Enhancing Wind Power Integration through Optimal Use of Flexibility in Multi-Carrier Energy Systems from the Danish Perspective

Denmark’ goal of being independent of fossil energy sources in 2050 puts forward great demands on all energy subsystems (electricity, heat, gas and transport, etc.) to be operated in a holistic manner. The Danish experience and challenges of wind power integration and the development of district heating systems are summarized in this paper. How to optimally use the cross-sectoral flexibility by intelligent control (model predictive control-based) of the key coupling components in an integrated heat and power system including electrical heat pumps in the demand side, and thermal storage applications in buildings is investigated.

Energy Management and Optimization of Vehicle-to-grid Systems for Wind Power Integration

An approach to smoothing the fluctuations of largescale wind power is investigated using vehicle-to-grid(V2G)systems.First,an energy management and optimization system is designed and modeled.By using the wavelet packet decomposition method,the target grid-connected wind power,the required electric vehicle(EV)power,and supercapacitor power are determined.The energy management model for EVs is then developed by introducing a knapsack problem that can evaluate the needs of an EV fleet.Furthermore,an optimized dispatch strategy for EVs and wind power is developed by using a dynamic programming method.A case study demonstrates that the energy management and optimization method for V2G systems achieves noticeable performance improvements over benchmark techniques.

Reliability of Power System Integrated with Wind Generation Considering Carbon Tax

This paper proposes a method to evaluate the reliability of power system with different capacities of wind power while considering carbon tax. The proposed method is a hybrid approach which combines Frequency and Duration (F&D) method and Monte Carlo Simulation (MCS) method. MCS method is used to achieve a model to simulate the random status of power system. Also, the proposed method is applied on the IEEE 14-bus test system to investigate the effects of integrating different capacities of wind energy to the reliability of power system with considering carbon tax.

Overview of Mechanism and Mitigation Measures on Multi-frequency Oscillation Caused by Large-scale Integration of Wind Power

In recent years,the large-scale integration of re-newable energy sources represented by wind power and the widespread application of power electronic devices in power systems have led to the emergence of multi-frequency oscillation problems covering multiple frequency segments,which seriously threaten system stability and restrict the accommodation of renewable energy.The oscillation problems related to renewable energy integration have become one of the most popular topics in the field of wind power integration and power system stability research.It has received extensive attention from both academia and industries with many promising research results achieved to date.This paper first analyzes several typical multi-frequency oscillation events caused by large-scale wind power integration in domestic and foreign projects,then studies the multi-frequency oscillation problems,including wind turbine’s shafting torsional oscillation,sub/super-synchronous oscillation and high frequency resonance.The state of the art is systematically summarized from the aspects of oscillation mechanism,analysis methods and mitigation measures,and the future research directions are explored.

Wind power forecasting errors modelling approach considering temporal and spatial dependence

The uncertainty of wind power forecasting significantly influences power systems with high percentage of wind power generation. Despite the wind power forecasting error causation, the temporal and spatial dependence of prediction errors has done great influence in specific applications, such as multistage scheduling and aggregated wind power integration. In this paper, Pair-Copula theory has been introduced to construct a multivariate model which can fully considers the margin distribution and stochastic dependence characteristics of wind power forecasting errors. The characteristics of temporal and spatial dependence have been modelled, and their influences on wind power integrations have been analyzed.Model comparisons indicate that the proposed model can reveal the essential relationships of wind power forecasting uncertainty, and describe the various dependences more accurately.

Positive- and Zero-Sequence Impedance Estimation of YNyn0+d-Connected Main Power Transformers in Wind Power Applications

With the increased penetration of non-conventionalrenewable energy resources, such as wind power plants (WPPs),into the power system, a lot of interest has been placed on studyingtheir impact for system protection, planning and operationsto ensure continued reliability of the electric grid. The impactof WPPs on the grid is typically identified during generationinterconnection studies. One of the challenges faced by protectionand planning engineers, at an early stage in this process, isthat many of the studies involving these power plants must beperformed without specific data available because the equipmentis not built yet. Among all the needed data, a particular interest inthis study is placed on the positive- and zero-sequence impedancesof the main power transformer (MPT) that interconnects a windpower plant to the transmission system due to its contribution toshort-circuit current during ground faults. The most commonlyfound in practice MPT winding configurations is a high-voltagewinding in wye with neutral bushing;a low-voltage windingin wye with neutral bushing without phase shift between thesewindings, and a stabilizing tertiary winding connected in deltathat is not designed for external loading designated as YNyn0+d.Thus, this paper proposes a methodology to estimate the sequenceimpedances of YNyn0+d transformers from a statistical point ofview applying clustering and regression analyses on existing MPTtest report data.

Dispatch Model for Integrated Heat and Power Systems Considering Internal Composition of CHP Plants

An integrated heat and power system(IHPS)is a promising approach for alleviating wind curtailment problems.In an IHPS,the combined heat and power(CHP)plant is the key component,which supplies both heat and electric loads,and couples the thermal system and power system.However,existing research commonly ignores or simplifies the internal composition of CHP plants,which could lead to some unavoidable errors.This paper focuses on the internal composition of CHP plants,and models the physical processes in different components and flexible resources in the CHP plant.Furthermore,a joint dispatch problem of an IHPS with the above CHP plant models is formulated,and an iterative algorithm is developed to handle the nonlinearity in this problem.Case studies are performed based on a real CHP plant in Northern China,and the results indicate that the synergistic effect of different energy resources in the CHP plant is realized by the joint dispatch model,which promotes wind power accommodation and reduces fossil fuel consumption.

High Frequency Stability Constraints Based MMC Controller Design Using NSGA-III Algorithm

The occurrence of high frequency resonances(HFRs)has been frequently observed in several MMC-HVDC projects.To avoid these HFRs,the controller design of an MMC must satisfy two requirements:1)The controller should remain stable while in the high frequency range,and 2)MMC impedance should not possess a negative real part in the high frequency range.So far,majority of the related studies on MMC controller design have been unable to address these requirements precisely.This paper first describes the simplified high frequency MMC impedance model developed indigenously by the authors.Subsequently,the driving mechanism of two kinds of HFRs is revealed using the said developed model,including:1)MMC controller instability,and 2)Interaction instability between MMC and AC cables.Furthermore,the mathematical expressions outlining the controller stability constraint and positive damping constraint are proposed.Additionally,NSGA-III based multi-objective optimization algorithm is adopted,to identify the region most suitable for satisfying the proposed stability constraints under the MMC controller parameters.The proposed controller design method is capable of effectively evading the HFRs triggered by the incompatible MMC.The detailed time-domain simulations generated using PSCAD/EMTDC software validate the proposed designed method and endorse the improved results.