CN2611909Y

CN2611909Y - Reactive power measuring circuit based on digit integration for carrying out phase shift

Info

Publication number: CN2611909Y
Application number: CN 02280053
Authority: CN
Inventors: 马小妹; 费宇航
Original assignee: Shanghai Beiling Co Ltd
Current assignee: Shanghai Beiling Co Ltd
Priority date: 2002-11-28
Filing date: 2002-11-28
Publication date: 2004-04-14
Anticipated expiration: 2012-11-28

Abstract

A reactive-load power-measuring circuit based on digital integration to realize phase-shifting comprises an A/D converter (4) disposed on an electric current channel, a high pass filter (2), an A/D converter (5) disposed on a voltage channel, and a digital multiplier (3) for multiplying digit amperage and digit voltage, wherein a digital integral phase-shifting network (1) which can make amperage shift 90 degrees is further disposed between the A/D converter (4) and the high pass filter (2). The utility model can realize the function of measuring reactive power only by adding simple circuit on the prior circuit for measuring active power, and which is realized by digital circuit. The utility model has strong noise-proof feature, and high degree of accuracy, which realizes 90-degree phase-shifting by using the digital integration method, has nothing to do with signal frequency, and the phase-shifting can also excellently remain 90 degrees, even frequency of electrified wire netting deviates, thereby guarantees accurate measure of the reactive power.

Description

Realize the wattless power measurement circuit of phase shift based on digital integration

Technical field

The utility model relates to a kind of watt-hour meter reactive power/electric energy measurement circuit, relates in particular to a kind of circuit of realizing the measurement reactive power of phase shift based on digital integration.

Background technology

From the basic definition formula of reactive power, calculating reactive power has two kinds of fundamental method: a kind of method is based on 90 ° of phase shifts; Another kind method is based on the calculating of applied power and active power.In the method based on applied power and active power, calculating reactive power needs to determine earlier three amounts: active power, voltage effective value, current effective value--P, and U, I, not only calculation of complex, and precision is difficult to guarantee.By contrast, just can obtain the reactive power suitable with the active power precision based on the method for 90 ° of phase shifts as long as guarantee the precision of phase shift, computing method are relative with implementation structure simple.Along with the development of phase shift technology and Digital Measuring Technique, people mainly adopt the measurement of finishing reactive power based on the method for 90 ° of phase shifts at present.Reactive power calculating method based on 90 ° of phase shifts has three kinds at present: a kind of is the phase method of striding, and it is to adopt active power meter by changing the measurement that the mode of connection realizes reactive power.Its weak point is: stride the measurement that the phase method only is applicable to three phase reactive power, and it will produce very big original reason error with the realizing being called the basis of three-phase circuit when circuit is asymmetric; Second kind is to adopt the method for analog phase shifter to realize 90 ° of phase shifts, promptly constitute phase shift network by a series of capacitance resistances and amplifier, such circuit shortcoming is: when signal center frequency (being assumed to be 50HZ) when changing to some extent, the accuracy meeting of phase shift reduces greatly; The third is for digital sampled signal, multiply each other by register realize being separated by for the four/one-period current signal and the voltage signal of (promptly 90 °), obtain reactive power, it is the constant integer times (claiming synchronized sampling again) in measured signal cycle that this method requires the sampling period, therefore need use phaselocked loop and many storage unit circuits, more complicated.

From the above, all there is the bigger than normal or realization complicated problems of generation error in the existing circuit of measuring reactive power.

Summary of the invention

Technical problem to be solved in the utility model provides a kind of by 90 ° of phase shifts of digital integration realization input current, thereby realizes accurately measuring the metering circuit of reactive power.

In order to solve the problems of the technologies described above, the technical solution of the utility model: be as theoretical foundation with 90 ° of phase-shift theories, design a kind of wattless power measurement circuit of realizing phase shift based on digital integration, circuit in original measurement active power promptly comprises the A/D converter of being located at current channel, Hi-pass filter, the A/D that is located at voltage channel changes device, and on the basis of the digital multiplier that digital current amount and digital voltage amount are multiplied each other, between described A/D converter and Hi-pass filter, add a digital integration phase shift network that can make 90 ° of magnitude of current phase shifts, described digital integration phase shift network comprises digital addition circuit and digital delay circuit, described digital delay circuit is with clock period of signal delay, the signal plus of described totalizer after with original signal and time-delay is finishing integration, thereby the calculating that realizes reactive power is measured.

The utility model only needs to add that simple circuit just can realize measuring the function of reactive power on the circuit of asking active power originally, and the utility model is realized by digital circuit, noise immunity is strong, the degree of accuracy height, and realize 90 ° of phase shifts with the digital integration method, irrelevant with signal frequency, even mains frequency is offset to some extent, phase shift still can remain on 90 ° well, guarantees the accurate measurement of reactive power.This scheme both can be used in the three-phase circuit, also can be used in the single-phase circuit.The utility model circuit implementation structure simply, relatively is easy to analyze, accuracy of measurement height, the not influence of acceptor center frequency shift (FS).

Description of drawings

Fig. 1 is the circuit theory synoptic diagram of metering circuit of the present utility model;

Fig. 2 is a digital phase-shifting technique Principles of Network synoptic diagram shown in Figure 1;

Fig. 3 is integrating network physical circuit figure shown in Figure 2;

Fig. 4 is the circuit block diagram of existing measurement active power.

Fig. 5 is applied to the concrete system chart of wattless power measurement for the utility model.

Embodiment

As shown in Figure 1: wattless power measurement circuit of the present utility model is to add the measurement that the digital integration phase shift network 1 that can make 90 ° of magnitude of current phase shifts is realized reactive power in original wattful power messurement circuit, under the situation that does not increase a lot of system designs and circuit design burden, obtain the reactive power consistent with the active power precision.Here, digital integration phase shift network 1 is responsible for the digital current signal that obtains through mould/number conversion in the current channel is carried out 90 ° of phase shifts, this signal multiplies each other by digital multiplier 3 with voltage signal by Hi-pass filter 2 backs then, can obtain accurate reactive power.Described Hi-pass filter 2 can be used to the DC component that integrating circuit brings in the filtering digital integration phase shift network 1.

Specifically describe the realization principle of digital integration phase-shift network 1 among Fig. 2: described digital integration phase-shift network 1 comprises that one is provided with the integrating circuit 11 of totalizer 111 and digital delay circuit 112; After be connected to the gain circuitry 12 of integrating circuit 11; The clock circuit 13 that is connected with gain circuitry 12, shift register 112 respectively.Described in the present embodiment digital delay circuit 112 is a shift register, and the gain effect of gain circuitry 12 is the variation of compensating signal phase shift front and back amplitude, and the size of the size of its value and sampling clock frequency is inversely proportional to.

Fig. 3 is the specific implementation circuit diagram of the integrating circuit 11 when being N bit of the current digital signal after mould/number conversion, and it comprises N totalizer; Correspondence is connected in N the shift register of the N after the totalizer 112, a N buffer circuit successively one by one, and described totalizer 111 is a full adder, and shift register 112 is a d type flip flop.The difference equation of described integrating circuit 11 is:

Y (n)=x (n)+y (n-1) wherein shift register 112 finishes the signal delay task of a clock period; Totalizer 111 promptly is to finish integral action with the signal plus after original signal and the time-delay.

Fig. 4 is the measurement active power circuit block diagram of prior art, mainly comprises the phase compensating circuit 7 of the A/D conversion circuit 4 of being located at current channel, down-sampled circuit 6, the high-pass filtering circuit 2 of removing the high frequency quantizing noise, the A/D converter 5 of being located at voltage channel, offset current voltage two paths of signals phase differential in the system and connects the digital multiplier 3 of current channel and voltage channel, low-pass filter circuit that the filtering radio-frequency component is got its direct current signal, digital signal is converted to the numeral/freq converting circuit of frequency signal.Fig. 5 is applied to the physical circuit block diagram of wattless power measurement for the utility model, go up as seen from scheming, as long as in the Fig. 4 that measures active power 90 ° of digital integration phase-shift networks 1 of adding, just can obtain the reactive power the same with the active power precision.

Above-mentioned only for the usefulness that the utility model is described; but not to restriction of the present utility model; person skilled in the relevant technique; under the situation that does not break away from spirit and scope of the present utility model; can also make various conversion or variation, so all technical schemes that are equal to also should belong to protection category of the present utility model.

Claims

1, a kind of wattless power measurement circuit of realizing phase shift based on digital integration, comprise the A/D converter (4) of being located at current channel, Hi-pass filter (2), be located at the A/D converter (5) of voltage channel, and the digital multiplier (3) that digital current amount and digital voltage amount are multiplied each other, it is characterized in that, between described A/D converter (4) and Hi-pass filter (2), also be provided with a digital integration phase shift network (1) that can make 90 ° of magnitude of current phase shifts, described digital integration phase shift network (1) comprises totalizer (111) and digital delay circuit (112), described digital delay circuit (112) is clock period of signal delay, and the signal plus of described addition (111) after with original signal and time-delay is to finish integration.

2, the inactivity metering circuit based on digital integration realization phase shift according to claim 1 is characterized in that described digital delay circuit (112) is a shift register.

3, the wattless power measurement circuit of realizing phase shift based on digital integration according to claim 2, it is characterized in that, be connected to the gain circuitry (12) of totalizer (111) and the clock circuit (13) that all links to each other with gain circuitry (12), shift register (112) after described digital integration phase shift network (1) also comprises.

According to the described wattless power measurement circuit of claim 1, it is characterized in that 4, described totalizer (111) is that N full adder formed based on digital integration realization phase shift.

According to the described wattless power measurement circuit of claim 4, it is characterized in that 5, described digital delay circuit (112) is that N d type flip flop formed, and connects one to one with N full adder based on digital integration realization phase shift.

6, the wattless power measurement circuit based on digital integration realization phase shift according to claim 5 is characterized in that, described N is determined by the conversion figure place of A/D converter (4).