Wind Curtailment Research Articles

Operation optimization for gas-electric integrated energy system with hydrogen storage module

Hydrogen is gradually becoming one of the important carriers of global energy transformation and development. To analyze the influence of the hydrogen storage module (HSM) on the operation of the gas-electricity integrated energy system, a comprehensive energy system model consisting of wind turbines, gas turbines, power-to-hydrogen (P2H) unit, and HSM is proposed in this paper. The model couples the natural gas network and power grid bidirectionally, and establishes a mixed integer nonlinear programming problem considering HSM. The linearization model of the natural gas pipeline flow equation and the generator set equation is constructed by piecewise linearization method to improve the efficiency of solving the model. And the energy flow distribution in the gas-electricity integrated energy system is finally solved. In Model 1, compared with not considering the installation of P2H units, when the hydrogen doping ratio is 10%, the operating cost can be reduced by 6.63%, and the wind curtailment cost can be reduced by 17.54%, and the carbon emission can be reduced by 298.7 tons. The optimization results of Model 2 reveal that compared with no HSM, the system operating cost is reduced by 5.96%, the hydrogen content level in the natural gas pipeline network is increased by 42.12%, and the carbon emission of the system is reduced by 117.6 tons, and the fluctuation of wind power is suppressed. This study demonstrates the feasibility of large-scale absorption of renewable energy through HSM.

A systematic analysis of integrating variable wind power into Fujian power grid

To realize the carbon emission peak and carbon neutrality objectives in China, efforts should focus on the electricity system, with an emphasis on creating low-carbon and renewable energy sources. The improvement of installed capacities of variable wind power and photovoltaics in the power system affect the entire power system. With the relatively independent power system of Fujian Province as an example, this study comprehensively considers the startup/shutdown, ramp-up/down, and power generation costs of the generators. Furthermore, the study uses the multi-period direct-current optimal power flow with unit-commitment method to analyze the impacts of variable wind power on the outputs of generators in the power system. The results show that at the current wind power-capacity level, the power system can still achieve the optimal dispatch without wind curtailment, and the marginal cost of wind power is relatively low. With further improvement of the installed capacity of wind power, it is necessary to fully mobilize the flexibility of all generators and PSHs, which will raise the overall operating cost of the whole power grid system. Finally, the study concludes with some policy recommendations for lowering the systematic integration cost of variable renewables.

Capacity configuration of a hydro-wind-solar-storage bundling system with transmission constraints of the receiving-end power grid and its techno-economic evaluation

The hydro-wind-solar-storage bundling system plays a critical role in solving spatial and temporal mismatch problems between renewable energy resources and the electric load in China. An efficient bundling system capacity configuration can improve the consumption level and reduce the renewable energy transmission cost. However, the restriction between economic feasibility and technical transmission constraints of the bundling system is not well understood. This restriction is becoming more and more obvious with the decrease of renewable energy price compensation year by year. This study compares the role of technical and economic indicators of capacity configuration, as well as the constraint relationship between electricity price and transmission constraints. Three screening principles of capacity configuration are proposed to reveal the techno-economic interaction. This paper explores a practical engineering case of Northwest China using a bundling system capacity configuration model. The internal rate of return is assumed as 8% for the bundling system. The results show that reducing the wind curtailment rate can effectively reduce the cost per MWh when the transmission guarantee rate is larger than 90%. Moreover, an integrated feed-in tariff based on market competitiveness is obtained if the wind curtailment rate is controlled by 5%. For example, the integrated feed-in tariff is 463.7 RMB/MWh when the wind curtailment rate is less than 5% and the transmission guarantee rate is larger than 95%. These results verify that the techno-economic interaction of the bundling system offers important theoretical support for selecting techno-economic indicators and capacity configuration.

Economic assessment of a renewable energy-electricity-hydrogen system considering environmental benefits

Improving the penetration of renewable energy in the power system is a development trend. However, renewable energy cannot be fully utilized due to its uncertainty, and the further research of renewable energy application integrated with hydrogen storage is necessary. This paper proposes a renewable energy-electricity-hydrogen system that aims to make the most use of renewable energy and achieve carbon emission reduction. From the perspective of the whole life cycle, the economic benefits and environmental benefits evaluation model of this system is built considering environmental benefits quantification. A wind farm project in China is analyzed to study the feasibility of proposed system. The results show that the optimal power of the hydrogen production system when considering the economic and environmental benefits comprehensively (19.8 MW) is larger than that when only considering the economic benefits (17.5 MW). The benefits of wind farm are increased in both cases, but with the emphasis on environmental benefits, the wind curtailment rate of the wind farm is lower (1.12 %) and the carbon emission reduction is over 27,500 tons a year. The total benefits considering the environmental benefits quantification reach to 66.95 million US$. Moreover, sensitivity analysis shows that carbon trading price and hydrogen selling price are the key factors to the benefits of the project. This study not only verifies that hydrogen production by renewable energy curtailment is economically feasible and has significant environmental benefits, but also could provide a guiding for relevant decision-makers.

Flexible operation of integrated energy system with HVDC infeed considering multi-retrofitted combined heat and power units

For the coal-dominated power system, facilitating the thermo-electric decoupling of combined heat and power (CHP) units through flexibility retrofit technologies is an effective approach to strengthen the peak-shaving capacity of the system and promote wind accommodation. This paper focuses on exploiting the flexible regulation potential of the large-scale CHP units in the power and heat integrated energy system (PHIES) with high voltage direct current (HVDC) transmission infeed, in order to well deal with the dual peak-shaving pressure arising from the HVDC delivery power and the high share of fluctuant wind power. The internal and external retrofit technologies including zero output of low-pressure cylinders (ZO-LPC), bypass compensation heating (BCH), and thermal energy storage (TES) are adopted for CHP units as retrofit options. Firstly, the PHIES including multi-retrofitted CHP units, HVDC transmission systems, and a high share of wind power is described and modeled. Then, a two-stage day-ahead scheduling model based on the improved information gap decision theory (IGDT)-stochastic method is proposed considering the probability distribution information of uncertain variables. Finally, an annual system-wide benefits evaluation framework is formulated to assess the economic and environmental benefits of multi-retrofitted CHP units and compare the system gain value of different retrofit projects. Numerical results indicate that the thermo-electric feasible operating regions of CHP units can be comprehensively expanded with the cooperation of the proposed retrofit technologies, so as to greatly relieve wind curtailment and reserve risk of the whole system. Moreover, sensitivity analysis for diverse operation features of HVDC and different wind power installed capacity is illustrated to further verify the robust adaptability and effectiveness of multi-retrofitted CHP units in the PHIES with HVDC infeed.

Study on the effect of changing stator structure on wind permanent magnet eddy current heating device

With the development of new energy, the proportion of wind power in the global power production structure is increasing year by year, and it has broad development prospects. This article discusses a new type of wind-powered permanent magnet eddy current heating device, which converts excess wind energy into heat energy and stores it in a heat storage medium, so as to achieve the function of storing heat energy. Thermal energy can be directly supplied to users and can also be used for thermal power generation when the power supply is insufficient, which is of practical significance to alleviating the problems of energy shortage and large amount of wind curtailment. Based on the law of electromagnetic induction and eddy current phenomenon, this paper establishes a model of permanent magnet eddy current heating device, and then simulates and analyzes the permanent magnet eddy current heating device to improve the heating power and material utilization of the device. The focus is on the influence of stator groove type, the number of stator slots and the thickness of the stator on the heating power. Finally, the simulation analysis of the permanent magnet eddy current heating device before and after the optimization is carried out in MATLAB. The simulation results prove the effectiveness of the optimization.

Integrated models in action: Analyzing flexibility in the Canadian power system toward a zero-emission future

Canada's power system is directly responsible for around 8.4% of the country's greenhouse gas emissions. Integrating new variable renewable energy resources is posited as one of the core pathways to decarbonizing the system. However, the inherent variability of many renewable energy resources necessitates greater spatial and temporal flexibility. Transmission expansion can deliver spatial flexibility while bulk storage can deliver temporal flexibility. Assessing flexibility adequacy requires an operational perspective employing fine temporal and spatial resolutions. In this study, a novel bidirectionally linked framework is developed to leverage insights from both operational and planning models. Wind curtailment is selected as a metric to analyze operational flexibility, which informs iterative revisions in the planning model. The results from four cases show that: (1) Transmission and storage capacities beyond the planning model's initial output are required to maintain sufficient operational flexibility in a zero-emission power system in 2050; (2) Wind capacity overestimation in initial results must be corrected; and (3) Increased total system costs can be partially offset by improvements in wind curtailment, congestion, and load shedding. It is concluded that the iterative expansion-dispatch framework proposed in this analysis yields important insights beyond stand-alone analyses, particularly in the context of a net-zero power system.

A comprehensive model and its optimal dispatch of an integrated electrical-thermal system with multiple heat sources

As essential parts of the combined heat supply network with multiple heat sources, the electrical-heating and heat storage technology can simultaneously achieve the goal of clean heating and renewable energy accommodation. The paper introduces the integrated electrical-thermal system with multiple heat sources that consist of combined heat and power (CHP), coal-fired boiler (CB), and electrical boiler (EB) with thermal energy storage (TES). Considering the integration of electrical and thermal networks, we construct a comprehensive model that includes the electrical energy transmission and the overall heat transfer and storage processes based on the heat current method. Based on the comprehensive model, the optimal dispatch of the integrated system is discussed, and an iteration solving method is proposed, which can achieve acceptable convergence and solving efficiency. The simulation results show the combined operation of multiple heat sources has higher system operation efficiency but not necessarily a higher utilization rate of renewable energy. In the test system the combined operation of CHP and coal-fired boiler can reduce the coal consumption of the system by 2%. However, the wind utilization of the system decreases by 4.17%. Moreover, the introduction of an electrical boiler with a TES device can improve the system's flexibility and reduce wind curtailment, wherein the test system is 12.11% more wind consumption. Further, the heat load level can affect the operation efficiency of CHP, the combined operation of multiple heat sources can achieve the balance between reducing coal consumption and increasing renewable energy power generation.

Joint Optimal Scheduling of Renewable Energy Regional Power Grid With Energy Storage System and Concentrated Solar Power Plant

Under the path of global low-carbon development, increasing the proportion of renewable energy in the power grid will become the main goal in the future. But, it will also aggravate the problem of wind and solar curtailment. A joint optimal scheduling model of a renewable energy regional power grid with an energy storage system and concentrated solar power plant is proposed in this study. The proposed model takes the lowest comprehensive operation cost of the power grid as the optimization goal and considers various constraints of concentrated solar power plants, energy storage systems, thermal power units, wind power, and photovoltaic power generation. Finally, a modified IEEE 9-bus system is used to verify the validity. The results show that the model can effectively improve the system node voltage, promote the accommodation of wind and solar power, and alleviate the peak shaving of thermal power units under the premise of optimal economy pressure.

Utilization of surplus renewable energy for a gas-fired power plant's carbon recycling considering gas storages and imposed regret of uncertainties

The advent of power-to-gas (P2G) technology has established an extensive capacity for energy systems to integrate and coordinate renewable energy sources (RES) with other energy suppliers. This paper employs a P2G system to coordinate with a standalone gas-fired generation unit (GFGU) to tackle the adverse impacts of greenhouse gas emissions by reducing CO2 and implementing RES. The exhausted carbon from the gas turbine is directly converted via an on-site carbon capture facility, preventing further transportation of CO2. This work considers the inflow/outflow value of gas molar in detail besides electric and thermal power input/output in each device. The mathematical relationships of all devices are explained thoroughly. The proposed GFGU-P2G utilizes wind turbine and GFGU to decrease the carbon emissions and reduce the wind curtailment. This will occur through exploiting excessive wind energy. Two gas storages of CO2 and CH4 are supplemented to the proposed model to increase the efficiency by charging/discharging gas to the system. Stochastic p-robust is applied to measure the encountered risk by solving the risk-based optimization problem. The risk is alleviated by minimizing regret through obtaining the best possible value of p for the decision-maker. Three cases have been proposed to evaluate the impacts of P2G and gas storage on GFGU with and without considering risk. The results illustrate that using P2G instead of a single GFGU will increment the expected carbon emission by 39 %. Moreover, the expected CO2 emission will decrease by 48 % and 16 % when implementing gas storage compared to standalone GFGU and P2G, separately.

Chance-constrained performance of power-to-gas system incorporating gas-fired power plant and wind power producer with CO2 recycling

The power-to-gas (P2G) technology is one of the primary solutions to the global warming crisis due to its rapid technological development. The environment is under the devastating influence of greenhouse gases such as CO2, leading to the integration of multiple systems and components on the supply and demand side, such as P2G, in coordination with renewable energy (RE) to tackle this problem. P2G can efficiently perform alongside gas- or coal-fired power plant to accomplish the carbon recycling process. The primary energy source for P2G is surplus RE which is easily accessible. In this article, the proposed model uses an on-site carbon capture, which has the advantage of preventing CO2 from being transported to distant areas. The recycling process of the carbon is fulfilled through water carbon capture, water electrolyzer and methanation facilities. The whole goal of this system is to use the surplus wind energy to convert CO2 to CH4, resulting in excessive natural gas as fuel and less carbon emission. The gas flow in mole value for input/output is considered to model the energy conversion and relations between devices alongside power and heat flows. The mathematical formulation of all devices' operating range is considered to model the proposed energy system realistically. This model has the ability to reduce carbon emission and wind curtailment significantly. Moreover, in the case of measuring risk, chance-constrained programming (CCP) is implemented in the model to enhance the decision-making strategies. Various confidence levels control the CCP; decreasing it will result in a more risk-taker approach and less conservatism. According to the results, the CO2 will be decreased to 32% when using P2G. Implementing P2G and two gas storages will reduce the carbon emission to 39%. Moreover, decreasing confidence level from 100% to 75% results in 34% carbon reduction for a single power plant.

Capacity Allocation Method of Economic Model Considering Hybrid Energy Storage Battery to Suppress Wind Power Fluctuation

This paper aims at the problem that the cost of energy storage in the wind power hybrid energy storage system exceeds the economic loss caused by wind curtailment. Firstly, the frequency allocation method using wavelet packet analysis divides the wind power into three parts: expected grid-connected power, high frequency power and low frequency power. The flywheel energy storage is used to smooth the high frequency power; the lithium battery is used to reduce the low frequency power. Secondly, an economic model of annual comprehensive cost is constructed based on initial investment, operation and maintenance, wind curtailment and energy shortage costs. Genetic algorithm is used to find the critical point of energy storage capacity allocation. Finally, through Matlab/Simulink simulation, it is verified that this capacity allocation method is economical and effective.

Conceptual design and preliminary analysis of a hybrid wind-nuclear power system for on-demand power supply

ABSTRACT China prioritizes clean energy for power generation in response to climate change and air pollution. By the end of 2021, the installed capacity of wind power has reached 328.48 GW, accounting for 13.8% of China’s total installed capacity of 2376.92 GW. However, wind power is inherently unstable and its output depends on resources, which poses challenges for the national grid. Wind curtailment is often encountered when electricity production is plentiful. The main objective of this work is to develop a clean energy generation system for on-demand power supply to improve the utilization of wind resources. The LBE reactor is also a clean energy source with flexible power regulation that helps mitigate the impact of wind variability. Therefore, a hybrid wind-nuclear power system (HWNPS) is proposed. This paper demonstrates the technical feasibility of the LBE reactor and conducts a preliminary analysis of the economics of the HWNPS. The additional cost of HWNPS due to power regulation is about $ 9.04/MWh, which has potential for research and development.

Can Texas mitigate wind and solar curtailments by leveraging bitcoin mining?

An increased capacity to produce renewable energy has led to power curtailments due to the lack of storage for energy oversupply. This excess energy could make a profit if it was used and managed effectively. Bitcoin, with its recent boom, associated market values, and excessive energy consumption during mining presents a win–win proposition for managing renewable energy curtailments. Therefore, in a bid to minimize renewable energy curtailments from the perspective of the independent system operator (ISO) while maximizing the profit for the investor, this study attempts to discover the optimal planning and operation of a bitcoin mining farm to minimize renewable energy curtailments. Specifically, renewable energy curtailments for the Energy Reliability Council of Texas (ERCOT) at an hourly resolution and the difficulty and price, respectively of bitcoin mining during 2020 and 2021, were considered in our analysis of the cost and profitability of bitcoin mining using curtailed renewable power. Besides, a greenhouse gas (GHG) analysis was also conducted to evaluate the annual emissions from each of the cases considered in this study. The results demonstrated that 93% of the curtailed energy could be used at a minimal cost to generate a $239 million profit. From an investor's perspective, 69.8% of the curtailed power could be used to generate a profit of $605 million. Cost minimization case scenario had the least amount of emissions followed by profit maximization case with penalty scenario. Sensitivity analyses and Monte-Carlo simulations were performed to investigate the effect of system parameters on the optimization results for an in-depth analysis of possible policy and investment decisions from the perspectives of both the ISOs and investors. Despite the uncertainties associated with the price of bitcoin, it was estimated that ERCOT, with its current renewable energy curtailments, would still be profitable in the case of profit maximization if the bitcoin price remains above $6800 throughout the year. Accordingly, bitcoin mining has substantial potential for becoming an effective medium to prevent renewable energy curtailments and turn energy oversupply into profit.

Data-driven assisted chance-constrained energy and reserve scheduling with wind curtailment

Chance-constrained optimization (CCO) has been widely used for uncertainty management in power system operation. With the prevalence of wind energy, it becomes necessary to consider wind curtailment as a dispatch variable in CCO. However, the wind curtailment will cause an impulse for the uncertainty distribution, yielding challenges for explicit modeling of chance constraint. In this paper, a novel data-driven framework is developed to handle this issue. By modeling the wind curtailment as a cap enforced on the wind power output, the proposed framework constructs a data-driven surrogate to describe the relationship between wind curtailment and the tightening boundary of chance constraints. This allows us to reformulate the CCO with wind curtailment as a mixed-integer second-order cone programming (MI-SOCP) problem. An error correction strategy is developed by solving a convex linear programming (LP) to improve the modeling accuracy. The notable characteristic of the proposed method is that the chance constraints with wind curtailment can be explicitly and accurately handled without any distribution assumptions, which provides great convenience for the power dispatch under a high percentage of renewables. Case studies performed on the PJM 5-bus and IEEE 118-bus systems demonstrate that the proposed method is capable of accurately accounting the influence of wind curtailment dispatch in CCO. It shows that the proposed method outperforms existing methods by producing more economic and secure solutions for the chance-constrained energy and reserve scheduling problem under uncertainties.

Optimising onshore wind with energy storage considering curtailment

Operating energy storage alongside onshore wind can improve its economics, whilst providing a pathway for otherwise curtailed generation. In this work, we present a framework to evaluate the economic potential of onshore wind co-located with battery storage (BS) and a hydrogen electrolyser (HE). This model is applied to a case study in Great Britain using historic data, and considering local network charges and the cost of using curtailed power, capturing an often neglected element of competition. We use a Markov Chain to model wind curtailment, and determine the optimised scheduling of the storage as we vary price parameters and storage sizing. Finally, by considering storage CAPEX and comparing against the case with no storage, we can determine the value added (or lost) by different sized BS and HE for an onshore wind owner, as a function of power purchase agreement (PPA) and green hydrogen market price. Results show that value added increases when HE is increased and when BS is decreased. Additionally, a 10 MW electrolysers uses 27% more curtailed wind than 10 MW BS.

Optimal Scheduling of Cogeneration System with Heat Storage Device Based on Artificial Bee Colony Algorithm

The rigid constraint of using heat in determining electricity for thermal power units is eliminated to improve the absorption capacity of wind power. In this study, heat storage devices and electric boilers are added to the cogeneration system to alleviate the wind curtailment phenomenon. First, the main reasons for wind curtailment are analyzed according to the structural characteristics of the power supply in the northern part of China. Second, a scheduling model of a cogeneration system, including a heat storage device and an electric boiler, is constructed. An improved artificial bee colony algorithm program is also designed and compiled based on MATLAB. Finally, the feasibility of the proposed scheme is verified by simulation examples, and an economic analysis of wind power consumption is performed. Results show that adding electric boilers lessens coal consumption costs and improves economic benefits.

A novel coordinated optimization strategy for high utilization of renewable energy sources and reduction of coal costs and emissions in hybrid hydro-thermal-wind power systems

In multi-source-based energy systems, the ultimate target of optimal operation of the generation units is to create an efficient power system with cleaner production. In this paper, a novel coordinated operation strategy optimizing the commitment of hydro, thermal and wind generation units is proposed. The strategy consists of two hierarchical optimization goals. In the primary goal, utilization of wind and hydro energy units is optimized, and the objective functions involve maximizing hydro energy utilization and minimizing wind curtailment. In the secondary goal, coal costs and carbon emissions are minimized after meeting the utilization goal. The overall execution of the strategy is governed by three power production decisions including peak-load shaving, valley-load filling and generation. The first two decisions suppress the fluctuation in wind power while the generation decision makes full use of the hydro units to replace the working thermal units. The presented operation strategy is applied to an improved IEEE 118-node power system. The optimization ensures the highest utilization of wind energy while coping with the day-ahead wind power forecasting error. Moreover, a particle swarm optimization method is applied to optimize the coal costs and carbon emissions. The presented results demonstrate the capability of the proposed strategy to configure the operation of the multi-source-based energy system with high efficiency and low emissions. Finally, several recommendations to amend the existing management of multi-source-based energy systems are presented.

Impact of implementing a price-based demand response program on the system reliability in security-constrained unit commitment problem coupled with wind farms in the presence of contingencies

Large scale penetration of highly intermittent wind energy sources has caused new challenges to the reliable operation of power systems. To address these challenges, demand response program is considered as an efficient solution to manage shift-able loads. In this paper, the impact of demand response on power system reliability has been evaluated by developing a two-stage stochastic security constraint unit commitment that considers both the wind volatility and line outages at the same time. The allocation of ramping products and spinning reserves to cover these uncertainties has also been modeled. wind curtailment and load shedding are considered as alternative strategies, and an optimal exchange between them and the use of spinning reserves and flexible ramping products has been modeled in the objective function. To assess the system reliability, the expected load not served (ELNS) index was evaluated in different cases. The proposed scheme as a mixed-integer linear programming problem was solved by a scenario-based two-stage stochastic programming method. The IEEE test systems 6-bus, modified 24-bus, and 118-bus were examined numerically. The results show that the simultaneous consideration of demand response and flexible ramping product coordinated with wind energy has adequate flexibility to reduce the reliability index and system operational cost.

Coordinated investment in wind‐rich regions using dynamic line rating, energy storage and distributed static series compensation to facilitate congestion management

Wind farms installed at wind-rich regions often located in remote areas increase overloads in the weak adjacent transmission network. As a result of this congestion, extra transmission capacity is required to avoid wind energy or load curtailment that can be achieved by applying some modifications. New line construction and line uprating have been recognised as conventional solutions for the transmission capacity increase. Meanwhile, in the last decade, these solutions have brought several serious issues for the network operators, forcing them to evaluate and install different types of assets based on state-of-the-art technology in order to harvest the existing lines at the maximum possible level. An investment model is developed to relieve the congestion, including dynamic line rating (DLR), distributed static series compensation and energy storage systems (ESS), with a simplified unit commitment implementation. The resulting mixed-integer linear model is then solved with the classic Benders decomposition. Installations of DLR and distributed static series compensator (DSSC) on the same line are formulated, with techno-economic analysis performed for different asset combinations on the IEEE RTS 24 bus system, for high wind energy share scenarios. Wind curtailment levels are studied for different DLR/DSSC approaches, including the impact of practical implementation requirements. Based upon additional interlinking constraints, the robustness of investment decisions for independent DLR and DSSC investments is compared against approaches where DLR and DSSC investments are permitted on the same line. The investment based on sequential incorporation of the unit commitment in the study is also investigated to reflect the importance of the integration of the unit scheduling in the model for high renewable systems.