High Variable Renewable Energy Penetration Research Articles

A hybrid system dynamics model for power mix trajectory simulation in liberalized electricity markets considering carbon and capacity policy

Policy design during the energy system transition requires systematic thinking to navigate its complexity and mitigate potential side effects that policies may induce. Policy design based on System Dynamics (SD) simulations offers a tool to analyze real-world complexities. Given the difficulty of strictly simulating grid dispatch through causal loops, the Screening Curve (SC) method is widely employed in SD policy simulation models within closed commercial software platforms. Nevertheless, as Variable Renewable Energy (VRE) rises, the SC method faces challenges in accurately simulating grid dispatch operation due to its oversight of the power plants' limited output adjustment capabilities. This study developed a hybrid SD model as an alternative to the typical SD-SC combined method, allowing the SD model to simulate the power mix trajectory change incorporating high VRE penetration. After examining the simulation results with Hokkaido as a case study, the SC method may overestimate the abatement outcomes of the carbon pricing, and underestimate the support from capacity mechanism for the coal power plants. The difference between the two model increases along with the VRE share rising, when the VRE share exceeds about 40 % the results of the hybrid model will be more reliable.

The pitfall in designing future electrical power systems without considering energy return on investment in planning

Measuring the limitations of transitioning to 100% renewable energy systems partly equates with the capability of quantifying associated net-energy production. To foresee future possibilities, an advanced systemwide energy-return-on-investment (EROI) model was constructed. Driven by the thorough consideration of the existing weaknesses of EROI, the model integrates the concept of energy statistics, life cycle assessment techniques and energy system modelling in order to overcome the underlying primary energy quality issues, boundary condition problems and energy system design related uncertainties that compromises comparability of EROI during the energy transition. This model was applied to the Israeli power system that presents a unique opportunity to examine the vulnerability of depending on limited resources and the connection of EROI to system design. This study demonstrates the dependency of EROI on the energy transition path, system design requirements expressed via interactive linkages of curtailment, variable renewable energy penetration and storage system design, and resource diversity. Achieving a very high variable renewable energy penetration by 2050 with solar photovoltaics carries a risk of falling below an EROI value of 10, such vulnerability can be largely minimised by well-conducted manoeuvring of the system design and resource diversification. Despite the large uncertainty of this study, the need for a multicriteria designing technique is out of the question.

Assessment of the carbon emissions reduction potential in Thailand’s power sector with high penetration of variable renewable energy sources and electric vehicles in the year 2030

Abstract The power sector has substantial carbon emissions reduction potential that could achieve the new nationally determined contribution target in 2030 by increasing low-carbon technologies, e.g. variable renewable energy sources and electric vehicles (EVs). Therefore, two approaches were suggested in this work. In the first approach, Thailand’s power sector was modelled by using PLEXOS software to find the impact of the high penetration of variable renewable energy (RE) and EV charging load for the projected year 2030. The second approach proposed a demand–response and energy storage system solution with carbon pricing in the model to assess the targets. As a result, the electricity demand from charging EVs will cause a new peak demand at night, while the high variable RE penetration will cause curtailment in the power system due to excess supply at noon. Therefore, Thailand’s power sector has the potential for carbon emissions reduction by 45% with clean energy technologies, which could increase to 68% with carbon pricing, easily achievable by the nationally determined contribution target in 2030. However, these benefits could only be derived if various entities involved in the energy regulatory, transport and power sectors coordinate to implement the required technological and financial policies.

Assessing the potential of demand-side flexibility to improve the performance of electricity systems under high variable renewable energy penetration

Assessing the potential of demand-side flexibility to improve the performance of electricity systems under high variable renewable energy penetration

Towards reliability competition: Non-cooperative market mechanism under high variable renewable energy penetration

To encourage variable renewable energy (VRE) penetration, scholars put efforts in building cooperative market mechanisms. Under these mechanisms, VRE generators are treated as negative uncontrollable loads. The advantage of cooperative mechanism is that by cooperative aggregation of the uncertain sources (VREs and uncontrollable loads), some fluctuations cancel out. However, this study points out that the nature of cooperative mechanism will hinder further improvement for either the society-wise production efficiency or the VRE-wise economic efficiency. The key issue is that it is hard for the cooperative mechanisms to define positive marginal cost for VRE, thus blocking the value chain of carbon reduction. To solve the problem, this study proposes to consider reliability as a production characteristic of VRE generators. Based on these proposals, this study establishes a novel non-cooperative reliability competition mechanism for VRE market participation. Under this mechanism, the system is able to generated power at the lowest marginal cost considering both carbon cost and reliability cost. What’s more, the numerical simulation shows that: more VRE generators are able to achieve higher economic efficiency under non-cooperative mechanism compared to cooperative mechanism; the non-cooperative mechanism can provide clear signals for the internal and external marginal cost of generation reliability of VRE. It is shown that under the proposed mechanism, the reliability of VRE-included power generation system can reach the limit of technology in the long run.

Energy mix for net zero CO2 emissions by 2050 in Japan

AbstractThis study investigated cost‐effective energy strategies for realizing net zero CO2 emissions in Japan by 2050, employing an energy system optimization model with hourly electricity balances. The detailed temporal resolution enables the model to capture the intermittency of variable renewable energy (VRE) and the costs of system integration measures. Siting constraints on VRE, such as prohibiting solar PV and onshore wind developments in forests and offshore wind developments inside fishery rights areas, are incorporated in the model to reflect the environmental protection and social acceptance perspectives. Simulation results imply that a well‐balanced power generation mix, combining renewables, nuclear, gas‐fired with carbon capture and storage, as well as ammonia‐fired, would contribute to curbing mitigation costs. In contrast, a simulation case with very high VRE penetration poses economic challenges. The average shadow price of electricity in 2050 in a 100% renewables case (RE100) is projected to be more than doubled from a reference case which is based on middle‐of‐the‐road assumptions. Marginal CO2 abatement cost in 2050 increases from 49,200 JPY/tCO2 in the reference case to 75,300 JPY/tCO2 in the RE100 case. The economic viability of high VRE penetration is improved by relaxing the siting constraints, although it may raise environmental and social concerns.

Competing choices: Planning infrastructure investments [Editors’ Voice

Recent issues of power & energy magazine reviewed the transformational implications of high variable renewable energy penetration. This, coupled with the emerging ability to coordinate the operation of smart devices and systems at the distribution and customer levels of the grid bring a new perspective to the future of power system planning and operations.

Facing the high share of variable renewable energy in the power system: Flexibility and stability requirements

Power systems with a high share of variable renewable energy (VRE) represent a challenge to system operators because of the increased flexibility requirements and stability. This study analyses the performance of a real power grid with a high penetration of VRE (mainly wind and solar photovoltaic). A rule-based power model is developed to simulate the power system behaviour. One European country was selected (Spain), with limited international interconnections and well-established decarbonisation scenarios by national and European organisations. Flexibility requirements in the future power system were found through power plants' flexibility and stability constraints (i.e., inertia) and the expected changes in grid interconnection. The model results indicate that the ambitious targets for grid decarbonisation are not realistic because of these requirements. Considering the share of VRE for a sustainable transition (ST) scenario in 2030 (33% power generation) and in 2040 (35%), CO2-equivalent emissions will be reduced up to 157 and 159 kg CO2/MWh, respectively, which is well above Paris targets. Furthermore, no scenario allows meeting the expected environmental targets. Therefore, in power systems with more than 39% VRE, the results suggest that new technologies should be considered with emissions below ∼113 kgCO2/MWh, a maximum cost of ∼134 €/MWh, and an inertia constant above 5 s.

Transmission Planning With Battery-Based Energy Storage Transportation For Power Systems With High Penetration of Renewable Energy

Battery-based Energy Storage Transportation (BEST) is the transportation of modular battery storage systems via train cars or trucks representing an innovative solution for a) enhancing Variable Renewable Energy (VRE) utilization and load shifting, and b) providing a potential alternative for managing transmission congestions. This paper focuses on point b) and proposes a long-term transmission-planning model coordinated with both stationary and mobile storage units. The planning-problem objective function minimizes the total system cost, i.e., the sum of i) the investment cost of candidate transmission lines, stationary and mobile storage systems, and ii) the operation cost, including conventional generating units fuel consumption, load shedding penalty and BEST transportation costs. An alternative approach for BEST vehicle scheduling problem is implemented. The contribution lies in the accomplishment of the spatial-temporal scheduling of the mobile storage units by including the Number-of-nonzero mathematical function in the optimization model set of constraints instead of using additional binary variables as generally accomplished. The identification of either storage systems optimal location, or both optimal location and size of storage systems is also allowed. BEST usefulness is analyzed and discussed for a test-system emulating a reals system in China-Northwestern-grid with high VRE penetration divided in five regional areas, of which the most promising one for BEST implementation is identified.

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Techno-economic analysis of long-duration energy storage and flexible power generation technologies to support high-variable renewable energy grids

Coordinated operation of water and electricity distribution networks with variable renewable energy and distribution locational marginal pricing

Water and electricity distribution networks are two highly interdependent and critical infrastructures in the world today. This paper investigates the coupling of water and electricity distribution networks through the electrical energy demand of water pumps. Further, with additional variable renewable energy (VRE) sources in the distribution system, utilities face significant challenges stemming from the VRE stochasticity. In this paper, a coordinated operational model of urban water and electricity distribution networks is proposed. Stochastic VRE generation is handled by using a data-driven probability efficient point (PEP) method based on historical wind and solar datasets without the need for any probability distribution function. Case studies are performed on a modified Institute of Electrical and Electronics Engineers (IEEE) 13-node electricity distribution network coupled with a 10-node water distribution network, typical of a small-town setting. Results show the impact of coordinating water and energy networks on the cost of operation and the distribution locational marginal prices (DLMPs). The inclusion of water tanks as alternative storage devices in the electricity distribution network are shown to slightly reduce voltage violations, line congestion, and VRE curtailments in a case with high VRE penetration.

The curtailment paradox in the transition to high solar power systems

Summary Rising penetrations of variable renewable energy (VRE) in power systems are expected to increase the curtailment of these resources because of oversupply and operational constraints. We evaluate the effect on curtailment from various flexibility approaches, including storage, thermal generator flexibility, operating reserve eligibility rules, transmission constraints, and temporal resolution, by using a highly resolved realistic system. Results reveal two aspects of a curtailment paradox as the system evolves to higher solar penetration levels. First, thermal generator parameters, especially in restricting minimum operating levels and ramp rates, affect VRE curtailment more in mid-PV penetration levels (∼25%–40%) but much less at lower (∼20%) or higher (∼45%) PV penetration levels. Second, although allowing VRE and storage to provide operating reserve results in significant operating costs and curtailment benefits, the price suppression effect from these resources reduces incentives for PV to provide operating reserves with curtailed energy.

Preliminary analysis of long‐term storage requirement in enabling high renewable energy penetration: A case of East Asia

Integrating a high penetration of renewable energy for developing sustainable and low-carbon electric energy system is becoming a common trend around the world. Many studies have evaluated the energy storage requirement for accommodating variable renewable energy (VRE). However, in the situation of high renewable penetration, there will be a huge potential requirement of long-term energy storage for addressing the seasonal energy imbalance between VRE and load demand. Thus, a key element of evaluating the storage demand in enabling high VRE penetration is identifying the timescales of storage needed and the economic combination of long-term and short-term energy storages. This is neglected in existing researches. In this study, we quantitatively analyse the role of long-term seasonal storage in enabling high VRE penetration. A generation expansion planning model is formulated to optimise the least-cost generation portfolio with a renewable penetration target. Based on the proposed model, an empirical analysis for East Asia in 2050 is performed. The results indicate that (1) long-term storage contributes to addressing the long-term energy imbalance issue, (2) the optimal duration time of long-term storage is around 720 h (a month), and (3) the long-term storage becomes economical when the renewable penetration is above 70% (54.2% VRE penetration).

Flexible CCS Technologies To Reduce the Cost of Net-Zero Carbon Electricity Systems

Studies have shown that firm, low-carbon sources of power such as fossil-fueled power plants with carbon capture and storage (CCS) can reduce the cost of net-zero carbon electricity systems. But other developments on the path to decarbonization, particularly the proliferation of variable renewable energy (VRE) such as wind and solar, complicate the design of CCS-equipped plants, which must operate with reduced capacity factors and increased cycling. An increasing number of jurisdictions are committing to net-zero carbon electricity systems with high penetration of VRE. This paper considers the implications for CCS- equipped power plants via examination of grid capacity expansion and production cost modelling. The need to reconsider the optimal design and operations of CCS plants is presented, with focus on tradeoffs between capital cost, efficiency, and CO2 capture rate. Approaches to economic optimization via minimizing cost and maximizing operational profits are discussed. Finally, the case will be made that future CCS plants must either enable maximum power plant flexibility or change the operating paradigm so that plants can operate under more steady-state conditions and shift their electrical output to the grid via storage or provide another service such as removing CO2 from the air.

Improvement of Variable Renewable Energy Penetration of Stand-Alone Microgrid Hosting Capacity by Using Energy-Storage-System Based on Power Sensitivity

Recently, the demand for high penetration of variable renewable energy (VRE) penetration in a power system is increased. In consequence, distribution systems including microgrids confront the increased installation of VRE-based distributed generation. Despite of the high demand of VRE-based distributed generation in a distribution system, the installation of photovoltaic (PV) system in a distribution system has been restricted by various problems. In other words, the hosting capacity for high VRE penetration in a distribution system is limited. This paper analyzes the improvements of hosting capacity VRE penetration of stand-alone microgrid (SAMG) with energy storage system (ESS) by considering virtual-slack (VS) control based on power sensitivity. With the pre-defined power sensitivity, the ESS operates as virtual slack in the SAMG by controlling its bus voltage and phase angle indirectly. Therefore, the ESS enables the increase of VRE penetration in the SAMG. The proposed VS control is realized by analyzing the ESS as a virtual slack in power flow analysis based on power sensitivity. Then its validity is demonstrated with the case study on the SAMG in South Korea with practical data.

Transmission Expansion Planning Test System for AC/DC Hybrid Grid With High Variable Renewable Energy Penetration

Test systems are important tools and benchmark for power system research. Currently, there is a lack of standard test systems for modern transmission expansion planning (TEP) research, especially under high variable renewable energy (VRE) penetrations. This article describes a 38-bus test system named the HRP-38 system dedicated to TEP. “HRP” stands for high renewable penetration. The objective of establishing such a system is to provide a consistent platform for different TEP methods to be tested and compared. The test system considers high VRE penetration of more than 30% energy share, which will be an important feature in many power systems in the future. Both AC and DC candidate lines are given to provide sufficient transmission planning alternatives. The complexity of the test system is well balanced considering calculation tractability and the ability to test the performance of the TEP planning model. The network topology, generation mix and load characteristics are described in detail. Year-round time series of VRE (wind power and PV) output and load curves for each bus are provided to facilitate a detailed evaluation of the transmission grid configuration under high VRE penetration. Finally, four benchmark results with different optimization settings are provided for the HRP-38 system.

Ramping ancillary service for cost-based electricity markets with high penetration of variable renewable energy

System operators and electricity market stakeholders are facing new challenges related to increasing variability in both generation and demand. Rising generation levels of variable renewable energy (VRE) sources cause fluctuations in net loads that need to be met in real time by the rest of the system resources. While in some bid-based markets ancillary services have been proposed to procure ramping in an economic and efficient way, cost-based markets are struggling to define products and mechanisms that can accommodate to their rules, so as to incentivize and properly remunerate their procurement. In this paper we conceptualize a ramping ancillary service (RAS) for cost-based electricity markets with high penetration of VRE. The proposed RAS scheme is evaluated through simulations of the Chilean electric system. Numerical results show that it can be implemented in cost-based markets with positive technical and economic results, and that it may be a suitable solution to alleviate net load changes caused by high penetration of VRE.

Efficiency Loss for Variable Renewable Energy Incurred by Competition in Electricity Markets

Variable renewable energy (VRE) has undergone rapid development worldwide. Currently, VRE is gradually accepted as a regular power source to participate in the power market. However, due to the fluctuating and uncertain nature, the strategic offering behaviors of VRE generation companies (GENCOs), especially in terms of available capacity withholding, are difficult to supervise and regulate. To explore the hidden danger of VRE GENCOs’ strategic offering behaviors and the sequential impacts on the market operation, this paper proposes an analysis framework, which is built based on day-ahead and real-time two-stage markets, with multiperiod coupling. The bilevel model is utilized to analyze the decision-making process of the strategic VRE GENCOs. The bilevel model is nonlinear, which is then transformed into a mixed integer linear format by applying linearization methods. An illustrative example, with a high penetration of VREs, is proposed. The strategic offering behaviors of VRE GENCOs are comprehensively analyzed. The incurred efficiency loss and payment increase are discussed with various market settings. To demonstrate the effects of the regulatory policies on the VRE strategic offering behaviors, a deviation penalty policy imposed on the deviation of VRE outputs is also proposed and tested.

Examining the causality structures of electricity interchange and variable renewable energy: a comparison between Japan and Denmark

Shifting from fossil fuels to renewable energy to cut CO2 emissions while achieving sustainable development is an important challenge worldwide. Wind power and solar photovoltaics are classified as types of variable renewable energy (VRE), which have both pros and cons. Interregional trading of VRE is a key factor to make the most of it. Early studies of demand response or smart grids demonstrated the effective matching of supply and demand in a region. Studies of virtual power plants provided important implications for the selection of control parameters. However, questions remain when regions are crossed. The purpose of this study is to clarify the role of cross-border interconnectors in achieving high VRE penetration and to find the causality structures of interconnector operations for VRE. By developing multi-regression models for Denmark, a nation that has accepted VRE, and comparing them with 3 areas with different VRE progress stages in Japan, who is trying hard to achieve the target of 44% zero-emission sources in its generation mix by 2030, the general configuration of cross-border interconnectors with VRE that can be extended to other countries was clarified. This is the first report on the direct effects of power exchange to VRE using newly developed models. The results show that Japan still maintains traditional network planning. If countries such as Japan use flexible policies, a much higher VRE penetration might be achieved, thereby reducing the CO2 emissions. This model might also be applicable to other developing countries in which electricity supply is crucial for economic growth.

Techno-economic assessment of high variable renewable energy penetration in the bolivian interconnected electric system

Bolivia plans significant investments in conventional and renewable energy projects before 2025. Deployment of large hydro-power, wind and solar projects are foreseen in the investment agenda. Howe ...