Over the last decade, many power systems have significantly changed with the proliferation of renewable generation sources, such as wind and solar photovoltaic. Due to their variability and ...nonsynchronous nature, new challenges and complexities have emerged regarding operational security of modern power systems. The 2016 South Australia (SA) blackout was the first known blackout due to such a high renewable situation. An official report has recently been published to review the causes and provide the corresponding recommendations for improvement of network operation, control, and security. However, there are still a number of critical issues and debates which remain unsolved, such as network bottleneck identification, overvoltage explanation, pole slip concern, frequency dip mystery, and frequency/voltage instability debate. In this paper, based on the reconstruction of the event, these unsettled issues are prudently analyzed to unveil their root causes. In addition, an innovative scheme is proposed to prevent the blackout by identifying the network separation at an early stage. This research will not only further advance the understanding of the 2016 SA blackout, but also will provide valuable guidelines for the management of future renewable-rich networks.
Variable speed wind turbine generators (WTGs) are replacing traditional fossil fuel based synchronous generators in the generation fleet as wind penetration increases. These variable speed WTGs are ...decoupled from the grid by power electronics inverters and usually generate less fault current compared to synchronous generators. As a result, system strength (indicates the fault recovery capability) at the point of common coupling (PCC) of wind power plants may reduce. A minimum value level of system strength is essential for wind power plants to properly identify and overcome a fault. To enhance system strength at wind PCC buses, supplementary devices such as synchronous condenser and Static VAR Compensator (SVC) can be deployed to have additional fault current. Since these devices are expensive, their optimal allocation considering economic feasibility is a major concern. In the existing literature, locations and ratings of the optimally allocated synchronous condenser are reported. However, this approach may cause oversizing of synchronous condensers. In addition, a SVC can be utilised instead of a synchronous condenser to enhance system strength. However, no detailed study is carried out yet to find the optimal size of SVCs. Evidently, both synchronous condenser and SVC can be installed to improve system strength. However, no comprehensive techno-economic assessment is performed for selecting an appropriate choice between them. To address these research gaps, this paper develops a framework to find the optimal sizes of synchronous condensers and SVCs by taking into account the long-term financial viability. Also, to ensure the maximum possible fault contribution, synchronous condensers/SVCs are connected directly to those wind PCC buses where system strength is below the acceptable limit. Afterwards, a detailed techno-economic assessment using synchronous condenser and SVC is performed in a wind dominated grid. In addition, post-fault voltage recovery characteristics with optimally sized synchronous condenser and SVC are explored. The developed methodology is applied to the IEEE 39 bus test system considering 45% wind power penetration scenario. Also, the performance of the proposed approach is compared to that of an existing technique. Finally, based on the technical and economic aspects, a better choice between synchronous condenser and SVC is recommended to improve system strength under high wind penetration.
•System strength is improved in a wind dominated grid.•Optimal sizes of synchronous condenser and SVC are found.•Long-term techno-economic assessment is performed.•Technical and economic aspect of synchronous condenser and SVC are compared.•Synchronous condenser is found to be a better choice than SVC.
This paper proposes a peer-to-peer (P2P) energy trading scheme that can help a centralized power system to reduce the total electricity demand of its customers at the peak hour. To do so, a ...cooperative Stackelberg game is formulated, in which the centralized power system acts as the leader that needs to decide on a price at the peak demand period to incentivize prosumers to not seek any energy from it. The prosumers, on the other hand, act as followers and respond to the leader's decision by forming suitable coalitions with neighboring prosumers in order to participate in P2P energy trading to meet their energy demand. The properties of the proposed Stackelberg game are studied. It is shown that the game has a unique and stable Stackelberg equilibrium, as a result of the stability of prosumers' coalitions. At the equilibrium, the leader chooses its strategy using a derived closed-form expression, while the prosumers choose their equilibrium coalition structure. An algorithm is proposed that enables the centralized power system and the prosumers to reach the equilibrium solution. Numerical case studies demonstrate the beneficial properties of the proposed scheme.
The harmonic currents produced by nonlinear loads and renewable energy sources (RES) like PV and wind energy have had a growing impact on industrial distribution networks in recent times. Along with ...harmonic distortions, lack of adequate reactive power support in a heavily loaded renewable‐rich industrial network has made the operation vulnerable to fault‐induced delayed voltage recovery (FIDVR). Due to poor post‐fault voltage recovery, an industrial microgrid is exposed to cascading loss of distributed generators (DGs). Dynamic var sources are being used to prevent cascade tripping. However, they may result in deterioration of the network's THD scenarios. Single tuned passive filters are widely used to suppress harmonic contents. The goal of this work is to design filters so that these become capable to lower overall harmonic distortion while also minimizing the risk of blackouts caused by inadequate post‐fault voltage recovery. To determine the allocation and rating of single tuned passive filters in a renewable‐penetrated industrial microgrid, an optimization model is developed. To show the feasibility and efficacy of the proposed formulation, simulations are performed on a modified IEEE 43 bus system. The findings suggest that the proposed design methodology produces effective solutions to minimize the necessity of additional reactive power sources.
The goal of this work is to design filters in an effective manner so that they become capable to offer adequate reactive power and accelerate fault‐induced delayed voltage recovery (FIDVR). To determine the allocation and rating of single tuned passive filters in a renewable‐penetrated industrial microgrid, an optimization model is developed. The findings suggest that the proposed design methodology produces effective solutions to minimize the necessity of additional reactive power sources.
In this study, a new technique is proposed to forecast short-term electrical load. Load forecasting is an integral part of power system planning and operation. Precise forecasting of load is ...essential for unit commitment, capacity planning, network augmentation and demand side management. Load forecasting can be generally categorized into three classes such as short-term, midterm and long-term. Short-term forecasting is usually done to predict load for next few hours to few weeks. In the literature, various methodologies such as regression analysis, machine learning approaches, deep learning methods and artificial intelligence systems have been used for short-term load forecasting. However, existing techniques may not always provide higher accuracy in short-term load forecasting. To overcome this challenge, a new approach is proposed in this paper for short-term load forecasting. The developed method is based on the integration of convolutional neural network (CNN) and long short-term memory (LSTM) network. The method is applied to Bangladesh power system to provide short-term forecasting of electrical load. Also, the effectiveness of the proposed technique is validated by comparing the forecasting errors with that of some existing approaches such as long short-term memory network, radial basis function network and extreme gradient boosting algorithm. It is found that the proposed strategy results in higher precision and accuracy in short-term load forecasting.
•A new dynamic-adaptive load shedding technique is proposed.•Load buses are ranked and feeders are dynamically selected for load shedding.•Effectiveness of the proposed methodology is demonstrated ...via simulations.
Frequency stability is one of the major concerns for secured operation of a power system. A severe disturbance causes rapid frequency decline, which may instigate power system blackout in an extreme case. In emergency situations, load shedding is applied to arrest frequency excursion. Therefore, a load shedding scheme needs to be sufficiently adaptive to tackle sudden generation loss. Note that conventional load shedding schemes may fail to provide satisfactory frequency response in certain cases. To address this challenge, a new dynamic-adaptive load shedding mechanism is proposed in this paper. The proposed methodology considers the actual contingency size, frequency sensitivity due to load damping, frequency response and ranking of load buses according to voltage stability index. The method ensures that the actual load cut is sufficiently close to the required load shedding to keep system frequency within the given acceptable limit. To do so, it ranks the load buses within a zone and dynamically selects appropriate feeders for load shedding. It also proportionally applies higher amount of load shedding to relatively weaker buses for taking care of the voltage stability. To examine the performance of the proposed scheme, it is applied to the IEEE 39 bus test system that is divided into six zones. It is found from simulations that for 600 MW, 700 MW and 900 MW generation loss events in zone-3, the required amounts of load shedding are 430 MW, 531 MW and 730 MW respectively to keep system frequency above 49.1 Hz. However, these quantities increase to 450 MW, 550 MW and 749 MW respectively to retain system frequency above 49.2 Hz. Furthermore, the impact of 400 MW generation loss in zone-1 is explored. It is found that after shedding additional loads in zone-1 and zone-2, the risk of tie line overloading is mitigated that eventually assures tie line security. In addition, performances of the proposed algorithm are compared to that of an adaptive technique and a semi-adaptive technique. It is noticed that the proposed methodology provides better results than the existing methods. Therefore, it can be articulated that the developed scheme ensures the correct amount of load shedding to maintain satisfactory frequency response and voltage stability.
•An approach is proposed evaluate small-scale FPV's potential in achieving SDG 7 goals.•Case study is conducted on ULAB campus, Dhaka, Bangladesh.•Social survey results indicate a positive attitude ...toward FPV installation.•A comparative analysis with rooftop solar plants highlights FPV's economic viability.•FPV integration into campus reduces energy generation costs.•Small-scale FPV shows satisfactory outcomes in the evaluated technical, economic, and environmental aspects.
Floating photovoltaic systems (FPVs) are gaining popularity in the Asian subcontinent, particularly in densely populated countries like Bangladesh. Small-scale FPV plants, especially on university campuses, can be crucial to fulfilling SDG7 objectives by providing clean energy and addressing economic concerns, which are currently unexplored in the context of Bangladesh. To this end, this paper proposes a systematic methodology to comprehensively assess the potential of small-scale FPV in achieving SDG 7 goals, covering technical, economic, environmental, and social aspects. This study is the first to present an assessment of water evaporation deduction analysis (environmental aspect) and a systematic survey to evaluate the social aspects of the small-scale FPV plant in Bangladesh. To demonstrate the proposed approach, a simulation case study is conducted for a test FPV plant with a capacity of 116.5 kW in a small water reservoir (pond) located within the University of Liberal Arts Bangladesh (ULAB) campus in Dhaka. The results demonstrate that the proposed FPV plant can generate approximately 169.5 MWh yearly with a levelized cost of energy (LCOE) of 0.032 $. Additionally, the plant can prevent 3,715.32 m3 of water from evaporating and reduce 61 tons of GHG emissions annually, saving 93,025 $ of social cost of carbon (SCC) during its entire lifespan. In addition, the conducted survey shows a positive attitude towards FPV installation in the chosen area. Furthermore, a comparison with a rooftop solar plant in the same region highlights FPV's potential as an alternative solar-based energy source in techno-economic evaluations. Implementing the proposed FPV can significantly decrease the yearly total generating cost to meet the university's demand while ensuring clean energy in alignment with SDG7. This study can aid in the integration of renewable energy into the grid and assist policymakers in facilitating future small-scale FPV installations in Bangladesh.
Power system security concerns due to significant wind generation could be twofold: first, the frequency response and second, the short-circuit performance. Continuous development of wind energy may ...cause economic replacement and retirement of existing synchronous generators. Modern wind turbine generators do not inherently offer inertia and governor response after a disturbance, which may result in declining frequency response behaviour. Besides, they have limited fault current contribution, which may cause unacceptable short-circuit ratio at the grid connection point of those wind power plants. Traditionally, frequency response and short-circuit performance are individually improved. However, both of them are concurrently affected by high wind penetration. Hence, a common approach to simultaneously enhance both indices is essential. Therefore, this study introduces an idea of operating some of the retired synchronous generators in the synchronous condenser mode, which is termed as ‘post-retirement scheme (PRS)’. Such a second use of the retired synchronous generators can jointly upgrade frequency response and short-circuit strength during high wind generation. This study also proposes a methodology to evaluate when and how much PRS should be deployed for ensuring an adequate security performance in a wind dominated power system.
Due to globalization and industrial development, the need of power is increasing day by day. In addition, due to the high demand for clean energy sources, the use of renewable systems has expanded in ...recent years. Wind systems can take advantage of the copious and free energy provided by the wind, which is a significant benefit. However, changing incident energy from renewables generate harmonics, which may result in poor system performance. The power quality has therefore become an important issue for both the power suppliers and consumers. Power electronic devices and nonlinear loads have been used frequently in industries hence introducing harmonic distortions in the industrial power distribution network. Harmonics have adverse effects on the power quality like degradation of power generation efficiency, higher operational costs, overheating of equipment, saturation of transformer, electromagnetic interference etc. In order to solve these problems, the implementation of suitable filtration techniques and the evaluation of efficiency with harmonic reduction are crucial. Since, utilities are always aiming to improve the power quality with minimum filtering units, this paper compares the performance of two available filter implementation plan, namely the shunt active power filter (SAPF) and the single tuned filter (STF) in a renewable penetrated industrial distribution network. Based on the outcome of the comparison, a genetic algorithm (GA) based approach is proposed in this paper to determine the optimum size and position of the minimum required filtering units that improves the network’s existing harmonic scenarios. Simulation results to validate the proposed methodology are presented. According to the results, the proposed method of incorporating filtering units significantly outperformed in lowering total harmonic distortion (THD) in an industrial power distribution network with a higher renewable penetration.
•A harmonic mitigation approach is proposed.•Total harmonic distortion of voltage is used as power quality index.•Optimal size and location of filtering units are determined.•Simulations are carried out at various renewable penetration levels.
The aim of this paper is to develop a new Time of Use (TOU) tariff scheme for Demand Side Management (DSM) of residential consumers in Bangladesh. In this advanced era of technology, the requirement ...of electrical energy is continuously increasing. However, the overall growth of electricity generation is comparatively slower due to depletion of fuel sources. In this situation, a strategic plan needs to be implemented at consumer end to mitigate the energy crisis. As such, the concept of DSM is introduced where consumers can save electricity bills by changing their consumption pattern. It subsequently reduces the generation requirement during peak hours, which offers operational flexibility and financial benefits to utility. In the literature, DSM has been used in residential, commercial, and industrial sectors. However, the existing techniques do not explicitly consider the low-income consumers when TOU scheme is utilised. It may result in financial repercussion for these consumers. To overcome this challenge, a TOU scheme is proposed in this paper by ensuring financial benefits for all types of residential consumers and utility. To this end, an optimisation model is formulated by taking into account the various consumer groups such as low-income, middle-income and high-income. Two different meters (meter 1 and meter 2) are prudently allocated to these consumers. Using genetic algorithm technique, optimisation model is solved to provide electricity tariff and block sizes for various consumers under two meters. The proposed algorithm is applied to the residential inhabitants of a practical distribution system in Bangladesh. The results suggest that significant amount of annual savings can be achieved simultaneously by consumers and utility. The low-income consumers remain financially least affected while the proposed TOU tariff scheme is executed. In addition, the proposed TOU approach is compared to existing methods and found that optimisation based TOU outperforms the conventional ones.
•A new Time of Use tariff scheme for demand side management is proposed.•Profits for utility and consumers are simultaneously ensured.•Proposed algorithm is applied to a practical distribution system.
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