ADSP-CM403 HAE在太陽能應(yīng)用中的諧波分析

簡介

太陽能光伏逆變器轉(zhuǎn)換來自太陽能面板的電能并高效地將其部署到公用電網(wǎng)中。早期太陽能PV逆變器只是將電能轉(zhuǎn)儲到公用電網(wǎng)的模塊。但是，新設(shè)計(jì)要求太陽能光伏逆變器對電網(wǎng)的穩(wěn)定性作出貢獻(xiàn)。

本文將回顧最新的ADI技術(shù)如何以HAE(諧波分析引擎)的方式改善智能電網(wǎng)的集成度，并監(jiān)控電網(wǎng)上的電源質(zhì)量，從而極大地增強(qiáng)電網(wǎng)穩(wěn)定

智能電網(wǎng)

什么是智能電網(wǎng)？IMS Research將智能電網(wǎng)定義為“一種自身能夠高效匹配和管理發(fā)電和用電并可最大程度地利用各種可用資源的公用供電基礎(chǔ)設(shè)施”。若要將新一代太陽能光伏逆變器接入智能電網(wǎng)，則逆變器需要越來越高的智能程度才能實(shí)現(xiàn)。這本身就是一個(gè)難題，主要是因?yàn)楫?dāng)電力需求在別處時(shí)，此處卻連接了過多的電網(wǎng)，從而發(fā)生不平衡?；谶@個(gè)原因，如前文所述，太陽能光伏逆變器需要具備更高的智能程度，并且這種智能應(yīng)側(cè)重于電網(wǎng)集成，其中系統(tǒng)需協(xié)助穩(wěn)定電網(wǎng)，而非作為電網(wǎng)的一個(gè)簡單電源使用。

這要求更好地對注入電網(wǎng)的電能進(jìn)行測量、控制和質(zhì)量分析。當(dāng)然，這會促成新指令的發(fā)布以及更高的技術(shù)要求，進(jìn)而直接導(dǎo)致新技術(shù)的產(chǎn)生。

ADSP-CM403XY HAE外設(shè)模塊

HAE模塊本質(zhì)上是一個(gè)數(shù)字PLL，其簡化原理圖如下圖所示。HAE連續(xù)接收V和I數(shù)據(jù)，并且數(shù)個(gè)周期后將鎖定至輸入波形的基波。HAE模塊的輸入范圍為45 Hz至66 Hz。最多可分析40個(gè)諧波，每次12個(gè)。對于每個(gè)諧波，PLL會試圖鎖定至所需的信號頻率

諧波引擎硬件模塊與諧波分析儀共同處理結(jié)果。由于諧波引擎產(chǎn)生的結(jié)果為最終格式，這些結(jié)果數(shù)據(jù)保存在結(jié)果存儲器中。HAE引擎在無衰減的2.8 kHz通帶內(nèi)計(jì)算諧波信息(相當(dāng)于3.3 kHz的-3 dB帶寬)，用于45 Hz至66 Hz范圍內(nèi)的線路頻率。

同時(shí)可使用相電流和來分析零線電流。在新采樣周期的最初時(shí)刻，諧波引擎在含有數(shù)據(jù)RAM內(nèi)的預(yù)定義位置循環(huán)，該數(shù)據(jù)RAM含有分析儀處理結(jié)果。若有需要，內(nèi)容可進(jìn)一步處理。

電壓和電流數(shù)據(jù)可來自Sinc模塊或ADC(兩者均存儲在SRAM中)，并輸入至HAE模塊，速率為8 kHz。該速率下可產(chǎn)生一個(gè)中斷，提示太陽能光伏逆變器輸入可用數(shù)據(jù)。進(jìn)行數(shù)據(jù)分析并執(zhí)行下列計(jì)算時(shí)，HAE模塊將產(chǎn)生另一次中斷，提示太陽能光伏系統(tǒng)準(zhǔn)備顯示諧波分析數(shù)據(jù)。ADSP-CM403還可將HAE至DMA的全部結(jié)果數(shù)據(jù)直接傳輸至SRAM，之后系統(tǒng)代碼便可顯示結(jié)果。這會導(dǎo)致整個(gè)HAE系統(tǒng)的少許代碼開銷。

ADSP-CM403XY HAE結(jié)果

圖4中的HAE結(jié)果清楚表明觀察電壓均方根數(shù)據(jù)時(shí)，系統(tǒng)中存在哪些諧波。圖中50 Hz基波清晰可見，但250 Hz和350 Hz處的較低諧波(如諧波5和7)亦可在本示例結(jié)果中看到。

這些計(jì)算中采用的特定等式如下所示；下列等式同時(shí)適用于基波和諧波計(jì)算。

Harmonic Engine Outputs and Registers where Values are Stored

表1. HAE數(shù)學(xué)計(jì)算

Quantity	Definition	HAE Registers
RMS of the Fundamental Component	V1,I1	F_VRMS, F_IRMS
RMS of the Harmonic Component	Vn,In,n = 2,3,...,12	Hnn_VRMS, Hnn_XIRMS
Active Power of the Fundamental Component	P1 = V1I1cos( φ1 - γ1)	F_ACT
Active Power of the Harmonic Component	Pn = VnIncos(φn - γn), n = 2,3,...,12	Fnn_ACT
Reactive Power of the Fundamental Component	Q1 = V1I1sin(φ1 - γ1)	F_REACT
Reactive Power of the Harmonic Component	Qn = VnInsin(φ1 - γ1), n = 2,3,...,12	Hnn_REACT
Apparent Power of the Fundamental Component	S1 = V1I1	F_APP
Apparent Power of the Harmonic Component	Sn = VnIn, n = 2,3,...,12	Hnn_APP
Power Factor of the Fundamental Component		F_PF
Power Factor of the Harmonic Component		Hnn_PF
Harmonic Distortion of a Harmonic Component		Hnn_VHDN, Hnn_IHDN

編程示例

INT HAE_CONFIG(VOID)
{ INT I;

HAE_INPUT_DATA(VOUTPUT, SINC_VEXT_DATA);
HAE_INPUT_DATA(IOUTPUT, SINC_IMEAS_DATA);

RESULT = ADI_HAE_OPEN(DEVNUM, DEVMEMORY, MEMORY_SIZE, &DEV);
RESULT = ADI_HAE_REGISTERCALLBACK(DEV, HAECALLBACK, 0);
RESULT = ADI_HAE_SELECTLINEFREQ(DEV, ADI_HAE_LINE_FREQ_50);
RESULT = ADI_HAE_CONFIGRESULTS(DEV, ADI_HAE_RESULT_MODE_IMMEDIATE, ADI_HAE_SETTLE_TIME_512,ADI_HAE_UPDATE_RATE_128000);
RESULT = ADI_HAE_SETVOLTAGELEVEL (DEV, 1.0);
RESULT = ADI_HAE_ENABLEINPUTPROCESSING(DEV, FALSE, FALSE); /* FILTER ENABLED */
/* ENABLE ALL HARMONICS (IN ORDER) */
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_1, 1);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_2, 2);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_3, 3);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_4, 4);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_5, 5);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_6, 6);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_7, 7);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_8, 8);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_9, 9);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_10, 10);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_11, 11);
RESULT = ADI_HAE_HARMONICINDEX (DEV, ADI_HAE_HARMONIC_INDEX_12, 12);

RESULT = ADI_HAE_SUBMITTXBUFFER(DEV, &TXBUFFER1[0], SIZEOF(TXBUFFER1));
RESULT = ADI_HAE_SUBMITTXBUFFER(DEV, &TXBUFFER2[0], SIZEOF(TXBUFFER2));
RESULT = ADI_HAE_ENABLEINTERRUPT(DEV, ADI_HAE_INT_RX, TRUE);
RESULT = ADI_HAE_ENABLEINTERRUPT(DEV, ADI_HAE_INT_TX, TRUE);
RESULT = ADI_HAE_CONFIGSAMPLEDIVIDER(DEV, 100000000);
RESULT = ADI_HAE_RUN(DEV, TRUE);
// RESULT = ADI_HAE_CLOSE(DEV);

}

/* EVENTS */

VOID HAECALLBACK(VOID* PHANDLE, UINT32_T EVENT, VOID* PARG)/* ISR ROUTINE TO LOAD / UNLOAD DATA FROM HAE

{

UINT32_T N;
ADI_HAE_EVENT EEVENT = (ADI_HAE_EVENT)EVENT;/* RESULTS RECEIVED FROM HAE 128MS */
IF (EEVENT == ADI_HAE_EVENT_RESULTS_READY)

{/* GET RESULTS */

PRESULTS = (ADI_HAE_RESULT_STRUCT*)PARG;/* POINTER TO TXBUFFER1 OR TXBUFFER2 */

/* DO SOMETHING WITH THE RESULTS */
FOR (N=0; N

{

IRMS[N] = PRESULTS[N].IRMS;

VRMS[N] = PRESULTS[N].VRMS;
ACTIVEPWR[N] = PRESULTS[N].ACTIVEPWR;

}

}/* TRANSMIT INPUT SAMPLES TO HAE – 8KHZ */

IF (EEVENT == ADI_HAE_EVENT_INPUT_SAMPLE)

{/* FIND LATETS SAMPLES FROM SINC BUFFER . */

ADI_HAE_INPUTSAMPLE(DEV, (SINC_IMEAS_DATA[PWM_SINC_LOOP]),(SINC_VEXT_DATA[PWM_SINC_LOOP]));
INDEX++;
IF (INDEX >= NUM_SAMPLES) INDEX = 0;

}

COUNT++;

}