Gwọ́n Múlẹ̀ Náà fún ìṣàkóso Ìtúnbọ́ Substation: Láti Ìdàbò Fún Ọ̀nà àti Àwọn Ìyípadà Ní Ẹniyan
1. Ƙarshen Faɗa da Kwallon Teknologi na Regulators Voltage na Tsarin
Regulator Voltage na Tsari (SVR) shine wurin mai muhimmanci wajen kawo shiga voltage a mafi girman substations, tana samun faɗa masu inganci domin kawo shiga voltage a cikin mekanismi na tap-changing. Ingantaccen ƙarshensu suna yi amfani da tsarin tsarin transformer ratio adjustment: idan an sami wasu voltage, zai iya gudanar da mota wajen canza taps don kawo shiga tsarin winding turns ratio, kuma kawo shiga output voltage. SVRs masu yawan abubuwa sun bayar da ±10% voltage regulation ta hanyar step increments na 0.625% ko 1.25%, kafin ci gaba da standard ANSI C84.1 don fluctuations voltage.
1.1 Mechanism na Regulation na Tsarin
- Tap Switching System: Tana haɗa da mota-driven mechanical switches da solid-state electronic switches. Yana amfani da tsarin "make-before-break" tare da transition resistors don kawo shiga circulating current, tare da kawo shiga power supply. Zai iya gudanar da switching a kan 15–30 ms, tare da kawo shiga voltage sags for sensitive equipment.
- Microprocessor Control Unit: Tana da 32-bit RISC processors don real-time voltage sampling (≥100 samples/sec). Yana amfani da DSP-based FFT analysis don kawo shiga fundamental and harmonic components, tare da kawo shiga measurement accuracy na ±0.5%.
1.2 Teknologi na Digital Control Masu Yau
Akwai multifunctional control modules masu yawan abubuwa don kawo shiga scenario optimization:
- Automatic Voltage Reduction (VFR): Tana kawo shiga output voltage a lokacin system overload, tare da kawo shiga losses tare da 4–8%. Formula: Eff. VSET = VSET × (1 - %R), idan %R (typically 2–8%) defines the reduction ratio. Misali, a 122V system tare da 4.9% reduction outputs 116V.
- Voltage Limiting: Tana set operational bounds (e.g., ±5% Un). Zai iya gudanar da automatic intervention during voltage violations, overrideable by local/remote operators or SCADA.
- Fault Ride-Through: Tana da basic regulation during faults (e.g., voltage drops to 70% Un). EEPROM storage tana kawo shiga critical parameters for ≥72 hours post-outage.
2. Solutions na Integration na Substation System
2.1 Transformer Tap Control & Parallel Compensation
Voltage regulation requires coordinated control of multiple devices:
- On-Load Tap Changer (OLTC): Primary regulator with ±10% range. Modern OLTCs use electronic position sensors (±0.5% accuracy) to transmit real-time data to SCADA.
- Capacitor Banks: Automatically switched based on reactive power demand. Typical configurations: 4–8 groups, capacity at 5–15% of transformer rating (e.g., 2–6 Mvar for 33kV systems). Control strategies must balance voltage deviation and power factor (target: 0.95–1.0) to avoid overcompensation.
2.2 Technologies na Line Drop Compensation
Long-distance feeders use distributed regulation strategies:
- Series Compensation: Install series capacitors on 10–33kV overhead lines to compensate 40–70% of line reactance. Example: A 2000μF capacitor at 15 km mid-point boosts end voltage by 4–8%, protected by MOV surge arresters.
- Line Voltage Regulators (SVRs): Deployed 5–8 km from substations. Capacity: 500–1500 kVA, range ±10%. Integrated with Feeder Terminal Units (FTUs) for localized automation, reducing communication dependency.
2.3 Equipment Configuration
|
Device Type |
Function |
Key Parameters |
Typical Location |
|
OLTC Transformer |
Primary voltage control |
±8 taps, 1.25%/step, <30s response |
Substation main transformer |
|
Capacitor Banks |
Reactive compensation |
5–15 Mvar, <60s switching delay |
35kV/10kV bus |
|
Line Regulator (SVR) |
Mid-voltage compensation |
±10 taps, 0.625%/step, 500–1500kVA |
Feeder midpoint |
|
SVG |
Dynamic compensation |
±2 Mvar, <10ms response |
Renewable grid connection |
3. Advanced Control Strategies
3.1 Traditional Nine-Zone Control & Improvements
The voltage-reactive power plane is divided into 9 zones to trigger predefined actions:
- Zone Logic: Boundaries set by voltage limits (e.g., ±3% Un) and reactive limits (e.g., ±10% Qn). Example: Zone 1 (low voltage) triggers voltage increase.
- Limitations: Boundary oscillations cause frequent device actions (e.g., capacitor switching in Zone 5), and fail to handle multi-constraint coupling (e.g., voltage violation + reactive deficiency).
3.2 Fuzzy Control & Dynamic Zoning
Modern systems adopt fuzzy logic to overcome limitations:
- Fuzzification: Defines voltage deviation (ΔU) and reactive deviation (ΔQ) as fuzzy variables (e.g., Negative Large to Positive Large), with trapezoidal membership functions.
- Rule Base: 81 fuzzy rules enable nonlinear mapping, e.g.:
- IF ΔU is Negative Large AND ΔQ is Zero THEN Raise Voltage.
- Dynamic Adjustment: Expands voltage dead zones during heavy loads (±1.5%→±3%), reducing device actions by 40–60%.
3.3 Multi-Objective Optimization
For distributed energy integration scenarios:
- Objective Function:
Min[Ploss + λ1·(Uref - Umeas)² + λ2·(Qbalance) + λ3·(Tap_change)]
(λ: weighting coefficients; Tap_change: tap operation cost) - Constraints:
- Voltage safety: Umin ≤ Ui ≤ Umax
- Device capacity: |Qc| ≤ Qcmax
- Daily tap operations: ∑|Tap_change| ≤ 8
- Algorithm: Improved PSO optimization with 50 particles converges in <3s, meeting real-time requirements.
4. Communication & Automation Support Systems
4.1 IEC 61850 Communication Architecture
- GOOSE Messaging: Supports inter-station commands with <10ms delay. Enables coordinated voltage control (e.g., sub-stations respond within 100ms to main-station commands).
- Information Modeling: Defines logical nodes (e.g., ATCC for tap control, CPOW for capacitors), each with 30+ data objects (e.g., TapPos, VoltMag) for plug-and-play integration.
4.2 SCADA System Integration
- Data Acquisition: RTUs sample critical data (voltage, current, tap position) every 2 seconds, prioritizing voltage data transmission.
- Control Functions:
- Remote parameter adjustment (e.g., VSET, %R).
- Seamless auto/manual mode switching.
- Automatic operation lock during device faults.
- Visualization: Dynamic single-line diagrams (voltage violations highlighted in red), trend curves, and audible alarms.
4.3 Key Communication Protocols
|
Layer |
Technology |
Performance |
Application |
|
Station Level |
MMS |
Delay <500ms |
Monitoring data upload |
|
Process Level |
GOOSE |
Delay <10ms |
Protection & control |
|
Inter-Station |
R-GOOSE |
Delay <100ms |
Multi-station coordination |
|
Security Layer |
IEC 62351-6 |
AES-128 encryption |
All communication layers |
5. Performance Optimization & Validation
5.1 Voltage Optimization (VO) Protocol Implementation
U.S. Energy Association’s three-tier approach:
- Fixed Voltage Reduction (VFR): Full-time 2–3% reduction (e.g., 122V→119V). Suitable for stable loads. Annual savings: 1.5–2.5%, but risks motor startup issues.
- Line Drop Compensation (LDC): Dynamically adjusts voltage based on load current.
- Automatic Voltage Feedback (AVFC): Closed-loop control using 3–5 remote sensors/feeder. PID algorithm with 30s cycles.
5.2 Performance Quantification
- Data Collection: 0.2S-class power analyzers record voltage, THD, and power parameters (1s intervals, 7-day duration).
- Energy Savings Calculation: Regression analysis excludes temperature effects.
- Key Metrics:
- Voltage compliance rate: >99.5%
- Daily device actions: <4
- Line loss reduction: 3–8%
- Capacitor switching lifespan: >100,000 cycles.
5.3 Optimization Technique Comparison
|
Technique |
Cost |
Energy Savings |
Voltage Improvement |
Applicability |
|
VFR |
Low |
1.5–2.5% |
Limited |
Stable load areas |
|
LDC |
Medium |
2–4% |
Significant |
Long feeders |
|
AVFC |
High |
3–8% |
Excellent |
High-demand zones |
|
Fuzzy Control |
High |
5–10% |
Optimal |
High renewable penetration |
