SES Contributions

Model Simplification of Extensive Grounding Systems at Solar Power Plants

Jinxi Ma

Introduction

A solar power generation facility is generally much more extensive than a conventional substation. The dedicated grounding system installed at a solar power generation facility usually consists of ground loops at the power conversion station (inverter station) sites which are interconnected by a main ground loop. In the grounding analysis however, the completed grounding system should include the steel piles which support the solar panels. As a result, the number of conductors in the grounding system is very large. Consequently, the computer model has to be simplified adequately to reduce computer memory requirements and computation time while maintaining the accuracy of the results. This article shows an example of how such a grounding system should be simplified.

Comparison of Measured and Computed Electric Fields near a 330 kV Tower

Winston Ruan and Simon Fortin Tony Auditore

SES Ltd. LineTech Consulting Ltd., Hamilton, New Zealand

Introduction

LineTech Consulting ltd was tasked by PowerLink Queensland of Australia to conduct an electromagnetic study on various overhead line tower configurations from 110 kV to 500 kV. The objective of the study was to see if the live-line workers were exposed to EMF fields in excess of the allowable limits for compliance with the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). This article presents a comparison of measured and computed electric fields near a 330 kV steel tower. The HIFREQ and TRALIN modules of the CDEGS package are used for the investigation.

Lightning Shielding Design Study for a Large Plant Using SESShield-3D

Stéphane BARON and Robert Southey

Introduction

This article describes a lightning shielding study of a large plant, completed by SES under somewhat unusual circumstances. Rather than provide a usable 3-D model of the plant or a detailed set of drawings with both plan and elevation views of the buildings and equipment to be protected, the client provided limited data, consisting of general arrangement drawings marked-up with the heights of the tallest and most extensive structures in each plant area. As a result, SES was left to its own devices (so to speak) and adopted a block volume protection approach, based primarily on shield wires, supplemented by a look-up table for mast-protection of equipment extending outside the block volumes in the primary plant areas. The shielding study was carried out in accordance with the Electrogeometric Model (EGM) and associated Rolling Sphere Method (RSM) described in IEC 62305, with a strike radius of 45.0 m, which corresponds to a Class III lightning protection system. Calculations and design of the shielding system were carried out with the SESShield-3D module of the CDEGS software package.

Effect of Site Improvement on the Performance of Substation Grounding Systems

Jinxi Ma

Introduction

When a new electrical substation or power plant is built, the site of the substation or power plant often needs to be modified because of civil engineering considerations. For example, the design grade of a new substation can be higher than the existing earth surface. Therefore, additional soil needs to be added on top of the existing earth surface to achieve design grade. The substation grounding grid in this case will be imbedded in the added soil volume. Obviously, the site improvement will affect the performance of the grounding system. The main objective of this article is to evaluate this effect. Another objective is to show how such a situation can be accurately modeled in the grounding analysis by combining available analysis techniques.