Wind Power Curtailment Research Articles

Coordination Strategy of Large-Scale DFIG-Based Wind Farm for Voltage Support With High Converter Capacity Utilization

Due to the long-distance transmission, external grid cannot effectively support the access point voltage (APV) of the large-scale wind farm (WF), which thus entails DFIG-based WF to provide its ancillary services on reactive power generation. Considering factors of limited down-sized converter capacity, various operating modes of wind turbines (WTs), and the large pressure of large-scale WF communication on the central governor, this paper proposes a distributed active power and reactive power coordination scheme for APV support. A reactive power self-allocation scheme is developed and operated in each WT for reactive power dispatch. Based on the mechanism of distributed consensus control and aligning with the principle of preferential and proportional utilization of spare reactive power capacity (RPC), the proposed method collaborates the rotor side converters and the grid side converters of all WTs but without the necessity of knowing the total RPC. Further, in case that the total RPC is insufficient for the demand, a coordinating factor for RPC extension is generated to weaken the active power. Through a current-enforced PQ coordinating loop, it guarantees a high utilization of converter capacity as well as an exact compensation on the reactive power imbalance, which thereby reduces the wind power curtailment for the RPC release. Several case studies verify the effectiveness of the proposed method.

Accommodation of Curtailed Wind Power by Electric Boilers Equipped in Different Locations of Heat-supply Network for Power System with CHPs

Electric boilers (EBs) provide an alternative method to deal with the accommodation of curtailed wind power. To pursue the minimum coal consumption in the system, a dispatching model integrating combined-heat-and-power (CHP) plants and EBs in different locations is developed, and the penalty of wind power curtailment and cost of EB employment are also incorporated in the model. The transmission loss and transportation lag of heat-supply network as well as the elasticity of heat load are considered in this paper. A kind of constrained programming with stochastic and fuzzy parameters is applied to deal with the uncertainties. A case in East Inner Mongolia in China demonstrates that the EBs are able to absorb curtailed wind power and supply the heat. The results indicate that the utility of EBs in the primary or secondary heat-supply network to accommodate curtailed wind power is mainly related to the efficiency of heat transmission and the elasticity of heat load.

Exploiting the Inherent Flexibility in Transmission Network for Optimal Scheduling, Wind Power Utilization, and Network Congestion Management

Owing to the economic, social, and political problems in the expansion of transmission infrastructure, novel transmission topologies are in demand to efficiently utilize the existing infrastructure. On the other hand, there is a tremendous increase in wind power generation around the globe. One of the main challenges hindering the penetration of large-scale wind power generation is the network congestion due to limited network capacity. To address these two issues, this study develops a co-optimized optimal transmission switching (OTS) and dynamic line rating (DLR) model to optimize system resources by mitigating network congestion and maximizing wind power accommodation. This new concept of exploiting the inherent flexibility in transmission network is named as flexible transmission dynamic line rating (FTDLR), which deploys OTS in coordination with DLR as a control tool to utilize existing assets. A two-stage stochastic unit commitment framework is used to deploy the proposed FTDLR model, which is used to dynamically increase the line capacity based on the meteorological parameters and at the same time optimally select candidate lines to be switched off from the network. A comprehensive analysis is performed to characterize the FTDLR performance on system operation cost, network congestion, and wind power curtailment. The proposed FTDLR model is further tested as a part of contingency analysis where both generator failure and transmission line outages are considered. Test results performed on the IEEE 24-bus network demonstrate that by using FTDLR, the service operator could substantially reduce system dispatch cost, improve wind power accommodation, and relieve network congestion. The scalability and feasibility of the FTDLR optimization problem is validated on the larger network of the IEEE 118-bus system.

A Two-Stage Distributionally Robust Optimization Model for Wind Farms and Storage Units Jointly Operated Power Systems

To explore the benefit of energy storage for countering high-level wind power fluctuations, a two-stage distributionally robust optimization model is proposed for wind farms and storage units (SUs) jointly operated power systems. First, the 1-norm and ∞-norm confidence sets are presented to model the fluctuations of wind power output, then a two-stage distributionally optimization model is formed to minimize system total cost with secure operation constraints, where the ON-OFF status of generators and SUs are determined in the first stage by day-ahead dispatching, while the power output of generators, wind power curtailment, load shedding and SUs charging/discharging power are optimized in the second stage. Afterward, the column-and-constraint generation (CCG) algorithm is presented to solve the proposed two-stage model. Finally the influence of confidence level of confidence sets and SU capacities on system total cost is analyzed, and the effectiveness of the proposed model is also validated by the case studies.

Research on Two-stage Game Strategy of Virtual Power Plant in Deep Peak Regulation Auxiliary Service Market

There is a large number of combined heat and power units in northern China, and due to the limit of heating demand, the operating mode of setting electricity by heat of combined heat and power units has seriously took over the consumption space of other energy, resulting in severe wind power curtailment and rationing situation in some areas, so this paper studies the deep peak regulation bidding strategy problem considering multiple uncertainties on virtual power plants, and established a two-staged optimization model of virtual power plant to maximize the net revenue, then introduced the Shapely value method with correction coefficient redistribute the peak regulation revenue. The simulation results showed that the two-stage bidding model can not only improve the market competitiveness of the virtual power plant, but also promote the consumption of renewable energy and reduce the market peak regulation service cost. Meanwhile, the improved apportion method can effectively guarantee the enthusiasm of all kinds of units to participate in the deep peak regulation market.

Frequency-Voltage Characteristics Concerned Optimal Dispatch

The rapid development of integrated wind power bring serious challenges to power system operation. In order to address the increasing wind power curtailment problem, the frequency-voltage characteristics concerned optimal dispatch for power system with large-scale wind power integration is proposed in this paper. Through integration of the optimization of frequency characteristics and voltage characteristics into the traditional power system economic dispatch model, the flexibility resources of generation side and load sides in power systems are mobilized to promote large-scale wind power accommodation. The formulated frequency-voltage characteristics concerned optimal dispatch mathematical model is a nonlinear programming model, which is solved by the GAMS platform. The numerical analysis for an actual provincial power grid indicates that the proposed frequency-voltage characteristics concerned optimal dispatch method can promote wind power utilization efficiency and improve the economy of power system operation.

Multi-Objective Optimization Strategy of Integrated Electric-Heat System Based on Energy Storage Situation Division

There are the transmission loss of the electric power network, the delay and loss of the heating network, the insufficient utilization of flexible resources such as energy storage in the integrated electric-heat system, which may lead to the imbalance of supply and demand and energy waste. In this paper, the coordinated dispatch of integrated electric-heat system (IEHS) considering the transmission characteristics of the electric power network and heating network, which is formulated as a convex quadratic program. The strong linkage of electric power and heat supplies can be decoupled to reduce wind power curtailment by exploiting the energy storage and regulation capabilities of the district heating network (DHN), storage batteries, electric boilers (EBs) and heat storage tanks (HSs). The energy storage system works according to the situation division strategy designed in this paper. This paper introduces the wind curtailment boundary power and optimizes dispatch based on the wind curtailment boundary power and unit output, which can make full use of the energy storage capacity and reduce the wind abandonment power. Since the electric power system (EPS) and the distribution heating system (DHS) are controlled separately by different operation organizations, IEHS is solved using double-λ iterative algorithm. The double-λ iterative algorithm, with guaranteed convergence for convex programs, can achieve a fully distributed solution for the IEHS and requires only a small amount boundary information exchange between the EPS and the DHS. At last, one integrated electric-heat system was studied to demonstrate the effectiveness of the proposed method which achieves the effective solution in a moderate number of iterations. This system includes two 10-nodes heating system and one 14-nodes electric power system.

Considering various optimization model of energy storage in wind power load auxiliary trading game

In winter heating period, the heating mode of "setting electricity by heat" in northeast China causes a large number of wind abandoning, and the wind abandoning absorption rate can be improved by absorbing heat and absorbing wind. The operation of the traditional heat storage system is not linked with the wind farm, and there are still many wind curtailment. In order to track the purchase of wind curtailment in real time, based on the pre-evaluation of short-term power of wind curtailment, a day-before market centralized transaction mode of wind power curtailment reported by wind farms and demand function reported by heat storage enterprises was proposed in the market of auxiliary peak shaving service for wind power storage. By establishing the multi-party game optimal demand function model of heat storage enterprises, the unified clearing price and wind abandoning subscription situation are obtained, and the intra-day settlement method is proposed for intra-day unbalanced electricity quantity.

Investigation of the Multi-Point Injection of Green Hydrogen from Curtailed Renewable Power into a Gas Network

Renewable electricity can be converted into hydrogen via electrolysis also known as power-to-H2 (P2H), which, when injected in the gas network pipelines provides a potential solution for the storage and transport of this green energy. Because of the variable renewable electricity production, the electricity end-user’s demand for “power when required”, distribution, and transmission power grid constrains the availability of renewable energy for P2H can be difficult to predict. The evaluation of any potential P2H investment while taking into account this consideration, should also examine the effects of incorporating the produced green hydrogen in the gas network. Parameters, including pipeline pressure drop, flowrate, velocity, and, most importantly, composition and calorific content, are crucial for gas network management. A simplified representation of the Irish gas transmission network is created and used as a case study to investigate the impact on gas network operation, of hydrogen generated from curtailed wind power. The variability in wind speed and gas network demands that occur over a 24 h period and with network location are all incorporated into a case study to determine how the inclusion of green hydrogen will affect gas network parameters. This work demonstrates that when using only curtailed renewable electricity during a period with excess renewable power generation, despite using multiple injection points, significant variation in gas quality can occur in the gas network. Hydrogen concentrations of up to 15.8% occur, which exceed the recommended permitted limits for the blending of hydrogen in a natural gas network. These results highlight the importance of modelling both the gas and electricity systems when investigating any potential P2H installation. It is concluded that, for gas networks that decarbonise through the inclusion of blended hydrogen, active management of gas quality is required for all but the smallest of installations.

Integrated Electrical, Heating, and Water Distribution System to Accommodate Wind Power

With the rapid development of communication technology, the cooperation between electrical systems and other energy systems has become possible to promote wind power accommodation. As a common kind of energy carrier, the water distribution system has not been researched so far to help accommodate wind power when integrated with other energy systems. This paper proposes a novel model of integrated electrical, heating, and water distribution system to accommodate wind power. The optimal scheduling of heat pump and water pump are studied to make full use of the abundant wind power. The heat transmission loss is considered and thus the best siting of the heat pump can be determined. The demand response program is also included in the schedule structure to make the modeling more comprehensive. Moreover, a novel two-layer decentralized optimization algorithm is proposed to protect the data privacy of each energy system. The effectiveness of the proposed integrated system model and the two-layer decentralized algorithm are verified on two test systems. The results indicate that system integrations can reduce the wind power curtailment significantly and decrease the operation cost of each energy system. Besides, the proposed two-layer algorithm performs well in terms of the algorithm efficiency and scalability.

Minimizing Wind Power Curtailment Using a Continuous-Time Risk-Based Model of Generating Units and Bulk Energy Storage

Wind power curtailment (WPC) occurs because of the non-correlation between wind power generation (WPG) and load, and also due to the fast sub-hourly variations of WPG. Recently, advances in energy storage technologies facilitate the use of bulk energy storage units (ESUs) to provide the ramping required to respond to fast sub-hourly variations of WPGs. To minimize the sub-hourly WPC probability, this paper addresses a generic continuous-time risk-based model for sub-hourly scheduling of energy generating units and bulk ESUs in the day-ahead unit commitment (UC) problem. Accordingly, the Bernstein polynomials are hosted to model the continuous-time risk-based UC problem with ESU constraints. Also, the proposed continuous-time risk-based model ensures that the generating units and ESUs track the sub-hourly variations of WPG, while the load and generation are balanced in each sub-hourly intervals. Finally, the performance of the proposed model is demonstrated by simulating the IEEE 24-bus Reliability and Modified IEEE 118-bus test systems.

Integration Design and Operation Strategy of Multi-Energy Hybrid System Including Renewable Energies, Batteries and Hydrogen

In some areas, the problem of wind and solar power curtailment is prominent. Hydrogen energy has the advantage of high storage density and a long storage time. Multi-energy hybrid systems including renewable energies, batteries and hydrogen are designed to solve this problem. In order to reduce the power loss of the converter, an AC-DC hybrid bus is proposed. A multi-energy experiment platform is established including a wind turbine, photovoltaic panels, a battery, an electrolyzer, a hydrogen storage tank, a fuel cell and a load. The working characteristics of each subsystem are tested and analyzed. The multi-energy operation strategy is based on state monitoring and designed to enhance hydrogen utilization, energy efficiency and reliability of the system. The hydrogen production is guaranteed preferentially and the load is reliably supplied. The system states are monitored, such as the state of charge (SOC) and the hydrogen storage level. The rated and ramp powers of the battery and fuel cell and the pressure limit of the hydrogen storage tank are set as safety constraints. Eight different operation scenarios comprehensively evaluate the system’s performance, and via physical experiments the proposed operation strategy of the multi-energy system is verified as effective and stable.

Hierarchical dispatch method for integrated heat and power systems considering the heat transfer process

The coordinated operation of integrated heat and power systems (IHPSs) is a promising solution for accommodating renewable energy and improving energy efficiency. A practical, effective dispatch method that coordinates the electric power system (EPS) and district heating system (DHS) is of great concern. This paper proposes a practical, non-iterative hierarchical dispatch method that introduces the concepts of the feasible region of boundary variables (FRBV) and optimal function of boundary variables (OFBV). In the proposed method, the private information of the DHS is protected in both the FRBV and OFBV. Moreover, they are transmitted between the EPS and the DHS operators only once to reduce communication overhead. This paper further proposes a method to conservatively estimate the FRBV and OFBV of the DHSs when the heat transfer process is considered in the model. Case studies are presented for an actual IHPS located in a northern city in China, and the results show that: 1) The heat generation capacity is over-estimated when the heat transfer process is not considered. 2) The hierarchical dispatch method obtains a larger regulating range of the combined heat and power units compared to those of the traditional “heat-led” operation mode and reduces the total coal consumption and the curtailed wind power by 4.46% and 38.50%, respectively. 3) The approximation-based hierarchical dispatch method obtains a solution that is less optimal than the exact method, but this difference in optimal value is less than 1%.

Robust optimisation framework for SCED problem in mixed AC‐HVDC power systems with wind uncertainty

Wind power uncertainties have made the large integration of wind power generating units in the power system highly challenging. One promising solution to overcome the challenges associated with the intermittency of the renewable energy resources (RESs) is to connect areas with diverse renewable energy portfolios via high voltage direct current (HVDC) transmission lines with controllable power transfer capability. The installation of HVDC transmission lines in the power system has resulted in the evolution of conventional alternating current (AC) networks to mixed AC-HVDC power systems. In this study, to address wind power uncertainties in mixed AC-HVDC multi-area power systems, a modified robust optimisation (RO) model for the security-constrained economic dispatch (SCED) problem is proposed. The proposed RO model is used to minimise the generation cost and wind power curtailment under the worst-case scenario of actual wind power. Unlike the existing RO models, the proposed RO model considers a modified uncertainty set based on the wind power admissibility and addresses the budget of uncertainty more accurately to adjust the solution's level of conservatism. Extensive numerical studies demonstrate the economic and operational advantages of the proposed RO model for solving the SCED problem in mixed AC-HVDC power systems with high penetration of RESs.

Techno-economic and environmental assessment of the coordinated operation of regional grid-connected energy hubs considering high penetration of wind power

Nowadays, the high penetration of renewable energy sources (RESs) with non-uniformly distributed patterns has created unprecedented challenges for regional power systems to maintain system flexibility and reliability. These technical challenges obligate power system operators to curtail part of the produced renewable energy at various scheduling intervals. Motivated by these challenges, grid-connected energy hubs are seen as a way forward to boost system flexibility, decrease the rate of renewable power curtailment, and increase energy efficiency. However, simplified models may significantly affect the performance of the grid-connected energy hubs in practice. Hence, this paper proposes a holistic structure to determine the optimal coordinated operation of the grid-connected energy hubs and the regional power system by relying on the high penetration of wind power. In this regard, various fundamental challenges that have not yet been addressed in an integrated manner, including the CO2 emission rate and the amount of curtailed renewable energy along with total operating costs of the integrated energy system, are among the main objectives of the optimization problem. The proposed structure is developed in the form of tractable mixed-integer nonlinear programming (MINLP) problem to handle the day-ahead security-constrained unit commitment (SCUC). The information-gap decision theory (IGDT)-based robust model is used for accurate modeling of wind power uncertainty. The characteristics of the proposed IGDT-based robust SCUC model and its benefits are investigated through several technical case studies conducted on the modified 6-bus and 24-bus test systems. The simulation results validate the effectiveness and feasibility of the proposed structure. According to the obtained results for the 6-bus test system, networked energy hubs can help the system operator to reduce the total operating cost, wind power curtailment cost, and CO2 emission cost by 16.62%, 100%, and 30.44%, respectively, through utilizing up-to-date energy conversion facilities and energy storage systems as well as managing energy demands. It can be seen that the proposed strategy is a very effective step towards achieving a 100% renewable energy system.

A Coordinated Dispatching Model Considering Generation and Operation Reserve in Wind Power-Photovoltaic-Pumped Storage System

Large-scale grid integration of renewable energy increases the uncertainty and volatility of power systems, which brings difficulties to output planning and reserve decision-making of power system units. In this paper, we innovatively combined the non-parametric kernel density estimation method and scenario method to describe the uncertainty of renewable energy outputs, and obtained a representative set of renewable energy output scenarios. In addition, we proposed a new method to determine the reserve capacity demand. Further, we derived the quantitative relationship between the reserve demand and the power system reliability index, which was used as the constraint condition of a day-ahead power generation dispatch. Finally, a coordinated dispatching model of power generation and reserve was established, which had the lowest penalty for curtailment of wind power and photovoltaic, as well as the lowest total operating cost for thermal power units, gas power units, and pumped storage power station. By simulating three different working conditions, the proposed model was compared with the traditional deterministic model. Results showed that our proposed method significantly improved system efficiency while maintaining system reliability.

Turbines of the Caribbean: Decarbonising Suriname's electricity mix through hydro-supported integration of wind power

The Caribbean nation of Suriname has historically depended on a mix of hydropower and oil-based fossil fuels for meeting electricity needs. Continued reliance on fossil fuels poses challenges both for climate change mitigation and for energy security. This paper explores the potential for increasing the share of renewables in Suriname's electricity mix, with a special focus on the complementary role of existing hydropower and future wind power infrastructure. We show that these resources have great synergetic potential for displacing fossil fuel-based power generation. Flexible operation of the Afobaka hydropower plant, newly in full possession of Suriname, allows significant wind power integration without violating grid stability and associated power quality requirements. Considering the trade-off between displacing expensive fossil fuels and limiting wind power curtailment on Suriname's island-like grid, our results suggest that integrating wind power in the Surinamese electricity mix is economically advantageous up to a share of 20–30%, independently of near-term demand growth. These results have wider relevance for climate policy in various Caribbean countries and other island states with existing hydropower infrastructure and substantial wind/solar power potential, for which this study fills an important literature gap.

Evaluation of hydrogen storage technology in risk-constrained stochastic scheduling of multi-carrier energy systems considering power, gas and heating network constraints

The operation of energy systems considering a multi-carrier scheme takes several advantages of economical, environmental, and technical aspects by utilizing alternative options is supplying different kinds of loads such as heat, gas, and power. This study aims to evaluate the influence of power to hydrogen conversion capability and hydrogen storage technology in energy systems with gas, power, and heat carriers concerning risk analysis. Accordingly, conditional value at risk (CVaR)-based stochastic method is adopted for investigating the uncertainty associated with wind power production. Hydrogen storage system, which can convert power to hydrogen in off-peak hours and to feed generators to produce power at on-peak time intervals, is studied as an effective solution to mitigate the wind power curtailment because of high penetration of wind turbines in electricity networks. Besides, the effect constraints associated with gas and district heating network on the operation of the multi-carrier energy systems has been investigated. A gas-fired combined heat and power (CHP) plant and hydrogen storage are considered as the interconnections among power, gas and heat systems. The proposed framework is implemented on a system to verify the effectiveness of the model. The obtained results show the effectiveness of the model in terms of handling the risks associated with multi-carrier system parameters as well as dealing with the penetration of renewable resources.

Exploiting flexibility of combined-cycle gas turbines in power system unit commitment with natural gas transmission constraints and reserve scheduling

With the integration of large-scale renewable energy including wind power into the power grid, efficient flexible resources are required for wind power accommodation. The combined-cycle gas turbines (CCGTs) are widely used in the power system with flexible operation characteristics, which leads to enhanced interdependencies between the power grid and the natural gas network. In this paper, a unit commitment (UC) model with natural gas transmission constraints and reserve scheduling considering the flexibility of CCGT with quick startup-shutdown and flexible operation characteristics is proposed, to reduce wind power curtailment and high startup and shutdown cost of conventional generation units in the power system. Considering the complex operating conditions of CCGT and the non-convexity of Weymouth equation in natural gas network, this paper adopts an improved mode-based model (MBM) for modeling of CCGT and converts the Weymouth equation into a second-order cone relaxation (SOCR) formulation with penalty term through a concave-convex process (CCP) to make the relaxation tight, thus transforming the UC model into an iterative mixed-integer second-order cone programming (MISOCP) problem to be efficiently solved. The effectiveness of the proposed model on reducing wind power curtailment and startup-shutdown cost is demonstrated through case studies.

Interval optimal scheduling of integrated electricity and district heating systems considering dynamic characteristics of heating network

Coordinated operation of integrated electricity and district heating system (IEDHS) has great potential to enhance the flexibility of the power system to cope with the wind power curtailment. This study proposes an interval optimal scheduling algorithm for IEDHSs, considering the dynamic characteristics of the heating network. The model of the district heating system with dynamic characteristics including transmission delay and heat losses, is established in detail, and the uncertainties of both wind power and electricity and heating loads are described with interval numbers. Then an interval optimal scheduling model of the IEDHS is formulated to minimise the IEDHS operation cost. The impacts of the transmission delay and heat losses of the heating network on the scheduling of the IEDHS are analysed. Case studies are performed on the PJM 5-bus electricity system with a 6-node district heating system and IEEE 39-bus electricity system with a 12-node district heating system to evaluate the effectiveness of the proposed model. The results demonstrate that the dynamic characteristics of the heating network can integrate more wind power and enlarge the width of the cost interval.