CN102914694A - Intelligent electric meter with load measurement function - Google Patents

Abstract

The invention discloses an intelligent electric meter with a load measurement function. Voltage, current, active data and inactive data required for load model measurement can be obtained by a voltage and current signal input module, a signal conditioning module, a sampling module, an A/D conversion module, a storage module, a communication interface and a microprocessor arranged on the intelligent electric meter; according to a voltage grade on which the electric meter is located on as well as a jurisdiction load type, a proper load model is built, and the 24-hour uninterrupted load model structure and parameter identification work are carried out; relevant load information identified and measured by the intelligent electric meter is collected by layers and centrally sent to a master station by an automatic meter reading system, so that a flow of basis data is provided for load modeling and load prediction. According to the intelligent electric meter with a load measurement function, which is disclosed by the invention, a load model measurement algorithm is transplanted to the intelligent electric meter, the accessed load model structure and parameter can be subjected to on-line identification by the voltage and current input amount of the electric meter, and a measurement result is sent to the master station via the automatic meter reading system so as to realize the wide area load modeling for power system load.

Description

Have load measuring and distinguish the intelligent electric meter of function

Technical field

The invention belongs to the Power System and its Automation technical field, relate to a kind of intelligent electric meter.

Background technology

Modeling for Electric Loads is the also very difficult work of a very important while, and the accuracy of load model has very important impact to electric power system design, analysis and calculation, particularly the result of power system safety and stability analysis is had direct impact.

The difficult point of load model research is that load exists the characteristics such as randomness, time variation, dispersiveness, diversity and uncontinuity, for a long time, experts and scholars have carried out research extensively and profoundly both at home and abroad, four kinds of methods have totally been formed, method, fault simulation method and mixing method are distinguished in Component Based, total body examination, and these methods have all obtained good effect at different aspect.But electric system is the system of development, along with the use of the variation of system scale, new technical equipment, all work has brought lot of challenges to load modeling in the introducing of distributed energy.

In fact, any load modeling method needs that all the composition of load and proportion are had accurately understanding, and there are enough samples to guarantee the effect of modeling, statistical data is incomplete and a major issue is for a long time loaded exactly, and reason is that obtaining of statistical data is a huge engineering.The obtain sales check, the user that generally derive from electrical equipment that load forms inventory declare document etc.; Load uses data source in the periodic measurement of consumer; According to user's power consumption form, in order to determine the proportion of each type load in overall.Because of a great variety, the enormous amount of load and constantly increasing changes, have in the region simultaneously and have dispersiveness, a statistical work also is difficult to finish once in a while, has said nothing of regular statistics, even finished statistical work, but the randomness of load also has no way of holding.

Electric energy meter is the electric system electric energy measuring equipment, extensive, the most basic electric power data acquisition, measurement and processing unit of a kind of distribution, and all useful various uses electric energy meter meters at all levels of system, from the electric supply meter of least significant end, feeder line table that power distributing meter is stood to factory, Source of Gateway Meter etc.

Intelligent electric meter is the emphasis that global intelligent grid is built, along with carrying out of intelligent grid construction, the development of intelligent electric meter and use and also to have reached higher level, modern electric energy meter are the parameters of electric power comprehensive monitoring equipments that integrates the several functions such as meritorious, reactive energy-meter, maximum demand meter, meritorious, reactive volt-ampere meter, power factor meter, frequency meter, voltage table, rate of qualified voltage table, electric energy quality monitor, noisy data registering instrument, load governor.Not only can monitor and record electric parameter, can also form a day typical load curve, even can carry out some and control on the spot.At present a lot of ammeters have all adopted high-performance MCU and dsp chip, and signal handling capacity unprecedentedly improves, and along with its computing power of development of technology will further improve, and price constantly descends, and this is just so that ordinary electric meter has very high computing and processing power.The application of the technology such as power line communication, radio communication has greatly promoted again the development of Automatic meter reading system, and power department can be copied power taking meter reading and relevant information by the technological means such as power-line carrier communication (PLC) or GPRS (GPRS) realization remote auto.

Summary of the invention

The objective of the invention is: the method to set up that a kind of intelligent electric meter is provided, make intelligent electric meter have load measuring and distinguish function, transplant therein load model structure and parameter identification algorithm, make ammeter have the load model survey and distinguish function, to load by Automatic meter reading system and to send main website on the relevant information, can realize the wide area modeling of power system load.

The technical scheme that the present invention takes is: have the intelligent electric meter that load measuring is distinguished function, utilize the input of the voltage and current signal that intelligent electric meter is provided with, signal condition, sampling, the A/D conversion, storage, communication interface and microprocessor (being ready-made hardware resource basically), obtain the load model survey and distinguish required voltage, electric current, meritorious, the data such as idle, according to ammeter place electric pressure, the jurisdiction Overload Class, set up appropriate load model and carry out continual load model structure and parameter identification work in 24 hours, send the load modeling main website on the relevant information that will add up and pick out by Automatic meter reading system, thereby be load modeling, load prediction provides endlessly basic data.

The load relevant information layering of intelligent electric meter being measured and being picked out by Automatic meter reading system is collected and is concentrated and send main website.

Load model surveyed distinguish that algorithm is transplanted in the intelligent electric energy meter, utilize the voltage of electric energy meter, electric current input quantity that the load model structure and parameter of access is carried out on-line measurement and identification.Realize the identification of load statistics and model parameter; At last, by electric meter data collecting system will add up and identification information collect and put in order, the load relevant information of all each levels is carried out comprehensive statistics, analyzes and checked, final load composition, proportion and the time response etc. of obtaining, thus set up the load model that tallies with the actual situation.

The key content of power system load modeling comprises model structure and two aspects of parameter identification, and in general, the load composition is simply then determined rational model structure easily, and its parameter of model rational in infrastructure is just easily identification also, and accuracy is also high.Follow this thinking, at first for certain piece intelligent electric meter, one family user typical load is for example added up the composition of its typical consumer, from physical essence and the mechanism of load, sets up the load model that tallies with the actual situation; Secondly, in the intelligent electric meter handling procedure, implant suitable Online statistics modeling algorithm, realize the identification of load statistics and model parameter; At last, by electric meter data collecting system will add up and identification information collect and put in order, the load relevant information of all each levels is carried out comprehensive statistics, analyzes and checked, final load composition, proportion and the time response etc. of obtaining, thus set up the load model that tallies with the actual situation.Step is as follows:

1) algorithm picks:

Because intelligent electric meter is widely distributed, from probability, the intelligent electric meter of different regions and different electric pressures always experiences various disturbances, therefore, can formulate different identification schemes for different situations.For example in the larger area of some voltage fluctuation or electric pressure (voltage slowly fluctuation the surpasses 10%) survey that can carry out static model distinguish, can carry out the survey of dynamic model for the multiple area of disturbance (the voltage rapid fluctuations surpasses 5%) and distinguish.By being set, certain disturbance differentiates threshold, can identify the system disturbance mode, carrying out the model survey of different modes distinguishes, and for more susceptible condition, voltage fluctuation is actual to be difficult to reach above-mentioned scope, but voltage might often run in the quick variation of (generally about 2%) among a small circle, therefore for this more generally situation, can adopt the discrimination method of " moving rear quiet first ", obtain simultaneously dynamically and static parameter.

Be provided with load model and parameter and survey know algoritic module, load model is surveyed the knowledge algoritic module with parameter and is carried out following flow process: obtain the static nature coefficient of loading from dynamic model.At first, adopt dynamic model to remove to describe load; Secondly depart from when very little at voltage and frequency and initial value, can be with the static model linearization, adopt the method for this " moving rear quiet first; as to be association of activity and inertia ", can obtain very easily the static nature coefficient by the dynamic model of identification gained, increase hardly calculated amount and can obtain simultaneously dynamic model and static model, this algorithm is very suitable for voltage among a small circle (about 2%) the fast on-line identification of intelligent electric meter under situation of change.

2) communication interface: expand the Automatic meter reading system Content of Communication of intelligent electric meter, increase the relevant content of load model, be convenient to reception and the statistics of load modeling main website.

The invention has the beneficial effects as follows:

1) the present invention utilizes the resources such as the existing hardware of intelligent electric meter, communication, network, and coverage rate is the widest, does not have blind spot, does not increase the additional hardware equipment investment.

2) the present invention can make up wide area load modeling system, can be the user endlessly basic load data are provided, thereby promote carrying out of every research work.

3) the invention solves in the past extremely importantly to load modeling but be difficult to again simultaneously the load statistical work finished, and realize that load statistics and the survey of 24 hours continual wide areas distinguish work, set up permanent mechanism.

4) the various achievements in research that form of in the past load modeling can be inherited and use.

The invention discloses a kind of intelligent electric meter technical scheme that function is distinguished in the load model survey that has, this scheme is surveyed load model and is distinguished that algorithm is transplanted in the intelligent electric energy meter, utilize voltage, the electric current input quantity of electric energy meter that the load model structure and parameter of access is carried out on-line identification, survey distinguishes that the result delivers to main website by Automatic meter reading system, realizes the wide area load modeling of power system load.

Description of drawings

Fig. 1 has the intelligent electric meter schematic diagram of load model structure and parameter discriminating function.

Embodiment

1) algorithm picks: according to the load modeling method of aforesaid " moving rear quiet first, as to be association of activity and inertia ", its expression formula is:

The formula of dynamic model is as follows:

$\mathrm{\ΔP}=(\mathrm{dP}/\mathrm{dU}){|}_{\stackrel{U=U_0}{f=f_0}}\mathrm{\ΔU}+(\mathrm{dP}/\mathrm{df}){|}_{\underset{f=f_0}{U=U_0}}\mathrm{\Δf}$

$\mathrm{\ΔQ}=(\mathrm{dQ}/\mathrm{dU}){|}_{\stackrel{U=U_0}{f=f_0}}\mathrm{\ΔU}+(\mathrm{dQ}/\mathrm{df}){|}_{\underset{f=f_0}{U=U_0}}\mathrm{\Δf}---\left(1\right)$

That is:

$\left[\begin{array}{c}\mathrm{\ΔP}\\ \mathrm{\ΔQ}\end{array}\right]=\left[\begin{array}{c}\mathrm{dP}/\mathrm{dU}\mathrm{dP}/\mathrm{df}\\ \mathrm{dQ}/\mathrm{dUdQ}/\mathrm{df}\end{array}\right]\left[\begin{array}{c}\mathrm{\ΔU}\\ \mathrm{\Δf}\end{array}\right]---\left(2\right)$

Δ U wherein, Δ f is that voltage and frequency are input variables, Δ P, Δ Q for meritorious and idle be output variable.

Secondly, (voltage and frequency are changing among a small circle) dynamic model deteriorates to static model under steady state conditions, and its state equation is:

$\frac{\mathrm{dX}}{\mathrm{dt}}=\mathrm{AX}+\mathrm{BV}$

Y＝CX+DV （3）

Wherein:

X: state vector

Y: output state vector

V: control vector

A: coefficient of regime matrix

B: control coefrficient matrix

C: output state matrix of coefficients

D: output control coefrficient matrix

According to the physical essence of loading as can be known, each variable derivative is the zero static model that namely get in the dynamic model, order: $\frac{\mathrm{dX}}{\mathrm{dt}}=0,$ Can get:

Y＝[-CA ^-1B+D]V （4）

Wherein: Y=[Δ P, Δ Q] ^T, V=[Δ U, Δ f] ^T

Comparison expression (2) can get with (4):

$\left[\begin{array}{cc}\mathrm{dP}/\mathrm{dU}& \mathrm{dP}/\mathrm{df}\\ \mathrm{dQ}/\mathrm{dU}& \mathrm{dQ}/\mathrm{df}\end{array}\right]=-{\mathrm{CA}}^{-1}B+D---\left(5\right)$

And the static nature coefficient is:

$p_u=(\mathrm{dP}/\mathrm{dU})\frac{U_0}{P_0},p_f=(\mathrm{dP}/\mathrm{df})\frac{f_0}{P_0}$

$q_u=(\mathrm{dQ}/\mathrm{dU})\frac{U_0}{Q_0},q_f=(\mathrm{dQ}/\mathrm{df})\frac{f_0}{Q_0}---\left(6\right)$

P wherein _u, p _f, q _u, q _fBe the Static Load characteristic coefficient, and dP/dU, dP/df, dQ/dU, dQ/df can be tried to achieve by dynamic model, have so just obtained the static nature coefficient of load from dynamic model.

2) program portable: program according to above-mentioned model, it is transplanted in the central microprocessing unit (MCU) of ammeter, obtain the parameters such as the voltage, electric current of electric energy computation chip, meritorious, idle, frequency, power factor, finish the exploitation of the intelligent electric meter with load model structure and parameter discriminating function.

3) ammeter is installed.

Claims (3)

1. have load measuring and distinguish the intelligent electric meter of function, it is characterized in that: utilize the input of the voltage and current signal that intelligent electric meter is provided with, signal condition, sampling, the A/D conversion, storage, communication interface and microprocessor, obtain the load model survey and distinguish required voltage, electric current, meritorious, the data such as idle, according to ammeter place electric pressure, the jurisdiction Overload Class, set up appropriate load model and carry out continual load model structure and parameter identification work in 24 hours, the load relevant information layering of intelligent electric meter being measured and being picked out by Automatic meter reading system is collected and is concentrated and send main website; Thereby for load modeling, load prediction provide endlessly basic data.

2. according to claim 1 have an intelligent electric meter that load measuring is distinguished function, it is characterized in that: load model is surveyed distinguished that algorithm is transplanted in the intelligent electric energy meter, utilize the voltage of electric energy meter, electric current input quantity that the load model structure and parameter of access is carried out on-line measurement and identification.Realize the identification of load statistics and model parameter; At last, by electric meter data collecting system will add up and identification information collect and put in order, the load relevant information of all each levels is carried out comprehensive statistics, analyzes and checked, final load composition, proportion and the time response etc. of obtaining, thus set up the load model that tallies with the actual situation.

3. according to claim 1 and 2 have an intelligent electric meter that load measuring is distinguished function, it is characterized in that: the content of power system load modeling comprises model structure and two aspects of parameter identification, intelligent electric meter at first, add up the composition of its typical consumer, from physical essence and the mechanism of load, set up the load model that tallies with the actual situation; Secondly, in the intelligent electric meter handling procedure, implant suitable Online statistics modeling algorithm, realize the identification of load statistics and model parameter; At last, by electric meter data collecting system will add up and identification information collect and put in order, the load relevant information of all each levels is carried out comprehensive statistics, analyzes and checked, final load composition, proportion and the time response of obtaining, thus set up the load model that tallies with the actual situation; Step is as follows:

1) algorithm picks:

Formulate different identification schemes for different situations.In the larger area of some voltage fluctuation or the survey of carrying out static model when slowly fluctuation surpasses 10% of electric pressure, voltage distinguish; For the multiple area of disturbance, voltage rapid fluctuations surpass 5%, the survey of carrying out dynamic model distinguishes; Differentiate threshold by disturbance is set, identify the system disturbance mode, carry out the model survey of different modes and distinguish; Be difficult to reach above-mentioned scope to voltage fluctuation is actual, but voltage adopts the discrimination method of " first moving after quiet " when 2% among a small circle quick variation, obtain simultaneously dynamically and static parameter;

Be provided with load model and parameter and survey know algoritic module, load model is surveyed the knowledge algoritic module with parameter and is carried out following flow process: obtain the static nature coefficient of loading from dynamic model.At first, adopt dynamic model to remove to describe load; Secondly depart from when very little at voltage and frequency and initial value, with the static model linearization, adopt the method for this " moving rear quiet first; as to be association of activity and inertia ", dynamic model by the identification gained obtains the static nature coefficient very easily, increase hardly calculated amount and can obtain simultaneously dynamic model and static model, this algorithm is very suitable for voltage in the among a small circle fast on-line identification of intelligent electric meter under the situation of change;

2) communication interface: expand the Automatic meter reading system Content of Communication of intelligent electric meter, increase the relevant content of load model, be convenient to reception and the statistics of load modeling main website.

3) formula of dynamic model is as follows:

That is:

Δ U wherein, Δ f is that voltage and frequency are input variables, Δ P, Δ Q for meritorious and idle be output variable.Secondly, be that voltage and frequency dynamic model when changing among a small circle deteriorates to static model under steady state conditions, its state equation is:

Y＝CX+DV （3）

Wherein:

X: state vector

Y: output state vector

V: control vector

A: coefficient of regime matrix

B: control coefrficient matrix

C: output state matrix of coefficients

D: output control coefrficient matrix

According to the physical essence of loading as can be known, each variable derivative is the zero static model that namely get in the dynamic model, order:

Can get:

Y＝[-CA ^-1B+D]V （4）

Wherein: Y=[Δ P, Δ Q] ^T, V=[Δ U, Δ f] ^T

Comparison expression (2) can get with (4):

And the static nature coefficient is:

P wherein _u, p _f, q _u, q _fBe the Static Load characteristic coefficient, and dp/dU, dP/df, dQ/dU, dQ/df can be tried to achieve by dynamic model, have so just obtained the static nature coefficient of load from dynamic model.