A kind of low-voltage network line impedance on-line measurement system and method
Technical field
The invention belongs to low-voltage network line impedance fields of measurement, and in particular to a kind of low-voltage network line impedance exists
Line measuring system and method.
Background technique
Nerve endings of the low-voltage network as entire bulk power grid, couples huge numbers of families, and operating status directly affects
Power supply quality, the production of client, life are brought and are directly affected.Wherein, low-voltage network line impedance parameter is always electricity
The key issues for netting research, accessing new power equipment and system evaluation and line fault anticipation to power grid has important ginseng
Examine meaning.
Summary of the invention
The present invention aiming at the shortcomings in the prior art, provides a kind of low-voltage network line impedance on-line measurement system and side
Method.
To achieve the above object, the invention adopts the following technical scheme:
A kind of low-voltage network line impedance on-line measurement system characterized by comprising main website platform and several acquisitions
Terminal;The basic power information of the acquisition terminal measurement low-voltage network corresponding line, calculates line impedance parameter value, then
Main website platform is sent to by GPRS network.
To optimize above-mentioned technical proposal, the concrete measure taken further include:
The acquisition terminal includes primary processor, metering chip, storage chip, clock chip, GPRS communication module, in master
Under the control of processor, timeticks are obtained by clock chip first, it is each then to measure acquisition power distribution network by metering chip
Basic power information at node, and it is recorded in storage chip, then calculate by primary processor and obtain line impedance parameter value, most
Main website platform is transferred data to by GPRS communication module afterwards;Wherein, the basic power information includes voltage and current.
Furthermore, it is also proposed that a kind of measurement side using low-voltage network line impedance on-line measurement system as described above
Method, which is characterized in that on acquisition terminal after electricity operation, with " day " for the period, execute following steps:
Step 1: resetting constant M, constant Rt, constant Sn;
Step 2: according to fixed intervals T, measurement obtains current voltage Uj, electric current Ij, wherein 1≤j≤N, N=24*60*
60/T;
Step 3: voltage Ui, the electric current Ii recorded according to previous cycle calculates voltage change Δ Ui=| Uj-Ui |, electricity
Flow changing value Δ Ii=| Ij-Ii |, wherein i=j-1,0≤i≤N-1;
Step 4: route real-time impedance value Ri is calculated, if 0 < Δ Ui < UCLMT and Δ Ii ≠ 0, Ri=Δ Ui/ Δ Ii,
M 1, the Rt that adds up adds up Ri, otherwise Ri=0, and wherein UCLMT indicates voltage jump exception limit value;
Step 5: judging whether the same day terminates, continue step 2 if being not finished, otherwise carry out step 6;
Step 6: calculatingWherein Ri ≠ 0, Ravg=Rt/M, Ravg indicate route
Impedance mean value;
Step 7: line impedance real value R0, R1, R2 ... Rx of the statistics same day all measurements are in confidence intervalInterior quantity is K, wherein x=N-1;
Step 8: calculating line impedance parameter valueWherein Ri is in confidence intervalIt is interior;
Step 9: by GPRS module, same day line impedance parameter value RL being sent to main website platform.
T value 5 seconds, UCLMT value 4.0V.
The beneficial effects of the present invention are: proposing a kind of feasible low-voltage network line impedance on-line measurement of economic technology
System and method, accessing new power equipment and system evaluation and line fault anticipation to power grid has important references meaning.
Detailed description of the invention
Fig. 1 is the whole composition schematic diagram of system.
Fig. 2 is acquisition terminal composition block diagram.
Fig. 3 is the flow diagram of method.
Specific embodiment
In conjunction with the accompanying drawings, the present invention is further explained in detail.
System integrally forms as shown in Figure 1, being mainly made of main website platform and several acquisition terminals, and acquisition terminal measurement is low
The basic informations such as power grid corresponding line voltage and current are press-fitted, calculate line impedance parameter value, then send to by GPRS network
Main website platform.
For acquisition terminal as key equipment, composition block diagram is as shown in Figure 2.Acquisition terminal by primary processor, metering chip,
The main components such as storage chip, clock chip, GPRS communication module composition passes through clock core under primary processor control first
Piece obtains timeticks, is then measured by metering chip and obtains the basic power information such as each voltage at node electric current of power distribution network,
And it is recorded in storage chip, then calculate by processor using related algorithm and obtain line impedance parameter value, finally by GPRS
Communication module transfers data to main website platform.
Measurement method is as follows:
On acquisition terminal after electricity operation, with " day " for the period, following steps are executed:
Step 1: resetting constant M, constant Rt, constant Sn;
Step 2: according to fixed intervals T, measurement obtains current voltage Uj, electric current Ij, wherein 1≤j≤N, N=24*60*
60/T, T value 5 seconds;
Step 3: voltage Ui, the electric current Ii recorded according to previous cycle, calculating voltage change Δ Ui (Δ Ui=| Uj-Ui
|), current variation value Δ Ii (Δ Ii=| Ij-Ii |), wherein i=j-1,0≤i≤N-1;
Step 4: route real-time impedance value Ri is calculated, if 0 < Δ Ui < UCLMT and Δ Ii ≠ 0, Ri=Δ Ui/ Δ Ii,
M 1, the Rt that adds up adds up Ri, otherwise Ri=0, and wherein UCLMT indicates voltage jump exception limit value, value 4.0V;
If Δ Ui > UCLMT, system thinks that this measurement point is power distribution network exception overshoot current or other abnormal generations, meter
Automatic rejection falls this measurement point when calculation;
Step 5: judging whether the same day terminates, continue step 2 if being not finished, otherwise carry out step 6;
Step 6: calculatingWherein Ri ≠ 0, Ravg=Rt/M, Ravg indicate route
Impedance mean value;
Line impedance number of measurement values is more, and Normal Distribution Characteristics can integrally be presented, and is calculated using normal distribution correlation formula,
Further obtain effective sample;
Step 7: line impedance real value R0, R1, R2 ... Rx of the statistics same day all measurements are in confidence intervalInterior quantity is K, wherein x=N-1;
Step 8: calculating line impedance parameter valueWherein Ri is in confidence intervalIt is interior;
Step 9: by GPRS module, same day line impedance parameter value RL being sent to main website platform.
The above is only the preferred embodiment of the present invention, protection scope of the present invention is not limited merely to above-described embodiment,
All technical solutions belonged under thinking of the present invention all belong to the scope of protection of the present invention.It should be pointed out that for the art
For those of ordinary skill, several improvements and modifications without departing from the principles of the present invention should be regarded as protection of the invention
Range.