Significant Amount Of Wind Power Research Articles

A Grouping-Based Frequency Support Scheme for Wind Farm Under Cyber Uncertainty

The injection of a significant amount of wind power tends to increase the difficulty of the grid frequency control. Therefore, wind farm (WF) has to have the ability to participate in system frequency support. However, during the frequency control process in a large WF, individual wind generators may prone to instability due to possible over-deceleration. In addition, the deeply-intertwined cyber physical power system (CPPS) has gradually replaced the traditional grid due to the development of information and communication technology. However, CPPS also introduces cyber uncertainties that have a significant negative impact on the real-time control of power system. To address above issues, this paper considering possible cyber uncertainty, and proposes a grouping-based hierarchical frequency support scheme for WF. In the proposed scheme, the variable speed wind turbines (VSWTs) are clustered into several groups, according to their wind profiles at first, by dispatching the same control commands to the VSWTs belonging to the same group. As a result, the number of the VSWTs and control variables reduces significantly. Then, a hierarchical control scheme based on virtual inertial control is proposed with consideration of possible cyber uncertainty. The top-layer controller determines whether cyber uncertainty exists, and calculates power increment based on frequency deviation and cyber uncertainty. The bottom-layer controller coordinates the power increment distribution on the basis of ensuring the safe operation of all VSWTs. By do this, it is expected to achieve not only optimal frequency response but also wind generator stability. The effectiveness of proposed scheme is verified on a simulation platform built using MATLAB.

Nonlinear Model Predictive Control of Wind Farm for System Frequency Support

The injection of a significant amount of wind power tends to increase the rate of change of the grid frequency. Therefore, it is a trend for wind farm to participate in the grid frequency regulation. However, during the frequency control process, individual wind generators in a wind farm may prone to instability due to possible over-deceleration. To address this issue, this paper presents a new nonlinear model predictive control (NMPC) scheme for the wind farm frequency response. By incorporating the nonlinear dynamics of each individual wind generator into the NMPC design, it achieves both objectives of dynamically optimal frequency response and wind generator stability. This scheme has a three-layer structure. Based on the linear model predictive control and moving horizon estimation, a top-layer controller computes the overall wind farm power reference to support the frequency control. This overall power reference is fed to the middle-layer NMPC, and is further distributed among multiple wind generators. The dispatched power references are then sent to the bottom-layer wind generators local controllers for execution. Simulation results verify the effectiveness of the proposed scheme.

Going with the wind: temporal characteristics of potential wind curtailment in Ireland in 2020 and opportunities for demand response

The Republic of Ireland and Northern Ireland have ambitious targets for 40% of electricity to be supplied by renewables by 2020, with the majority expected to be supplied by wind power. There is, however, already a significant amount of wind power being turned down, or ‘curtailed’, and this is expected to grow as wind penetrations increase. A model-based approach is taken to estimate curtailment using high-resolution wind speed and demand data covering four years, with a particular focus on the temporal characteristics of curtailment and factors that affect it. The model is validated using actual wind output and curtailment data from 2011. The results for 2020 are consistent with previously published estimates, and indicate curtailment levels ranging from 5.6 to 8.5% depending on assumptions examined in this study. Curtailment is found to occur predominantly at night, and to exhibit stochastic variability related to wind output. To accommodate high penetrations of wind power, the findings highlight the value of flexible demand over relatively long time-periods. The model's output data have been made publicly available for free for further investigation.

A long-term analysis of pumped hydro storage to firm wind power

Although pumped hydro storage is seen as a strategic key asset by grid operators, financing it is complicated in new liberalised markets. It could be argued that the optimum generation portfolio is now determined by the economic viability of generators based on a short to medium term return on investment. This has meant that capital intensive projects such as pumped hydro storage are less attractive for wholesale electricity companies because the payback periods are too long. In tandem a significant amount of wind power has entered the generation mix, which has resulted in operating and planning integration issues due to wind’s inherent uncertain, varying spatial and temporal nature. These integration issues can be overcome using fast acting gas peaking plant or energy storage. Most analysis of wind power integration using storage to date has used stochastic optimisation for power system balancing or arbitrage modelling to examine techno-economic viability. In this research a deterministic dynamic programming long term generation expansion model is employed to optimise the generation mix, total system costs and total carbon dioxide emissions, and unlike other studies calculates reserve to firm wind power. The key finding of this study is that the incentive to build capital-intensive pumped hydro storage to firm wind power is limited unless exogenous market costs come very strongly into play. Furthermore it was demonstrated that reserve increases with increasing wind power showing the importance of ancillary services in future power systems.

Market Designs for the Primary Frequency Response Ancillary Service—Part II: Case Studies

The second part of this two-paper series analyzes the primary frequency response (PFR) market design developed in its companion paper with several case studies. The simulations will show how the scheduling and pricing change depending on whether requirements for PFR are included as well as how the requirements are defined. We first perform simulations on the base case IEEE RTS and show differences in production costs, prices, and amount of PFR when incorporating the PFR constraints. We show how new market designs can affect other linked markets when performing co-optimization. We then test a system with a significant amount of wind power, which does not provide PFR or synchronous inertia, to see how the incorporation of PFR constraints may become more critical on future systems. We then show how pricing can reduce make-whole payments and ensure resources needed for reliability reasons are incentivized. Lastly, we show how resources that improve their capabilities can earn additional profit if the improvement is needed ensuring the incentives can work for innovation in PFR capabilities.

A Framework for the Integrated Optimization of Charging and Power Management in Plug-in Hybrid Electric Vehicles

This paper develops a dynamic programming (DP)-based framework for simultaneously optimizing the charging and power management of a plug-in hybrid electric vehicle (PHEV). These two optimal control problems relate to activities of the PHEV on the electric grid (i.e., charging) and on the road (i.e., power management). The proposed framework solves these two problems simultaneously to avoid loss of optimality resulting from solving them separately. The framework furnishes optimal trajectories of PHEV states and control inputs over a 24-h period. We demonstrate the framework for 24-h scenarios with two driving trips and different power grid generation mixes. The results show that addressing the aforementioned optimization problems simultaneously can elucidate valuable insights. For example, for the chosen daily driving scenario, grid generation mixes, and optimization objective, it is shown that it is not always optimal to completely charge a battery before each driving trip. In addition, reduction in CO2resulting from the synergistic interaction of PHEVs with an electric grid containing a significant amount of wind power is studied. The main contribution of this paper to the literature is a framework that makes it possible to evaluate tradeoffs between charging and on-road power management decisions.

How to save energy to reach a balance between production and consumption of heat, electricity and fuels for vehicles

There is a potential to utilize a significant amount of renewable energy in Sweden and European union (EU). Biomass can fulfil some 8500–12,500 TW h/y in EU, while the total utilization was 16,084 TW h/y 2009. Even though there is a significant amount of wind power, hydro power and potentially also solar power, it still is most economical to reduce the consumption of heat, electricity and fuels for vehicles. A saved kWh is normally cheaper than to produce one extra. In this paper different opportunities for saving energy will be discussed. This includes manufacturing industries, process industries, power plants and energy systems including distribution of power and smart grids, food production and transportation. There is also a major potential to save energy in buildings, both in the north where it is cold, and in the south where it can be very hot summer time. Here the potential is to avoid cooling instead. Technical solutions as well as economic incentives are covered. Environmental aspects are addressed, so that the solutions will be long term sustainable.

Large penetration of wind and dispersed generation into Danish power grid

The present Danish power grid is characterised by large penetration of wind power and local combined heat and power (CHP) units. Today, there are two large offshore wind farms commissioned in the Danish power grid. Construction of two more offshore wind farms (430 MW) with grid connection to the Danish transmission power grid will be by the year 2009. The Danish power grid is undergoing a change from a classical power network with few centralised large power plants into a power network with a significant amount of wind power and dispersed generation. Presently, there must be at least three large power plant units in operation in Western Denmark to control voltage and frequency and maintain security of the power system operation. The technology change to wind power and dispersed generation implies that power supply and control from the large power plants – and, consequently, also ancillary services such as, e.g. voltage and frequency control capability – have to be reduced in favour of dispersed generation and wind. Such a change constitutes a challenge with respect to maintaining security of the power system operation in different operational situations, and creates a need for new solutions with voltage and frequency control and compliance with planned power balance between the Danish power system and the neighbouring areas. This article focuses mainly on issues with regard to short-term voltage stability of the power grid.