Relay ng Proteksyon sa Linya Microcomputer-Based Line Protection Solution

1. Abstract ug Background​
   Nag-increase ang komplikado sa struktura sa power grid—partikular ang pag-usbong sa ultra-high-voltage direct current (UHVDC) transmission, pag-integrate sa renewable energy sa dako, ug maramihon nga parallel transmission lines—ang performance requirements para sa protection sa transmission line nakaabot sa kaunti nga gipasabot. Ang core challenge molahiha sa pagsunod sa duha ka critical demands: siguraduhon ang extremely high-speed operation sa mga device sa protection samtang may fault aron maprotektahan ang system stability, apan sama usab siguraduhon ang strong selectivity aron mapigilan ang unnecessary tripping ug pag-agpas sa fault. Mas malamya kini sa complex grid configurations sama sa parallel double-circuit lines, diin ang traditional single-ended protection principles naglantaw og significant limitations.

Ang solusyon kini nagamit og advanced microcomputer-based protection technology, naa ang tulo ka core modules: power frequency variation distance protection, double-terminal traveling wave fault location, ug adaptive auto-reclosing strategies. Nagahimo kini aron mapalambo ang reliability, speed, ug intelligence sa line protection, naghatag og critical support aron maporma ang robust ug smart grid.

​2. Core Challenge Analysis​

• ​Kontra sa speed ug selectivity: Ang traditional protection schemes kasagaran magkinahanglan og delayed operation aron masiguro ang selectivity, naglabay sa kinahanglan sa rapid fault clearance aron maprotektahan ang system stability.
• ​Precise fault location sa parallel double-circuit lines: Ang mutual inductance sa double-circuit lines nagkomplika sa fault characteristics, nagbawas sa accuracy sa traditional fault location methods ug naghambog sa fault identification ug power restoration.
• ​Uncertainty nga gihatag sa integration sa renewable energy: Ang integration sa wind ug solar power plants nag-usab sa short-circuit current levels ug characteristics, mahimong magresulta sa protection maloperation o failure. Kasagaran, ang ilang output fluctuations nagchallenge sa success rate sa auto-reclosing strategies.

​3. Core Technologies of the Solution​

​3.1 Power Frequency Variation Distance Protection (ΔZ Protection)​​

• ​Teknikal nga Principle: Kini nga teknolohiya walay epekto sa load current sa normal nga operation sa system. Igi-compute niya ang fault impedance gamit ang power frequency variations sa voltage ug current nga giproduce sa instant nga adunay fault. Ug high starting thresholds, ini nga directional, highly selective, ug insensitive sa system oscillations ug transition resistance.
• ​Performance Advantages:
• Ultra-high-speed operation: Extremely fast response, usual nga operation times less than 10ms.
• High reliability: Epektibo nga iwasan ang misoperation tungod sa load current influences.
• ​Application Case: Sa ±800kV UHVDC transmission line, ang teknolohiya kini nagreduce sa total fault clearance time (protection operation + circuit breaker tripping) sa near-end faults within 80ms, significantly enhancing the transient stability of the UHVDC system.

​3.2 Double-Terminal Traveling Wave Fault Location​

• ​Teknikal nga Principle: Ang fault mogenerate og traveling waves nga mopropagate ha duha ka end sa line. Gamit ang high-precision GPS/BDS synchronized clocks, ang protection devices sa duha ka end precise record sa arrival times sa initial current traveling waves (t1 ug t2). Ang fault location accurate calculate gamit ang formula L = (v * Δt) / 2, diin v ania ang wave velocity ug Δt = |t1 - t2|.
• ​Performance Advantages:
• Ultra-high accuracy: Ang fault location wala maaffect sa line mutual inductance, system operation mode, transition resistance, o current transformer (CT) saturation.
• Parameter-independent: Wala magdepende sa line impedance parameters, eliminating errors caused by inaccurate parameters in traditional impedance-based methods.
• ​Application Case: Ang deployment sa 500kV double-circuit line sa same tower nagreduce sa fault location error less than 200 meters, improving accuracy by over 80% compared to traditional single-ended impedance-based methods. Kini greatly facilitates rapid fault identification ug maintenance.

​3.3 Adaptive Auto-Reclosing Strategy​

• ​Teknikal nga Principle: Ang microcomputer-based protection device intelligent distinguish fault types (transient or permanent):
1. ​Transient faults: After tripping, ang line dielectric strength self-restores. Ang device detect insulation recovery ug promptly issue a reclosing command.
2. ​Permanent faults: Ang device detect ang persistent fault ug block reclosing aron mapigilan ang secondary circuit breaker tripping, ensuring equipment safety.
   Additionally, ang strategy dynamically adjust ang dead time sa auto-reclosing based on real-time system conditions (e.g., renewable energy output share) aron match system recovery characteristics.
• ​Performance Advantages:

• Increased success rate: Avoids reclosing on permanent faults, significantly improving the success rate of auto-reclosing and power supply reliability.
• Reduced impact: Prevents unnecessary secondary shocks to the system, safeguarding equipment.

• ​Application Case: Implementation sa critical wind farm outgoing line increased the auto-reclosing success rate from 72% to 93%, effectively reducing wind turbine disconnections caused by transient line faults.

​4. Solution Value Summary​
Kini nga integrated microcomputer-based protection solution delivers core value to customers through the synergistic application of its three key technologies:

1. ​Enhanced system stability: Ultra-high-speed protection isolates faults rapidly, securing critical time to maintain grid stability.
2. ​Improved power supply reliability: Intelligent adaptive auto-reclosing maximizes power restoration, reducing outage duration and losses.
3. ​Increased operational efficiency: High-precision fault location transforms maintenance from "line patrolling" to "point inspection," significantly reducing costs and time.
4. ​Adaptability to new power systems: Its exceptional performance makes it highly suitable for complex modern grid scenarios, including UHVDC, renewable energy integration, and multi-circuit lines.