The Manitoba Hydro-Electric Board, operating as Manitoba Hydro, is the electric power and natural gas utility in the province of Manitoba, Canada. Founded in 1961, it is a provincial Crown Corporation, governed by the Manitoba Hydro-Electric Board and the Manitoba Hydro Act. Today the company operates 15 interconnected generating stations. It has more than 527,000 electric power customers and more than 263,000 natural gas customers. Since most of the electrical energy is provided by hydroelectric power, the utility has low electricity rates. Stations in Northern Manitoba are connected by a HVDC system, the Nelson River Bipole, to customers in the south. The internal staff are members of the Canadian Union of Public Employees Local 998 while the outside workers are members of the International Brotherhood of Electrical Workers Local 2034.Manitoba Hydro headquarters in the downtown Winnipeg Manitoba Hydro Place officially opened in 2009..
Wildfire smoke introduces fine particulate matter into the atmosphere, altering the insulating properties of air used in HV AC transmission systems. This study experimentally evaluates how wildfire smoke affects air-gap insulation under controlled laboratory conditions. A sealed smoke chamber was used to measure breakdown voltage, partial discharge inception voltage, phase-resolved discharge behavior, and partial discharge time-frequency characteristics at varying smoke and humidity conditions. Breakdown measurements using sphere–sphere gaps showed no significant deviation across all smoke conditions. In contrast, partial discharge inception voltage in needle–plane gap increased consistently with smoke density, rising by nearly 100% at the highest concentrations. Phase-resolved partial discharge patterns and partial discharge indicators show that smoke suppresses negative polarity discharges at low voltage, whereas at higher voltage it enhances partial discharge activity and increases pulse rate. Time–frequency analysis further revealed waveform-shape changes under combined smoke–humidity conditions.
This paper introduces an automated dynamic frequency scanning tool designed to predict stability in power systems. The tool integrates frequency scanning and stability analysis into a single, user-friendly platform, which is validated through Electromagnetic Transients (EMT) simulations and traditional small-signal stability techniques. Case studies involving a modular multi-level converter (MMC) system are conducted using two grid-forming (GFM) controller strategies: voltage-source type and current-source type virtual synchronous generators (VSGs). The effectiveness of the tool is demonstrated by comparing stability predictions from the scanning method with results from root locus analysis and EMT simulations, showing that it provides a reliable and efficient approach for predicting system stability. A key contribution of this paper is the comparative analysis of the two GFM controller types, offering valuable insights into their performance and stability characteristics. The results highlight that the current-source type VSG can operate effectively in a strong ac system, which is a challenge typically faced by the voltage-source type VSG.
This paper presents a comprehensive method for modeling and assessing the impact of stray currents from the DC light rail transit system (LRT) on nearby transmission line structures. The proposed method utilizes CDEGS (Current Distribution, Electromagnetic Fields, Grounding, and Soil Structure Analysis) software to simulate the interactions between LRT systems and foundations of transmission lines, focusing on the effect of key parameters, including the soil resistivity, ballast resistance, locomotive current, and separation distance. A sensitivity study is conducted to evaluate the effect of these parameters on the stray current corrosion, and empirical equations are derived to estimate the DC voltage on transmission line structures. The proposed method is validated using field measurements, demonstrating a high accuracy with an error margin less than 12.5%. Practical maintenance guidelines are then proposed to determine the minimum separation distance between the LRT and the transmission line structure to avoid stray current corrosion due to the LRT system. The results highlight the need for proactive measurements to prevent transmission line structural deterioration and ensure the long-term reliability of the transmission line system if they are located less than the recommended separation distance away.
Earlier research has identified that the phenomenon of cascaded commutation failure (CF) in multi-infeed LCC-HVdc systems connected into weak ac grids is not caused merely by ac voltage reduction, but also significantly by the presence of low order voltage harmonics. Traditional CF mitigation strategies, such as controller optimization have limited effect in reducing such cascaded CFs. In this paper, we propose a novel approach involving the addition of shunt ac filters tuned to the 2nd and 3rd harmonics to mitigate cascaded CF by inhibiting inter-inverter harmonic propagation. These filters significantly reduce the equivalent impedance magnitudes at the relevant harmonics as seen from the local inverter ac bus to the common receiving end grid. As a result, the current harmonics generated by CF in the local inverter are less likely to propagate to remote inverters via the connecting tie-lines. Electromagnetic transient simulations demonstrate that the proposed scheme substantially reduces the probability of cascaded CF under various fault conditions. Furthermore, it is shown that installing only the 2nd or 3rd harmonic-tuned filter, as done in some previous studies, may inadvertently increase the risk of cascaded CF, underscoring the importance of the proposed filtering scheme which targets multiple low order harmonics.
The paper presents a comprehensive analysis of losses in several battery energy storage system (BESS) converters using EMT simulations. The work is motivated by the critical need to determine converters’ semiconductor losses, particularly due to the high-frequency dc-dc converters that interface batteries. Two general classes, namely modular multilevel and two-level converter topologies, are considered. A simulation-based, computationally efficient, and accurate loss calculation method, which utilizes device data sheet loss curves, is used to estimate semiconductor losses based upon post-processing of EMT simulation results of the converters. The paper quantifies the impact of switching frequency and circulating current suppression controller on the losses. Comparative assessments of the merits of each topology are also presented.
