Project Outline:

Interactive review of a grounding study focusing on the zone of influence around an extensive solar plant ground system, accounting for the contribution of a nearby major power plant, in the event of 132 kV fault conditions at its associated high-voltage substation.

Project Outline:

Investigation of the material properties of the ArcAngel™ product developed by Copperweld, in order to reconcile high-current test lab results with those predicted by simple equations in IEEE Std. 80. SES carried out numerical thermal transient analyses and found that the highly non-linear thermal properties of steel result in much different behavior and therefore greater maximum current-carrying limits than predicted by IEEE Std. 80 equations.

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Support and review of a study of interactions between a DC traction station and adjacent urban infrastructure, including a nearby swimming pool, during 69 kV fault conditions.

Project Outline:

Lightning transient analysis for two transition stations on either side of a river beneath which an HVDC transmission line runs underground. The buried cables, station grounds, and transmission lines were modeled, for lightning strikes to lightning masts at each station, in order to determine the GPR of the grounding system with and without various arrangements of extensive counterpoise conductors. Cable jacket stress voltages were calculated throughout the cable length with two types of cable jackets. Fault conditions at the two stations were studied as well, and touch/step voltages were compared with tolerable levels.

Project Outline:

As a continuation of Phase 1 of the Eversource Substation Lightning Interference Study, the focus of Phase 2 was to develop an accurate model of the relevant control cables to determine how the relays were impacted by the present control cable topology and interconnection philosophy and how to develop mitigation measures to prevent control equipment failures. Several computer models were built and their lightning performance analyzed. The results from various computer models show similar trends and maximum electrical stress values of the same order of magnitude for specific soil structure models. This study has shown that adequate mitigation measures can reduce stress voltages on control cables and associated equipment by an order of magnitude. Appropriate company standards and mitigation measures have the potential to prevent equipment damages for all but the most severe lightning strikes, resulting in significant economical savings and avoidance of outages.

Project Outline:

Fall-of-potential, touch and step voltage tests were carried out at the Riel Converter Station using multiple test frequencies to verify the predictions of the design study. Testing was carried out on this very large station (approximately 1.4 km in extent), while the station was in operation. The fall-of-potential impedance measurements were found to match model predictions within roughly 10% and touch voltages within 7%.

Project Outline:

Final as-built station grounding study during 230 kV fault conditions, both within and outside the station, as a function of seasonal variations and for contingency conditions. Interactions between the station grounding system and an adjacent storage area were modeled. The effect of induced voltage from overhead lines and bus work on touch and step voltages throughout the grounding system was considered.

Project Outline:

Fall-of-potential, touch and step voltage tests were carried out at the Keewatinohk Converter Station using multiple test frequencies to verify the predictions of the design study. Testing was carried out in sub-zero temperatures on this large northern station (roughly 0.7 km in extent) while the station was in operation. The fall-of-potential impedance measurements were found to match model predictions very closely; touch and step voltages were well within the design limits and reproduced their anticipated relative magnitudes throughout the station. New test techniques were developed to contend with the high resistivity of the frozen surficial soil.

Project Outline:

On April 26, 2019, lightning struck the Eversource 345/115/138.8 kV substation multiple times, including one very strong cloud-to-ground strike (-146 kA). The storm resulted in a lightning fault on one of the 230 kV line terminals followed by a subsequent phase-to-ground fault. The relays failed to operate and trip the line, resulting in a major outage on the Eversource power system network. Consequently, Eversource determined that a systematic design approach on the transient analysis of the event with mitigation measures and remedial actions were required to retrofit existing substations and to design future substations where such events must be considered. SES confirmed that the damages observed were consistent with voltage and current stresses that the lightning strikes would have inflicted. The study revealed that potential differences along the control cables were sufficiently large to potentially damage or disrupt the protection system, due to the dielectric breakdown of the cable insulation or electronic components located at the ends of the control cable, and recommendations were made for further investigation.

Project Outline:

Study of touch, step and equipment transfer voltages in construction zone, and assessment of safety precautions required in the absence of crushed stone surfacing, at Riel Converter Station. Both 230 kV and 500 kV fault conditions near the construction zone were studied.

Project Outline:

Quality control test developed to verify 69 kV transmission line pole ground resistances in areas close to the Trans Mountain pipeline. The test was conducted while the transmission line was in operation.

Project Outline:

Peer review by SES of a preliminary distribution station grounding study and further modeling by SES. The review included preparation of a detailed model of the substation grounding system, surrounding municipal water system, and adjacent neighborhood fences. The sensitivity of the results to the soil model chosen was illustrated and recommendations were made with respect to the final grounding study.

Project Outline:

Final as-built station grounding study during 500 kV and 230 kV fault conditions, both within and outside the station, as a function of seasonal variations and for contingency conditions. Variations in fill material thickness were considered using finite-volume soil models. Interactions between the station grounding system and adjacent towers and a railway spur were modeled.

Project Outline:

Study of as-built station grounding during 500 kV and 230 kV fault conditions, as a function of seasonal variations, for construction conditions, during which final grading will not be present everywhere. Variations in fill material thickness were considered using finite-volume soil models. Areas of concern were identified and corrective measures proposed.

Project Outline:

SES was called upon to assist TSK in designing a satisfactory grounding system for a geothermal plant, in a high resistivity soil. By combining deep soil resistivity sounding with consideration of all grounded metallic infrastructure associated with the plant, including transmission lines, pipes and adjacent plants, SES was able to meet and exceed the owner’s design requirements.

Project Outline:

Grounding study of 0.5 km x 0.5 km 230 kV AC / 500 kV DC converter station, connected to five 230 kV transmission lines and one 500 kV HVDC transmission line, in northern Manitoba. Used MultiFields software to simultaneously carry out fault current split calculation and grounding, accounting for inductive coupling between overhead lines and bus work in the station with grounding conductors, thus reducing computed touch and step voltages significantly. Induced currents in the soil were found to yield an apparent grid impedance with a capacitive reactance, due to very high soil resistivity at deep layers and low to moderate soil resistivity at shallow layers. Optimized grounding performance, accounting for soil freezing down to 4.5 m, difficulty driving ground rods much deeper than 12 m, need to meet IEEE Standard 80 limits in certain areas without an insulating layer of crushed stone, saving millions of dollars.

Project Outline:

Grounding design study for gas yard adjacent to Wildcat Point Generation Facility. Included modeling of interactions of cathodic protection system of gas yard with adjacent 500 kV switchyard and other plant grounding and identified locations with peak leakage current densities.

Project Outline:

Two-part grounding study, first to determine safety in area of plant being rebuilt, in the absence of grounding conductors, in the event of a 500 kV fault, and recommend required mitigation, next to evaluate the final conceptual design for the entire plant area, consisting of existing and new generation.

Project Outline:

Short-circuit study, fault current split calculation and grounding recommendations for TransCanada Napanee Generating Station. Included modeling of interconnected and interacting grounding systems of two power plants and one major adjacent 500 kV / 230 kV transformer station, two major three-winding, three-phase auto-transformers, six 500 kV circuits, four 230 kV circuits, local generators, 4 remote generators, 3 remote transformer stations and equivalent transfer impedances between them. Study demonstrated that consideration of all interacting system components made it possible to meet grounding design criteria without any need for deep wells or additional remote grounding electrodes outside the generating station, as would otherwise have been required.

Project Outline:

Grounding study of 2,300 ft long 765 kV / 345 kV / 138 kV substation. Faults studied at multiple locations throughout station, accounting for circulating currents. Demonstrated potential savings on the order of $1 M with cost-effective mitigation approach.

Project Outline:

Grounding study of a large power plant next to a lake. Studied grounding performance with and without supplementary grid in lake, using finite-volume soil structures to represent water, soil and rock. Modeled 138 kV transmission line system up to 39 miles away (11 circuits), in order to find worst case fault location and benefit as much as possible from fault current split provided by conductive shield wires.

Project Outline:

Study of the impact of an HVDC electrode in the sea and transferred potentials to nearby gas pipeline. The sensitivity of the results to the method used to represent the sea bed was examined: e.g., infinitely long sloped plane versus trapezoidal volumes.

Project Outline:

Study of the optimal method to ground a 230 kV GIS to the grounding system of an existing air-insulated substation. Included the modeling of the phase conductors and bus enclosures and associated inductive coupling and provided training in field testing of the substation: soil resistivity measurements, fall-of-potential test, touch and step voltage measurements.

Project Outline:

Lightning shielding design study for utilities & offsites areas of 2 km x 2 km Habshan-5 gas development project. Grounding study as well for the entire plant, for 132 kV and 220 kV faults at the 4 high-voltage substations on site. Study also of resistance versus solid grounding for 132 kV transformers at this site.

Project Outline:

Riel Station is a 230kV/500 kV power station Manitoba Hydro is planning to build. In addition to several 230 kV and 500 kV AC power lines, 500 kV DC lines are also planned to be connected to the station. The station is extensive, about 1700 m by 800 m, and is located near an extensive system of water pipes, which must be considered in the calculation of earth potential gradients and transferred potentials. The objective of the study is to design a satisfactory grounding system, which will ensure the safety of personnel and the integrity of the equipment at the station under fault conditions, accounting for contingency conditions and seasonal variations (freezing and thawing of soil).

Project Outline:

This study consisted of a detailed parametric analysis of underground cable systems and safety of personnel during load and fault conditions, for different contact situations, cable types, vault types and safety bonding scenarios. Different ground mat designs for switch handles of overhead distribution lines were also compared.

Project Outline:

Two 500 kV series capacitor banks are to be installed midway along a pair of transmission lines, at a location where the soil resistivity is extremely high (on the order of 4,000 to 5,000 ohm-m). The size of the station is 244 m by 124&m. The first objective of the study is design a grounding system resulting in acceptable touch and step voltages. A second objective is to determine the GPR of the station, which is highly dependent on the ground impedance of the 500 kV transmission line shield wires. A specification to measure the equivalent ground impedance presented by the shield wires was developed by SES, which also participated in the testing.

Project Outline:

This is an extensive grounding study involving the modeling of the two interconnected power plants, an associated switching station expansion, and two Ford motor plants, the objective being to investigate safety in the switching station expansion area and at the other facilities to which the substation is connected and to recommend any required mitigation.

Project Outline:

This study involved detailed modeling of a system of two 260 kV/144 kV substations, three 144 kV substations, two large generating plants, and 5 well pad substations, along with the interconnecting 260 kV and 144 kV transmission lines (over 100 km), the objective being to evaluate safety at the substations and plants and make recommendations, as applicable, to meet IEEE Standard 80, Canadian Electrical Code, and Alberta Electrical and Communication Utility Code safety requirements. It was found that grounded plant infrastructure and the optical shield wires used for the transmission system had a major impact on the results.

Project Outline:

Modeling of a 1 mile x 1 mile oil sands site and two offsites, with 15 substations ranging from 34.5 kV to 260 kV, two overhead 260 kV circuits, buried and overhead 34.5 kV circuits, cable/pipe racks and a good number of pipelines, whose through-earth and magnetic field interactions were studied, in designing a conceptual grounding system for the entire VUP meeting IEEE Standard 80. It was found that consideration of the grounding provided by supporting infrastructure (piles and interconnecting structures) tremendously reduced the need for any additional buried grounding conductors.

Project Outline:

A wind farm with 109 turbines, 2.1 MW each, was studied. Conceptual grounding designs for the main 230 kV/34.5&kV substation and for the turbines were evaluated, accounting for collector line grounding and current return in the 230 kV transmission line static wires. A total of 74 representative faults were simulated on the 34.5 kV collector system and at wind turbines, in addition to faults at the main 230 kV/34.5 kV substation. Frozen, partially frozen and unfrozen soil conditions were considered. Recommendations were made with respect to the most cost-effective grounding, accounting for the interactions of all wind farm components.

Project Outline:

This study involved the verification of the grounding of a 230 kV substation located in an area with high soil resistivities (on the order of 3000 – 6000 ohm-m near the surface and 700 ohm-m below that). Detailed soil resistivity measurements were made in both winter and summer and considered in the analysis. Various contingencies, such as the loss of a line or loss of ground rods, were also examined. It was found that the high surface soil resistivities, while resulting in greater touch and step voltages, also resulted in allowable touch and step voltage limits, ultimately providing a satisfactory solution to an otherwise difficult problem.

Project Outline:

This study involved two urban 115 kV substations with GIS and 60 kA fault levels. SES demonstrated that the buried cable ground conductor/concentric pipe return paths and the metallic water system surrounding the substations reduced grounding requirements significantly despite the high fault current levels. SES also demonstrated the effectiveness of the unipolar Wenner method for soil resistivity testing.

Project Outline:

This two-part study involved a preliminary analysis of modifications in antenna radiation patterns due to the presence of a 230 kV vertical transmission line circuit running past an antenna farm, followed by an analysis of the impact of a horizontal 230 kV transmission line circuit, with and without shield wires, on antenna radiation patterns.

Project Outline:

Study of the impact on circuit impedance and ground return conductor leakage currents of magnetic field interactions between three single-phase AC cables and an adjacent large steel surface, in a low resistivity medium.

Project Outline:

Study of the grounding performance and therefore the AC mitigation performance of ARTAZN LifeRibbon™ and comparison with the performance of traditional zinc conductors with diamond cross-section.

Project Outline:

Detailed third-party review by SES of AC interference mitigation study of extensive exposure of Atlantic Coast Pipeline to 18 Duke Energy transmission lines ranging from 115 kV to 500 kV, including a continuous parallel exposure to roughly 24 miles of 500 kV line and close proximity to a major substation. The AC interference mitigation study report, associated computer models and new data collected by SES were reviewed.

Project Outline:

Detailed third-party review by SES of AC interference mitigation study of a PNG pipeline exposed to a Duke Energy 230 kV transmission line near a proposed new receiver station. Review included collection of additional power system and pipeline data, study of the third-party report, and examination of computer model inputs and outputs.

Project Outline:

Computer modeling of induced voltages in twisted wire pair telephone cables by wind turbine harmonics in underground collector cables with ground cable. Worst case combination of positive and negative sequence components of harmonic noise from the first 50 harmonics was considered and translated into the expected noise metallic on three telephone circuit branches, applying a C-message filter and typical telephone circuit balance. The interference levels were also expressed in terms of Ground Return I*T. The report included attachments designed to make it easier for power engineers to understand the terminology, calculations and measurements used by telephone companies to assess noise levels.

Project Outline:

Preliminary AC induction mitigation study between a planned double-circuit 138 kV/69 kV transmission line with distribution underbuild and two railways, during fault and load conditions, including parametric analysis of interference levels versus load unbalance in transmission and distribution circuits, ballast resistance, locations of railroad insulated joints, installation of buried counterpoise mitigation, installation of a second distribution neutral, and extension of the distribution neutral along the transmission line beyond the end of distribution underbuild. Most of the proposed mitigation measures were related to load unbalance levels and the integrity of one set of railroad insulated joints.

Project Outline:

Third-party review of studies previously conducted, and related to the mitigation required to address the impact of the Sheridan 69 kV Substation upon nearby Trans Mountain pipelines during fault conditions. The review entailed the study of the computer models that had been used, collection of additional data, a detailed modeling of the transmission system (including substation transformers), and an analysis of predicted coating stress voltages.

Project Outline:

Review of calculations of direct arcing risk to Trans Mountain pipeline from BC Hydro transmission lines and application thereof to further commentary on methodology that had been applied in developing a proposed mitigation strategy. Detailed recommendations for suitable protection of the pipeline were provided by SES.

Project Outline:

PSE&G Aldene – Warinanco - Linden (AWL) project to rebuild five (5) miles of aging 230 kV transmission infrastructure on an existing railroad ROW, in order to accommodate higher thermal load requirements. At 27 locations along the ROW, the separation between an existing high pressure gas pipeline and the transmission line structures was less than 10 feet; paralleling railroad tracks and several encroachments were also taken into account, including homes, garages, pools, perimeter fences, and other structures. The proposed work raised concerns associated with electrical interference, grounding effects, and personnel safety on the ROW. Safe Engineering Services & technologies ltd. (SES) was asked to assist and support PSE&G engineers in carrying out the study at SES offices, followed by remote project-specific support, and then to provide an expert review on the report.

Project Outline:

Further study of the corridor shared by an existing Trans Mountain Canada pipeline and proposed ATCO 69 kV transmission line, in order to provide construction tolerances for areas where transmission line poles are to be installed in close proximity to the pipeline.

Project Outline:

Third-party review of an AC interference mitigation study that was submitted to PNG for a proposed PNG pipeline exposed to a Duke Energy 230 kV transmission line, over a distance of approximately 4.5 miles. Detailed recommendations were made following collection of extensive data from stakeholders and a review of the report and computer models.

Project Outline:

Further to an initial third-party review conducted by SES of AC interference mitigation design studies, alternative mitigation designs were proposed by SES to address concerns related to direct arcing, supported by the modeling of lightning strikes to the 69 kV transmission line under study.

Project Outline:

Detailed review of a third-party AC interference mitigation study related to the exposure of Williams’ 24” Cardinal Lateral to Duke Energy 230 kV and 500 kV transmission lines over a distance of approximately 22 miles. SES provided cost-saving recommendations after a detailed review of extensive new data, the third-party report, and associated computer models.

Project Outline:

Third-party review by SES of an AC interference study of a 12” high pressure natural gas pipeline connection to a combined cycle plant supplying power to a network of 115 kV and 230 kV transmission lines.

Project Outline:

Third-party review by SES of an AC mitigation study of portions of the proposed Trans Mountain pipeline running in close proximity to BC Hydro transmission lines. A detailed report, detailing cost-saving recommendations, was submitted.