Generation Adequacy Research Articles

Assessing cross-border integration of capacity mechanisms in coupled electricity markets

There is momentum in a number of European electricity markets towards the implementation of national generation capacity mechanisms. This renewed interest in capacity mechanisms raises the question of the cohabitation of both relatively well-integrated short-term energy markets and national generation capacity mechanisms. This paper examines a key issue of generation adequacy policies in a multi-market environment: the effect of foreign generators’ and interconnectors’ inclusion in national capacity mechanisms. The results show that the absence of cross-border participation could lead to significant social welfare losses associated with over and under-capacity procuring risk. This implies a vicious circle: as capacity mechanisms over or under-procure capacity, cross-border trade of electricity becomes more distorted, which in turn undermines the effectiveness of capacity mechanisms themselves. The findings also show that the inclusion of interconnectors in national capacity mechanisms could induce investments in merchant interconnections by compensating for network externalities and adjusting profit levels on the basis of the interconnection costs. However, despite the participation of interconnectors in capacity mechanisms, the exclusion of foreign generation of this market-based scheme undermines efficiency. In the absence of a wider EU single capacity mechanism, the inclusion of foreign generators and interconnectors in national capacity mechanisms should ensure the most efficient cohabitation of the EU Single Market and national capacity mechanisms.

Energy security impacts of a severe drought on the future Finnish energy system

Finland updated its Energy and Climate Strategy in late 2016 with the aim of increasing the share of renewable energy sources, increasing energy self-sufficiency and reducing greenhouse gas emissions. Concurrently, the issue of generation adequacy has grown more topical, especially since the record-high demand peak in Finland in January 2016. This paper analyses the Finnish energy system in years 2020 and 2030 by using the EnergyPLAN simulation tool to model whether different energy policy scenarios result in a plausible generation inadequacy. Moreover, as the Nordic energy system is so heavily dependent on hydropower production, we model and analyse the impacts of a severe drought on the Finnish energy system. We simulate hydropower availability according to the weather of the worst drought of the last century (in 1939–1942) with Finnish Environment Institute's Watershed Simulation and Forecasting System and we analyse the indirect impacts via reduced availability of electricity imports based on recent realised dry periods. Moreover, we analyse the environmental impacts of hydropower production during the drought and peak demand period and the impacts of climate change on generation adequacy in Finland. The results show that the scenarios of the new Energy and Climate Strategy result in an improved generation adequacy comparing to the current situation. However, a severe drought similar to that experienced in 1940s could cause a serious energy security threat.

Energy Use: Electricity System in West Africa and Climate Change Impact

This article investigates a low carbon pathway, the theoretical frame for understanding the trade-offs between economic development and climate change. An already developed model - Electricity Planning-Low Carbon Development (EP-LCD) - was adapted and modified to examine the nonlinear relationship between generation adequacy and greenhouse gas (GHG) emission reduction for better targeted strategic regional intervention on climate change. Two broad scenarios - Base and LCD Option - were tested for the West African Power Pool (WAPP). The cost impact of increasing generation capacity in the LCD Option was estimated at US$1.54 trillion over a 50 year period. Achieving the goal of low carbon pathway would be largely influenced by government decision. Four strategies, in line with the Nationally Determined Contribution in Paris Agreement, were recommended. These are: a) enforced improved efficient electricity generation through increased energy efficiency that should result in increased capacity factor; b) decreased energy intensity of economic activities to result in reduced emission factor in existing plants; c) attract new investment through low tax or tax exemption to reduce cost of constructing power plants for the benefit of base-load plants; and d) subsidized cost of low-carbon fuels in the short run to benefit intermediate load plants and allow for the ramping up of low-/no-carbon fuel generation capacity. These are recommended considering the region’s specific economical and political conditions where funds are tremendously difficult to raise. Implementing these recommendations will allow the electric power industry in West Africa to contribute to achieving sustainable development path.

Generation Adequacy Analysis of Multi-Area Power Systems With a High Share of Wind Power

There is growing concern regarding generation adequacy within the power system industry. The ever-increasing injection of intermittent renewable resources makes it harder than before to estimate the reliability of modern power systems using traditional approaches. This paper develops a framework for estimating the reliability of modern power systems that have considerable levels of wind power generation. Monte Carlo simulation is applied using a very efficient importance sampling technique based on the cross-entropy method as well as the Copula theory. Tailor-made importance sampling functions for conventional generation, load, and wind power generation drastically reduce the number of samples required to estimate reliability parameters of interest. The methodology enables simulation of multi-area power systems with considerable amount of correlated wind power generation in each of the different areas. Simulation results confirm the efficiency as well as the accuracy of the proposed method and show that it is orders of magnitude faster than crude Monte Carlo simulation.

Assessing the Potential Impact of Grid-Scale Variable Renewable Energy on the Reliability of Electricity Supply in Kenya

Securing a sufficient supply of reliable and affordable electricity is a major challenge for countries in sub-Saharan Africa (SSA), due to low current access levels, and rapid population and economic growth. This article will review application and technical modelling issues associated with generation adequacy assessment (i.e. assessing the risk of available generation being less than demand) in the context of SSA countries with significant capacities of renewable energy, with Kenya as the main case study. One major challenge in performing such studies in SSA is often availability of the necessary data on renewable resource and demand – the article will further demonstrate how useful information may be gained on the extent to which wind and hydro energy resources complement each other in Kenya, in the context of limited data availability.

Impact‐increment based decoupled reliability assessment approach for composite generation and transmission systems

Improving the computational efficiency of reliability assessment is a long-term goal for researchers. Regarding this issue, an impact-increment-based decoupled reliability assessment approach (IID) is proposed in this study. First, a new formulation of reliability indices is derived by decoupling the reliability index of composite systems into two parts: generation adequacy and transmission reliability. Then, an impact-increment-based state enumeration reliability assessment method is implemented to both the parts, which are more efficient than tradition methods. Thereafter, a reduction technique for the higher-order contingency states is developed for the transmission reliability evaluation. With this technique, the number of analysed contingencies can be significantly reduced, which improves the computational speed significantly. Finally, the overall framework of the proposed IID approach is demonstrated. Case studies are performed on the RTS-79, RTS-96 and a provincial system of China. Results indicate that the proposed method has superior performance to the traditional reliability assessment methods in terms of accuracy and computational speed, particularly on large-scale composite systems.

Assessing the contribution of nightly rechargeable grid-scale storage to generation capacity adequacy

Abstract This paper is concerned with assessing the contribution of grid-scale storage to generation capacity adequacy. Results are obtained for a utility-scale exemplar involving the Great Britain power system. All stores are assumed, for the purpose of capacity adequacy assessment, to be centrally controlled by the system operator, with the objective of minimising the Expected Energy Not Served over the peak demand season. The investigation is limited to stores that are sufficiently small such that discharge on one day does not restrict their ability to support adequacy on subsequent days. We argue that for such stores, the central control assumption does not imply loss of generality for the results. Since it may be the case that stores must take power export decisions without the benefit of complete information about the state of the system, a methodology is presented for calculating bounds on the value of such information for supporting generation adequacy. A greedy strategy is proven to be optimal for the case where decisions can be made immediately after a generation shortfall event has occurred, regardless of the decision maker’s risk aversion. The adequacy contribution of multiple stores is examined, and algorithms for coordinating their responses are presented.

Capacity value of energy storage considering control strategies.

In power systems, energy storage effectively improves the reliability of the system and smooths out the fluctuations of intermittent energy. However, the installed capacity value of energy storage cannot effectively measure the contribution of energy storage to the generator adequacy of power systems. To achieve a variety of purposes, several control strategies may be utilized in energy storage systems. The purpose of this paper is to study the influence of different energy storage control strategies on the generation adequacy. This paper presents the capacity value of energy storage to quantitatively estimate the contribution of energy storage on the generation adequacy. Four different control strategies are considered in the experimental method to study the capacity value of energy storage. Finally, the analysis of the influence factors on the capacity value under different control strategies is given.

Low-carbon development strategy for the West African electricity system: preliminary assessment using System dynamics approach

BackgroundPolicy makers seek to understand the trade-offs needed between economic growth and climate change. This provides the context to explore low-carbon development (LCD) pathways for the West African electricity system.MethodsThe study relied on both primary and secondary sources to elicit required information. These data were elicited from relevant authorities in the West African electricity system, namely, West African Power Pool and ECOWAS Regional Electricity Regulatory Authority. The objectives were to evaluate the planning processes in the West African Power Pool electricity system vis-a-vis low-carbon development strategy (LCDS), develop a System dynamics (SD) model, and assess the relevance of the developed model to examine the nonlinear relationship between generation adequacy and greenhouse gas emission (GHG) reduction. The SD model examined the tension between providing adequate supply capacity against reducing emission from the generation technologies in the West Africa electricity system. This model arranged the complexities in the system and established the basic interconnecting structure to conduct the analysis. High leverage points were identified.ResultsFour high leverage points were identified: capacity factor (CF), emission factor (EF), time to adjust capacity, and expectation formation. CF and EF improvement increased efficiency in the system. The expectation formation periods were determined at 7.5 years for the base case scenario and 7 years for the low-carbon development option scenario. Time to adjust capacity was located at 21 and 20 years respectively; deduced from the average time, it will take to construct a combined cycle gas power plant (3 years) and an allowance of 2 years for delays and its decommissioning time. Between 2011 and 2012, in LCD option scenario, emission of GHG to the atmosphere dropped as generation did but began a steady rise for the simulation period to a value of 6.154 billion tCO2 in 2060.ConclusionsElectricity Planning-Low-Carbon Development (EP-LCD) model—with three modules, was developed for assessing WAPP in low carbon economy. High leverage points identified in the model simulation situate three policy options for overcoming poverty and mitigation targets as regards resource mix, investment cost recovery, and technical factors to reduce system’s environmental footprint.

Energy Storage System Sizing Based on a Reliability Assessment of Power Systems Integrated with Wind Power

The available capacity is a major factor that influences the reliability contribution of energy storage in power systems integrated with wind power. This paper presents the capacity value of the energy storage metrics to quantitatively estimate the contribution of energy storage to the generation adequacy. A method in accordance with EFC approach has been introduced to model the capacity value of energy storage. The adequacy-oriented model of the energy storage available capacity is proposed for the energy storage system, regarding the roles of the key parameters for the CVES analysis. The case study results indicate that the capacity value of energy storage quantitatively weigh the contribution of the energy storage to system reliability. The sensitivity analysis of the impact factors for the CVES is conducted.

Capacity value estimation of a load-shifting resource using a coupled building and power system model

Understanding the contribution a resource can make to the power system could indicate where its value lies. This paper estimates the capacity value of a load-shifting resource which is capable of providing multiple services. The capacity value represents the contribution of a resource to generation adequacy and an understanding of this contribution is important to compare how different power system resources can assist power system operators and planners. Additionally, policy-makers and market operators need an appreciation of the capacity value of different resources in order to design capacity remuneration mechanisms. A building energy model coupled with a power system model, co-optimizing the supply-side and the demand-side, is employed in this paper to estimate the capacity value of a specific load-shifting resource. The resource examined is electric thermal storage heating devices for space and water heating. Ireland is used as a test case. It was found that these load-shifting devices can provide an adequacy contribution to the power system and thus have a capacity value. The capacity value, for the Irish case, can be up to 26% for the DR resource in question for the given year but the values are typically much lower due to operational constraints (reserve provision) and due to occupancy profile impacts. The results highlight the need for holistic modeling of demand response resources, as well as the need for additional work for different load-shifting resources and more data.

An Overview of Frequency Control as a Criterion of Power System Reliability and International Survey of Determining Operating Reserve

In this paper an extensive literature review of power system frequency control regulation and in relation to this, operating reserve determination policy have been highlighted. In terms of power system reliability and stability aspect, frequency control mechanism is the most important factor; hence there is a need for sufficient capacity reserve in case of contingency. An investigation of operating reserve policy in different regions, e.g., US, Canada, Europe and Asia have been conducted to clearer understand of reserve policy. It has been identified that, probabilistic approach is the best suited for determining generation adequacy in terms of economic and reliability point of view. Different type of reserve is allocated at different level of frequency control level. So, technical specification and timing for frequency control level of different system operator have been discussed widely. A comparison of frequency control framework between European and US is also presented. To ensure reliability and stability, it is recommended to adopt special protection scheme alongside new technologies – WAMS, SmartGrid.

How to benefit from a common European electricity market design

The realization of an Internal Electricity Market in Europe is currently, on the one hand, progressing, in particular thanks to the wide-spread implementation of market coupling solutions for cross-border congestion management. On the other hand, diverging national market designs pose a threat to the continuation of this process. Given the challenges to electricity market design in a multi-regional context, we analyze how different design aspects, namely cross-border congestion management and capacity mechanisms, affect welfare and generation adequacy in Europe. In doing so, we rely on an agent-based simulation model for electricity wholesale markets which we apply within several numerical, computational case studies for the region of Central Western Europe (2012–2030). Our results confirm the benefits of market coupling in terms of welfare as well as generation adequacy. Furthermore, we find indications that coordinating market designs across regions supports these targets. Therefore, we recommend that European energy policy forms a stable, transparent regulatory framework with cross-border market coupling as an integral component. In this context, energy policy targets should be clearly defined and operationalized, which also needs to consider potential conflicts between them. Finally, electricity market designs need to be coordinated among states to benefit most from a common European market.

Generating adequacy analysis of Mexico’s national interconnected power system

Purpose Long-term reliability analysis of generation capacity based on the forecasted load demand helps to identify the optimal generation expansion plan of the system. This paper analyzes the generation adequacy of Mexico’s National Interconnected Power System (MNIPS) using loss of load expectation (LOLE) and loss of energy expectation (LOEE) indices. Design/methodology/approach These indices are calculated through an analytical (recursive) method and are then compared with values recommended by the North American Electric Reliability Council (NERC). Weekly indices are computed to analyze the load curtailment options that may occur in some periods. Findings Forecasted values, including load and generation capacity considering maintenance schedules, additions of new generating units and permanently shut down units in accordance with the long-term expanding-system plan have been considered. The load forecast uncertainty is also included. Originality/value This is original work.

Prioritising energy efficiency and demand side measures over capacity mechanisms under EU energy law

Energy efficiency has been given high strategic priority in European Union energy law. In addition to energy efficiency, reducing or shifting demand have been identified as key elements not only for improving the functioning of the internal electricity market but also for achieving the EU sustainability objectives and ensuring security of supply. This article argues that the EU regulatory framework for ensuring generation adequacy and introducing capacity mechanisms should be interpreted to prioritise demand side measures over capacity mechanisms. Through this contextual interpretation of the relevant regulatory framework, this article aims to identify the ways in which the Commission uses demand side assessments as justification for declaring capacity mechanisms (in)compatible with the internal market and how energy efficiency and demand side measures can, in practice, be designed to complement capacity remuneration for supply side measures.

Wind generation impact on electricity generation adequacy and nuclear safety

This paper presents the results of the analysis of the generating adequacy in the power system considering the introduction of wind generating power units. The Loss of load probability is the measure utilized for the evaluation of the electricity generation adequacy. The uncertainty of the wind generators output power and power system peak load uncertainty are considered in the analysis. The implication of the substitution of nuclear power plants with wind generating units on the risk of the remaining operational nuclear power plants within the analysed power system is evaluated.The obtained results show that the introduction of wind generating units in the power system results in the change of the Loss of load probability. The obtained Loss of load probability depends on the uncertainty of the peak load size and the wind speed shape parameters. The increase of the share of the wind generation in the power system results in increased Loss of load probability. The change of the generation adequacy results in the change of the risk of the nuclear power plants. Substitution of the nuclear power plants with wind generating units results in small decrease of overall risk within the analysed power system.

Analysis of design options for the electricity market: The German case

The effectiveness of the energy-only market (EOM) in providing sufficient incentives for investments is intensively discussed in Europe. While supporters claim that an improved EOM can guarantee generation adequacy, energy suppliers in particular favor the introduction of a capacity market to finance power plant investments. However, there is a lack of quantitative assessment of market design options taking into account individual decisions of market players. Existing studies mainly include a system view based on a central planner optimization. This paper on the other hand is based on an agent-based simulation model for the German electricity market. This method can explicitly incorporate individual investment decisions and aggregate them to present a holistic view of the system.Our results show that an EOM extended with a strategic reserve can incentivize investments, and guarantee supply security in a market with high share of renewable energies. However, the generation adequacy can be more easily achieved with a capacity market. Furthermore, the cost advantage of an EOM diminishes in the long-term, as scarcity prices in the EOM lead to similar system costs as with a capacity market.

RELATIONSHIP BETWEEN LOSS OF LOAD EXPECTATION AND RESERVE MARGIN FOR OPTIMAL GENERATION PLANNING

Generation planning utilizes reliability indices as criteria to ensure adequacy in terms of total installed capacity. Reserve Margin and Loss of Load Expectation (LOLE) are the most widely-used indices in generation adequacy evaluation. Reserve Margin is a measure of available capacity over and above the capacity needed to meet normal peak demand levels. In Peninsular Malaysia, the amount of Reserve Margin has been perceived to be high. Generally, high Reserve Margin can provide high reliability. However, it acquires more generation plant, for which some of them may not be necessary. This may indicate over investment which will be reflected in the tariff structure. LOLE is a probabilistic measure which indicates the risk at which the generation capacity fails to meet the demand and its evaluation involves specific parameters such as the plant capacity and outage rate of each generating unit. Therefore, in order to have optimum generation planning and investment efficiency, it is necessary to perform a study on the practical Reserve Margin level with respect to the current LOLE requirement without endangering the overall power system reliability. This research studies the factors affecting LOLE and evaluates the relationship between Reserve Margin and LOLE under various conditions. A modified Peninsular Malaysia system is simulated using Wien Automatic System Planning (WASP -IV) to determine LOLE focusing on thermal power plants. This study concludes that peak load and forced outage rate give significant impacts to the LOLE and thus, the reliability of the system. Effort to ensure availability especially during peak load may need to be intensified. The study also establishes an inverse exponential curve for the relationship between Reserve Margin and LOLE. It is found that the outcome of the study is to enhance generation planning decision making in obtaining the optimum Reserve Margin considering the LOLE under various conditions.

Effect of Islanding and Telecontrolled Switches on Distribution System Reliability Considering Load and Green-Energy Fluctuations

To improve electrical distribution network reliability, some portions of the network could operate in autonomous mode, provided that the related technical issues are addressed. More specifically, when there is not a path from those portions to the primary substation due to a fault in the network, such portions could be disconnected from the main network and supplied by local generation only. Such a mode of operation is known as “intentional islanding” and its effectiveness, in terms of adequacy, depends on the ability of the local generation to meet the island’s load. In fact, the ratio between the available local generation and load demand can frequently change during islanding due to load variations and, especially, due to the strongly irregular behavior of the primary energy sources of renewable generators. This paper proposes an analytical formulation to assess local generation adequacy during intentional islanding, accounting for the aforementioned variations. More specifically, the fluctuations of load and green-energy generators during islanding are modeled by means of Markov chains, whose output quantities are encompassed in the proposed analytical formulation. Such a formulation is used by the analytical equations of load points’ outage rate and duration. The evaluation of the reliability indices accounts for a protection scheme based on an appropriate communication infrastructure. Therefore, a brief overview on the telecommunications technologies has been presented with reference to their suitability for the specific application. In particular, distribution network safety issues have been considered as the main concern. The results show that neglecting load and generation fluctuations leads to a strong overestimation of the ability of distributed generators to meet the island load. Through a case study it is observed that the error on the load point outage rate is greater than the one affecting the outage duration.

The electricity generation adequacy problem: Assessing dynamic effects of capacity remuneration mechanisms

Following liberalization reforms, the ability of power markets to provide satisfactory incentives for capacity investments has become a major concern. In particular, current energy markets can exhibit a phenomenon of investment cycles, which generate phases of under and over-capacity, and hence additional costs and risks for generation adequacy. To cope with these issues, new mechanisms, called capacity remuneration mechanisms (CRM), have been (or will be) implemented. This paper assesses the dynamic effects of two CRMs, the capacity market and the strategic reserve mechanism, and studies to what extent they can reduce the investment cycles. Generation costs and shortage costs of both mechanisms are also compared to conclude on their effectivity and economic efficiency. A simulation model, based on system dynamics, is developed to study the functioning of both CRMs and the related investment decisions. The results highlight the benefits of deploying CRMs to solve the adequacy issue: shortages are strongly reduced compared to an energy-only market. Besides, the capacity market appears to be more beneficial, since it experiences fewer shortages and generation costs are lower. These comparisons can be used by policy makers (in particular in Europe, where these two CRMs are mainly debated) to determine which CRM to adopt.