Mpango wa Combined Instrument Transformer (CIT): Perspektiva ya Ujenzi na Integresheni

1. Mwongozo wa Utatuzi Msingi: Platform ya Moduli na Uzio wa Kijamii

Mfano: Unda platform moja, ya moduli yenye kazi za kutambua mzunguko na umeme ndani ya muundo mmoja unaofanana.
Uzio: Tumia uzio wa kijamii. Imetengenezwa chaguo mbili:

Gas SF6: Ina nguvu ya kijani ya juu na vitendo vya kutosha kwa kiwango cha juu (mfano, 72.5 kV na zaidi). Mfano unahusisha utafiti wa ukungu na teknolojia ya kufunga iliyotathmini.
Nyumba ya Jumbe (Uzio wa Kijamii): Suluhisho la asili linatumia vifaa vya polymer viwili na sheds za silicone. Ni bora kwa kiwango cha chini hadi kati au ambapo lazima kuacha SF6. Imefanyika kwa ajili ya umbali wa creepage na matukio ya jioni.

2. Mikakati ya Kutumia Teknolojia ya Kutambua

Sensor: Rogowski coils zenye ufanisi wa juu na temperature-compensated. Yalichaguliwa kwa:

Mchezo Mrefu: Ulinzi mzuri kutoka kwa sehemu ndogo ya mzunguko wa asili hadi kwa mzunguko wa hitimisho (mfano, >40 kA).
Hakuna Saturation: Faida msingi kwenye CTs ya iron-core, kuchoma hatari ya saturation wakati wa hitimisho.
Lightweight: Huongeza stresi ya mekani ya jumla.

Integration: Coils zimeelekezwa kwa busara ndani ya uzio wa insulator, concentric na primary conductor. Mounting ya mekani inayotumai vibaya vibaleo.

Sensor: Capacitive voltage dividers (CVDs) zenye ustawi wa juu kama chaguo msingi. Resistive dividers (RVDs) zimehitajika kwa maeneo maalum ya DC au maeneo ya wide-bandwidth yanayohitaji majibu yasiyo na muda.
Integration: Sensing electrodes (low-impedance) zimeunganishwa moja kwa moja ndani ya muundo wa insulator. Grading electrodes zenye upana hupewa kwa kutosha kwa ajili ya utaratibu wa joto na jioni. Shielding muhimu huokoa kutokana na kutokana na magonjwa ya nje.

3. Modeling ya Mpana Mkuu na Isolation (Changamoto Kubwa ya Uhandisi)

Modeling: Inahitajika, modeling ya Finite Element Method (FEM) ya kutosha ya kila platform:

Inacharacterize electromagnetic fields ndani kwa kila mtazamo wa kazi (sinusoidal, transient, distorted waveforms).
Inaevalue proximity effects kutoka kwa conductors, enclosure, na adjacent phases.

Physical Separation: Muundo mzuri wa sensing elements (coils, CVD electrodes) kulingana na matokeo ya modeling. Ongeza umbali kwa mikakati.
Active Shielding: Tumia electrostatic shields zilizokuwa na ground kulingana na data ya simulation ya mpana.
Guard Rings: Tumia guard rings za conduction zilizoko katika output za Rogowski coil kutoa displacement currents.

Dedicated Signal Paths: Routing signals kutoka kwa individual sensors kutumia shielded, twisted-pair cabling ndani ya enclosure mara tu baada ya kupata.
Compensated Circuit Design: Electronic conditioning circuits zimeundwa kwa mbinu za kutosha za FEM models.
Validation: Testing kamili ya factory (ikiwa ni harmonic injection tests) kucharacterize na kuthibitisha isolation margins na crosstalk levels (< 0.1% specified).

4. Digital Processing na Interfaces Standardized

ASICs zenye nguvu ndogo au microcontrollers zenye imani ya juu zimeunganishwa moja kwa moja ndani ya platform ya sensor au module sealed.
Vigezo vinavyotumika: Rogowski coil integrator, scaling, ADC conversion, harmonic computation (ikiwa ni muhimu), linearization, temperature compensation, na timestamping.

Embedded Interfaces: Incorporate IEC 61869 compliant digital output circuitry directly within the CIT unit.
Protocols: Standardized support for:

IEC 61850-9-2: Sampled Values (SV) stream over Ethernet (typically multicast).
IEC 61850-9-3LE: Lightning Edition SV profile for guaranteed low-latency determinism.

Additional Options: Provision for legacy outputs (analog, IEC 60044-8 FT3) where required via optional modules.

Data Quality: Integrated Merging Unit (MU) functionality meeting relevant IEC 61869 accuracy (TPE/TPM class) and timing (PLL synchronization) standards.

5. Engineering Design & Integration Considerations

Thermal Management: Models include thermal performance analysis. Power dissipation from electronics actively managed using low-power components, potential localized heatsinks, and optimized convection paths within the insulator.
EMC/EMI Robustness: Conformal coating, shielded enclosures, ferrites, and optimized grounding strategies applied to internal electronics. Surge protection compliant with relevant standards (IEC 61000-4-5).
Mechanical Integrity: Structural analysis performed for seismic loads, wind loading, ice loading, and dynamic forces during faults. Optimized use of materials (composite/porcelain/SF6) contributes to lower seismic mass.
Factory Calibration & Testing: Comprehensive calibration against reference standards (optical/VTBI methods). Includes verification of EM isolation effectiveness, timing accuracy, protocol compliance, and full-power dielectric testing.
Lifecycle & Serviceability: Designed for minimal maintenance (especially SF6 or solid insulation). Modular electronics potentially accessible/testable without major disassembly. End-of-life disposal pathways considered (SF6 recovery/recycling).

Benefits Realized through this Design & Integration Approach:

Footprint Reduction: Up to 40-50% space savings vs. separate CTs/VTs – crucial for retrofits and compact GIS/AIS designs.
Enhanced Accuracy & Safety: Eliminates traditional CT saturation risks, improves transient response (Rogowski/CVD), reduces external connections/risks.
Simplified Installation: Single unit mounting and commissioning significantly reduce field labor and cabling complexity.
Lower Lifecycle Costs: Reduced installation, cabling, civil work, maintenance overhead.
Digital Substation Readiness: Direct IEC 61850-9-2/3LE output enables seamless integration into modern protection, control, and monitoring systems (SAS).
Future-Proof Platform: Modular design accommodates evolving sensor technologies and communication standards.
Reduced Environmental Impact (Solid Insulation Option): Eliminates SF6 usage and associated risks.