Tambayar da Tattalin Kisan Gargajiya na Turanci 35 kV Outdoor Combined Transformer

1. Bayani

Yadda yake da PT dabiya da fuse mai karamin sauran jama'a a cikin combined transformers ya zama wani abu mai zurfi da ke taimakawa wadannan tsarin masana'antu na noma ta hanyar kula da kuma tsaftace gwamnatiyar gida. Wannan littafi yana neman matsalolin da suka faruwa a kan PT da kuma fuse a cikin combined transformer na 35 kV, yana bincika sabbin masu maitaccen bayanai, yana ba da kayan aiki, da kuma yana sake tabbatar da adadin kilowattota da aka fito a cikin al'amari. Wannan yana taimaka wajen ya kawo kammalin gwamnatiyar gida da kuma inganta masu wasu.

1.1 Bayani game da Combined Transformers

A cikin tsarin masana'antu, combined transformers suna da muhimmanci a cikin al'amari da kuma gwamnatiyar gida. Suna samun shugaban voltage transformers (PT) da kuma current transformers, suna amfani da farkon tsari a cikin primary da secondary coils don in tabbatar da primary - side currents da voltages da suke so kuɗi zuwa currents da voltages masu kyau don secondary instruments da kuma relay protection. Amma, suna taimaka waɗanda suke yi aiki a cikin secondary side don hankali masu aiki da kuma ƙasashen kwallo.

2. Masu Dabba da Take da Faults a Cikin Combined Transformers

Saboda haka, PT a cikin combined transformer yana da muhimmanci a cikin tsarin masana'antu, yana da shugaba kan nan da za a yi aiki a cikin al'amari/daidaitaccen bayanai. Idan PT ya zama da maƙashe ko high - voltage fuse ya dabiya, akwai masu dabba kamar:

• Al'amari Mai Yawan Tabbataccen : Maƙashe da PT da kuma dabiya da fuse mai yawa ita ce za su iya haɓaka errors a cikin tsarin al'amari, zai iya haɓaka tushen al'amari da kuma inganta nasara a cikin masu aiki da mutanen.

• Zuwarta da Kafin Yawan Daɗi : Maƙashe da PT zai iya haɓaka system voltage imbalance (mai kadan/mai tsaki), zai iya haɓaka tushen system; maƙashe da transformer zai iya haɓaka aiki daidaito, zai iya inganta risuka da yake daɗi.

• Masaloli mai Kasa : Combined transformers suna da high - voltage. Idan suka da maƙashe, zai iya haɓaka insulation breakdown da leakage, zai iya inganta kasa ga masu aiki da kuma masu ƙarfafa.

3. Sabbin Masu Maitaccen Overvoltage Faults a Cikin Combined Transformers

Idan a yi aiki, combined transformers suna da maƙashe da dabiya da fuse mai karamin sauran jama'a. Sabbin masu maitaccen include:

• Ferromagnetic Resonance Overvoltage : Ferromagnetic components suna da linear under rated voltage. Idan an samu fault, magnetic circuit yake tsaya, da inductance yake canza non - linear. Zai iya ƙare oscillation loop da system capacitance, zai iya ƙare ferromagnetic resonance. Overvoltage yana haɓaka dabiya/burnout da PT high - voltage fuses, zai iya inganta kasa ga grid.

• Excessive Secondary Load : Excessive secondary load zai iya haɓaka transformer zuwa hotu da yake daɗi, da kuma heat dissipation. Internal winding temperature yake tsayi, yana ƙare burnout da PT.

• Primary - Secondary Side Short Circuit : Short circuits a cikin primary/secondary side na PT zai iya ƙare currents masu yawan, zai iya ƙare dabiya da fuse mai karamin sauran jama'a da kuma equipment burnout.

• Switching Overvoltage : Aikinsu mai yawan zai iya ƙare overvoltage, zai iya ƙare dabiya da PT high - voltage fuse.

• Lightning Overvoltage : Direct/inductive lightning overvoltage zai iya ƙare winding insulation, zai iya ƙare damage da equipment.

4. Case Analysis
4.1 Basic User Information

A ranar 23 ga Agusta, 2021, an samu maƙashe da PT burnout fault a cikin combined transformer na 35 kV user, wanda yake ƙare al'amari mai yawan tabbataccen. A shekarar da ya ɗauke, wannan combined transformer ya samu 3 faults. Idan an samu karfin Janairu, 2021, user ya samu power supply daga 35 kV Shazi Substation da al'amari mai tsarki. Ba ƙanan Agusta, 2021, an yi ƙaramin supply zuwa 35 kV outgoing line na 110 kV Zhoujiaba Substation (Zhouwan Line #353 da Zhouri Line #354 dual - circuit power supply). Total line length yana da yarda 1.5 km. 35 kV side yana da ground via arc - suppression coil. Metering points suna da shugaban 2 - circuit 35 kV outgoing lines na 110 kV Zhoujiaba Substation. Primary wiring yana nuna a Figure 1.

4.2 Metering Points and Fault Timeline

Duk metering points suna amfani da 35 kV combined transformers, da three - phase three - wire connection da V/V connection don voltage transformers. Daga cikinsu:

• 35 kV Zhouri Line #354 (Metering Point 2): Yana yi aiki da tsarki, babu faults;

• 35 kV Zhouwan Line #353 (Metering Point 1): Yana samu faults da yawa.

Fault Timeline:

• 23 ga Agusta, 2021: First PT burnout, an ƙara da products na Henan Xinyang Hutong Electric Co., Ltd.;

• 4 ga Maris, 2022: PT burns out again, an ƙara da combined transformers na Jiangxi Gandi Electric Co., Ltd.;

• 13 ga Yuni, 2022: C - phase high - voltage fuse melts, voltage loss;

• 21 ga Satumba, 2022: A - phase high - voltage fuse melts, voltage loss again.

4.3 Fault Analysis

A lokacin da fault ya faru, user load yana da kyau, secondary wiring yana da tsarki, da kuma babu short circuit. Ba a yi test:

• Line grounding resistance yana da tsarki, da kuma ana da shugaban non - effective grounding system. Grounding faults zai iya ƙare lightning current ba zai iya discharge, zai iya ƙare dabiya da fuse;

• Babu overvoltage a cikin operation and maintenance, ana ƙara human factors.

A ƙare da fault phenomena da common causes, ana neman sabbin maitaccen za a ƙare ferromagnetic resonance overvoltage, da specific triggering scenarios:

• Triggered by Grounding Faults: Idan single - phase grounding ya faru a cikin line, PT winding da line - to - ground capacitance suna ƙare parallel circuit, yana neman conditions don ferromagnetic resonance. Single - phase grounding zai iya ƙare voltage na biyu phases tsayi, iron core zai tsayi, da kuma resonance zai iya ƙare winding current zuwa surge, dabiya da high - voltage fuse; long - term overcurrent zai iya ƙare burnout da PT.

• Triggered by Improper Operation: Three - phase load na system yana da tsarki, amma a lokacin da a yi switching operations, biyu phases ba su ƙare synchronized (closing/opening ba su ƙare simultaneous), zai iya ƙare inrush current a cikin voltage transformer winding da iron core saturation, ƙare ferromagnetic resonance overvoltage.

4.4 Solutions

Ba a yi analysis da sabbin masu maitaccen, ana ƙara da measures:

• Install Harmonic Elimination Devices: Install 1 set of harmonic elimination devices a 35 kV bus side na substation don in ƙara recurrence da ferromagnetic resonance.

• Overvoltage Protection on Secondary Side: Install overvoltage protection devices a cikin secondary side don in ƙara overvoltage da take da environmental factors da kuma protect internal insulation na transformer.

• Harmonic Detection and Treatment: Amfani da on - site electric energy meter calibrator don in detect harmonics a cikin secondary voltage. Idan akwai abnormalities, ƙara users don in treat them don in neman compliance da GB/T 14549 - 1993 "Power Quality - Harmonics in Public Power Grids": Total harmonic distortion rate na 35 kV voltage ≤ 3%, odd - order harmonics ≤ 2.4%, even - order harmonics ≤ 1.2%.

Implementation Effect: Ba a ƙara da measures, combined transformer yana yi aiki da tsarki, babu PT burnout ko fuse melting faults.

4.5 Electricity Quantity Reconciliation Calculation

Tushen al'amari na electric energy yana da muhimmanci ga economic interests na both power supply and consumption parties. Faults ƙara reconciliation. Wannan littafi yana ƙara third fault a cikin example da kuma amfani da correction coefficient method don in ƙara calculation:

Principle: Compare active power during correct metering and incorrect metering don in neman correction coefficient k, da kuma ƙara reconciliation electricity quantity \(\Delta W\). Assuming three - phase load balance, formula na correction coefficient k ce:

(1) Interpretation of Correction Coefficient k

Idan k > 1, active power during correct metering yana da tsayi da incorrect metering. Energy meter yana under - register electricity during the fault, da kuma customer yana ƙara reconciliation electricity. Idan k = 1, energy meter yana neman tsarki. Idan 0 < k < 1, energy meter yana over - register electricity, da kuma reconciliation electricity yana ƙara refund to the customer. Idan k < 0, energy meter yana reverse, da kuma customer yana ƙara reconciliation electricity.

(2) User - related Metering Parameters

User's receiving capacity yana da 2500 kVA, da kuma metering method yana da high - supply high - metering (metered by a high - voltage combined metering box). Voltage ratio yana da 35000 V/100 V, da kuma current ratio yana da 50 A/5 A. Comprehensive metering multiplier yana da 3500. Energy meter capacity yana da 3&times;100 V/3&times;1.5 - 6 A, da accuracy da 0.5S.

User's third fault yana faru a 13 ga Yuni, 2022, idan phase C yana lose voltage. Power yana ƙara a ƙanan 8:00 a 4 ga Agusta, 2022. Time - of - use electricity pricing yana faru a 1 ga Yuli, 2022. Collected data such as system voltage, power, and power factor yana nuna a Table 1.

Calculation of Reconciliation Electricity Quantity for the First Stage

As can be seen from Table 1, during the period from 13 ga Yuni, 2022 to 30 ga Yuni, 2022, voltage na phase A yana da tsarki, average power factor yana da 0.82, da kuma element angle yana da 34&deg;(L). Then power factor angle &phi;=4&deg;(L).Assuming that the load is balanced, the correction coefficient is:

The calculation of the reconciliation electricity quantity is as follows:

From Formula (2) and Formula (3), it can be seen that k > 1, meaning the electricity is under - measured, and an additional electricity quantity of 15,134 kWh should be recovered.(2) Calculation of Reconciliation Electricity Quantity for the Second Stage.During the period from 1 ga Yuli, 2022 to 4 ga Agusta, 2022, voltage na phase A yana da tsarki, average power factor yana da 0.87, da kuma element angle yana da 29&deg;(L). Then power factor angle &phi;=0&deg;.Assuming that the load is balanced, the correction coefficient is:

The calculation of the reconciliation electricity quantity is as follows:

From Formula (4) and Formula (5), it can be seen that k > 1, meaning the electricity is under - measured, and an additional electricity quantity of 51,996 kWh should be recovered.Total reconciliation electricity quantity to be recovered:

5. Conclusion

A cikin aiki, combined transformers suna da maƙashe da dabiya da high - voltage fuses, wanda ke haɓaka kammalin grid. Duk da cewa wadannan issues suna da resonance overvoltage, amma akwai kuma improper equipment design/selection da parameter mismatches.

A lokacin da a yi analysis da faults: Kafin, check for transformer defects and verify high - voltage fuse capacity. Kafin, install proper primary harmonic elimination devices don in ƙara resonance overvoltage. Ba a faru accident, respond promptly and handle correctly don in ƙara escalation and social impacts. Kafin, learn from experience, improve fault - handling skills, and ensure grid safety.