CN104122439B - Electric energy meter capable of improving phase correction precision - Google Patents

Abstract

The invention provides an electric energy meter capable of improving phase correction precision. The electric energy meter comprises a current sensor, a voltage sensor, a first analog-digital converter, a second analog-digital converter, a phase correction module and an electric energy computing module. The current sensor is used for receiving and sensing a current signal. The voltage sensor is used for receiving and sensing a voltage signal. The first analog-digital converter is used for converting an analog phase current signal into a digital current sampling signal. The second analog-digital converter is used for converting an analog phase voltage signal into a digital voltage sampling signal. The phase correction module is connected with the first analog-digital converter and the second analog-digital converter and used for correcting phases of the current sampling signal and the voltage sampling signal in real time and respectively generating a current synchronizing signal and a voltage synchronizing signal. The electric energy computing module is connected with the phase correction module and is used for receiving the current synchronizing signal and the voltage synchronizing signal, computing active electric energy and inactive electric energy and outputting computation results. The electric energy meter overcomes the defects in current/voltage signal delaying manner and is capable of realizing high-precision phase correction, simple in hardware implementation and low in system cost.

Description

Improve the electric energy meter of phasing precision

Technical field

The present invention relates to Electric Energy Metering Technology and circuit implementation technology field thereof, in particular it relates to one Plant the electric energy meter improving phasing precision.

Background technology

Before not having the present invention, electric energy meter phasing uses the mode of current/voltage signal lag.This The shortcoming of mode is that correction accuracy is restricted by ADC (analog-digital converter) manipulator operating frequency, phasing Can only carry out with a certain particular step size relevant to ADC manipulator operating frequency, thus be difficult to reach the highest phase Bit correction precision.

Fig. 1 is the internal module structure chart of a kind of typical case's single-phase electric energy meter of the prior art.As it is shown in figure 1, This typical single-phase electric energy meter 100 can be by current sensor 101, voltage sensor the 102, the oneth Sigma-Delta (sigma-delta) manipulator the 103, the 2nd Sigma-Delta (sigma-delta) manipulator 104, the phase place of employing signal lag method Correction module the 107, first FIR filter the 105, second FIR filter 106, electric energy computing module 108 groups Become.Its input is phase current signal i (t), phase voltage signal v (t), is output as active energy and reactive energy.The One Sigma-Delta modulator the 103, second Sigma-Delta modulator the 104, first FIR filter 105, Second FIR filter 106, phase correction module 107 and electric energy computing module 108 are generally by one piece of integrated circuit (IC) realize.Current sensor 101 has copper-manganese sheet, current transformer, Luo-coil, hall effect sensor Etc. kind, voltage sensor 102 has the kind such as divider resistance, voltage transformer.Due to current sensor 101, The possible nonlinear characteristic of voltage sensor 102 self, picked electric current, voltage signal phase place is it may happen that partially Moving, therefore the phase contrast between electric current, voltage may change, so that deviation occurs in electric energy metrical.

If stable phase current i (t) virtual value is I, initial phase isPhase voltage v (t) virtual value is V, initially Phase place isTake initial phase differenceSo, active-power P_a=VIcos φ, reactive power P_r=VIsin φ.If after being caused electric current and voltage-phase skew by sensor, phase difference delta is α (i.e. phase contrast Become φ+α), then active power becomes P_a'=VIcos (φ+α), reactive power becomes P_r'=VIsin (φ+α). Clearly as the reason of signal phase difference increment α, P_a' compared to P_aThere is certain deviation, and P_r' compared to P_rHave Certain deviation.Owing to active energy is the active power integration to the time, reactive energy is that reactive power is to the time Integration, the deviation of active power and reactive power will cause the inaccurate of active energy and reactive energy measurement.? In this case, a phase correction module is generally set in electric energy meter, is used for passing by current sensor and voltage The signal phase difference increment (α) that sensor causes is corrected, and eliminates its impact on electric energy metrical.

And electric energy meter is carried out phasing it may first have to the value of signal phase difference increment α is estimated. During electric energy meter produces and debugs, the estimation of α value is typically carried out by electric energy meter tester table, and step is as follows: (1) under the conditions of power factor PF=0, active power yield value is corrected；(2) at PF=0.5L, (perception is negative Carry) under the conditions of, measure electric energy metering error E；(3) phase contrast is calculated(radian). Generally, due to the existence of tester table measurement error, α ' is the approximation of α, takes α=α ' here.

After estimating signal phase difference increment α, accordingly electric energy meter can be carried out phasing.Existing Electric energy meter method for correcting phase is current/voltage signal lag method (as shown in Figure 2).First by signal phase difference The time deviation that increment α is converted between current signal and voltage signal is (with two Sigma-Delta modulator Sampling interval is unit):

$d=\mathrm{round}\left(\frac{\left|\mathrm{\α}\right|\·f_m}{2\mathrm{\π}{f}_i}\right)---\left(1\right)$

F in above formula_iFor current signal and voltage signal frequency (50/60Hz), f_mIt is that two Sigma-Delta adjust The operating frequency of device processed.Round () represents that round off mode rounds.

The principle of current/voltage signal lag method is: positive negativity and d value according to α select electric current single-bit code stream Signal i_b(n) and voltage single-bit signal bit stream v_bN () alternative one carries out time delay, make the two align in time, Thus reach the purpose of phasing.For realizing the time delay of curtage signal, electric energy meter phase correction module needs FIFO (First Input First Output, the FIFO) depositor wanting a group leader to be N (N >=d), uses To store i_b(n) or v_b(n) signal.When α >=0, current signal needs time delay, and fifo register storage is i_b(n) Signal.Now phase correction module is output as:

i_x(n)=i_b(n-d) (2)

v_x(n)=v_b(n) (3)

It may be noted that when α=0, d=0, i_x(n) actually with i_bN () is equal.

As α, < when 0, voltage signal needs time delay, and fifo register storage is v_b(n) signal.Now phase place school Positive module is output as:

i_x(n)=i_b(n) (4)

v_x(n)=v_b(n-d) (5)

i_x(n) and v_xN () is the single-bit signal bit stream after phasing.i_xN (), through FIR filter, obtains electricity Stream synchronous sampling signal i_y(n)；v_xN (), through FIR filter, obtains voltage synchronous sampling signal v_y(n)。i_y(n) With v_yN () input electric energy computing module, carries out the calculating of active energy and reactive energy.

Obviously, when using current/voltage signal lag method, the precision of phasing is by two Sigma-Delta Operating frequency f of manipulator_mRestriction, phasing can only be with 360f_i/f_m(spending) is that step-length is carried out.Such as, Work as f_mDuring=1.024MHz, the step-length of phasing is about 0.017 °.The existence of calibration step makes current/voltage Signal lag method is difficult to reach the highest phasing precision, thus is unfavorable for the high-precision function of measuring of electric energy meter Realize.

Summary of the invention

The technical problem to be solved is to provide a kind of electric energy meter improving phasing precision, it is possible to gram The shortcoming taking existing current/voltage signal lag mode, can not only realize high-precision phasing, and firmly Part realizes simple, and system cost is low.

For solving above-mentioned technical problem, the present invention provides a kind of electric energy meter improving phasing precision, including:

Current sensor, receives and senses a phase current signal；

Voltage sensor, receives and senses a phase voltage signal；

First analog-digital converter, is connected with described current sensor, by the described phase current signal conversion of simulation Current sampling signal for numeral；

Second analog-digital converter, is connected with described voltage sensor, by the described phase voltage signal conversion of simulation Voltage sampling signal for numeral；

Phase correction module, is connected with described first analog-digital converter and described second analog-digital converter respectively, Described current sampling signal and described voltage sampling signal are carried out real-time phasing, generates current synchronization respectively Signal and voltage synchronous signal；

Electric energy computing module, is connected with described phase correction module, receive respectively described current synchronous signal and Described voltage synchronous signal, and calculate active energy and reactive energy accordingly with outwards output.

Alternatively, described phase correction module includes:

All-pass filter coefficient parameter depositor, the coefficient parameter of the all-pass filter after storing quantization；

α positive negativity depositor, for according to α>0, α<0 and α=0 these three situation respectively correspondingly arrange 0,1 With 2 these three numerical value, α is signal phase difference increment；

The all-pass filter of single order and relevant gating circuit, in described phase correction module respectively with described all-pass Filter coefficient parameter depositor negativity positive with described α depositor is connected, and reads for first and represents the positive negativity of α Described numerical value, determine described all-pass filter be placed in when whether being bypassed and be not bypassed which signal lead to Road, then read the computing for described all-pass filter of the described coefficient parameter after quantifying, and then to described electric current Sampled signal and described voltage sampling signal carry out phasing, generate described current synchronous signal and described electricity respectively Pressure synchronizing signal.

Alternatively, the application of described all-pass filter is divided into α>0, α<0 and α=0 these three situation, α is signal Phase difference delta；

As α > 0 time, the phase place of described current sampling signal needs to delay, and described all-pass filter is placed in electric current In signalling channel, voltage signal passage is without described all-pass filter；

As α, < when 0, the phase place of described voltage sampling signal needs to delay, and described all-pass filter is placed in described In voltage signal passage, described channel current signal is without described all-pass filter；

When α=0, the phase place of described current sampling signal and described voltage sampling signal all need not delay, institute State in channel current signal and described voltage signal passage the two passage all without described all-pass filter, described all-pass Wave filter is in the state of being bypassed.

Alternatively, described all-pass filter coefficient parameter depositor and described α positive negativity depositor are non-volatile Property depositor.

Alternatively, described all-pass filter coefficient parameter depositor and described α positive negativity depositor are flash-type Depositor.

Alternatively, the size of described α positive negativity depositor is 2 bits.

Alternatively, described current sensor is that copper-manganese sheet, current transformer, Luo-coil or Hall effect pass Sensor.

Alternatively, described voltage sensor is divider resistance or voltage transformer.

Alternatively, described first analog-digital converter, described second analog-digital converter, described phase correction module and Described electric energy computing module is realized by one piece of integrated circuit.

Alternatively, described electric energy meter can serve as single-phase electric energy meter or Heterogeneous electric energy meter.

Compared with prior art, the invention have the advantages that

The present invention calculates according to reality, in electric current and signal frequency f of voltage_i=50Hz, the sampling of analog-digital converter Frequency f_s=4kHz, signal phase difference increment | α |≤4 °, the coefficient parameter k word length of all-pass filter are 16 bits Under conditions of, the error of phasing is less than 10^-4Degree.As can be seen here, the employing all-pass filter that the present invention proposes Mode can reach the highest phasing precision, far above existing current/voltage signal lag method, this is right Phasing precision in raising electric energy meter is very favorable.On the other hand, due to single order all-pass filter structures Simply, when realizing with integrated circuit, expense is less, and the electric energy meter of the most this structure is in the realization of phasing Simple and easy to do.

In sum, the present invention can overcome the shortcoming of existing current/voltage signal lag mode, can not only be real Existing high-precision phasing, and whole electric energy meter hardware realizes simple, and system cost is low.

Accompanying drawing explanation

The above and other features of the present invention, character and advantage will be by below in conjunction with the accompanying drawings and embodiment Description and become readily apparent from, wherein:

Fig. 1 is the internal module structure chart of a kind of typical case's single-phase electric energy meter of the prior art；

Fig. 2 is the method current/voltage signal lag method of a kind of electric energy meter phasing of the prior art Schematic diagram (is divided into α >=0 and 0 liang of class situation of α ＜)；

Fig. 3 is the internal module structure chart of the electric energy meter improving phasing precision of one embodiment of the invention；

Fig. 4 is that the all-pass filter in the electric energy meter improving phasing precision of one embodiment of the invention exists -1 < k < 0, the phase versus frequency response charac t in the case of k=0 and 0 < k < 1 these three；

Fig. 5 is answering of the all-pass filter in the electric energy meter improving phasing precision of one embodiment of the invention With being divided into α>0, α<0 and the schematic diagram of α=0 these three situation；

Fig. 6 is the phase correction module in the electric energy meter improving phasing precision of one embodiment of the invention Internal structure schematic diagram.

Detailed description of the invention

Below in conjunction with specific embodiments and the drawings, the invention will be further described, elaborates in the following description More details so that fully understanding the present invention, but the present invention obviously can be different from that this describes with multiple its Its mode is implemented, those skilled in the art can in the case of intension of the present invention according to reality application feelings Condition is made similar popularization, is deduced, the most should be with content constraints protection scope of the present invention of this specific embodiment.

Fig. 3 is the internal module structure chart of the electric energy meter improving phasing precision of one embodiment of the invention. Fig. 3 show this electric energy meter 200 and is used as the situation of single-phase electric energy meter.Obviously, pass through on the basis of single-phase measurement Structural extended, this electric energy meter 200 is also used as Heterogeneous electric energy meter, now by for each phase current signal and Voltage signal carries out phasing respectively.Wherein, as single-phase electric energy meter when, its internal structure is main Including following comprising modules: current sensor 201, voltage sensor the 202, first analog-digital converter (ADC) 203, the second analog-digital converter (ADC) 204, phase correction module 207 and electric energy computing module 208 etc.. In addition to current sensor 201, voltage sensor 202, other modules can be generally by one piece of integrated circuit (IC) Realize.Wherein, current sensor 201 can be copper-manganese sheet, current transformer, Luo-coil or Hall effect The variety classeses such as induction sensor, it receives and senses phase current signal i (t).Voltage sensor 202 can be point The variety classes such as piezoresistance or voltage transformer, it receives and senses phase voltage signal v (t).First modulus turns Parallel operation 203 is connected with current sensor 201, is adopted by the electric current that phase current signal i (t) of simulation is converted to numeral Sample signal i_s(n).Second analog-digital converter 204 is connected with voltage sensor 202, by the phase voltage signal of simulation V (t) is converted to the voltage sampling signal v of numeral_s(n).Phase correction module 207 respectively with the first analog-digital converter 203 It is connected with the second analog-digital converter 204, to current sampling signal i_s(n) and voltage sampling signal v_sN () carries out reality Time phasing, respectively generate current synchronous signal i_y(n) and voltage synchronous signal v_y(n).Electric energy computing module 208 are connected with phase correction module 207, receive current synchronous signal i respectively_y(n) and voltage synchronous signal v_y(n), And calculate active energy and reactive energy accordingly with outwards output.

Main idea is that the phase shift characteristic using all-pass filter, come reverse cancellation current and electricity The signal phase difference increment α of pressure.The advantage of all-pass filter is while changing signal phase, keeps signal width It is worth constant.For making implementation simple, use the single order all-pass filter of following system function H (z):

$H\left(z\right)=\frac{k+z^{-1}}{1+{\mathrm{kz}}^{-1}}---\left(6\right)$

In above-mentioned wave filter, coefficient parameter k is real number, limit z_p=-k.For making filter stability, should ensure that |z_p|<1.Therefore the span of k is-1 < k < 1.Fig. 4 show the raising phase place of one embodiment of the invention The all-pass filter in the electric energy meter of the correction accuracy phase-1 < k < 0, in the case of k=0 and 0 < k < 1 these three Frequently response characteristic.As seen from Figure 4, this all-pass filter is applicable to the occasion making signal phase delay.For electricity Can the phasing of table, the application of all-pass filter can be divided into α>0, α<0 and α=0 these three situation (such as Fig. 5 Shown in): (1) is as α > 0 time, due to current sampling signal phase place need delay, all-pass filter 213 quilt Being placed in channel current signal, voltage signal passage is without all-pass filter 213；(2) when α is < when 0, due to electricity The phase place of pressure sampled signal needs to delay, and all-pass filter 213 is placed in voltage signal passage, and current signal leads to Road is without all-pass filter 213；(3) when α=0, due to current sampling signal and the phase place of voltage sampling signal All need not delay, all without all-pass filter 213 in channel current signal and voltage signal passage the two passage, All-pass filter 213 is in the state of being bypassed.

The now relation of derivation single order all-pass filter unique coefficient parameter k and signal phase difference increment α.Work as ADC Sample frequency is f_sTime, signal normalization angular frequency is θ=2 π f_i/f_s.Function is transmitted according to single order all-pass filter, Obtain filter frequency domain to respond:

$H\left(e^{\mathrm{j\&theta;}}\right)=\frac{k+{\left(e^{\mathrm{j\&theta;}}\right)}^{-1}}{1+k{\left(e^{\mathrm{j\&theta;}}\right)}^{-1}}---\left(7\right)$

Due to e^jθ=cos θ+jsin θ, above formula can be reduced to:

$H\left(e^{\mathrm{j\&theta;}}\right)=\frac{(k\cos \mathrm{\&theta;}+1)+\mathrm{jk}\sin \mathrm{\&theta;}}{(\cos \mathrm{\&theta;}+k)+j\sin \mathrm{\&theta;}}---\left(8\right)$

For enabling all-pass filter to offset the impact of α, H (e should be made^jθ) phase angle equal to-| α |, i.e.

∠H(e^jθ)=-| α | (9)

According to above formula, can solve:

$k_{\mathrm{1,2}}=\frac{-\mathrm{tg}\left|\mathrm{\&alpha;}\right|\&PlusMinus;\sin \mathrm{\&theta;}\sqrt{1+{\mathrm{tg}}^2\left|\mathrm{\&alpha;}\right|}}{\sin \mathrm{\&theta;}+\cos \mathrm{\&theta;}\&CenterDot;\mathrm{tg}\left|\mathrm{\&alpha;}\right|}---\left(10\right)$

Absolute value in view of α is a less number (typically within 3 °), should according to Fig. 4, k Take on the occasion of.Therefore, in two solution of k expressed by above formula, take higher value, obtain:

$k=\frac{-\mathrm{tg}\left|\mathrm{\&alpha;}\right|+\sin \mathrm{\&theta;}\sqrt{1+{\mathrm{tg}}^2\left|\mathrm{\&alpha;}\right|}}{\sin \mathrm{\&theta;}+\cos \mathrm{\&theta;}\&CenterDot;\mathrm{tg}\left|\mathrm{\&alpha;}\right|}---\left(11\right)$

Above formula is i.e. the formula calculating k value according to α.

In the phase correction module 207 of electric energy meter 200 (as shown in Figure 6), an all-pass wave filtering it is provided with Device coefficient parameter depositor 211, in order to store the coefficient parameter k of the all-pass filter 213 after quantization.Phase place school Be provided with the α positive negativity depositor 212 of 2 bit sizes in positive module 207 again, for working as α>0, α<0 During with α=0 these three situation, depositor is respectively correspondingly set to 0,1,2 these three numerical value (register values It is 3 meaningless).Positive negativity depositor 212 the two of all-pass filter coefficient parameter depositor 211 and α is deposited Device is non-volatile depositor (such as flash-type depositor).Tester table carries out phase place to electric energy meter 200 Timing, calculates k value according to α, and writes all-pass filter coefficient parameter depositor 211 after k value quantization. Would indicate that the numerical value write α positive negativity depositor 212 of the positive negativity of α simultaneously.

All-pass filter 213 and relevant gating electricity it is also provided with in the phase correction module 207 of electric energy meter 200 Road 214, is connected with the positive negativity depositor 212 of all-pass filter coefficient parameter depositor 211 and α respectively.Electricity When energy table 200 normally works, α positive negativity depositor 212 representing, the numerical value of the positive negativity of α is first read, and passes Give all-pass filter 213 and relevant gating circuit 214, be used for determining all-pass filter 213 whether be bypassed with And be placed in when not being bypassed in which signalling channel.Coefficient parameter k value after quantization is read, for all-pass again The computing of wave filter 213.Under the effect of above-mentioned two register parameters, electric current is adopted by phase correction module 207 Sample signal and voltage sampling signal carry out real-time phasing, generate current synchronous signal and voltage synchronous letter respectively Number.

The present invention calculates according to reality, in electric current and signal frequency f of voltage_i=50Hz, the sampling of analog-digital converter Frequency f_s=4kHz, signal phase difference increment | α |≤4 °, the coefficient parameter k word length of all-pass filter are 16 bits Under conditions of, the error of phasing is less than 10^-4Degree.As can be seen here, the employing all-pass filter that the present invention proposes Mode can reach the highest phasing precision, far above existing current/voltage signal lag method, this is right Phasing precision in raising electric energy meter is very favorable.On the other hand, due to single order all-pass filter structures Simply, when realizing with integrated circuit, expense is less, and the electric energy meter of the most this structure is in the realization of phasing Simple and easy to do.

In sum, the present invention can overcome the shortcoming of existing current/voltage signal lag mode, can not only be real Existing high-precision phasing, and whole electric energy meter hardware realizes simple, and system cost is low.

Although the present invention is open as above with preferred embodiment, but it is not for limiting the present invention, any ability Field technique personnel without departing from the spirit and scope of the present invention, can make possible variation and amendment.Therefore, Every content without departing from technical solution of the present invention, according to appointing that above example is made by the technical spirit of the present invention What amendment, equivalent variations and modification, within each falling within the protection domain that the claims in the present invention are defined.

Claims (9)

1. the electric energy meter (200) improving phasing precision, including:

Current sensor (201), receives and senses a phase current signal；

Voltage sensor (202), receives and senses a phase voltage signal；

First analog-digital converter (203), is connected with described current sensor (201), described in simulation Phase current signal is converted to the current sampling signal of numeral；

Second analog-digital converter (204), is connected with described voltage sensor (202), described in simulation Phase voltage signal is converted to the voltage sampling signal of numeral；

Phase correction module (207), respectively with described first analog-digital converter (203) and described second modulus Transducer (204) is connected, and described current sampling signal and described voltage sampling signal are carried out real-time phase place Correction, generates current synchronous signal and voltage synchronous signal respectively；

Electric energy computing module (208), is connected with described phase correction module (207), receives described respectively Current synchronous signal and described voltage synchronous signal, and calculate active energy and reactive energy accordingly with the most defeated Go out；

Wherein, described phase correction module (207) including:

All-pass filter coefficient parameter depositor (211), the all-pass filter (213) after storing quantization Coefficient parameter (k)；

α positive negativity depositor (212), for according to α>0, α<0 the most corresponding with α=0 these three situation 0,1 and 2 these three numerical value are set, α is signal phase difference increment；

The all-pass filter (213) of single order and relevant gating circuit (214), in described phase correction module (207) deposit with described all-pass filter coefficient parameter depositor (211) and the positive negativity of described α respectively in Device (212) is connected, and represents the described numerical value of the positive negativity of α for first reading, determines described all-pass wave filtering Device (213) is placed in which signalling channel, then reading quantization when whether being bypassed and be not bypassed after Described coefficient parameter (k) is for the computing of described all-pass filter (213), and then adopts described electric current Sample signal and described voltage sampling signal carry out phasing, generate described current synchronous signal and described respectively Voltage synchronous signal.

Electric energy meter the most according to claim 1 (200), it is characterised in that described all-pass filter (213) Application be divided into α>0, α<0 and α=0 these three situation, α is signal phase difference increment；

As α > 0 time, the phase place of described current sampling signal needs to delay, and described all-pass filter (213) is put In channel current signal, voltage signal passage is without described all-pass filter (213)；

As α, < when 0, the phase place of described voltage sampling signal needs to delay, and described all-pass filter (213) is put In described voltage signal passage, described channel current signal is without described all-pass filter (213)；

When α=0, the phase place of described current sampling signal and described voltage sampling signal all need not delay, institute State in channel current signal and described voltage signal passage the two passage all without described all-pass filter (213), Described all-pass filter (213) is in the state of being bypassed.

Electric energy meter the most according to claim 2 (200), it is characterised in that described all-pass filter system Number parameter depositor (211) and described α positive negativity depositor (212) are non volatile register.

Electric energy meter the most according to claim 3 (200), it is characterised in that described all-pass filter system Number parameter depositor (211) and described α positive negativity depositor (212) are flash-type depositor.

Electric energy meter the most according to claim 4 (200), it is characterised in that the positive negativity of described α is deposited The size of device (212) is 2 bits.

Electric energy meter the most according to claim 5 (200), it is characterised in that described current sensor (201) For copper-manganese sheet, current transformer, Luo-coil or hall effect sensor.

Electric energy meter the most according to claim 6 (200), it is characterised in that described voltage sensor (202) For divider resistance or voltage transformer.

Electric energy meter the most according to claim 7 (200), it is characterised in that described first analog digital conversion Device (203), described second analog-digital converter (204), described phase correction module (207) and described electric energy Computing module (208) is realized by one piece of integrated circuit.

Electric energy meter the most according to claim 8 (200), it is characterised in that described electric energy meter (200) Can serve as single-phase electric energy meter or Heterogeneous electric energy meter.