Power System Transition Research Articles

Development of an optimization-aided small modular reactor siting model – A case study of Saskatchewan, Canada

As an emerging clean technology, the replacement of coal plants and the integration with renewable power generation are two appealing options for the deployment of SMRs in the power system. However, both these applications and SMR siting issues for power systems have multiple complexities that have been difficult to be considered in past studies. Accordingly, an optimization-aided small modular reactor siting (OASS) model is initiated in this study to support decisions of siting, sizing, and timing for small modular reactor (SMR) development. The proposed OASS model is specialized for obtaining possible SMRs siting schemes, wind-SMRs combination schemes, and power system transition schemes with coal plant closure and SMRs deployment. This research initiates the application of an optimization-based modelling approach to tackle SMRs site selection issues for Saskatchewan, Canada. The results disclose that electricity imports and natural gas power will fill the electricity demand gap in Saskatchewan’s power system in the short term. Results obtained from this model can also identify optimized patterns of SMRs and wind farms deployment and siting in Saskatchewan. Power stations with large capacity and independent transmission grid will become the primary choice in the SMRs and wind farms site selection process. Such patterns and alternatives would enable decision-makers obtain optimized energy structure by introducing SMR reflecting trade-offs between overall system costs and greenhouse gas (GHG) emissions from both economic and environmental perspectives.

Investigating the market effects of increased RES penetration with BSAM: A wholesale electricity market simulator

Currently electricity markets worldwide encounter a transition phase into cleaner energy. This is specially the case in Greece, where not only the market structure changes to a harmonized EU target model, but also ‘green electricity’ is projected to reach 50% share by 2030 according to the National Energy and Climate Plan of Greece. This paper presents the extension of the Business Strategy Assessment Model (BSAM) into a computationally efficient central-dispatch wholesale market model. BSAM integrates agent-based profit-maximizing policy making with unit commitment scheduling, into one novel tool that can be used to explore the effects of mid-term market design policies in wholesale electricity markets. BSAM is subsequently utilized to model the Greek market’s transitional phase and explore the effects of even higher RES penetration scenarios. Results indicate that the planned short-to-mid-term “de-lignification” and transition of the Greek power system is feasible and will not lead to an excessive RES curtailment situation, but would yield significant CO2 emissions’ reductions and small reductions in the system marginal price, with even more ambitious RES shares also being possible.

Pathway towards 100% renewable energy in Indonesia power system by 2050

This study assesses Indonesia power system's transition pathway to reach 100% renewable energy in 2050. The pathway is determined based on least-cost optimisation in the TIMES model comparing 27 power plants and 3 energy storage technologies and using hourly demand and supply operational profile using 24-h time slices. From this study, it can be concluded that nuclear and solar PV utility-scale will play an essential role up to 16% and 70% of total electricity production, corresponding to 1396 TWh in 2050. The investment cost in 2050 is three times higher, and the emission is one-sixth lower than in Business as Usual, equal to 95 billion USD and 215 million tons of CO2-eq. The RE mix based on current policy generates a higher CO2 abatement cost, 120 USD/ton CO2-eq in 2050. The optimistic demand projection will increase the coal by 82% in Business as Usual also nuclear and solar PV utility-scale of about 126% and 62% in 100% RE, respectively. The exclusion nuclear in power system increase the installed capacity of solar PV utility-scale and battery, increase land requirement by 78%–83%, increase the variability of supply from other power plants and batteries, and increase 9.7% of electricity production cost.

Evolution of the Electricity Distribution Networks—Active Management Architecture Schemes and Microgrid Control Functionalities

The power system transition to smart grids brings challenges to electricity distribution network development since it involves several stakeholders and actors whose needs must be met to be successful for the electricity network upgrade. The technological challenges arise mainly from the various distributed energy resources (DERs) integration and use and network optimization and security. End-customers play a central role in future network operations. Understanding the network’s evolution through possible network operational scenarios could create a dedicated and reliable roadmap for the various stakeholders’ use. This paper presents a method to develop the evolving operational scenarios and related management schemes, including microgrid control functionalities, and analyzes the evolution of electricity distribution networks considering medium and low voltage grids. The analysis consists of the dynamic descriptions of network operations and the static illustrations of the relationships among classified actors. The method and analysis use an object-oriented and standardized software modeling language, the unified modeling language (UML). Operational descriptions for the four evolution phases of electricity distribution networks are defined and analyzed by Enterprise Architect, a UML tool. This analysis is followed by the active management architecture schemes with the microgrid control functionalities. The graphical models and analysis generated can be used for scenario building in roadmap development, real-time simulations, and management system development. The developed method, presented with high-level use cases (HL-UCs), can be further used to develop and analyze several parallel running control algorithms for DERs providing ancillary services (ASs) in the evolving electricity distribution networks.

Provision of Synthetic Inertia Support for Converter-Dominated Weak Grids

Insufficient inertia is the paramount challenge in power system transition toward <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ 100\%$</tex-math></inline-formula> converter-based generation. A promising solution to this issue is utilizing distributed virtual inertia (DVI) concept, i.e., releasing energy stored in the dc-link capacitors of power converters employed in the grid following a frequency disturbance. Nevertheless, this method has two drawbacks: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ 1$</tex-math></inline-formula> ) the dc-link voltage is not reverted to its reference value after the power mismatch between generation and demand, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ 2$</tex-math></inline-formula> ) it yields instability of a local mode associated with the control system when the converter operates in weak grids. To overcome the aforesaid problems, the conventional DVI loop is modified so as not to affect the outer loop voltage regulator after transient. Moreover, an efficient compensator is presented in this article which eliminates the adverse impact of DVI technique on the converter stability in weak grid connections. The efficacy of proposed control scheme is depicted by simulations in MATLAB. The results illustrate that an improvement of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ 23\%$</tex-math></inline-formula> is evident in the grid frequency rate of change following a frequency contingency collated with the case in which the DVI loop staying nullified.

Flexibility metrics for analysis of power system transition - A case study of Japan and Sweden

This paper discusses how flexibility metrics can be used in analysis of the balancing challenges arising from power system transition towards high shares of variable renewable energy sources. Using some metrics suggested in the literature as a starting point, new metrics are developed that combine the advantages of existing metrics and improve the connection to flexibility properties and balancing capability metrics. The metrics are applied to scenarios with 50% variable renewable energy in Japan and Sweden as a case study. The results show differences and similarities in the balancing challenges of these two systems. While diurnal variations increase more in Japan, Sweden is challenged by inter-week and seasonal variations. The results also show how the feasibility of inflexible base power production depends on large volumes of energy storage in the system.

Preventive protection of marine electrical power system from the transition of generating sets to motoring mode

The approaches that ensure the trouble-free operation of marine power system in abnormal modes were considered. Such modes are usually associated with the system elements failure during operation. Particular attention was paid to the processes occurring in the circuit during transition of one of the generators to the motoring operation mode. The relevance of the considered marine power system issue was substantiated. According to the research results, using time-delay when generating a signal to disable a failed unit operating with reverse power can contribute to defect development in the primary motor. Moreover, time-delay can also lead to zero voltage in the marine electric power system. This circumstance creates the possibility of an emergency that can potentially lead to a shipping accident with the most serious consequences. The problem of timely shutdown of a faulty electrical machine before its transition to the motoring mode is defined in the research, as well as the overload prevention problem for primary motors remaining in working condition. An original diagnostic indicator was proposed based on study, which allows identifying the inoperative state of generator unit during operation. The new approach was developed, which implements the preventive control method for the marine power system in case of element failure. The forecasting of the system operation modes in case of a generator set failure, and its structural adaptation to the occurred malfunction is carried out. In contrast to the existing methods, the practical implementation of the proposed solution will allow accident-free transition of marine power system to a partially operational state without the emergency. This will have a beneficial effect on the safety of ship as a whole.

Power system transition in China under the coordinated development of power sources, network, demand response, and energy storage

AbstractChina is transiting its power system towards a more flexible status with a higher capability of integrating renewable energy generation. Demand response (DR) and energy storage increasingly play important roles to improve power system flexibility. The coordinated development of power sources, network, DR, and energy storage will become a trend. This paper examines the significance of source‐network‐demand‐storage coordinated development. Furthermore, an outlook of the power system transition in China is provided by virtue of source‐network‐demand‐storage coordinated planning. The paper also assesses the integration of multiple urban infrastructures in China and its impacts on source‐network‐demand‐storage coordination. Lastly, challenges for achieving the source‐network‐demand‐storage coordination and suggested measures are discussed.This article is categorized under: Energy Research &amp; Innovation &gt; Systems and Infrastructure Energy and Urban Design &gt; Systems and Infrastructure

Putting the process into the policy mix: Simulating policy design for energy and electricity transitions in Japan

This study develops a framework to facilitate the participation of scientists to policy design towards energy transition, building upon existing literatures on science policy nexus, policy process, and energy system modelling. The framework assumes that policy design is embedded within systems and influenced by other actors, which is represented by incorporating a model of policy process derived from the Multiple Streams Framework that Kingdon (1984) originally developed. In order to support policy design for the transition of the energy system considering stakeholders’ primary interests and the possibility for a reshaping of the political dynamics, a cognitive mapping approach based on interviews to stakeholders is adopted. The newly developed framework is applied to a case study of a power system transition in Japan in order to confirm its effectiveness. The framework is identified to be able to support the creation of new policy alternatives by seeking options which satisfy the “policy process test”. Although the proposed framework remains a hypothetical tool which requires further validation and verification through additional practical applications toward policymaking, the policy process aspects captured by the framework are invaluable, especially given the current challenges in energy policy change and major determinants of policy direction.

Indicator system to evaluate the effectiveness and efficiency of China clean power systems

The mitigation of climate change demands a transition to low-carbon power generation systems. To identify effective transition strategies and accelerate the transition process, decision-makers require comprehensive information that can best be obtained through an evaluation of transition trajectories. However, little work has been done to develop comprehensive analysis systems that can evaluate this process. This study presents an indicator system to evaluate power system transitions that include 13 indicators capturing the technical, economic, environmental and policy dimensions. To test its efficacy, the dynamic target framework is applied to the power system transition in China, and comparisons are drawn against global market leaders such as Germany, the USA and Japan. This paper finds that the framework enables a more rigorous comparative analysis of power system transitions between countries than is currently offered by the application of piecemeal indicators. This framework complements contextually rich qualitative case studies. Empirical analysis shows that China’s transition trajectory has been convoluted because of its more severe environmental restrictions and policy guidance. Cooperation in the intelligent transition of the global power system can promote China’s power system transition. This approach should foster both the mitigation of climate change and adaptation to China’s resource constraints.

Frequency Stability of Synchronous Machines and Grid-Forming Power Converters

An inevitable consequence of the global power system transition toward nearly 100% renewable-based generation is the loss of conventional bulk generation by synchronous machines (SMs), their inertia, and accompanying frequency- and voltage-control mechanisms. This gradual transformation of the power system to a low-inertia system leads to critical challenges in maintaining system stability. Novel control techniques for converters, so-called grid-forming strategies, are expected to address these challenges and replicate functionalities that, so far, have been provided by SMs. This article presents a low-inertia case study that includes SMs and converters controlled under various grid-forming techniques. In this article, the positive impact of the grid-forming converters (GFCs) on the frequency stability of SMs is highlighted, a qualitative analysis that provides insights into the frequency stability of the system is presented, we explore the behavior of the grid-forming controls when imposing the converter dc and ac current limitations, the importance of the dc dynamics in grid-forming control design as well as the critical need for an effective ac current limitation scheme are reported, and finally, we analyze how and when the interaction between the fast GFC and the slow SM dynamics can contribute to the system instability.

Phase-space exploration of unit ensembles in energy management

Abstract Currently, a transition of the electrical power system occurs that results in replacing large-scale thermal power plants at transmission grid level by small generation units mainly installed in the distribution grid. A shift from the transmission to the distribution grid level and an increase in ancillary service demand is a direct result of this transition, demanding delegation of liabilities to distributed, small energy resources. Decoder-based methods currently are not able to cope with ensembles of individually acting energy resources. Aggregating flexibilities results in folded distributions with unfavorable properties for machine learning decoders. Nevertheless, a combined training set is needed to integrate e. g., a hotel, a small business, or similar with an ensemble of co-generation, heat pump, solar power, or controllable consumers to a single flexibility model. Thus, we improved the training process and use evolution strategies for sampling ensembles.

How Does Climate Change Affect the Transition of Power Systems: The Case of Germany

The effects of extreme weather events, such as heat waves and droughts are taken into account in both global and European policies. Accordingly, the protection of critical infrastructures and in particular, the resilience of the energy sector was the subject of intense research. There are regional differences in the degree of exposure to extreme events. In Northern Europe, their intensity has increased dramatically within a decade. In our analysis we identify emerging risks of extreme weather events, in particular, droughts and high temperatures, for the German power sector. Furthermore, we consider how European policy addressed these severe risks. Our analysis is based on extensive datasets covering temperature and drought data for the last 40 years. We find evidence of a higher frequency of power plants outages as a consequence of droughts and high temperatures. We investigate increases in the wholesale electricity price and price volatility and develop a capacity-adjusted drought index. The results are used to assess the monetary loss of power plant outages due to heatwaves and droughts. We stress that increasing frequencies of such extreme weather events will aggravate the observed problem, especially with respect to the transition of the power sector.

How does Climate Change Affect the Transition of Power Systems: The Case of Germany

The effects of extreme weather events, such as heat waves and droughts are taken into account in both global and European policies. Accordingly, the protection of critical infrastructures and in particular, the resilience of the energy sector was the subject of intense research. There are regional differences in the degree of exposure to extreme events. In Northern Europe, their intensity has increased dramatically within a decade. In our analysis we identify emerging risks of extreme weather events, in particular, droughts and high temperatures, for the German power sector. Furthermore, we consider how European policy addressed these severe risks. Our analysis is based on extensive datasets covering temperature and drought data for the last 40 years. We find evidence of a higher frequency of power plants outages as a consequence of droughts and high temperatures. We investigate increases in the wholesale electricity price and price volatility and develop a capacity-adjusted drought index. The results are used to assess the monetary loss of power plant outages due to heatwaves and droughts. We stress that increasing frequencies of such extreme weather events will aggravate the observed problem, especially with respect to the transition of the power sector.

Controlling a retailer's short‐term financial risk exposure using demand response

The transition of the electric power system to reach sustainability goals leads to new market conditions with larger uncertainties. This constitutes new challenges and opportunities for new as well as for existing market players such as retailers. In a future more volatile and unpredictable market, financial risk management becomes an important element for such actors in order to achieve viable businesses. Different instruments can be applied for this purpose, where demand response can contribute in the short-term to manage risks related to price variations and imbalance costs. This study contributes to the enhancement of retailer's businesses by presenting a stochastic optimisation model exploring the possibility to apply demand response to control financial risk exposure. The model considers trading and demand response scheduling for different customer clusters, generating optimal trading volumes for day-ahead markets while also considering the possibility to trade intra-day. The optimisation considers uncertainties in prices and loads as well as imbalance settlement costs. Risk management is integrated into the model by applying conditional value-at-risk as risk measures. The developed model has also been applied in a case study with data from the Swedish and Nordic electricity market together with simulated load profiles for different customer clusters.

Towards a smart grid power system in Brazil: Challenges and opportunities

The prospects for a smart power system have been widely discussed in the global electricity sector. Decarbonization, Digitalization and Decentralization are considered the main key drivers for this power system transition and Brazil is no exception to this universal trend. A search of the literature revealed few studies which attempt to address the main challenges and opportunities towards a smart grid power system in Brazil. This paper provides an up-to-date assessment of the present and potential capabilities of existing and future technologies, regulations and policies and attempts to identify how these elements are interrelated. Our findings add to a growing body of evidence suggesting that policies for Distributed Generation (DG), Demand-Side Management (DSM) and new tariff schemes are on a path of accelerated deployment in the country. The deployment of storage technologies, however, is at a slow pace of growth. We highlight the need to further develop new business models to address the various decentralized energy technologies and services that are emerging in the sector. The current net-metering system is considered a key issue to be addressed as this regulatory structure may shift the costs from DG to non-DG users.

Assessment of a cost-optimal power system fully based on renewable energy for Iran by 2050 – Achieving zero greenhouse gas emissions and overcoming the water crisis

Transition of Iran's power system from 2015 to 2050 through three scenarios was modelled. Two scenarios present a transition pathway towards a fully renewable run power system with different involved sectors (power only, power sector coupled with desalination and non-energetic gas sectors). The third scenario is based on the country's current policies. The energy model performs an hourly resolution to guarantee meeting energy demand for every hour of the whole year. It is found that renewable energy resources in Iran can satisfy 625 TWh of power sector demand in 2050. Further, it is technically and economically feasible that electricity demand for supplying 101 million m3 desalinated water and 249 TWhLHV synthetic natural gas for non-energetic industrial gas demand can be supplied via renewable resources. A 100% renewable power system with 54 €/MWhel levelised cost of electricity (LCOE) is more cost-effective than the current power system in Iran with 88.3 €/MWhel LCOE in 2015. LCOE of the system can decrease further and reach to 41.3 €/MWhel in 2050 via sector coupling. On the other hand, the current policies of the country lead to an inefficient power system with a LCOE of 128 €/MWhel and 188 Mt/a emitted CO2 in 2050.

Factors affecting the transition of the Polish power system

Energy systems face radical –almost revolutionary changes which, however, will be stretched over the long period. The critical factors influencing the future development of the Polish power sector are discussed in this paper. Development of intermittent energy supplies from renewable energy sources imposes a challenge on the entire power system and requires specific adaptations and responses from traditional generation units. Up to the present time they have been used to work in the stable mode while now they need more operational flexibility. The share of RES constantly increases. On one hand, this has a very positive environmental impact, but on the other it disturbs economics of classical generation units. Also liberalized electricity markets are impacted and the risks in power investments have increased. The capacity market could constitute a remedy, which will incentivise the investments necessary to fill the gap created by closing exhausted and inefficient plants. On the consumer side electromobility could change the demand, not only in quantity but also in terms of load profile. Climate policy tends to detriment coal based generation. For countries abundant in coal resources which make use of this cheap fuel, such as Poland, the question arises about its future role. Even in the most coal-supportive scenarios revised in this paper its relative share in electricity generation does not exceed 50% in 2050 while in others it rather goes much below 30%. .

The Role of Concentrating Solar Power Toward High Renewable Energy Penetrated Power Systems

Achieving high renewable energy penetrated power systems requires considerable operational flexibility to hedge the variability and uncertainty of variable renewable energy (VRE) generation. Compared with VRE sources, concentrating solar power (CSP) is an emerging controllable renewable generation technique that utilizes solar thermal power to generate electricity. The operational dispatchability of CSP would contribute to the power system transition toward high renewable penetration. In this paper, we explore how the generation portfolio will change toward high renewable energy penetrations, how much cost is involved, and what role CSP will play in realizing a high renewable energy penetrated power system. This study relies on a stochastic two-stage generation and transmission expansion planning model with CSP plants. The model captures the uncertainty and variability of renewable generation and the flexibility limits of thermal plants. With the target of achieving a renewable-dominated minimum-cost system with an expected renewable energy penetration level, the investments of both generation and transmission facilities are optimized. A case study on IEEE test systems with renewable technology cost data in 2050 is performed to analyze the value of CSP toward high renewable energy penetrated power systems.

Kemunduran dan Keruntuhan Daulah Bani Umawiyah di Damaskus dan Andalusia (Studi Pustaka)

Year 41 H (661), began the Umayyad rule in the history of the children of political Islam in Damaskus. The development of civilization covering the fields of architecture, military organizations, trade and fiscal reforms. Then suffered a setback that eventually collapse due to, among others, (1). The weakness of the khafilah. (2). The emergence of inter-group conflict. The emergence of inter-group conflict. The direct causes of the overthrow of the emergence of new powers, spearheaded by the descendants of al-Abbas ibn Abd al-Muttalib, this movement is supported by the Bani Hashim and the Shiite group of people who feel dikelasduakan mawali by Bani Umayyad rule.&#x0D; On May 14, 756, Kardova successfully conquered by Abdur Rahman and his followers. In a period of more than seven centuries of Muslim rule in Andalusia (Spain) achieve glory. in the field of intellectual progress: philosophy, science, jurisprudence, music and performing arts, language and literature. Then the physical development among others in Cordova (capital of Spain), trees and flowers imported from the east, there are 491 mosques, 900 baths, establish drainage from the mountains of length 80 km) while Granada is Al-Hamra palace, palace of al-Gajar, tower Girilda. Progress achieved daulah sons Umayyad West (Andalusia), decline and eventually collapse. The deterioration factor to cause the collapse, among others: (1). Lack of clarity about the transition of power systems. (2) Economic Difficulty. (3). The absence of a unifying ideology. (4) Islamic conflict with Christianity.