CN204992761U - Electric energy quality is synthesized and is observed and controled appearance - Google Patents

Abstract

The utility model relates to an electric energy quality is synthesized and is observed and controled appearance, MCU control module is connected to the man -machine interface module, and MCU control module connects measurement control module, communication interface, temperature detection module, zero -cross detection module and SD joint mouth, measurement control module junction current mutual -inductor signal acquisition circuit and control module 0 signal acquisition circuit. Consequently the utility model discloses an algorithm is judged to idle trend, is applicable to the big occasion of power factor change, and the action number of times is few, and control accuracy is high, has improved whole cabinet body production efficiency greatly, has reduced the probability of makeing mistakes, has improved whole product quality, appearance elegant appearance, general instrument size installation convenient to use.

Description

A kind of comprehensive power quality measurement and control instrument

Technical field

The utility model belongs to electrical network for distribution technique field, particularly relates to a kind of comprehensive power quality measurement and control instrument.

Background technology

At present, the quality testing of electric energy and control device occur, as Power System Fault Record instrument and reactive power compensator etc. with checkout gear and control device two kinds of forms respectively.Along with the development of electric power system, the shortcoming of simple function is obviously outstanding: one is that volume is large, cost is high, floor space is large, installing space is limited; Two is that Power Quality Detection controls to be separated, and Detection Information can not effectively utilize in real time, and control effects can not reflect preferably and verify.

Utility model content

The utility model be solve electric energy quality testing and control device function singleness, volume is large, cost is high, floor space is large, installing space is limited, Power Quality Detection controls to be separated, Detection Information can not effectively utilize in real time, the technical problem that control effects can not reflect preferably and verify and provide the comprehensive power quality measurement and control instrument that a kind of structure is simple, easy to install, increase work efficiency.

The technical scheme that the utility model is taked for the technical problem existed in solution known technology is:

Comprehensive power quality measurement and control instrument of the present utility model, this comprehensive power quality measurement and control instrument comprises: human-computer interaction interface module, MCU control module, metering control module, communication interface, current transducer signal Acquisition Circuit, voltage transformer signal acquisition circuit, temperature detecting module, zero passage detection module, SD card interface;

Human-computer interaction interface model calling MCU control module, MCU control module connects metering control module, communication interface, temperature detecting module, zero passage detection module and SD card interface, and metering control module connects current transducer signal Acquisition Circuit and voltage transformer signal acquisition circuit.

The utility model can also adopt following technical measures:

In the utility model, MCU control module connects metering control module by Serial Peripheral Interface (SPI).

Further, MCU control module is by serial ports RS485 and RS232 connecting communication interface.

Further, MCU control module connects SD card interface by Serial Peripheral Interface (SPI).

Further, the concrete connection of piezoelectric voltage transducer signal Acquisition Circuit is:

Inductance T1 contact resistance R1 and resistance R3, resistance R1 connect electric capacity C1 and resistance R2, resistance R3 and connect electric capacity C2 and resistance R4, and resistance R2 is connected with resistance R4.

Further, telecommunication signal circuit is adopted to adopt the current transducer signal Acquisition Circuit of differential mode.

Further, the concrete connection of current transducer signal Acquisition Circuit is: inductance T2 contact resistance R42 and resistance R49, resistance R46 and resistance R42 and resistance R49 in parallel, resistance R42 contact resistance R40, electric capacity C38, resistance R49 connects electric capacity C39 and resistance R50, electric capacity C39 and connects electric capacity C38.

The advantage that the utility model has and good effect are: due to the utility model it to be shown by digital-scroll technique or LCD and LED electrical hold state indicate coordinate keyboard form man-machine interactive interface, RJ45 port 485 communication interfaces, two groups of electricity current signal ends, one group of bus voltage signal end, control signal outputs and form with 232 communication interfaces of upper machine communication, control physical quantity be total cabinet voltage, total cabinet electric current, capacitor box electric current, power factor and reactive power, temperature again etc.; Adopt novel idle trend trend evaluation algorithm, be specially adapted to power factor and change large occasion, action frequency is few, control precision is high, substantially increases whole cabinet production efficiency, reduces probability of makeing mistakes, entirety is improved the quality of products, and good looking appearance is generous, and general purpose instrument size is easy to install.

Accompanying drawing explanation

Fig. 1 is the comprehensive power quality measurement and control instrument structural representation that the utility model embodiment provides;

In figure: 1, human-computer interaction interface module; 2, MCU control module; 3, metering control module; 4, communication interface; 5, current transducer signal Acquisition Circuit; 6, voltage transformer signal acquisition circuit; 7, temperature detecting module; 8, zero passage detection module; 9, SD card interface;

Fig. 2 is the voltage transformer signal acquisition circuit schematic diagram that the utility model embodiment provides;

Fig. 3 is the current transducer signal Acquisition Circuit schematic diagram that the utility model embodiment provides;

Fig. 4 is active power, reactive power, the relation schematic diagram between apparent power that the utility model embodiment provides;

Fig. 5 is the raising power factor schematic diagram that the utility model embodiment provides;

Fig. 6 is the loss schematic diagram of the reduction transmission line that provides of the utility model embodiment and transformer;

Fig. 7 is the workflow diagram of the comprehensive power quality measurement and control instrument that the utility model embodiment provides.

Embodiment

For summary of the invention of the present utility model, Characteristic can be understood further, hereby exemplify following examples, and coordinating accompanying drawing to be described in detail as follows: the software module used by the utility model all belongs to known module, when buying hardware module, is provided with software.There is not the innovation of software or method in the utility model.

Refer to Fig. 1:

As shown in Figure 1, the comprehensive power quality measurement and control instrument of the utility model embodiment mainly comprises: human-computer interaction interface module 1, MCU control module 2, metering control module 3, communication interface 4, current transducer signal Acquisition Circuit 5, voltage transformer signal acquisition circuit 6, temperature detecting module 7, zero passage detection module 8, SD card interface 9;

Human-computer interaction interface module 1 connects MCU control module 2, MCU control module 2 connects metering control module 3, communication interface 4, temperature detecting module 7, zero passage detection module 8 and SD card interface 9, and metering control module 3 connects current transducer signal Acquisition Circuit 5 and voltage transformer signal acquisition circuit 6;

MCU control module 2 connects metering control module 3 by Serial Peripheral Interface (SPI) (SPI);

MCU control module 2 is by serial ports RS485 and RS232 connecting communication interface 4;

MCU control module 2 connects SD card interface 9 by Serial Peripheral Interface (SPI) (SPI).

The utility model adopts the control core of STM32F407 Series MCU control module, ATT7022E is the core of metering control module, and the voltage that adapted electric current, voltage measuring transformer power network signal, SD card store data, ambient temperature detects, friendly human-computer interaction interface module and the RS485 port of outer end terminal called, the RS232 PORT COM passing to Surveillance center, power network monitoring are supporting, current over-zero measuring ability formed;

As Fig. 2 voltage transformer signal acquisition circuit, T is 1:1 voltage transformer (2mA to 2mA);

Concrete connection: inductance T1 contact resistance R1 and resistance R3, resistance R1 connect electric capacity C1 and resistance R2, resistance R3 and connect electric capacity C2 and resistance R4, and resistance R2 is connected with resistance R4.

As Fig. 3 current transducer signal Acquisition Circuit, T is current transformer (5A to 2.5mA), and telecommunication signal circuit adopts differential mode, and wherein in input circuit, 1.2K resistance and 0.01uf electric capacity constitute frequency overlapped-resistable filter; Circuit is particular about symmetrical, and adopting the good element of temperature performance to ensure, that comprehensive power quality measurement and control instrument obtains is good stability;

Inductance T2 contact resistance R42 and resistance R49, resistance R46 and resistance R42 and resistance R49 in parallel, resistance R42 contact resistance R40, electric capacity C38, resistance R49 connect electric capacity C39 and resistance R50, electric capacity C39 and connect electric capacity C38;

Be three-phase three-wire system when SEL and ground short circuit, phase three-wire three ammeter adopts two elements metering system, and B phase does not participate in electric energy metrical, terminal connections substitutes the VN of three-phase and four-line with VB;

Voltage sample input V4P and V4N, current sample input V3P and V3N can as independently signal inputs, the corresponding register of the readable B phase of its voltage, electric current, power, power factor value;

When any phase current and voltage reversal, chip the 40th pin REVP exports high level, can judge that whether wiring is wrong accordingly; Reactive energy pulse signal is then the idle instantaneous power obtained in metering circuit, to becoming reactive energy signal after time integral, go again to generate reactive energy pulse signal, fundamental active is also same, they all need, according to the conjunction phase energy accumulation mode of setting, three-phase electric energy is done absolute value and are added or algebraic value sum operation, and result is transformed to frequency signal, then carry out frequency division according to the divide ratio of user's setting, obtain the electrical energy pulse output signal that can be used for calibration;

Comprehensive power quality measurement and control instrument has calibration function, compensates exactly to each phase current gain, voltage gain, power gain, phase place; Phasing according to required precision, can consider that segmentation or not segmentation are carried out; Segmentation divides by the size of electric current, and comprehensive power quality measurement and control instrument can divide two sections to carry out phase compensation, and its starting current can use software design patterns with disconnected phase threshold voltage;

Have voltage, current correction in can arranging, starting current is arranged, and disconnected phase threshold voltage is arranged, the requirement all not in order; But carrying out power gain timing, please note first to arrange and close phase energy accumulation mode (as default value then can save this step required for you), voltage, current channel ADC gain and high frequency output parameter, this is the condition of capability correction, then first power gain calibration, carry out phasing again, phasing carries out after completing power gain correction;

The utility model compensation principle:

In alternating current circuit, have two kinds by power supply supply load rate: one is active power, one is reactive power; Active power keeps power consumption equipment normally to run required electrical power, namely converts electrical energy into the electrical power of other form energies (mechanical energy, luminous energy, heat energy); The symbol of active power represents with P, and there are watt (W), kilowatt (KW), megawatt (MW) in unit; Reactive power is more abstract, and it is the exchange for circuit internal electric field and magnetic field, and with setting up and maintain the electrical power in magnetic field in the electrical apparatus; It does not externally do work, but changes other forms of energy into; Every electric equipment having solenoid, set up magnetic field will consume reactive power; The symbol of reactive power represents with Q, and unit is weary (Var) or kilovar (kVar); Reactive power is useless power anything but, it very useful; The rotor field of motor is set up by obtaining useless power from power supply; Transformer needs reactive power too, the primary winding of transformer just can be made to produce magnetic field, induce voltage at secondary coil; Electric load in electrical network, as motor, transformer etc., belongs to the inductive load that existing resistance has again inductance; There is a phase difference between the phasor of the voltage and current of inductive load, usually represent with the cosine cos φ of angle phi; Cos φ is called power factor, is power rate again; Power factor is an important indicator of reflection power consumer equipment reasonable employment situation, utilization of power degree and management of power use level; The computing formula of three-phase activity coefficient is:

$\begin{array}{ccc}P=\sqrt{3}UI\cos \mathrm{\θ}& Q=\sqrt{3}UI\cos \mathrm{\θ}& S=\sqrt{3}\mathrm{UI}\end{array}$ cosθ＝P/S

Cos φ---power factor in formula;

P------active power, kw;

Q------reactive power, kVar;

S------apparent power, kv, A;

The rated voltage of U------power consumption equipment, V;

The running current of I------power consumption equipment, A;

Many point devices in electrical network are according to electromagnetic induction principle work; They set up alternating magnetic field in conversion process of energy, and equal at the power of the systemic power of one-period and release, this power is reactive power; In electric power system, not only active power balance, reactive power also will balance;

Relation between active power, reactive power, apparent power as shown in Figure 4

$S=\sqrt{P^2+Q^2}$

In formula

S------apparent power, KVA

P------active power, KW

Q------reactive power, kvar

φ angle is power-factor angle, and to be active power be called power factor with the ratio of apparent power and cos φ=P/S for its cosine (cos φ);

The general principle compensated is: having the device of capacitive power load and inductive load and being connected to same circuit, energy mutually exchanges between two kinds of loads; Like this, the reactive power compensation that the reactive power required for inductive load can be exported by capacitive load;

Improve power factor, as shown in Figure 5,

P------active power;

The S1------apparent power before compensation;

The S2------apparent power after compensation;

The Q1------reactive power before compensation;

The Q2------reactive power after compensation;

The φ 1------power-factor angle before compensation;

The φ 2------power-factor angle after compensation;

Can find out, under the prerequisite that active-power P is certain, after reactive power compensation (compensation rate Qc=Q1-Q2), power-factor angle is reduced to φ 2 by φ 1 φ, then cos φ 2 > cos φ 1 improves power factor;

Reduce the loss of transmission line and transformer

In three-phase circuit, the computing formula of power loss △ P is

$\mathrm{\Δ}P=3\frac{P^{2}R}{U^2{\left(\cos \mathrm{\θ}\right)}^2}\left(kw\right)$

P in formula---active power, KW

U------rated voltage, KV;

R------circuit all-in resistance, Ω;

As can be seen here, after powerfactorcosφ improves, in circuit, power loss declines greatly;

As shown in Figure 6, quality of voltage is improved

The computing formula of loss of voltage △ U in circuit

$\mathrm{\Δ}U=3\frac{P\×R+Q\×X_L}{U}\left(k\mathrm{\ν}\right)$

P in formula------active power, KW;

Q------reactive power, Kvar;

U------rated voltage, KV;

R------circuit all-in resistance, Ω;

X------circuit induction reactance, Ω;

From above formula, when in circuit, after reactive power Q reduces, loss of voltage △ U it also reduces;

The person of choosing of condenser capacity:

The person of choosing of capacitor installed capacity, according to the difference of application target, by improving power factor, can improve working voltage and reduction line loss etc. because usually determining;

Easy, clear and definite by the method improving power factor determination compensation capacity, by general both at home and abroad; According to the vector relations between power in power back-off figure (as Fig. 5), reactive compensation capacity Qc can be obtained;

Q _C,＝Q ₁-Q ₂＝P×tgθ ₁-P×tgθ ₂＝P(tgθ ₁-tgθ ₂)(kvar)

Or $Q_C=P_m(\mathrm{tg\θ}1-\mathrm{tg\θ}2)=P_m(\sqrt{\frac{1}{\cos {{\mathrm{\θ}}_1}^2}-1-\sqrt{\frac{1}{\cos {{\mathrm{\θ}}_2}^2}}}-1)---\left(\mathrm{kvar}\right)$

The utility model is according to hardware designs in conjunction with the rational program architecture of STM32F407 core design, and external interrupt all supported by its all I/O port, exchanges data between memory and peripheral hardware can have been controlled by DMA, support real-time clock function, DSP scientific calculation function etc.; The high accuracy bringing the real-time of electrical network electric energy quality monitoring, electrical network parameters to measure to the realization of comprehensive power quality controlling functions, the real-time of electric network data process and send out the accurate reliability of control command to terminal; System architecture adopts the timeslice poll based on class real-time system and coordinates the mode of external interrupt to write through me, moves value to STM32F407 test and continuous perfect to form, and basic procedure is as Fig. 7;

Comprehensive power quality measurement and control instrument optimum configurations can be arranged and the setting of reactive power bound power factor bound by upper computer software by RS232 serial ports, also (0.8 ~ 0.99 can be dropped into by the input through keyboard on human-computer interaction interface, excise delayed 0.91 ~ advanced 0.9, step-length 0.01), capacitor actions delay time setting (0 ~ 90S, step-length 1S, system performs switching and all should to meet the value sampling physical quantity in this delay time operate time and should to remain in stability range i.e. COS θ and do not cross and cross threshold value, reactive power change is no more than a step-length), overvoltage threshold sets (400 ~ 500, step-length 1V), sampling mutual inductor setting is (uncertain, depend on algorithm) control group number and respectively organize electric capacity (Q0 ~ Q29), harmonic protection parameter (3, 5, 7, 9, 11 what meaning first harmonic electric current exceed set point and namely protect) under above setting parameter state, 30S automatically returns to automatic running status without any operation, have harmonic wave, overvoltage, under-voltage, unload phase, power-failure protecting function: during protection act excision thrown electric capacity and forbidden throwing again, all input electric capacity all should be excised in 3min when above fault occurs, under remaining on malfunction after there is harmonic failure, until manual reversion auto state always, namely protection act order is sent out when harmonic voltage or harmonic current (3,5,7,9,11) exceed set point, overvoltage protection refers to that performing protection act when system voltage exceedes set point works as voltage lower than set point higher than 10% of rated voltage, system is sent out and is removed Capacitor banks switch disjunction action command signal and blocking capacitor group switch closure command, and overvoltage recovers rear system worked well, phase shortage, power-failure protecting refer to when any line voltage is lower than sending out protection act order during rated voltage 25%, under-voltage protection refers to when system voltage is lower than sending excision Capacitor banks order fast during set point,

Utilize the house dog carried in microcontroller to judge cold start-up or warm start, distinguishing run time version, involution output loop when start or fault, guarantees that microcontroller does not crash not cause at work and produces harmful effect to reactive power compensation, electric energy metrical, system protection;

Capacitor group switching algorithm

The utility model adopts one will carry out capacity configuration according to idle amount needed for capacitance group capacity and system, forms multistage capacity switching; N group electric capacity by a certain percentage 2 ⁿ-1 grade is not waited capacity switching; The corresponding group coding of every level capacity, the corresponding power factor section of every level capacity; Compensation capacity can by following formulae discovery:

$Q_C=P_m(\mathrm{tg\θ}1-\mathrm{tg\θ}2)=P_m(\sqrt{\frac{1}{\cos {{\mathrm{\θ}}_1}^2}-1-\sqrt{\frac{1}{\cos {{\mathrm{\θ}}_2}^2}}}-1)$

P _mfor per day active power (K _var),

Cos θ ₁for the power factor before compensation;

Cos θ ₂for the power factor after compensation, required compensation capacity Q _c(K _var);

Compensation capacity meets following formula:

$P_m(\sqrt{\frac{1}{\cos {{\mathrm{\θ}}_1}^2}-1-\sqrt{\frac{1}{\cos {{\mathrm{\θ}}_2}^2}}}-1)\≤Q_c\≤P_m(\sqrt{\frac{1}{\cos {{\mathrm{\θ}}_1}^2}-1-\sqrt{\frac{1}{\cos {{\mathrm{\θ}}_2}^2}}}-1)$

If but capacitance mis-arrange is by discontinuous or occur overlapping phenomenon for the power factor corresponding to causing encoding, therefore the former can not get because of the coding section that can not find in power factor section correspondence compensating, and the latter can cause the waste of capacitance; Not overlapping continuously for guaranteeing the power factor section corresponding to coding, specific algorithm is as follows:

When being in limited time not more than higher limit for during input first group of electric capacity Q1 under compensation power factor is close to given range, determining the capacitance of the first pool-size according to formula, substituting into formulae discovery and determining the coding of its correspondence; Here consider that calculation of capacity needs to affect real-time when flower, so adopt communication modes each capacitor automatically the machine number of the machine capacitance level correspondence to be reported main frame (after capacitor networking, other is set to main frame or power factor controller, refers to capacitor intelligent networking here); Main frame puts into compensation capacity database the numbering of capacitance and correspondence, and puts in place according to coding switching algorithm disposable compensation, and the deficiency that compensate for the production switching concussion in conventional switching cycle also compensate for the drawback of coding type switching;

The communications protocol that the utility model adopts adopts the MODBUS agreement of East China Power Grid standard, its organization definition

Partial code (definition of agreement storage area used) is as follows

The utility model basic function:

1, reactive-load compensator basic function:

Have the protections such as overvoltage, under-voltage, low stream, excess temperature, harmonic wave, when electrical network parameter exceedes a certain setup parameter, controller can send the order of excision electric capacity immediately.Capacitor for voltage protection safe operation, extends its useful life.

2, power quality measurement fundamental surveillance function

Adopt voltage, current sensor Real-time Collection power network signal measure electrical network three-phase fundamental voltage, current effective value; Reactive power, power factor, active power, fundamental power, phase place, voltage deviation, mains frequency etc.Measure non-equilibrium among three phase voltages, current unbalance factor, negative sequence voltage, electric current.Effectively can monitor electrical network the harmonic wave (2 ~ 40 times) can measured in electrical network and comprise voltage, the total harmonic distortion factor of electric current, each harmonic containing ratio, amplitude, phase place; The active power of each harmonic and reactive power etc.Therefore can accomplish that compensatory control accurately puts in place, there will not be and compensate vibration.

3, the utility model statistical function:

Comprehensive power quality measurement and control instrument has the Online statistics function to the main monitoring parameter index of electrical network, can add up the electrical network of (normally a day) in a time period monitoring want the maximum of monitoring parameter index, minimum value, mean value, 95% the large value of probability etc.

4, with local area network (LAN) Surveillance center to connection function:

The utility model has RS232 communication function, can extend out GPRS, Modem wireless or wired with the docking of local area network (LAN) center host.Background monitoring software simulating power system monitor can be joined, power system monitor software adopts the secondary development of three-dimensional force control electric power version configuration software to form, each station terminal can be monitored, comprise the voltage, electric current, reactive power, power factor, mains frequency, active power, harmonic number, phase place etc. that gather every station terminal.The reactive power compensation situation, harmonic protection situation etc. of each terminal can be checked simultaneously.

5, on-line monitoring New function is added

Can m-Acetyl chlorophosphonazo be detected, voltage fluctuation, flickering, voltage swells, in good time between interrupt, temporary overvoltage.

6, writing function

Be furnished with memory card interface in machine, user can insert storage card and preserve in real time fundamental surveillance content and enhancing monitoring content.Statistics time interval is for can arrange 3min (maximum), and storage mode presses first in first out, supports FAT32 file format, is convenient to read the historical data of electrical network for analysis and research with computer.

7, warning function

Can start corresponding warning according to the threshold value of the quality of power supply instruction of user's setting, on panel, corresponding alarm lamp is bright and can pass to Surveillance center by communication, and simultaneously to present networks compensator, protector sends out protecting control order corresponding.

8, operating voltage

Single-phase AC220V-20% ~+15% or three-phase 380V-20% ~+15%.

9, instrument transformer input

Current transformer input signal 5A/2.5mA, voltage transformer adopts current mode voltage transformer.Input signal 2mA/2mA.

10, the precision of Monitoring Data

Voltage, electric current: 0.2%, power, power: 0.5%, voltage three-phase imbalance: 0.2%, current three-phase is uneven: 0.5%; Harmonic wave to meet in GB GB/T14549-1993 A level in Appendix D; M-Acetyl chlorophosphonazo is with reference to A level in Appendix D in black GB/T14549-1993; Voltage fluctuation, flickering: 5%; Mains frequency deviation: 0.005HZ.

The above is only to preferred embodiment of the present utility model, not any pro forma restriction is done to the utility model, every according to technical spirit of the present utility model to any simple modification made for any of the above embodiments, equivalent variations and modification, all belong in the scope of technical solutions of the utility model.

Claims (7)

1. a comprehensive power quality measurement and control instrument, it is characterized in that, this comprehensive power quality measurement and control instrument comprises: human-computer interaction interface module, MCU control module, metering control module, communication interface, current transducer signal Acquisition Circuit, voltage transformer signal acquisition circuit, temperature detecting module, zero passage detection module, SD card interface; Human-computer interaction interface model calling MCU control module, MCU control module connects metering control module, communication interface, temperature detecting module, zero passage detection module and SD card interface, and metering control module connects current transducer signal Acquisition Circuit and voltage transformer signal acquisition circuit.

2. comprehensive power quality measurement and control instrument as claimed in claim 1, it is characterized in that, MCU control module connects metering control module by Serial Peripheral Interface (SPI).

3. comprehensive power quality measurement and control instrument as claimed in claim 1, is characterized in that, MCU control module is by serial ports RS485 and RS232 connecting communication interface.

4. comprehensive power quality measurement and control instrument as claimed in claim 1, is characterized in that, MCU control module connects SD card interface by Serial Peripheral Interface (SPI).

5. comprehensive power quality measurement and control instrument as claimed in claim 1, it is characterized in that, the concrete connection of voltage transformer signal acquisition circuit is: inductance T1 contact resistance R1 and resistance R3, resistance R1 connects electric capacity C1 and resistance R2, resistance R3 connects electric capacity C2 and resistance R4, and resistance R2 is connected with resistance R4.

6. comprehensive power quality measurement and control instrument as claimed in claim 1, is characterized in that, adopts telecommunication signal circuit to adopt the current transducer signal Acquisition Circuit of differential mode.

7. comprehensive power quality measurement and control instrument as claimed in claim 6, it is characterized in that, the concrete connection of current transducer signal Acquisition Circuit is: inductance T2 contact resistance R42 and resistance R49, resistance R46 is in parallel with resistance R42 and resistance R49, resistance R42 contact resistance R40, electric capacity C38, resistance R49 connects electric capacity C39 and resistance R50, electric capacity C39 and connects electric capacity C38.