Powertech Labs (Canada)

In this paper, a novel algorithm for partial discharge (PD) pulse waveform analysis and separation based on orthogonal series expansion using Laguerre polynomials is proposed. A system identification technique is also developed to help increase the accuracy rate of the signal classification. Laguerre polynomial series expansions are applied on the PD pulses to effectively extract important information and well-discriminative features. Laguerre expansion coefficients inherently contain information about the amplitude (intensity) and the relaxation time of a dynamic system and this helps direct characterization of PD pulses. The proposed technique is applied to PD pulses acquired from a laboratory set of multiple PD sources. It is shown that this statistical method can classify partial discharge signals with high accuracies, even when the signals are visually indistinguishable. In this research, two methods are developed for system identification. One is based on a deterministic approach in the form of a recursive formula and the other one is a stochastic method based on a group Lasso methodology. The aim of system identification is to improve the classification accuracy by removing the effect of the measurement system from the observed PD waveforms. The accuracy rate of the proposed algorithm is evaluated using the signals that are captured from simultaneous artificial defects in high pressure SF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> and in low pressure air.

This paper introduces Peak Reliability (‘PEAK’), online transient stability analysis tool (TSAT) that has been successfully running on a large scale West wide System Model (WSM) in the control room since late 2017. This new tool, henceforth abbreviated as ‘WSM-TSAT’, was implemented for applications of system model validation (MOD-033), dynamic RAS interaction monitoring, IROL/system stability limit calculation, and system inertia/frequency response real-time assessment for the Western Interconnection (WI). Practical implementation experience and lessons learned are presented in the paper. WSM-TSAT simulation and study results are provided for a few major system events.

Stray voltages have always been a power quality concern to utility companies and customers. The long-term exposure to sufficient stray voltage can be harmful to human being's and animals' health. The stray voltage in the low voltage network is generally related to the load unbalance, grounding condition and network structure. Through analytical study and detailed system simulations, this paper makes a sensitivity study on how serious these factors affect the stray voltage in low voltage networks. Therefore some recommendations can be formulated to prevent the excessive stray voltage. On the other hand, this paper also provides guidance on how to identify the cause of excessive stray voltage incidence if it is detected.

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;The worldwide automotive industry is currently preparing for a market introduction of hydrogen-fueled powertrains. These powertrains in fuel cell electric vehicles (FCEVs) offer many advantages: high efficiency, zero tailpipe emissions, reduced greenhouse gas footprint, and use of domestic and renewable energy sources. To realize these benefits, hydrogen vehicles must be competitive with conventional vehicles with regards to fueling time and vehicle range. A key to maximizing the vehicle's driving range is to ensure that the fueling process achieves a complete fill to the rated Compressed Hydrogen Storage System (CHSS) capacity. An optimal process will safely transfer the maximum amount of hydrogen to the vehicle in the shortest amount of time, while staying within the prescribed pressure, temperature, and density limits. The SAE J2601 light duty vehicle fueling standard has been developed to meet these performance objectives under all practical conditions. It defines the fueling protocol and operational fueling parameters that ensure both station and vehicle maintain their safety limits (e.g. SAE J2578) while delivering optimal fueling performance. The results of the standard allow a representative FCEV under the target conditions to be completely fueled within three minutes.&lt;/div&gt;&lt;div class="htmlview paragraph"&gt;The team working on SAE J2601 performed extensive simulation and sensitivity studies which were validated through laboratory testing with representative CHSS hardware and field testing with fuel cell vehicles. This report documents the lab and field validation testing for SAE J2601.&lt;/div&gt;&lt;/div&gt;

This chapter discusses the issues associated with the successful design and implementation of an online dynamic security assessment system. The need for, the benefits of, and the current application status of such systems are presented. The discussions are primarily focused on the practical issues for implementing an online Dynamic Security Assessment (DSA) system, based on the experiences gained from recent applications. Finally, an overview of some future directions on the online DSA technologies is provided.

This chapter illustrates, by a practical case study, an application of the dynamic model reduction for a large power system model. This example concerns the creation of a reduced-order model from a full WECC model, to be used by BC Hydro for on-line dynamic security assessment (DSA). This model reduction was conducted using the software DYNRED. The focus of this case study is on the objective of the model reduction, the approach and procedure, the results, and the benchmarking work to ensure the suitability of the reduced models for the required applications. It is shown that, following the procedure used in the case study, a reduced model can be obtained for use with a wide range of system conditions with acceptable results and computation time saving.

Summary form only given. The 120A° voltage source inverter (VSI) driven brushless dc (BLDC) motors are very common in many applications. This paper extends the previous work and presents an improved dynamic average-value model (AVM) for such BLDC motor-drive systems. The new model is explicit and uses a proper qd model of the permanent magnet synchronous machine with non-sinusoidal rotor flux. The model utilizes multiple reference frame theory to properly include the back EMF harmonics as well as commutation and conduction intervals into the averaged voltage and torque relationships. The commutation angle is readily obtained from the detailed simulation. The proposed model is demonstrated on a typical industrial BLDC motor with trapezoidal back EMF waveforms. The results of studies are compared with experimental measurements as well as previously established models, whereas the new model is shown to provide appreciable improvement.

This article presents a practical method for validating generator saturation factors together with direct-axis model parameters by collectively using several field test results conducted on the same generator. The method is devised from many years of WECC/NERC synchronous generator model validation experience. Model validation following this method can significantly eliminate the mismatch between the computer simulation results and field measurements for tests on generator direct-axis model parameters. The effectiveness of this method is demonstrated by comparing field test results on a hydro-turbine generator with computer simulation results using validated generator model parameters. Future application of the method is proposed and discussed.

This paper describes a novel acoustic monitoring technique of insulation delaminations during a thermal cycling test (TC) on a stator bar. Acoustic signals emitted from insulation delaminations within the stator bar were continuously recorded during a TC test. An increase in measured acoustic signals indicates insulation delaminations within the stator bar under test. Dissipation factor tests, partial discharge tests, tap tests, and dissections were performed. Those diagnostic test results were compared with the acoustic test data to verify insulation delaminations. The acoustic monitoring system can indicate which cycle insulation delaminations occurred and when they occurred in a given thermal cycle during a TC test.

The high cost and the critical nature of power transformers in power substations makes it is very important to prevent failures and detect problems as early as possible. This presentation reviews the diagnostic and monitoring tests and equipment available to assess the condition of transformers and provide an early warning of potential failure.