Cases-GoLead Intelligent

A 220 kV Substation of State Grid Hubei

Overview

This project serves the central and southern areas of Dongjin New District. The substation is equipped with two 180 MVA main transformers, with 46 existing 10 kV feeders, 45 of which are already in service, resulting in a feeder utilization rate of 98%.

The substation belongs to a Class B power supply area within Dongjin New District. There are currently two substations in operation, supplying 45 outgoing 10 kV feeders, of which 60% are shared feeders. The network includes 18 tie lines and 9 single-radial feeders.
Our smart phase-controlled circuit breaker is applied to the 10 kV capacitor bank in the #2 main transformer expansion project, where each capacitor bank has a rated capacity of 8,016 kvar with a 5% series reactor.

Pain Points & Solutions

Pain Point 1: Severe Inrush Current and Overvoltage During Closing

When conventional circuit breakers switch capacitor banks, the closing inrush current can reach 6.07 times the rated current, and overvoltage can rise to 1.70 p.u., leading to insulation aging, shortened capacitor bank lifespan, and even explosion risks.
Solution 1

Optimized Closing Control: The breaker is controlled to close at the capacitor-side voltage zero-crossing, suppressing inrush current to within 1.18 p.u. and reducing overvoltage to within 1.39 p.u..
Pain Point 2: High Risk of Reignition Overvoltage During Opening

During interruption, insufficient dielectric recovery between contacts may cause re-strike, resulting in reignition overvoltage.
Solution 2

By precisely controlling the arc duration, the arc is extinguished at the current zero-crossing, effectively preventing reignition overvoltage.
Pain Point 3: Short Equipment Lifespan and High Maintenance Costs

Conventional breakers switch capacitor banks about 200 times per year. Frequent inrush and overvoltage events cause vacuum interrupter damage and mechanical aging, reducing service life to only several thousand operations.
Solution 3

The smart phase-controlled circuit breaker offers a mechanical endurance of no less than 30,000 operations and supports condition-based maintenance, extending maintenance intervals, reducing planned outages, and avoiding outages caused by switching failures. This results in annual O&M cost savings of approximately 20–30%.
Pain Point 4: Insufficient Power Quality and System Stability

Inrush currents and overvoltages introduce harmonic pollution, degrade power quality, and may lead to bus outages or reactive power compensation failures.
Solution 4

After deploying the smart phase-controlled circuit breaker, closing inrush current is reduced from 6.07 p.u. to 1.1 p.u., and overvoltage is lowered from 1.70 p.u. to 1.07 p.u.. This avoids harmonic pollution, reduces unplanned outages, and helps alleviate tight feeder bay resources at the substation.

Values

Flexible & Reliable

Three-phase independently controlled permanent-magnet mechanism enables per-phase switching strategies (angle accuracy ≤ 10°), effectively handling capacitor imbalance and harmonic interference. Fully compliant with IEC 61850 for seamless integration with existing substation systems and future smart grid coordination.
Simple & Efficient

Integrated breaker–controller design with built-in online monitoring eliminates external devices and simplifies installation. Long-life permanent-magnet mechanism (≥ 30,000 operations) enables condition-based, near maintenance-free operation and reduces manual inspections.
Fast & Cost-Efficient

Millisecond-level adaptive phase control (time dispersion ≤ ±0.5 ms) ensures fast reactive power response and high power quality. Reduced fault risk, extended 30-year service life, and minimal maintenance allow cost recovery within 3–5 years.

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