Power System Adequacy Research Articles

Identifying Robust Decarbonization Pathways for the Western U.S. Electric Power System Under Deep Climate Uncertainty

AbstractClimate change threatens the resource adequacy of future power systems. Existing research and practice lack frameworks for identifying decarbonization pathways that are robust to climate‐related uncertainty. We create such an analytical framework, then use it to assess the robustness of alternative pathways to achieving 60% emissions reductions from 2022 levels by 2040 for the Western U.S. power system. Our framework integrates power system planning and resource adequacy models with 100 climate realizations from a large climate ensemble. Climate realizations drive electricity demand; thermal plant availability; and wind, solar, and hydropower generation. Among five initial decarbonization pathways, all exhibit modest to significant resource adequacy failures under climate realizations in 2040, but certain pathways experience significantly less resource adequacy failures at little additional cost relative to other pathways. By identifying and planning for an extreme climate realization that drives the largest resource adequacy failures across our pathways, we produce a new decarbonization pathway that has no resource adequacy failures under any climate realizations. This new pathway is roughly 5% more expensive than other pathways due to greater capacity investment, and shifts investment from wind to solar and natural gas generators. Our analysis suggests modest increases in investment costs can add significant robustness against climate change in decarbonizing power systems. Our framework can help power system planners adapt to climate change by stress testing future plans to potential climate realizations, and offers a unique bridge between energy system and climate modeling.

Integrated production simulation of renewable energy and transportation consumption

Abstract In order to improve the reserve adequacy of high proportion new energy power systems and realize the efficient consumption of large-scale new energy, the source of reserve resources is expanded to the source network and load storage, and the operating reserve level that can be provided by the source network and load storage flexible regulating resources is quantified in terms of the direction of regulation and the mode of participation. Then, according to the regulation idea of “synchronous units bear the responsibility during regular hours and multiple types of resources share the responsibility during special hours”, a coordinated and participatory operating reserve capacity allocation strategy of source, network, load, and storage is proposed, and a reserve distribution optimization model incorporating multiple types of heterogeneous resources is constructed to achieve the optimization of reserve distribution of each type of reserve resource in the whole network. The optimization model of standby distribution is constructed to incorporate multiple types of heterogeneous resources and realize the step-by-step refinement of standby resources distribution among the whole grid - resources of the same type - units/stations. A case study is carried out based on a provincial power grid, and the effectiveness of the proposed strategy is verified by comparing it with the existing operational reserve allocation guidelines.

Considering the reliability of gas supply to power plants in the analysis of electric power system adequacy

One of the promising directions for further development of the methodology for investigating and ensuring the reliability of energy systems is the consideration of integrated energy systems. This is caused by the need for the adequate reflection of their joint operation. Previously, the authors proposed several methodological approaches based on "node," "system," and "evaluation" to assess the adequacy of an electric power system when this is operating jointly with a gas supply system. In that case, the focus was made only on high-pressure gas supply systems (simplified calculation). This work aims to consider not only the high-pressure gas systems, but also to take into account the influence of lowpressure gas systems (refined calculation) on the adequacy of electric power system. This approach appears to be more technologically advanced and corresponds to the real conditions of the functioning of integrated power systems. The studies were carried out using the “node” approach, its reference calculation being the most accurate one. The methods applied in the research are probability theory and mathematical statistics: a particular theorem on the repetition of experiments (Bernoulli's trial), calculation of probability distribution series, theorems of addition and multiplication of probabilities. A comparative analysis of reference calculations of the electric power system adequacy was carried out for simplified and refined connection schemes in the gas system (two cases were considered: a highly reliable low-pressure gas system and a low-reliability one). The calculations were performed on an illustrative example of a power system. Assessment of the load supply reliability in integrated systems must factor in the process features of the systems at issue, the block diagram of their connections, as well as the accuracy of the results obtained and the complexity of searching and preparing initial data for the corresponding research model.

Reliability evaluation technique with the integration of wind power fluctuation through considering frequency regulation and failure restoration

The adequacy of power system can be elevated with the increasing grid-connected capacity of wind farm, and meanwhile, the power system reliability is also affected by the intermittent power fluctuation of wind farm. However, the traditional reliability evaluation technique cannot take the power fluctuation into account. Therefore, for considering the positive and negative influence of wind energy on the power system reliability, this paper proposes a reliability evaluation technique through considering static frequency regulation and failure restoration process. A failure restoration strategy which can be integrated into the reliability evaluation model is presented through designing system load curtailment, system frequency restoration, and system load restoration strategies. A series reliability calculating models which depended on the different failure restoration conditions are established. Case studies for different systems are investigated, and the results verify that the proposed method can consider both aspects of the positive and negative influence of wind farm on the power system reliability.

Power System Adequacy With Variable Resources: A Capacity Credit Perspective

Power System Adequacy With Variable Resources: A Capacity Credit Perspective

A methodological approach for assessing flexibility and capacity value in renewable-dominated power systems: A Spanish case study in 2030

Maintaining the security of supply is one of the challenges that system operators face. Variability and uncertainty increase due to the penetration of variable renewable energy sources such as solar and wind, while flexible technologies such as traditional thermal units are phased out to reduce emissions. The current methods for assessing power system adequacy are based on historical operations and are generally intended to be applied to thermal-dominated electricity systems. Therefore, it is necessary to improve current adequacy assessment methods since they usually neglect the flexibility of power systems. This paper presents a methodological approach for jointly assessing the adequacy and flexibility of power systems. The methodology’s usefulness is demonstrated through its application to the Spanish power system. For the case study, results show that new closed-looped pumped storage hydro technology provides 25% flexibility while contributing to adequacy due to higher installed capacity and round-trip efficiency. Due to shorter storage duration, batteries only contribute to flexibility, supplying 16% of the total operating reserves. Therefore, this study shows that metrics of flexibility and individual contribution to the power system adequacy complement each other and simultaneously enable the scarcities of power systems to be observed.

Towards a future-proof climate database for European energy system studies

In 2013, the European Network of Transmission System Operators (TSOs) for electricity (ENTSO-E) created the Pan-European Climate Database (PECD), a tool that has underpinned most studies conducted by TSOs ever since. So far, the different versions of the PECD have used so-called modern-era ‘reanalysis’ products that represent a gridded amalgamation of historical conditions from observations. However, scientific evidence suggests, and recent European regulation requires, that power system adequacy studies should take climate change into account when estimating the future potential of variable renewable resources, such as wind, solar and hydro, and the impact of temperature on electricity demand. This paper explains the need for future climate data in energy systems studies and provides high-level recommendations for building a future-proof reference climate dataset for TSOs, not just in Europe, but also globally.

THE EFFECT OF A TRAINING PROGRAM ACCORDING TO THE (HIIT) METHOD ON SOME PHYSICAL ABILITIES AND ACETYL CHOLINESTERASE ENZYME AMONG FOOTBALL PLAYERS

A group of training methods affect the physical ability of the body’s organs, thus this study aims to know the effect of training using the (HIIT) method on some physical abilities, explosive power, and respiratory circulatory system adequacy, and agility, strength characterized by speed, acetyl cholinesterase enzyme and body mass. In this study, the researchers used the experimental method as a way to solve the research problem, in addition to a deliberately chosen sample of Al-Esraa University College players participating in the Iraqi Universities Football Halls League, Rate them (10) players. Several tests of physical abilities and body mass were also used in order to measure and obtain the values of those variables. A ten-week training curriculum implemented by HIIT method. Each week, three training units, each unit time (60-80) minutes, with training ripple (1: 2) and training intensity (85-100%). After completing the pre-tests and implementing the curriculum and the post-tests, the results were collected and treated statistically. In this regard, the researchers reached several conclusions, the most important of which were: Training using the HIIT method and according to the scientific basis of training contributes to the development of physical abilities, acetyl cholinesterase enzyme, body mass, and the adequacy of the respiratory system among university students. Keywords: HIIT Training Method - Physical Abilities - Cholinesterase Enzyme (BMI) - Adequacy of The Respiratory Circulatory System

ELCC-based capacity value estimation of combined wind - storage system using IPSO algorithm

Combined wind-storage systems (CWSSs) could significantly improve the reliability of power systems. In order to quantify the contribution of wind power and storage systems on adequacy of power systems, this paper proposes a novel algorithm based on equivalent load carrying capacity (ELCC), improved particle swarm optimization (IPSO). Simulation results are also provided. First, a novel algorithm IPSO for evaluating ELCC is presented. Second, the ELCC of wind power under different wind power permeability is studied using scenario simulation. Third, the ELCC of CWSS under diverse capacity combinations of wind power and energy storage is analyzed based on scenario simulation. Also, the superiority of IPSO is verified by comparing the results of ELCC evaluation with secant method and non-iterative smoothing spline (NISS). The simulation results show that, 1) ELCC of wind power increases with the augment of wind power permeability but finally stabilizes when wind power permeability is 60%. 2) When the permeability of wind power is constant, ELCC of CWSS increases and then does not change basically with the addition of the maximum capacity of energy storage. 3) The permeability of wind power and the maximum capacity of energy storage augment simultaneously will not increase ELCC of CWSS indefinitely.

Development of a methodology for assessing the adequacy of electric power systems

This study presents the results of a research into the developing a methodology for assessing the adequacy of advanced electric power systems characterized by the integration of various innovative technologies, which complicates their analysis. The methodology development is aimed at solving two main problems: 1) increase the adequacy of modeling the processes that occur in the electric power system and 2) enhance the computational efficiency of the adequacy assessment methodology. This study proposes a new mathematical model to minimize the power shortage and enhance the adequacy of modeling the processes. The model considers quadratic power transmission losses and network coefficients. The computational efficiency of the adequacy assessment methodology is enhanced using efficient random- number generators to form the calculated states of electric power systems and machine learning methods to assess power shortages and other reliability characteristics in the calculated states.

Upgrading Transmission Capacity by Altering HVAC Into Fractional Frequency Transmission System

Transmission adequacy of power system has been challenged by high investment of new line construction and limit line-corridor space. In this paper, a novel solution to increase transmission capacity by altering HVAC lines into fractional frequency transmission system (FFTS) is proposed. FFTS is a transmission that utilizes a relatively low grid frequency, e.g., 50/3 Hz, to extend the transmission capacity of ac lines. The proposed solution can minimize the construction efforts since the existing HVAC transmission lines can be directly employed by FFTS without any change. The structure and principle of FFTS for transmission line conversion (TLC) are introduced firstly. Then, performance of conventional ac equipment in FFTS is evaluated and comparison with respective counterpart in HVDC is carried out. Next, the economic performance of FFTS for transmission capacity upgrade is conducted based on a typical benchmark, and sensitivity analysis results are presented to determine the economic zone of FFTS. The results show that the uniform annual value (UAV) of TLC into FFTS is 24.9% and 31.6% cheaper than TLC into HVDC and constructing new HVAC lines, respectively. Therefore, FFTS is a superior scheme for transmission capacity boost.

Low carbon transition of China's electric and heating sector considering reliability: A modelling and optimization approach

China has pledged for their carbon emissions to have peaked by 2030 and to achieve carbon neutrality by 2060. However, this requires restructuring of their entire energy system. This study establishes a bottom-up low-carbon transition model for electric and heating coupled systems. The power system's adequacy with high penetration of renewable energy is considered via an iterative calculation approach, the layout of the power and heat system and the future of coal power under carbon emission constraints are discussed. Different from other research, our results show that the capacity of coal power would further increase to support a reliable transition of power system towards a higher proportion of renewable electricity, and the current target of 1200 GW of wind and solar in 2030 is not enough to achieve rapid carbon reductions, and would result in an extra 1.6 to 2.2 billion t CO2 emitted compared to 2020. Achieving 50% of non-fossil electricity generation by 2030 is feasible, and the target needs to be raised to 1660 to 1850 GW at only 3% increase of total cost. Not building new coal power plants would result in a huge expansion of electricity storage in China, which is hard to realize because of extremely high investment cost.

Strategies for short-term intermittency in long-term prospective scenarios in the French power system

This paper depicts the power system adequacy with respect to nuclear strategies by coupling investment with dispatching. The long-term energy model POLES simulates the Paris Agreement worldwide and is soft-linked with a power market model applied to France, EcoNUK. The nuclear flexibility is described by cycling frequency and amplitude, constrained by reactors minimum rated power and half-hour ramping rates. Results in 2050 show that the French power system made of 26% nuclear and 71% renewables in POLES needs deeper and longer flexibility with nuclear and gas in EcoNUK, due mainly to higher granular time-steps than the prospective model; and that reactors perform more deep cycles than allowed by their license (230 instead of 200). We show that scenarios with high shares of renewables build on the arbitrage between nuclear and gas, notably during peak loads in winter and night periods. Meeting the double target to reduce nuclear and carbon emissions requires more renewables, hence significant gas and nuclear power for adequacy, facing the dilemma nuclear versus emissions. Coupling short-term operation with long-term investment indicates that nuclear flexibility varies with the time-step of intermittency modeling, so scenarios need to include reactors constraints to reach an informed decision on renewables and nuclear.

Analytical approach for adequacy assessment of cyber–physical multi-microgrid distribution systems with distributed generation

In recent years, there has been a marked increase in the deployment of information and communication technologies (ICTs) in power systems. ICTs impart a cyber-physical nature to power systems, and though they improve the power system performance in various respects, they themselves are prone to random failures. With even more extensive penetration of ICTs expected to strongly characterise the future power systems, it is imperative to systematically study the impact of failures in cyber-physical power systems on the adequacy of power systems. With this as backdrop, the paper presents a novel analytical approach to study the impact of failure of various control layers and the cyber links between them on the adequacy of multi-microgrid distribution systems consisting of distributed generation resources such as wind and solar units. The main adequacy index of interest is Expected Energy Not Served, based on which the interruption costs can be computed. A case study is presented where the developed methodology is applied to a multi-microgrid distribution system where four different operation modes are realisable—normal, joint, islanding, and shutdown modes. The results are validated against those of a recently developed Monte Carlo simulation approach.

Adequacy assessment using data-driven models to account for aerodynamic losses in offshore wind generation

Offshore wind generation has developed rapidly in the past few years, leading to an increasing importance in power systems. Therefore, it becomes essential to properly account for aerodynamic effects that affect the power extracted from the wind, and to assess their impact on the power system adequacy. In adequacy studies, due to computational constraints, the power output of offshore wind farms is currently modelled in a simple and approximate way, neglecting important factors such as turbulence and wake effects. This may lead to erroneous, and thus misleading adequacy estimations. Hence, the focus of this paper is to develop data-driven proxy models able to learn the complex relation between free flow wind information and the aggregated power of wind farms. Those Machine Learning-based models are used as fast and reliable surrogates of numerical simulations based on computational fluid dynamics. The developed models are then included in an adequacy study built upon sequential Monte-Carlo simulations. The obtained outcomes are compared with traditional modelling approaches, which allows to quantify the value of the proposed procedure.

Subsidizing Residential Low Priority Smart Charging: A Power Management Strategy for Electric Vehicle in Thailand

Government policies are crucial factors for supporting the growth of the electric vehicle (EV) industry—a growth that can be encouraged, for example, by subsidization designed to reduce the considerable anxiety stemming from the inconvenience of refueling at public charging stations. Subsidizing low priority charging for residential enables cost-effective load management for example controlling of EV charging power for grid reliability at the off-peak rate for 24 h. This solution provides the convenient recharging of EVs at home and prevents an expensive grid upgradation. To advance our understanding of the EV situation, this research used a regression model to forecast the growth rate of the EV market alongside the EV expansion policies in Thailand. The agreement between a policy and forecasting urges the government to prepare power system adequacy for EV loading. The analysis showed that power demand and voltage reduction in a typical low-voltage distribution system that assumes maximum EV loading constitute voltage violations. To address this limitation, this study proposed a rule-based strategy wherein low priority smart EV charging is regulated. The numerical validation of the strategy indicated that the strategy reduced power demand by 25% and 39% compared with that achieved under uncontrolled and time of use (TOU) charging, respectively. The strategy also limited voltage reduction and prolonged battery life. The study presents implications for policymakers and electricity companies with respect to possible technical approaches to stimulating EV penetration.

Research on the design and influence of unit generation capacity adequacy guarantee mechanism in the power market

With the advancement of power system reform and the improvement of renewable energy penetration, the situation of power generation enterprises and the generation capacity adequacy of power system are facing challenges. It is urgent to ensure reliable power supply in the market through new evaluation methods and guarantee mechanisms. Firstly, this paper proposes an evaluation method of generation capacity adequacy for multi-types units, which quantitatively calculates the adequacy capacity of each unit and the generation capacity adequacy of the system. Secondly, this paper designs a unit capacity compensation mechanism adapted to the initial stage of Power Market construction, which includes capacity pricing model, compensation capacity quota model, capacity fee settlement model. Among them, the capacity pricing model considers the investment cost of marginal units operating during annual peak load, while the compensation capacity quota model considers the actual generation capacity of units and the actual demand of the system. Finally, this paper takes a certain region of China as an example to verify the effectiveness and adaptability of the mechanism. The results show that the capacity adequacy guarantee mechanism designed in this paper can effectively reflect the overall level of power system generation capacity adequacy, fairly distinguish the reliability value of various generation units, help power generation enterprises recover fixed costs within the planned investment payback period and ensure the system generation capacity adequacy.

Assessment of the Impacts of Climate Change on Power Systems: The Italian Case Study

Climate change due to the greenhouse effect will affect meteorological variables, which in turn will affect the demand for electrical energy and its generation in coming years. These impacts will become increasingly important in accordance with the increasing penetration of renewable, non-programmable energy sources (e.g., wind and solar). Specifically, the speed and amplitude of power system transformation will be different from one country to another according to many endogenous and exogenous factors. Based on a literature review, this paper focuses on the impact of climate change on the current, and future, Italian power system. The paper shows a wide range of results, due not just to the adopted climate change models used, but also to the models used to assess the impact of meteorological variables on electricity generation and demand. Analyzing and interpreting the reasons for such differences in the model results is crucial to perform more detailed numerical analyses on the adequacy and reliability of power systems. Concerning Italian future scenarios, the double impact of uncertainties in national policies and changes in power plant productivity and demand, has been considered and addressed.

Orderly retire China's coal-fired power capacity via capacity payments to support renewable energy expansion

SummaryThe energy-only-market implemented in China cannot strongly support large-scale renewable energy expansion because the renewable energy expansion may disorderly phase out non-renewable power capacity. However, non-renewable power capacity, particularly the coal-fired power capacity in China, can provide vital power system adequacy needed by renewable energy expansion. We introduce capacity payments to orderly retire current coal-fired power capacity by transforming some of it into reserve capacity in order to support renewable energy expansion. Using generation and transmission expansion results from the SWITCH-China model, this paper proposes an orderly retirement path based on the assumption of implementing capacity payments. Our results show that roughly 100–200 gigawatts (GW) of coal-fired power capacity can continue to serve through 2050, and most of it is used as reserve capacity. Capacity payments of 400–700 billion yuan are needed to achieve this retirement path, and a higher adequacy requirement needs higher payments.

Battery Energy Storage Contribution to System Adequacy

The objective of this paper is to evaluate the contribution of energy storage systems to resource adequacy of power systems experiencing increased levels of renewables penetration. To this end, a coherent methodology for the assessment of system capacity adequacy and the calculation of energy storage capacity value is presented, utilizing the Monte Carlo technique. The main focus is on short-duration storage, mainly battery energy storage systems (BESS), whose capacity values are determined for different power and energy configurations. Alternative operating policies (OPs) are implemented, prioritizing system cost or reliability, to demonstrate the significant effect storage management may have on its contribution to system adequacy. A medium-sized island system is used as a study case, applying a mixed integer linear programming (MILP) generation scheduling model to simulate BESS and system operation under each OP, in order to determine capacity contribution and overall performance in terms of renewable energy sources (RES) penetration, system operating cost and BESS lifetime expectancy. This study reveals that BESS contribution to system adequacy can be significant (capacity credit values up to ~85%), with energy capacity proving to be the most significant parameter. Energy storage may at the same time enhance system reliability, reduce generation cost and support RES integration, provided that it is appropriately managed; a combined reliability-oriented and cost-driven management approach is shown to yield optimal results.