how to reduce the response time of metering library

venkatkrishna · ‎07-06-2016

Hi,

I am trying the twr_emeter demo in TWR-KM34Z50 board.While testing the Voltage and Ampere readings were changing very slowly.It takes approximate 10 sec to stabilise.I nead to adjust the response time to 20ms(1 cycle of 50Hz).

Is there any parameter to adjust the response time and average counts?.Please help me to solve this.

Thanks/regards,

K.Venkat

ivadorazinova · ‎07-07-2016

Hi Venkat!

Please, did you use the filter-based metering configuration tool for your configuration?

Did you have correctly set these parameters?

Please let me know if this helps.

Best Regards,

Iva

venkatkrishna · ‎07-08-2016

Hai Eva,

Thank you for your support.

1) I tried adjusting the HPF and LPF1 settings and i can able to get better response.

In HPF the least settiling time is 0.036sec and in LPF1 0.036sec is the least time.So the total settling time neaded for

correct reading is 0.72 sec.Am i correct? or the settling time of LPF2(least time) 0.217sec also come into the total time.

Please clarify me and help me to reduce this to 0.02 sec ie 20ms(one cycle time of 50hz)

2)In meterlib.h (democode)file i can able to see this.

/*! Metering library data structure definition - 2PH METER */

typedef struct

{

double umax; /*!< maximal voltage measurement range */

double imax; /*!< maximal current measurement range */

Frac32 thrd; /*!< sensitivity threshold */

int sens; /*!< sensor: 1-proportional, 2-derivative */

tBIASFILTER_COEF bias; /*!< dc bias supressor filter coefficients */

tBIASFILTER_COEF intg; /*!< integrator filter coefficients */

tBIASFILTER_DATA uDcb1[2]; /*!< ph1-voltage dc bias supressor data */

tBIASFILTER_DATA intd1; /*!< ph1-current integrator filter data */

tBIASFILTER_DATA iDcb1[2]; /*!< ph1-current dc bias supressor data */

tBIASFILTER_DATA uDcb2[2]; /*!< ph2-voltage dc bias supressor data */

tBIASFILTER_DATA intd2; /*!< ph2-current integrator filter data */

tBIASFILTER_DATA iDcb2[2]; /*!< ph2-current dc bias supressor data */

tPHSHFILTER_COEF hilb; /*!< Hilbert & delay filter coefficients */

tPHSHFILTER_DATA phSh1; /*!< ph1-Hilbert & delay filter data */

tPHSHFILTER_DATA phSh2; /*!< ph2-Hilbert & delay filter data */

tAVERFILTER_COEF aver; /*!< averager filter coefficients */

tAVERFILTER_DATA uRms1; /*!< ph1-voltage RMS averager data */

tAVERFILTER_DATA uRms2; /*!< ph2-voltage RMS averager data */

tAVERFILTER_DATA iRms1; /*!< ph1-current RMS averager data */

tAVERFILTER_DATA iRms2; /*!< ph2-current RMS averager data */

tAVERFILTER_DATA PAve1; /*!< ph1-active power averager data */

tAVERFILTER_DATA PAve2; /*!< ph2-active power averager data */

tAVERFILTER_DATA QAve1; /*!< ph1-reactive power averager data */

tAVERFILTER_DATA QAve2; /*!< ph2-reactive power averager data */

tENERGY_DATA Wh; /*!< active energy */

tENERGY_DATA VARh; /*!< reactive energy */

} tMETERLIB2PH_DATA;

This is the config tool generated meterlib2ph_cgf.h file.

If i build this file the error saying "braced around scaler initializer" always reported.

Then i compared the meterlib1ph_cfg.h in the emeter demo code folder and found some lines

additional with respect o the above structure Which i noted you in bold strikes letters.Please

clarify me what is the use of those additional parameters and also explain the METERLIB_KWH_DR

/**************************************************************************************

* Filter-based metering algorithm configuration structure

**************************************************************************************/

#define METERLIB2PH_CFG \

{ \

U_MAX, \

I_MAX, \

FRAC32(((+0.5000)/(U_MAX*I_MAX/2.0))), \

FRAC32((+0.0200)/I_MAX), \

1, \

{{0l,0l,0l},{0l,0l,0l}},{{0l,0l,0l},{0l,0l,0l}}, \

{{FRAC32(+0.99921521804155),FRAC32(-0.99921521804155),FRAC32(-0.99843043608309)}}, \

{{FRAC32(+0.13165249758740),FRAC32(+0.13165249758740),FRAC32(-1.0)}}, \

{{0l,0ll},{0l,0ll}}, \

{0l,0ll}, \

{{0l,0ll},{0l,0ll}}, \

{0l,0ll}, \

{{0l,0ll},{0l,0ll}}, \

{ 49, \

{ \

FRAC32(0.0),FRAC32(-0.02767909511717),FRAC32(0.0),FRAC32(-0.03031520404553), \

FRAC32(0.0),FRAC32(-0.03350628280924),FRAC32(0.0),FRAC32(-0.03744820311487), \

FRAC32(0.0),FRAC32(-0.04244130157922),FRAC32(0.0),FRAC32(-0.04897073735245), \

FRAC32(0.0),FRAC32(-0.05787451260303),FRAC32(0.0),FRAC32(-0.07073552031589), \

FRAC32(0.0),FRAC32(-0.09094567403011),FRAC32(0.0),FRAC32(-0.12732394894731), \

FRAC32(0.0),FRAC32(-0.21220658747347),FRAC32(0.0),FRAC32(-0.63661977126234), \

FRAC32(0.0),FRAC32(+0.63661977126234),FRAC32(0.0),FRAC32(+0.21220658747347), \

FRAC32(0.0),FRAC32(+0.12732394894731),FRAC32(0.0),FRAC32(+0.09094567403011), \

FRAC32(0.0),FRAC32(+0.07073552031589),FRAC32(0.0),FRAC32(+0.05787451260303), \

FRAC32(0.0),FRAC32(+0.04897073735245),FRAC32(0.0),FRAC32(+0.04244130157922), \

FRAC32(0.0),FRAC32(+0.03744820311487),FRAC32(0.0),FRAC32(+0.03350628280924), \

FRAC32(0.0),FRAC32(+0.03031520404553),FRAC32(0.0),FRAC32(+0.02767909511717), \

FRAC32(0.0) \

}, \

25, \

{ \

FRAC16(0.0),FRAC16(0.0),FRAC16(0.0),FRAC16(0.0),FRAC16(0.0),FRAC16(0.0), \

FRAC16(-1.0) \

} \

}, \

{ \

0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l, \

0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l \

}, \

0ll, \

{ \

0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l \

}, \

0l \

}, \

{ \

0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l, \

0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l \

}, \

0ll, \

{ \

0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l,0l \

}, \

0l \

}, \

{ \

{FRAC32(+0.00130728645170),FRAC32(+0.00130728645170),FRAC32(-0.99738542709660)}, \

}, \

{0ll,0ll,0l,0ll}, \

{ \

FRAC48((+0.0000/(U_MAX*I_MAX))),FRAC32(+1.0000), METERLIB_KWH_DR( 10000), \

{0ll,0ll,0ll},0ll,0l,FRAC16(-1.0), \

{FRAC32(+0.00779293629195),FRAC32(+0.00779293629195),FRAC32(-0.98441412741610)}, \

{0ll,0ll,0ll},{0ll,0ll,0ll} \

}, \

{ \

FRAC48((+0.0000/(U_MAX*I_MAX))),FRAC32(+1.0000),METERLIB_KVARH_DR( 10000), \

{0ll,0ll,0ll},0ll,0l,FRAC16(-1.0), \

{FRAC32(+0.00779293629195),FRAC32(+0.00779293629195),FRAC32(-0.98441412741610)}, \

{0ll,0ll,0ll},{0ll,0ll,0ll} \

} \

}

#endif /* __METERLIB2PH1_CFG_H */

Thanks/regards,

K.Venkat

ivadorazinova · ‎07-20-2016

Hi Venkat.

I apologize for my late response.

Transfer delays on cascade of the filter is equal to the sum of all transfer delays.

So, if the signal passes through two filters - every has 36ms and then the result is equal to 2*36ms = 72ms

If it passes through three filters, where two of them has 36ms and the one has 217ms = then result is (36+36+217)ms.

In general, if you need low transfer delay, the filter must quickly converge, but this convergence will affect very negatively transfer and phase characteristic. Thus you will quickly measure but with a large measurement error.

If you need quickly measure and accurately is suitable to use FFT algorithms, there is not settling time. The result is accurate and stable already after the first calculation.

Please, see for more details

FFT-Based Algorithm for Metering Applications

http://cache.nxp.com/files/32bit/doc/app_note/AN4255.pdf

Kinetis-M One-Phase Power Meter Reference Design

http://cache.nxp.com/files/32bit/doc/ref_manual/DRM143.pdf

Filter-Based Algorithm for Metering Applications

http://cache.nxp.com/files/32bit/doc/app_note/AN4265.pdf

I hope this helps you.

Best Regards,

Iva

venkatkrishna · ‎07-26-2016

Hi Iva,

Thank you for your suggestion.

I am trying FFT and simple peak detection method to get quick response.I will update the result soon.

Thanks/regards,

K.Venkat

venkatkrishna · ‎07-07-2016

Hai Eva,

I am using the demo code only.I have this config tool.

1)How to change in the existing demo code.

2)Is there any parameter regarding the response time.

I want the urms and irms results in very next cycle Pls help me.

3)Where to download the meterlib.c.

Thanks/regards,

K.Venkat

how to reduce the response time of metering library

how to reduce the response time of metering library

Kinetis M Series MCUs