Smart grid transformers and metering calibration equipment are legal core measuring instruments for power grid settlement, energy metering, condition monitoring and verification, covering voltage/current transformers, electronic transformers, energy meter testers, transformer calibrators and high‑voltage standard metering devices. They guarantee fair energy transaction, accurate measurement and economic grid operation. The high‑voltage power supply acts as the core critical component, providing ultra‑precision stable excitation for standard voltage references, calibration sources and metering standards. Its output accuracy, long‑term stability, temperature drift, linearity and harmonic distortion directly determine measurement error grades and the traceability credibility of the national energy metering system.
Metering‑grade applications impose extreme technical requirements far beyond conventional power supplies: 1.Metering‑level ultra‑high accuracy & linearity: For 0.2‑grade equipment, output accuracy ≤±0.05%; for 0.05‑grade national standards, accuracy ≤±0.01% with linearity error ≤0.005% and tuning resolution up to 10 ppm for continuous linear adjustment. Traditional industrial power supplies cannot meet such strict metering thresholds. 2.Ultra‑low temperature drift & lifelong stability: National verification regulations require annual drift ≤1/3 of total permissible error. For 0.05‑grade standards, annual drift ≤±0.005%, 8‑hour short‑term stability ≤±0.002% and temperature coefficient ≤±0.5 ppm/°C across −10 °C ~ +50 °C to ensure permanent traceable magnitude consistency. 3.Extremely low ripple & distortion: Ripple peak‑to‑peak ≤0.005% and Total Harmonic Distortion (THD) ≤0.01% with no spike noise, delivering pure DC or sine reference voltage to avoid additional measurement deviation. 4.Wide range output & full load adaptability: Continuously adjustable from 0 to full rating, covering 1 kV ~ 500 kV for all transformer voltage classes. Stable performance across resistive, inductive and capacitive loads with load regulation ≤±0.01% and line regulation ≤±0.005%. 5.High isolation & reinforced safety: Isolation withstand ≥2× maximum output voltage; impulse withstand ≥3× maximum output voltage. Non‑bypassable hardware protection prevents electric shock and insulation breakdown for high‑voltage metering environments. 6.High EMC immunity against complex substation interference: Fully compliant with GB/T 17626 and JJF 1059.1 to maintain precision under heavy field interference from inverters, switchgear and high‑voltage equipment. 7.Traceability & regulatory compliance: Fully traceable to national primary standards with complete calibration archives, editable correction coefficients and non‑tamperable historical data for official metering verification and legal traceability. 8.Intelligent digital control & smart grid compatibility: Supporting remote programmable tuning, auto calibration and error compensation via IEC 61850, Modbus and DL/T 645 for fully automated digital metering laboratories.
This methodology establishes a full‑process technical framework covering high‑precision topology design, full‑range low‑drift optimization, lifelong stability assurance, metering‑grade low‑ripple output and legal traceability. It supports all transformers, electronic sensors, meter test benches and national high‑voltage metering standards, delivering standardized design guidelines for domestic core component localization and performance upgrading in smart grid metering systems. To achieve ppm‑level precision, ultra‑low drift and ultra‑low distortion, the universal two‑stage high‑precision architecture is adopted: front‑stage LLC resonant soft‑switch isolation stabilization + rear‑stage high‑precision linear regulation + full‑digital low‑drift closed‑loop control, integrated with full‑temperature multi‑point calibration and metering‑grade noise suppression to eliminate traditional limitations of poor accuracy, large drift and unstable long‑term performance.
1.Metering‑grade high‑precision topology design: •Front full‑bridge LLC soft‑switch stage achieves ZVS/ZCS across full input 85–265 VAC and 10%–100% load range, minimizing switching noise with peak efficiency ≥93%. Dual industrial & high‑frequency isolation transformers provide reinforced insulation ≥2× full rating. •Rear high‑voltage linear regulation eliminates all switching ripple, achieving ripple ≤0.005%. 24‑bit+ DAC enables 10 ppm resolution with linearity ≤0.005%. For AC references, high‑fidelity linear power amplification ensures THD ≤0.01% and phase error ≤0.001°. •24‑bit Σ‑Δ ADC sampling at ≥1 MSPS with low‑noise instrumentation amplifiers and synchronous reference tracking ensures closed‑loop stability: load regulation ≤±0.01%, short‑term stability ≤±0.002%/8h.
2.Ultra‑low temperature drift & full‑range stability: •Metering‑grade component selection: reference TC ≤±0.2 ppm/°C, metal foil resistor TC ≤±0.1 ppm/°C, 24‑bit converter drift ≤±0.5 ppm/°C to minimize inherent drift. •Full‑temperature multi‑point factory calibration with 20+ temperature nodes and 100+ voltage setpoints establishes a 3D temperature‑voltage model stored in non‑volatile FRAM, restricting full‑range error ≤±0.01%. •Real‑time adaptive temperature compensation dynamically corrects output according to distributed temperature sensors, maintaining fluctuation ≤±0.005% from −10 °C to +50 °C. •Long‑term aging screening with 1,000 h high‑temperature burn‑in and secondary final calibration guarantees annual drift ≤±0.005%, fully complying with national metering stability rules.
3.Metering‑grade low‑ripple & low‑distortion output optimization: •Pure linear post‑regulation suppresses switching noise with ripple rejection ≥120 dB. •Nine‑stage cascaded filtering combining π‑type, LC and multi‑RC networks delivers total noise attenuation ≥160 dB, using low‑ESR low‑absorption polypropylene/polystyrene high‑voltage film capacitors for ripple ≤0.005% and noise density ≤1 μV/√Hz. •Ultra‑low distortion AC generation via high‑resolution DDS + fully differential negative‑feedback power amplifier with high‑order low‑pass filtering achieves THD ≤0.01%. •Double shielding: permalloy magnetic inner shield + aluminum electric outer shield (shielding efficiency ≥100 dB); separated shielding cavities for reference, sampling, power and control circuits with differential low‑noise PCB routing.
4.Wide range continuous output & full load adaptability: •Seamless 0–rated linear adjustment with no dead zone; multi‑range configuration covering 1 kV ~ 500 kV with calibrated consistency across all ranges. •Optimized loop compensation stabilizes capacitive transformer loads; maintains precision from no‑load to 120% overload with compatibility for resistive, inductive and capacitive profiles. Switchable constant‑voltage / constant‑current modes support diverse calibration workflows. •Dual hardware/software overcurrent & short‑circuit protection enables smooth auto recovery without overshoot after fault clearance.
5.Reinforced high isolation & absolute safety protection: •Dual transformer isolation + optical/fiber isolation between power and control sections; isolation withstand ≥2× rated voltage, impulse withstand ≥3× rated voltage; high‑voltage transformers with epoxy vacuum encapsulation prevent corona discharge. •Non‑bypassable hardware overvoltage/overcurrent/arc protection with response<1 μs; dual hard overvoltage clamping ensures safety even if control logic fails. •Multi safety interlocks (door, emergency stop, grounding, high‑voltage alarm) cut output within 1 μs if triggered; redundant fast discharge circuits reduce residual high voltage to safe levels within 100 ms; fully sealed non‑exposed high‑voltage terminals with grounding resistance ≤0.1 Ω. •Fully compliant with GB 4793.1, JJG 313 and JJG 597 for legal metering safety certification.
6.High EMC anti‑interference performance: •Soft‑switch LLC reduces dv/dt and di/dt at the source; optimized driving suppresses spikes; switching frequency avoids audio interference bands. •Four‑stage EMI input filtering with nanocrystalline common‑mode inductors achieves ≥120 dB conducted interference suppression. •Full double shielding with beryllium copper gasket seamless contact; double‑shielded cables and feedthrough filters eliminate external coupling. •All ESD, EFT, surge and magnetic field immunity reach GB/T 17626 Level 4, ensuring stable precision in harsh substation and laboratory environments.
7.Traceability & intelligent calibration system: •Built‑in reference standard fully traceable to national primary metrology institutes; non‑tamperable calibration data storage ≥10 years for official verification archives. •One‑click full‑range auto calibration with real‑time correction for nonlinearity, temperature drift and load deviation; remote calibration supported via digital interfaces. •Rich communication ports (RS232/RS485/GPIB/Ethernet/Fiber) supporting SCPI, Modbus, IEC 61850 and DL/T 645 for unmanned automatic meter verification lines and transformer calibration platforms.
8.Metering regulatory compliance & full scenario adaptability: •Fully compliant with JJF 1059.1, JJG 313, JJG 597 and GB/T 13000, passing legal pattern approval and mandatory verification; satisfying State Grid & China Southern Grid metering standard technical specifications. •Fully adaptable for voltage/current/electronic transformers, energy meter test benches, high‑voltage reference standards and power quality analyzers, supporting laboratories, substations, verification workshops and mobile metering vehicles.
In conclusion, this integrated framework solves core weaknesses of conventional high‑voltage power supplies for metering. It achieves ≤±0.01% output accuracy and 0.005% linearity, ±0.5 ppm/°C temperature drift, ≤±0.005% annual stability, ultra‑low ripple below 0.005% and THD ≤0.01%, with complete national metrology traceability. Widely applicable across all smart grid transformer and metering calibration equipment, it provides core independent technology for high‑end domestic metering device localization and precision breakthroughs.