1 / 21

IEEE Wind Farm Collector System Grounding for Personal Safety

IEEE Wind Farm Collector System Grounding for Personal Safety. Summary of Topics. Content. 1.0 INTRODUCTION 2.0 GENERAL REQUIREMENTS 3.0 ENVIRONMENT AND GEOTECHNICAL DATA 4.0 SOIL RESISTIVITY MODEL 5.0 SAFETY DESIGN CRITERIA 6.0 GROUND FAULT RETURN CURRENT

kanan
Download Presentation

IEEE Wind Farm Collector System Grounding for Personal Safety

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. IEEEWind Farm Collector System Grounding for Personal Safety Summary of Topics

  2. Content • 1.0INTRODUCTION • 2.0GENERAL REQUIREMENTS • 3.0ENVIRONMENT AND GEOTECHNICAL DATA • 4.0 SOIL RESISTIVITY MODEL • 5.0 SAFETY DESIGN CRITERIA • 6.0 GROUND FAULT RETURN CURRENT • 7.0 MINIMUM GROUND CONDUCTOR CROSS SECTIONAL AREA • 8.0GROUND ELECTRODE SYSTEM & IMPEDANCE • 9.0GROUND POTENTIALS • 10.0DESIGN OF SUBSTATION GROUND GRID AND LIGHTNING PROTECTION

  3. 1-Introduction • This document is a summary of questions/comments on a typical approach for the minimum design requirements of a Wind Power Plant Grounding System. • Aim to Define Topics for Future Standard or Guide

  4. 2 - General requirements • 2.1 Definitions: • Wind Power Plant (WPP) A Wind Power Plant is a single or multiple wind turbine generators electrically interconnected and where the collection system crosses a single or multiple private or public properties; and having one or more points of interconnection to the Utility electric system. • WTG • HV • LV • Grounding system • GPR • Etc..

  5. 2.2 Reference Standards and Documents • What reference standards, guides, codes, document to be used ? • ANSI/IEEE 80 Guide for Safety in AC Substation Grounding • ANSI/IEEE 81 Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System • ANSI/IEEE 998 Guide for Direct Lightning Stroke Shielding of Substations • ANSI/ IEEE 367 Recommended Practice for Determining the Electric Power Station Ground Potential Rise and Induced Voltage From a Power Fault • Other IEEE/ANSI?? • National Electrical Code [NEC] • National Electrical Safety Code [NESC] • International Electrotechnical Commission [IEC] • Underwriters Laboratories [UL] • Insulated Cable Engineers Association [ICEA]

  6. 2.3 What Consists a WPP Grounding System Interpreting NESC/IEEE 80 • Single point, • Multi point • 3 wires ? (Ex. Concentric neutral cable only without additional ground wire • 4 wires ? (Ex concentric neutral cable + additional ground wire) • Ungrounded System?

  7. 2.4 Grounding Design Tools • Grounding Design analysis software and calculation tools. • CDEGS ? • CYME ? • ETAP? • EPRI ? • Other? • Hand Calculation

  8. 2.5 Other Design Aspects • Design Life • Access to Site and Equipment • Public, private • Etc.

  9. 3.0 Environment and Geotechnical Data • 3.1 Climate • Altitude • Normal Ambient Temperature • Extreme Ambient Temperature • Humidity • Max Wind Speed • Precipitation • Seismic Hazard • Lightning Rate

  10. 3.2 Geotechnical data • What measurement & why? (Electrical Resistivity; Soil Acidity) • Measurement method? (Wenner, Schlumberger…) • Where? • Each WTG location? • Each Junction location? • Each switchgear location (pad or pole mounted) ? • Main Substation ? • Interconnection station ? • Met tower location ? • Any other location subjected to electrical hazard?

  11. 4.0 Soil Resistivity Models • Analyse collected data and determine an equivalent soil model for each test location. • Uniform soil? • 2 layers soil? • More than 2 layers

  12. 5.0 Safety Design CriteriaIn accordance with IEEE 80: 2000 • Body Resistance per IEEE 80: 2000 • Foot Resistance per IEEE 80: 2000 • Extra Foot Resistance Applicable or not applicable ? • Maximum HV Ground Fault Disconnection Time: 0.5s or 1s? • Maximum MV Ground Fault Disconnection Time: 0.133s, 0.5s or 1s? • System X/R Ratio (default value 20?) • Fibrillation Current Calculation per IEEE 80: 2000 & 50kg Body Weight • Starting Surface Layer Resistivity: Per applicable Soil Resistivity Model • Surface Layer Thickness • Sub-Surface Layer Resistivity • Imported Crushed Rock For Starting Surface • 2000 Ω.m wet Electrical Resistivity. Or more than 2000 Ω.m?

  13. 6.0 Ground Fault Return Current • 1-Phase-to-ground fault current calculations? • 2-Phase-to-ground fault current calculations?

  14. 6.1 HV Ground fault return current • Depends on the Main transformer HV winding connection: Generally Solidly grounded to provide a ground current return path back to the POI through the transformer HV neutral. • 6.2 MV Ground fault return current • The 34.5kV system neutral is generally solidly connected to ground at the main substation, with no intentional neutral to ground impedance. • Main substation grounding system connection to WTG? • The MV cable screening and bare horizontal ground conductor connection • 6.3 LV Ground fault return current • The LV system at the WTG with all local metalwork being solidly bonded to the LV Neutral of the WTG Transformer

  15. 7.0 Minimum Ground Conductor Cross-section Area • Determine the minimum ground conductors cross sectional area (Based on IEEE 80: 2000) (Section 11.3.1, Formula (37) or code tables?) • Conductor metal • Minimum ground conductor size • Max Ground Ambient temperature • Max Air Ambient temperature • Max bare conductor temperature • Max insulated conductor temperature • System X/R ratio: • HV design total ground fault current (+ Safety margin?) • MV design total ground fault current (+ Safety Margin?) • LV design total ground fault current (+ Safety Margin?) • Fault clearing time ?

  16. 8.0 Ground Electrode System & Impedance • Determine the Ground Electrode System impedance for the wind farm • Based on soil resistivity models and ground electrode conductor configurations • Main S/S & compound • What ohmic value? Common sense? • Cable trenches. • Each wind turbine and it’s associated transformer • What ohmic value? Common sense? • Each meteorological mast • What ohmic value? Common sense? • Each MV junction box/switchgear • etc.

  17. 9.0 Ground Potentials • 9.1 GPR, Transfer, Touch & Step Potential • Examine Ground potential rise due to HV MV & LV ground fault currents. • Compare maximum values to safety criteria for acceptance • 9.2 Zone of Influence (Hot Zone) Contour • Determine the Zone of Influence of Ground fault potential (Hot Zone) as per IEEE 367 (and /or local specific code) • Each site shall then be classified based on a 300V Zone of Influence contour limit as recommended by IEEE 367-1996, section 9.3 as: • a “Hot Zone of Influence” GPR >/= 300V. • a “Cold Zone of Influence”, GPR is < 300V everywhere across the Site .

  18. 10 Design of Substation Ground Grid and Lightning protection • 10.1 Base document & references data • IEEE 80 – IEEE Guide for Safety in AC Substation Grounding • IEEE 81 – IEEE Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System • IEEE 998 – IEEE Guide for Direct Lightning Stroke Shielding of Substations • The substation location and prevailing keraunic level & ground flash density. • Soil resistivity at all grounding points. • Fault Level Schedule.

  19. 10.2 Substation Grounding System • What design criteria specific to Wind Power Plant? • Do we specify a Max Ground Grid Impedance, Why? • What acceptable limits for touch & step potential? (in accordance with IEEE 80). • Fault disconnection time • minimum ground conductor size & material. • Burial depth. • Etc.. • 10.3 Substation Lightning Protection • Free standing lightning masts • Lightning rods installed atop substations structures, • Static wire strung between static masts? • Calculation of the Zone of Protection: rolling sphere / electrogeometric method (EGM)/other methods.

  20. PRESENTATION TITLE 22PT CAPS TREBUCHET. ONE OR TWO LINES PRESENTER NAME - CAPS 14PT JOB TITLE DATE CAPS – 14PT 21

More Related