taking commutation measure is the major way for administering three-phase current unbalance.
With the development of technology, periodic detection loading condition is now mostly used, according to line condition, phase-change switch movement is controlled and completes to change
Phase is finally reached three-phase balance.
In order to guarantee power supply quality, detection time space requirement is short as far as possible, currently, most of use Fixed Time Interval,
If detection in every 15 minutes is primary, if tri-phase unbalance factor is greater than some value, the phase by adjusting load completes adjustment.
Commutation movement is completed by relay, and the mechanical life of relay itself and electric life are limited.Current technology
Scheme only considers power supply quality, is not concerned about the life problems of relay.If the service life of a relay is movement 10000 times,
Under limiting case, as soon as executing within every 15 minutes time commutation movement, 10000 movements are reached within 100 days or so.The damage of relay
Direct economic loss is not only caused, thus bring cannot carry out the adjustment of power grid three-phase imbalance in time, can give power grid band
Carry out bigger hidden danger.
In the case where route underloading in general load factor is lower than 30%, even if degree of unbalancedness is very big, meeting user
Under the premise of electricity consumption, very big damage will not be generated to transformer；In route heavy duty, in general load factor is higher than 80% feelings
Under condition, if there is three-phase imbalance, being adjusted will not be greatly improved to imbalance.
When degree of unbalancedness is higher than to a certain degree (national grid performance assessment criteria is 15%), when load reaches a certain level, three
It is mutually uneven to bring bigger harm, face such as is related to bigger, user the low-voltage problem of loss of transformer and is compared
It is wide etc..
Current technology, not using above situation as reference conditions.
Summary of the invention
The purpose of the present invention is to guarantee power supply quality in factors such as load factor, the tri-phase unbalance factors of tradeoff power grid
Under the premise of, adjustment judges the period of power grid three-phase imbalance in real time, reduces the action frequency of relay.
To achieve the above object, the invention adopts the following technical scheme: a kind of three-phase load unbalance regulating cycle is cut
Strategy is changed, it is critical that
Degree of unbalancedness weightK 1 =a/ (a+b),
Load factor weightK 2 =b/ (a+b),
Wherein, a is that tri-phase unbalance factor adjusts limit value, and value range is that 0 ~ 100%, b is that load factor adjusts lower limit value, value model
Enclose is 0 ~ 100%；
It calculatesZmin=,
Wherein, x value 100, y value c, c are that load factor adjusts upper limit value, and value range is 0 ~ 100%；
Calculate correction factorK=(Tmin-Tmax)/Zmin,
Wherein,TminFor minimal adjustment time interval,TmaxFor maximal regulated time interval；
Substation, platform area calculates three-phase imbalance adjustment time interval according to real-time tri-phase unbalance factor x and line load rate y
Z,
Z(x,y)= *K+Tmax。
A value 15%, b value 30%, c value 80%.
Tmin=15 minutes,Tmax=1440 minutes.
If the tri-phase unbalance factor of power supply line is more than 15%, it is necessary to be adjusted；It is less than in route load factor
When 30%, even if degree of unbalancedness is very big, under the premise of meeting user power utilization, very big damage will not be generated to transformer, separately
Outside, when line load rate very little, adjustable load number is seldom, and adjustment will not work, and therefore, compares in route load factor
When small, adjustment period, i.e., the time interval adjusted twice are adjusted or extended without three-phase imbalance.
In the case that in route heavy duty, in general load factor is higher than 80%, if there is three-phase imbalance, it is adjusted
It will not be greatly improved to imbalance.
The present invention comprehensively considers the tri-phase unbalance factor and load factor of route, in the premise for the power supply quality for guaranteeing power grid
Under, the period of three-phase imbalance is adjusted according to route real time status switching at runtime, scientifically and rationally plans regulating time, reduce after
The action frequency of electric appliance extends the service life of relay.
Detailed description of the invention
The curve of tri-phase unbalance factor, line load rate and regulating cycle that Fig. 1 calculates for the present invention.
Specific embodiment
The present invention is used in Three-Dimensional Dynamic regression algorithm to determine three-phase load unbalance regulating cycle.Algorithm passes through following
Formula is realized:
Z= *K+T
In formula, degree of unbalancedness weightK 1 =a/ (a+b), load factor weightK 2 = b/(a+b)。
Wherein, a is that tri-phase unbalance factor adjusts limit value, and value range is 0 ~ 100%, when tri-phase unbalance factor is greater than a,
It needs to be adjusted；B is that load factor adjusts lower limit value, and value range is 0 ~ 100%, when line load rate is less than b, without
It adjusts.
K1The weight of route tri-phase unbalance factor is represented,K2The weight of line load rate is represented, two weights are interrelated.
It is required according to line powering different, thus it is possible to vary the value of a, b, to change the value of two weights.
In the present embodiment, a=15%, b=30% be can be calculatedK1=0.33,K2=0.67。
When line load rate is greater than some value, the adjustment of three-phase imbalance does not work substantially, in this case, no
It is adjusted.This value is that load factor adjusts upper limit value c, and value range is 0 ~ 100%.
In the present embodiment, c=80%.
When the tri-phase unbalance factor of route maximum, load factor maximum, the regulating cycle of three-phase imbalance can be minimum.
In the present embodiment, when x=100%, y=c=80%, circuit conditions are the most severe, need to be adjusted in the shortest time
Section.It is calculated by the above parameter:
Zmin= 。
Zmin=-16380。
Calculate correction factorK=(Tmin-Tmax)/Zmin。
Wherein,TminFor minimal adjustment time interval,TmaxFor maximal regulated time interval.
It in the present embodiment, is divided between the smallest regulating time 15 minutes, i.e., judgement in every 15 minutes adjusts a three-phase injustice
Weighing apparatus,Tmin=15 minutes；It is divided into 1 day between maximum regulating time, i.e.,Tmax=1440 minutes.
It calculates as a result,K=0.087。
Finally obtain calculation formula:
Z(x,y)= *K+Tmax。
Z(x,y)To be in tri-phase unbalance factorx, line load rate isyIn the case where, adjust the time of three-phase imbalance
Interval.
It, can be according to the historical empirical data of actual power supply line in order to make the result of algorithm more adapt to actual conditions
To weight parameterK1、K2、KIt advanced optimizes.
Historical empirical data can be manually determined with acquired route actual parameter, according to actual parameter between the optimum apjustment time
Every.
Historical empirical data is a data acquisition system, set each of data item beX,Y,Z, whereinZIt is three
Phase degree of unbalancedness isX, line load rate isYIn the case where, artificial determining optimal correction time interval.
For each group of data, carry out the following processing:
Using formula of the invention, calculating is in tri-phase unbalance factorx, line load rate isyIn the case where, it is uneven to adjust three-phase
The time interval of weighing apparatusZ(Xi,Yi)。
The mean square deviation of result and optimum apjustment time that calculation formula obtains:Ei=(Z(Xi,Yi)-Zi)2/2。
Wherein,Xi,Yi,ZiBe data set in i-th, i be 1 arrive n integer, n be data intensive data number.
If continuous 10 mean square deviations less than 5%, terminate.
Otherwise, following weight and correction factor optimization are carried out.
,
K 1=a/(a+b)+Δk 1 ,K 2=b/(a+b)+Δk 2
Regulations speedη=0.25。
According to what is newly obtainedK1、K2, recalculateK。
So far, the calculating function of the three-phase load unbalance regulating cycle for the route has been obtained:
Z(x,y)= *K+Tmax
Substation, platform area calculates three-phase imbalance adjustment time interval according to real-time tri-phase unbalance factor x and line load rate yZ(x,y), and judged according to this and adjusted.
It will be seen from figure 1 that regulating cycle shortens with tri-phase unbalance factor, the increase of line load rate, meet reality
Applicable cases.
When actual motion, substation, platform area samples tri-phase unbalance factor and line load rate, according to sampled result
Three-phase imbalance adjustment time interval is calculated, when the time reaching the time calculated, carries out the adjustment of three-phase imbalance.
In the present embodiment, sampling and calculating judge three-phase imbalance adjustment time for two parallel processes while running.
Sampling and calculating:
6.1, substation, platform area samples a tri-phase unbalance factor and line load rate per minute, when reaching 15 samplings, calculates
The average value of tri-phase unbalance factor and line load rate.
If 6.2, tri-phase unbalance factor is greater than a and line load rate is greater than b and is less than c, 6.3 are executed, is otherwise executed
6.4。
6.3, using average value as parameter, calculate three-phase imbalance adjustment time interval, by this calculate in first sample
Acquisition time plus calculated time interval as time point preservation；Sampled data is removed, executes 6.1.
6.4, all sampled datas are removed or retain 10 times nearest sampled datas, execute 6.1.
It is exemplified below.
For purposes of illustration only, at the beginning of being sampling with 00:00.
Sampling and calculating:
Time to 00:14, has acquired 15 samples, calculates 0:00--0:14 data, meets 6.2 condition, calculates between the time
60 points are divided into, the acquisition time of first sample is 00:00 in this calculating, in addition after sixty minutes, 01:00 is protected as time point
It deposits.Calculated 15 sampled datas are removed, restart to sample.
Time to 00:29, has acquired 15 samples, calculates data, is unsatisfactory for condition 6.2.
At this point it is possible to not consider the data sampled in the past, resampling is calculated.In the present embodiment, consider that history is adopted
The correlation of sample data: removing the sample of 00:15,00:16,00:17,00:18,00:19 acquisition, retains 10 nearest samplings
Data；Start to sample.
Time to 00:34, has 15 samples, and after calculating 00:20--00:34 data, calculating regulating cycle is 35 points,
00:55 is saved as time point.Calculated 15 sampled datas are removed, restart to sample.
Time to 00:49, has 15 samples, and after calculating 00:35--00:49 data, calculating regulating cycle is 60 points,
01:35 is saved as time point.Calculated 15 sampled datas are removed, restart to sample.
Judge three-phase imbalance adjustment time:
In the present embodiment, in 00:50,3 time points, i.e. 01:00,00:55,01:35 have been saved.
When current time reaches 00:55,00:55 is one of the time point saved, executes following steps at this time:
Carry out three-phase imbalance adjustment；
It removes all time points saved, in the present embodiment, removes two time points of 01:00,01:35.
At this point, having the sampled data since 00:50 in sampling and calculating process.Since three-phase has been carried out
Unbalanced adjustment, there is no reference significances for legacy data, therefore remove all sampled datas, execute 6.1, restart sampling meter
It calculates.
Actual motion shows using the present invention, it is possible to reduce 40% or more the movement of relay substantially prolongs relay
Service life, and then improve the power supply quality of route.
Claims (7)
1. a kind of switchover policy of three-phase load unbalance regulating cycle, which is characterized in that
Degree of unbalancedness weightK 1 =a/ (a+b),
Load factor weightK 2 =b/ (a+b),
Wherein, a is that tri-phase unbalance factor adjusts limit value, and value range is that 0 ~ 100%, b is that load factor adjusts lower limit value, value model
Enclose is 0 ~ 100%；
It calculatesZmin=,
Wherein, x value 100, y value c, c are that load factor adjusts upper limit value, and value range is 0 ~ 100%；
Calculate correction factorK=(Tmin-Tmax)/Zmin,
Wherein,TminFor minimal adjustment time interval,TmaxFor maximal regulated time interval；
Substation, platform area calculates three-phase imbalance adjustment time interval according to real-time tri-phase unbalance factor x and line load rate y
Z,
Z(x,y)=*K+Tmax。
2. switchover policy according to claim 1, which is characterized in that a value 15%, b value 30%.
3. switchover policy according to claim 1, which is characterized in that c value 80%.
4. switchover policy according to claim 1, which is characterized in thatTmin=15 minutes,Tmax=1440 minutes.
5. switchover policy according to claim 1, which is characterized in that right according to historical empirical dataK1、K2WithKIt carries out
Optimization,
Historical empirical data be data itemX,Y,ZSet, whereinZIt is to be in tri-phase unbalance factorX, line load rate isY
In the case where, optimal adjustment time interval,
For each data item, carry out the following processing:
Ei=(Z(Xi,Yi)-Zi)2/ 2,
Wherein,Xi,Yi,ZiBe set in i-th of data item, i be 1 arrive n integer, n be gather in data item number,
Record calculated resultEiIf continuous 10 calculated result less than 5%, terminates；
Otherwise,
,
K 1=a/(a+b)+Δk 1 ,K 2=b/(a+b)+Δk 2 ,
Whereinη=0.25,
It recalculatesK。
6. switchover policy according to claim 1 or 5, which is characterized in that
Sampling and calculating:
6.1, substation, platform area samples a tri-phase unbalance factor and line load rate per minute, when reaching 15 samplings, calculates
The average value of tri-phase unbalance factor and line load rate；
If 6.2, tri-phase unbalance factor is greater than a and line load rate is greater than b and is less than c, 6.3 are executed, otherwise executes 6.4；
6.3, using average value as parameter, calculate three-phase imbalance adjustment time interval, by this calculate in first sample adopt
Collect the time plus calculated time interval as time point preservation；Sampled data is removed, executes 6.1；
6.4, all sampled datas are removed, execute 6.1；
Judge three-phase imbalance adjustment time:
Current time reaches the time point saved for the moment, executes following steps:
Carry out three-phase imbalance adjustment；
Remove all time points saved；
All sampled datas are removed, execute 6.1.
7. switchover policy according to claim 6, which is characterized in that
Step 6.4 retains 10 times nearest sampled datas, executes 6.1.
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