Large-scale Wind Power Generation Research Articles

Two-Stage Optimal Configuration Strategy of Distributed Synchronous Condensers at the Sending End of Large-Scale Wind Power Generation Bases

The transmission end of large-scale wind power generation bases faces challenges such as high AC-DC coupling strength, low system inertia, and weak voltage support capabilities. Deploying distributed synchronous condensers (SCs) within and around wind farms can effectively provide transient reactive power support, enhance grid system inertia at the transmission end, and improve dynamic frequency support capabilities. However, the high investment and maintenance costs of SCs hinder their large-scale deployment, necessitating the investigation of optimal SC configuration strategies at critical nodes in the transmission grid. Initially, a node inertia model was developed to identify weaknesses in dynamic frequency support, and a critical inertia constraint based on node frequency stability was proposed. Subsequently, a multi-timescale reactive power response model was formulated to quantify the impact on short-circuit ratio improvement and transient overvoltage suppression. Finally, a two-stage optimal configuration strategy for distributed SCs at the transmission end was proposed, considering dynamic frequency support and transient voltage stability. In the first stage, the optimal SC configuration aimed to maximize system inertia improvement per unit investment to meet dynamic frequency support requirements. In the second stage, the configuration results from the first stage were adjusted by incorporating constraints for enhancing the multiple renewable short-circuit ratio (MRSCR) and suppressing transient overvoltage. The proposed model was validated using the feeder grid of a large energy base in western China. The results demonstrate that the optimal configuration scheme effectively suppressed transient overvoltage at the generator end and significantly enhanced the system’s dynamic frequency support strength.

Identification of vulnerable lines in power grids with wind power integration based on topological potential

Vulnerable transmission lines are one of the weak links in the operation of the power system, as their damage can trigger widespread blackouts and cascading failures. The integration of large-scale wind power generation into the grid has resulted in significant changes to both the topology and distribution patterns of power flows inside the system, exacerbating line vulnerabilities. Identifying these lines can enhance power system safety through vigilant monitoring or augmenting their carrying capacity. In this paper, a method for identifying vulnerable lines based on the theory of topological potential is proposed. The method is based on the N-1 fault model of optimal DC power flow, and a corresponding network is constructed for the power system. The task of pinpointing weak points in a complicated network is converted into an assessment problem of important nodes. The proposed index comprehensively considers the in-degree and out-degree topological potentials of nodes, and uses the entropy weight method for weight allocation. Meanwhile, the TLS distribution is used to fit the wind power prediction error. Finally, simulation experiments are conducted on the IEEE 39-bus system. Simulation results indicate that the most vulnerable transmission lines tend to be located at the hubs of the system’s topological network and in close proximity to wind farms.

A Novel Automatic Generation Control Method Based on the Large-Scale Electric Vehicles and Wind Power Integration Into the Grid.

In order to solve the problem of frequency instability of power system due to strong random disturbance caused by large-scale electric vehicles and wind power grid connection, an improved reinforcement learning algorithm, namely, optimistic initialized double Q, is proposed in this article from the perspective of automatic generation control. The proposed algorithm uses the optimistic initialization principle to expand the agent action exploration space, so as to prevent Q-learning from falling into local optimum by greedy strategy; meanwhile, it integrates double Q-learning to solve the problem of overestimation of action value in traditional reinforcement learning based on Q-learning. In the algorithm, the hyperparameter ατ is introduced to improve the learning efficiency, and the reward bτ based on exploration times is introduced to increase the Q value estimation to drive the exploration of the algorithm, so as to obtain the optimal solution. By simulating the two-area load frequency control model integrated with large-scale electric vehicles and the four-area interconnected power grid model integrated with large-scale wind power generation, it is verified that the proposed algorithm can obtain the global optimal solution, thus effectively solvinng the frequency instability caused by strong random disturbance in the grid-connected mode of large-scale wind power generation, and compared with many reinforcement learning algorithms, the proposed algorithm has better control performance.

Assessment of Wind Resource and Its Energy Potential in Three States of Northwest Nigeria

The growing need for clean energy to address the environmental issues caused by the usage of fossil fuels results to the need for Nigeria to develop an alternative energy from untapped wind which is in abundance in the region. The aim of this study is to evaluate wind power potential and wind energy resources of three locations (Kaduna, Kano and Katsina) of northwestern part of Nigeria. The Nigerian Meteorological agency (NIMET) provided the wind speed data spanning 25 years (1996-2020). In the analysis, Weibull two-parameter statistical model was used. The distribution of wind speed across Nigeria demonstrates that some areas in the North are equipped to generate wind. Microsoft excel was used in analyzing the wind speed data obtained. In addition, evaluation of the region’s wind energy resources shows that Kano recorded the highest potential, with WPD of 443.03 Wm-2 at 10m AGL with annual WED of 4.921 kWhm-2day-1 while Kaduna recorded the lowest potential of 198.43 Wm-2 with annual WED of 2.093 kWhm-2day-1. As a result, Kaduna is found to be ideal for small scale wind power generation, while Kano and Katsina may be suitable for large scale wind power generation.

A novel ultra-short-term wind power prediction method based on XA mechanism

A major difficulty in integrating large scale wind power generation in an electrical power system is that wind generated power appears to be erratic, intermittent, and volatile. In this paper, we demonstrate the efficacies of a novel ultra short term 1-step ahead wind generated power prediction model, by combining two best of breed machine learning models in their respective areas of applications: a deep convolutional neural network (CNN) model, known to be effective in classification problems, and a bi-directional long short term memory (Bi-LSTM) model, known to be effective in 1-step ahead time series prediction problems, using a cross attention (XA) mechanism on three challenging practical datasets: the East-China dataset, the Yalova (Turkey) dataset, and the 16 MW dataset.There are two alternative cross attention models: (1) using the CNN features as the key–value pair, and the Bi-LSTM features as the query, this we called a XA model, and (2) using the Bi-LSTM features as the key–value pair, and the CNN features as the query, this we called a XA_I model; we found empirically for a properly chosen sliding window length, whichever CNN model or Bi-LSTM model performs well in the 1-step ahead prediction, then its features should be used as the query in the cross attention mechanism, thus, the XA achieves better results than XA_I on the East-China dataset, while XA_I achieves better results than XA on the Yalova dataset, and on the 16 MW dataset. Where comparable results using other state-of-the-art models are available on the Yalova dataset and the 16 MW dataset, we found that our XA_I results are superior. Moreover, it is found empirically, that the cross attention mechanism model produces stable k-step ahead predictions, for k≤W2, where W is the sliding window length.

The use of innovative tools in the medium voltage grid development, a case study of series voltage regulator

The rapid technological improvements concerning the renewable energy sources and the energy policy of the European Union, and the National Energy Strategy are leading to a rapid increase in the number of intermittent renewable power plants. Thus, new challenges emerge in the operation of the distribution system. To operate the system efficiently, the use of innovative technologies must be considered, because conventional network development strategies cannot always provide an optimal solution for the problem. This paper analyses the effects of largescale wind power generation on a medium voltage system and a solution of the problems faced through a case study of a serial voltage regulator. The difference between the profiles of generation and loads causes the residential transformers at the end of the line to encounter large, more than 8% voltage fluctuation. To assess the site’s voltage profile, time series symmetrical load flow calculations were performed. After the thorough analysis of the circumstances a serial voltage regulator device was implemented at 3 different nodes of the system and a placement analysis was carried out with statistical tools. The results showed a 3% decrease in the voltage fluctuation at the end of the line even when the device was far from these nodes; and with an optimal placement, the device could halve the largest voltage fluctuation on the line.

Evaluating offshore wind power potential in the context of climate change and technological advancement: Insights from Republic of Korea

Offshore wind power is constantly being invested and expanded around the world. National plans for wind power generation must be evaluated in light of climate change and technological advancement since wind speed changes at sea level due to climate change along with continuous technological development significantly affect the wind power generation potential. Republic of Korea has set ambitious plans to develop and expand large-scale offshore wind power generation and with the aim of accurately predicting domestic wind power generation potential, the current study analyzed the patterns and consequences of changes in wind speed due to climate change. Furthermore, the contribution of developing a 15 MW large-scale wind power generator to the national target for offshore wind power generation was evaluated. Changes in wind speed under RCP 4.5 and RCP 8.5 scenarios were examined for 10-year interval changes and for seasonal variabilities from 2010 to 2100. Results indicate that the wind speed would continuously decrease in the RCP 8.5 scenario, suggesting that failing to reduce greenhouse gas emission would eventually lead to loss of wind resources and resultant decline in wind power generation. Analyses also revealed that installing 3 MW wind turbines (utilization rate of 22%) or 15 MW wind turbines (utilization rate of 29%) can respectively achieve 40% or 55% of the national electricity production target for 2030. Assuming an aggressive deployment in high wind speed areas, it was found feasible to achieve up to 64% of the 2030 target, and even 100% but with a high utilization rate of 42%.

Cooperative control of time-delay wind power grid-connected unit under actuator saturation based on Hamiltonian method

In large-scale wind power generation, wide area control is often employed to overcome power oscillation, but this can result in the appearance of time-delayed voltage, which is transmitted to the wind power grid-connected system as an input signal. Additionally, ensuring the security of multi-grid parallel connection requires limiting the amplitude of the input signal. To address these challenges, this paper investigates the cooperative control problem for time-delayed wind power grid-connected unit under actuator saturation constraints. A novel control strategy that combines passive control with synchronous control is proposed. The system is transformed into a Hamiltonian structure, and a passive controller is designed using the principle of interconnection and damping assignment passivity-based (IDA-PB) to ensure stability. Based on this, an output feedback synchronous controller is proposed to account for saturation when multiple grids are connected in parallel. Stability criteria are provided to ensure the asymptotic stability of each closed-loop system and synchronous stabilization of all systems. Finally, simulation results verify the effectiveness of the proposed control strategy.

Study on frequency characteristics of receiving power system with large-scale offshore wind power generation

With the rapid development of offshore wind power and large-scale grid connection, the mechanical inertia and frequency regulation ability of the power system are greatly reduced, which seriously affects the frequency stability of the receiving end power grid. Aiming at the frequency stability analysis of large-scale offshore wind power connected to the receiving end power grid, this paper proposes a frequency response aggregation model which includes the frequency limiting controller (FLC) and the wind turbine generator (WTG) with frequency modulation (FM) capability. The rationality of model aggregation and the stability of transfer function are proved by theoretical analysis. Taking a southern province in China as an example, the effects of wind turbine generator access form and DC block capacity on different frequency response indexes are analyzed by using the proposed frequency response aggregation model. Through theoretical and simulation analysis, the correlation of system inertia, FM capacity and DC FLC capacity with frequency deviation nadir and quasi-steady state frequency index is obtained, and the relevant conclusions affecting frequency stability indexes are drawn. Finally, through the model simulation method, the improvement of the system frequency stability when the wind turbine provides inertia and primary FM support is analyzed. This paper concludes that when the wind power penetration is in the range of 10%∼40% and the wind power assisted frequency modulation capacity reaches 5% of the installed capacity, the minimum frequency of the system can be maintained above 49.5 Hz.

Optimization of the offshore wind power grid-connected structure based on an improved genetic algorithm

Large-scale offshore wind power generation has become one of the research hotspots in the development of new energy in the world. However, the planning of far-reaching offshore wind power is faced with many technical difficulties, such as the need to consider the optimization of line transmission capacity caused by the truncation effect in combination with the wind power output probability, and solve the problem that traditional algorithms cannot solve the dynamic programming problem, and the greedy algorithm for solving the dynamic programming problem cannot solve the global optimal solution. Therefore, in order to solve the above problems, based on the full life cycle (FLC) investment calculation of the collecting and transmission system, the topology optimization model of the offshore wind power system is established. In addition, in order to solve the grid-connection problem of offshore wind farms, an improved topology optimization algorithm based on greedy idea is proposed. The optimization results show that the critical values of economic transmission distance of HVAC, FFTS and HVDC are usually 50 km and 170 km respectively. Finally, the collection scheme of the wind farm cluster including three far-reaching offshore wind farms are analyzed, and the results show that the total cost of the optimized point-to-point scheme is reduced by 5.6% and 10.2% respectively compared with the star topology and the circular collection topology, with significant economic benefits.

Optimal allocation and energy management of a wind–hydrogen generation system equipped with the speed regulating differential mechanism

The hybrid drive wind turbine (WT) can be friendly connected to the power grid by using a speed regulating differential mechanism (SRDM) instead of partially or fully rated converters, which has been considered as a promising solution for the stable consumption of large-scale wind power generation. To further improve the on-grid performance of hybrid drive WTs, this paper develops a multi-source power generation scheme, in which a hydrogen storage system (HSS) is integrated for mitigating the wind power generation intermittencies. The overall architecture and kinematic principles of the proposed wind–hydrogen generation system, called SRDM-based WT with HSS, are first analyzed. Then, the graphical descriptions of mathematical models are finalized via the Energetic Macroscopic Representation method, by which the physical characteristics and energy flow relationships are revealed. To ensure the economical and stable operation of the proposed wind–hydrogen scheme, an effective optimal allocation framework, considering the uncertainties from wind power output and load demand, is presented to HSS, targeting the maximum annual revenue. The effects of several key HSS parameters on the capacity allocation results are also investigated. Moreover, aiming at the different system working modes, an energy management approach is synthesized to achieve the interaction analysis and power supervision between energy sources and storage elements. Finally, experimental and simulation case studies are demonstrated. Results illustrate the effectiveness of the proposed approaches and the optimal performance for uninterrupted on-grid operation of the proposed wind–hydrogen energy system.

Development and Design of ADPSS Co-simulation Technology for Large-Scale New Energy Electromagnetic Transient Simulation in High Performance Calculation

As large-scale wind and photovoltaic power generation incorporating into the AC power grid, the impact of new energy fluctuation and uncertainty on the transient stability of power grid have attracted widespread attention among researchers and engineers in the power industry. It is necessary to improve the transient simulation and modelling ability of new energy to provide a more efficient simulation platform for the stability research of new energy generation connecting to large power grid. In this paper, the ADPSS technology of large-scale new energy electromagnetic transient simulation is mainly studied in depth, including the following contents: the design and development of the interface and program of ADPSS-Matlab co-simulation, the improvement and optimization of the parallel high performance computing, and the verification of the accuracy of co-simulation for the modelling and experimental research with large-scale new energy simulation.

Wind Energy Potential in Pakistan: A Feasibility Study in Sindh Province

The environment and the economy are negatively impacted by conventional energy sources, such as coal, gasoline, and other fossil fuels. Pakistan’s reliance on these resources has resulted in a catastrophic energy crisis. This has driven the government to make critical decisions such as early retail closures, power outages for the industrial sector, and an increase to two days a week vacations. Wind energy, accessible and affordable, will become a viable option for meeting Pakistan’s present and future energy demands. Approximately 3% of Pakistan’s land can produce nearly 132 GW of power with an installed capacity of 5 MW per km2. In this study, four zones (Karachi, Thatta, Badin, and Jamshoro) in Sindh province are assessed for the feasibility of wind energy generation. The installed capacity, generator types, and detailed specifications are provided for each zone. Moreover, the wind mapping of Pakistan is presented considering the four potential zones. The zones are analyzed using annual wind speed and power output considering wind data measured at 50 m height over one year. The higher mean speed is recorded at Jamshoro compared to other zones. The analysis indicates that all four sites are suitable for large-scale wind power generation due to their energy potential.

AC Loss Analysis and Modular Cryostat Design of a 10-MW High-Temperature Superconducting Double Stator Flux Modulation Machine

Superconducting (SC) machines are one of the best candidates for large-scale direct-drive wind power generation because of its high torque density. In a traditional SC synchronous machine, either armature windings or field windings need to rotate, which makes the structure of the machine complicated. To solve this problem, a high temperature superconducting (HTS) double stator flux modulation (DSFM) machine was proposed. In this machine, the armature windings and SC field windings are placed in outer stator and inner stator, respectively, and the machine works through flux modulation effect by reluctance rotor. Due to modulation effect, there is a high content of harmonic in this machine. Thus, it is important to analyze harmonics influence on SC coils, especially the SC coils ac loss. In this article, the losses of a 10MW HTS-DSFM machine are calculated and analyzed. It turns out that the ac losses of SC coils in this machine is higher compared with the traditional SC synchronous machine. From analytical calculation, the ac magnetic field perpendicular to the tape surface have strong impacts on the SC coils. In order to reduce the ac losses, some suppression methods are adopted on machine structures and SC thermostat. Then, cryostats are designed and the cooling budgets are evaluated. At last, the comprehensive performances of the machine are calculated and its economy in the long term is verified.

Stochastic Modelling and Stability Analysis of Large-Scale Wind Power Generation System with Dynamic Loads

As a result of dwindling fossil fuel reserves and the negative impact of greenhouse gases (GHGs) on the environment, it is important that the search for a power grid that will comprise of only variable renewable energy (VRE) generation sources such as wind or solar energy which is available everywhere for free is given much attention. The main challenge associated with these sources of energy is their variability and random nature. It is as a result of instability introduced by the VRE generation sources, that is why there is a strict control measures put in place by the regulators as to how much VRE generation sources can feed into the power grid in the case of its integration into an existing power grid. It becomes imperative to consider implications for grid stability and reliability when considering a power grid that will consist of VRE generation only. Eigenvalue approach was used to analysed the performance of anticipated large-scale VRE grid to ascertain its behaviour. Eigenvalue approach is one of the methods to examine the stability of a power system’s dynamic performance. The results indicated that it is possible to attain the necessary stability provided the assumptions made during the modelling stage is revised to improve upon the model.

Simulation Research on Wind Storage Joint Control of Wind Turbine Based on VSG

The fluctuation of wind energy has an impact on the stability of active power output and system frequency, resulting in the decline of power quality. In addition, the large-scale wind power generation which is connected to the power grid reduces the inertia of system. The use of VSG control can effectively deal with the lack of inertia response ability of traditional synchronous generators. In the state of large-scale distributed wind power generation connected to the power grid, the ability of wind turbines to suppress the power oscillation of the system can be enhanced. In order to improve this ability, the VSG control strategy is introduced into the control of network test converter, and the virtual inertia control technology is used to respond to the system frequency modulation. The voltage loop and current loop control strategy are adopted for the Generator side rectifier. Meanwhile, the energy storage control of the battery system is introduced. Realize the regulation of wind power active power. In the MATLAB/Simulink, a combined wind energy storage system is built to verify the correctness of the proposed scheme. Finally, the maximum wind energy tracking, the enhancement of system frequency regulation ability and the stabilization of active power output fluctuation are realized. It can effectively restrain the reduction of economic benefits after long-term operation of wind farm.

The Application of AVC System in Inner Mongolia Wind Farm

The key technologies of self-regulating voltage control for wind farms are studied, and the technical indicators of the AVC main and sub-stations of wind farms in the field of large-scale wind power generation are defined. Wind farm voltage control (AVC) control strategy, developed a wind farm AVC simulation test platform, prepared a wind farm AVC field test and conducted a field test. According to the actual control effect of wind farm AVC, the dynamic response characteristics of wind farm AVC and the reactive power performance of wind farm AVC are evaluated according to relevant technical standards.

Distributionally robust day-ahead operation of power systems with two-stage gas contracting

Due to stronger interactions between power and gas systems promoted by the deployment of fast-response gas-fired power plants and the advanced technology of power-to-gas facilities, secure and optimal energy management becomes highly challenging. In industrial practice, the two systems are operated by different regulatory authorities, which is commonly neglected in the existing studies, therefore, information exchange is limited, and bilateral energy transactions are vital. This paper revisits the day-ahead operation of the coupled power and gas system with large-scale wind power generation integration, where a two-stage gas contracting mechanism is proposed to incorporate cost-effective day-ahead and rarely-event real-time gas contracts. To balance the robustness and the conservativeness of the operation strategy, a distributionally robust optimization (DRO) based decision-making framework is derived, which effectively handles the proposed mechanism. The intractable DRO model is reformulated to be solved by the nested column and constraint generation algorithm. The nonconvex gas flow equations are approximated as convex ones, which are solved by a difference-of-convex programming-based procedure to find feasible solutions. Simulation results demonstrate the benefits of the DRO and two-stage contract modeling.

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.

Probabilistic Approaches to the Security Analysis of Smart Grid with High Wind Penetration: The Case of Jeju Island’s Power Grids

As the importance of renewable generating resources has grown around the world, South Korea is also trying to expand the proportion of renewable generating resources in the power generation sector. Among the various renewable energy sources, wind generating resources are emerging as a key alternative to conventional power generations in the electricity sector in Korea accounted for 17.7 GW of total capacity by 2030. As wind generating resources are gradually replacing traditional generating resources, the system security and reliability are negatively affected because of the variability, due to intermittent outputs. Therefore, existing power grids will need to be correctly re-measured to cover the large scale of renewable energy, including wind generation. To expand the grid, we must understand the characteristics of renewable energy and the impact of its adoption in the grid. In this paper, we analyze various characteristics of wind power generation, and then we propose a probabilistic power output modeling method to consider the uncertainty of wind power generation. For the probabilistic approach, Monte-Carlo simulation is used in the modeling method. The modeled wind power outputs can help planning for the reinforcement and expansion of power systems to expand the capacity for large-scale renewable energy in the future. To verify the proposed method, some case studies were performed using empirical data, and probabilistic power flow calculation was performed by integrating large-scale wind power generation to the Jeju Island power system. The probabilistic method proposed in this paper can efficiently plan power system expansion and play a key strategy of evaluating the security of the power system through the results of stochastic power flow calculation.