{"title":"Sub-Synchronous Resonance (SSR) in Series Compensated Networks with High Penetration of Renewable Energy Sources","authors":"Tinashe E. Chikohora, D. Oyedokun","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9041109","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9041109","url":null,"abstract":"This paper investigates the correlation between sub-synchronous resonance (SSR), its management onwards and the increase in renewable energy penetration levels in power grids. Future trends, problems and opportunities that arise within a changing power system adapting to ever increasing renewable energy sources (RES) integrations are discussed. Renewable energy integrations come with devices comprising power electronics that do not contribute synchronous inertial response to the power system grid. The paper presents theory of the types of SSR, both old and emerging ones and introduces methods of analyzing SSR. A review of the prevalent SSR management techniques and results over the years is shown. A correlation study is tabled and implemented in DlgSilent-Powerfactory with sample results presented. The simulation results showed that integration of more renewable energy sources has a direct effect of increasing SSR. Different renewable technologies e.g. wind and photovoltaic solar result in different SSR occurrences.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"229 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123307848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Winston Dyason, T. V. van Niekerk, R. Phillips, R. Stopforth
{"title":"Real-Time Optimization of Single Pole Low Pass Filter using Signal-to-Noise Ratio Maximization","authors":"Winston Dyason, T. V. van Niekerk, R. Phillips, R. Stopforth","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9040965","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9040965","url":null,"abstract":"In this paper, further studies have been made on improving the output performance optimization of the exponentially weighted moving average filter for real-time system applications. It has been shown in prior research that the filter is an effective, low-cost filtering algorithm; however, its output performance is dependent on the calibration of its gain parameter. As a result, the filter will produce sub-optimal outputs if not calibrated correctly. A method is sought that can provide an appropriate gain parameter for maximizing the signal-to-noise ratio of the filter's resulting output, thereby increasing the effectiveness of the filter for real-time system applications. A trial-and-error experimental approach was used to find the filter's optimal parameter gain that maximizes the filter's output signal to noise ratio for a known signal that is sampled using a Gaussian distribution model. It was found that the output signal performance of the complementary filter is highly dependent on its chosen parameter gain, and using a static parameter gain value is unsuitable. An equation was found that approximates an optimal parameter gain to produce a filtered output with the best signal to noise ratio and applied to a real-world application.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128879456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Transmission Line Damping Effects on Power System Inertia Response","authors":"M. Rainey, D. Oyedokun","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9040925","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9040925","url":null,"abstract":"As the effects of climate change are becoming an ever-growing concern, countries around the world are rapidly increasing the participation of renewable generation to reduce CO2 emissions. A large portion of this generation is interfaced to the power system through power electronic converters, and as their participation increases it begins to have undesirable effects on frequency stability. As the increase in their participation begins to displace traditional synchronous generation through end of life and/or early decommissioning, the power system inertia will decrease. This increases the rate of change of frequency (ROCOF) making the frequency of the system respond quicker to power imbalances. In this paper, the damping effects of transmission lines on the inertia response of a simple power system characterized by long transmission lines is explored. The outcome sets the foundation to address concerns on the ROCOF by lowering system inertia on networks with characteristically long transmission systems and high renewable energy penetration. The results showed that for frequency disturbances, longer transmission lines result in a lower ROCOF.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130198401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Low Cost PLC Uninterrupted Power Supply for use on AGVs with a Removable Battery Banks","authors":"A. Macfarlane, T. V. van Niekerk, U. Becker","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9040993","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9040993","url":null,"abstract":"When it comes to electrical AGVs, downtime due to charging batteries is a significant hurdle. This is often dealt with in numerous ways; including opportunistic charging, mobile charging, quick charging, etc. This paper will focus on the difficulties of using exchangeable “power units”, which entails making the entire battery system (including the battery management system) removable from the host machine. This eliminates downtime, due to charging, as the entire power plant is replaced with a “fresh” one. The depleted power unit can then be recharged at a sustainable (from a battery lifespan perspective) rate. The major disadvantage of this strategy is that with the power plant removed from the AGV, all control systems are unpowered thus deactivated. Hence the focus of this paper on creating a “control system UPS” to keep the control systems powered even when the main power unit is down and thus solving one of the major problems with a removable battery system.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127522959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Energy management opportunities exploration in a residential air source heat pump water heater","authors":"Mandlenkosi Sikhonza, S. Tangwe, M. Simon","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9041120","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9041120","url":null,"abstract":"Air source heat pump (ASHP) water heaters are classified as renewable and energy efficient device for sanitary hot water production. The study focused on the investigation and quantification of the wasted thermal energy dissipated at the ASHP's condenser of a 1.2 kW, 150 L split type residential ASHP water heater undergoing vapour compression refrigeration cycles due to controlled volume of hot water drawn off. Power meter, flow meters, temperature sensors, ambient temperature and relative humidity sensor were installed at designated positions on the ASHP water heater. Specific control volume of 150, 50 and 100 L were drawn off from the ASHP water heater during the morning, afternoon and evening periods each day throughout the monitoring period (October 2015 to September 2016). The results depicted that during the summer and winter periods the average input electrical energy consumed was 1.40 and 1.70 kWh, while the dissipated and the useful thermal energy were 13.65 and 4.10 kWh for summer and 14.70 and 4.07 kWh for winter, respectively. It can also be concluded that during the summer and winter periods only 30.01% and 27.63% of the dissipated thermal energy from the condenser was harnessed as useful thermal energy by the sanitary hot water stored in the 150 L geyser with the heating element disabled. Hence, by the application of energy management, almost 70% of wasted thermal energy can be utilized for space heating or as backup storage, provided the ASHP water heater is designed to function as both hot water and space heating device with an additional backup thermal storage.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"245 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127538446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Prediction Model to Improve Student Placement at a South African Higher Education Institution","authors":"Tasneem Abed, Ritesh Ajoodha, Ashwini Jadhav","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9041147","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9041147","url":null,"abstract":"There is a growing concern over the low pass rates of students in the Science Faculty at a South African Higher Education institution. The Admission Point Score (APS) used to place students into programs may appear to have good discretion in gauging student aptitude, but the reality is that between 2008 and 2015, about 50% of students who met the APS requirements for a Science program failed to meet the requirements to pass. This report attempts to build a recommendation engine that will advise students on their academic trajectory for a chosen program based on features suggested by the Tinto (1975) framework [1]. The results show that classification models from various archetypes of machine learning have good accuracy in predicting the final outcome of a new student. This research argues that a more complex view of student placement will improve the faculties success rates.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128050828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Measures to Mitigate Overfrequencies at an HVDC Rectifier Station","authors":"Leonel Fanequico, C. Gomes, J. Van Coller","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9041062","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9041062","url":null,"abstract":"Songo rectifier station is located 6 km away from the Cahora Bassa (CB) hydroelectric power station. It was designed to transmit 1920 MW from the 2075 MW generated to the Apollo inverter station in South Africa. Frequency fluctuation at Songo is very high because the active power balance is easily destroyed after an HVDC disturbance. Faults on the three HVAC transmission lines, faults on the two HVDC transmission lines and trips of the converter bridges make Songo rectifier station Busbar I (BBI) susceptible to overfrequencies. Load rejections can be large because the generators and converter bridges operate most of the time under full load conditions. Frequency fluctuation has a negative impact on the interconnected system. It causes the tripping of the sharply tuned AC harmonic filters and consequent tripping of the HVAC bus coupler (BC) at Songo, resulting in power reduction to Eskom or to ZESA. It may also cause the tripping of the converter valve cooling pumps due to overload and consequent tripping of the entire HVDC station. To propose mitigating measures to the overfrequencies occurring at Songo BBI, the actual behaviour of the Grid Master Power Controller (GMPC) and the actual behaviour of the HVDC scheme controls were analyzed through data recorded in the last 10 years by the Transient Fault Recorder (TFR) installed at Songo. The results reveal that frequency deviations have increased in recent years at the rectifier station mainly due to the failure of the inverter station to take over current control after HVDC disturbances. This increases the magnitude of the load rejections.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127005439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Investigation of Diverse Sampling Time for LFC of Hydro Power System using Discrete LQR with UPFC and RFB","authors":"Milan Joshi, Gulshan Sharma, I. Davidson","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9041072","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9041072","url":null,"abstract":"In this paper, an early attempt is made to design the optimal control technique based on discrete law for load frequency control (LFC) of an interconnected power delivery system having the electric power generation via hydro turbines in interconnected areas. In addition to above the effect of diverse sampling time on optimal LFC in discrete mode is also investigated. The performance evaluation of design LFC is carried out for standard load disturbance in one of the control area and the comparative analysis of diverse sampling time are shown via LFC responses, eigen values and closed loop feedback gains. At last, the unified power flow controller (UPFC) is added in series with the tie-line as well as the redox flow battery is integrated in area-2 of the interconnected system and the application results are assessed in order to show the merits of these devices in the enhancement of LFC performance.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134070718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nishai Kooverjee, Steven D. James, Terence L van Zyl
{"title":"Inter- and Intra-domain Knowledge Transfer for Related Tasks in Deep Character Recognition","authors":"Nishai Kooverjee, Steven D. James, Terence L van Zyl","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9041053","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9041053","url":null,"abstract":"Pre-training a deep neural network on the ImageNet dataset is a common practice for training deep learning models, and generally yields improved performance and faster training times. The technique of pre-training on one task and then retraining on a new one is called transfer learning. In this paper we analyse the effectiveness of using deep transfer learning for character recognition tasks. We perform three sets of experiments with varying levels of similarity between source and target tasks to investigate the behaviour of different types of knowledge transfer. We transfer both parameters and features and analyse their behaviour. Our results demonstrate that no significant advantage is gained by using a transfer learning approach over a traditional machine learning approach for our character recognition tasks. This suggests that using transfer learning does not necessarily presuppose a better performing model in all cases.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131865548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johannes Coetzer, Jacques P. Swanepoel, R. Sabourin
{"title":"Dynamic fusion of human and machine decisions for efficient cost-sensitive biometric authentication","authors":"Johannes Coetzer, Jacques P. Swanepoel, R. Sabourin","doi":"10.1109/SAUPEC/RobMech/PRASA48453.2020.9040973","DOIUrl":"https://doi.org/10.1109/SAUPEC/RobMech/PRASA48453.2020.9040973","url":null,"abstract":"Despite growing interest in human-machine collaboration for enhanced decision-making, little work has been done on the optimal fusion of human and machine decisions for cost-sensitive biometric authentication. An elegant and robust protocol for achieving this objective is proposed. The merits of the protocol is illustrated by simulating a scenario where a workforce of human experts and a score-generating machine are available for the authentication of handwritten signatures on, for example, bank cheques. The authentication of each transaction is determined by its monetary value and the quality of the claimed author's signature. A database with 765 signatures is considered, and an experiment that involves 24 human volunteers and two different machines is conducted. When a reasonable number of experts are kept in the loop, the average expected cost associated with the workforce-machine hybrid is invariably lower than that of the unaided workforce and that of the unaided machine.","PeriodicalId":215514,"journal":{"name":"2020 International SAUPEC/RobMech/PRASA Conference","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129494718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}