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Since the established wind farms (WFs) have a strong demand for reducing maintenance costs, the fatigue load suppression of wind turbines (WTs) has become more important in WFs. To suppress the fatigue load during operation, the traditional schemes are tried by allocating the optimized power setting value to each WT, which does not directly point to the key operating parameters that affect fatigue. In response to this, an advanced WT control model with two-degree-of-freedom (2Dof) is applied in this paper to ensure that the generator torque and pitch angle (two key parameters affecting fatigue load) of each WT are directly controlled. In order to achieve effective control of the above two parameters in multiple WTs, a hierarchical distributed control architecture with dynamic-local-reference is proposed to jointly optimize the above two configurable parameters at both the WT and WF levels. Several cases are compared to verify the proposed method, and simulation results show that the proposed 2Dof control model for WT and distributed control framework for WF can significantly reduce the fatigue load of each WT while completing the active power command of the whole WF. • Two-degree-of-freedom wind turbine control model is applied in wind farms. • Distributed model predictive control (DMPC) framework is adopted. • Dynamic WT reference power algorithm is proposed based on DMPC. • Fatigue load of all wind turbines in the wind farm are significantly reduced. [ABSTRACT FROM AUTHOR]

Virtual power plant (VPP) has become a promising technique to facilitate distributed energy resources (DERs) to participate in the power markets. Considering the respective interests of the VPP agent and distribution system operator (DSO), a bi-level optimisation model for VPP bidding in multiple retail markets (including active power, reactive power and spinning reserve market) as price-maker is formulated. In the upper layer, taking into account various DERs, the VPP agent aims to develop hourly bidding prices and quantities of multiple market commodities to maximise its operation profits. In the lower layer, DSO conducts the retail market clearing to minimise the system operation cost considering the network constraints and bidding plans of the market participants. Moreover, the quadratic coupling constraints among different market commodities due to capacity limitation of distributed generators and branches are formulated explicitly in the proposed model. The hybrid simulated annealing-genetic algorithm with self-adaptive parameters is adopted to cope with the non-linearity and compute the economic bidding plans for VPP. The effectiveness of the proposed approach is verified under different scenarios through case studies, which indicate its superiority and great potential for implementation. [ABSTRACT FROM AUTHOR]

Electric energy transport theory is one of the key factors in smart grid development. Electric energy and power transport theories enable the development of advanced energy metering, improve fault-location algorithms, electric network diagnostics algorithms, power conditioning of active filters and of smart grids, energy storage management at energy reservoirs, and new energy forecasting analytical algorithms. In this paper, the periodic averaged theories, including the periodic averaged formulation of Poynting vector theory, are presented. The presentation is conducted in a unique comparative formalism and approach, enabling the demonstration of equivalence between the various theories in general and the equivalence of some elements in the decomposition of the electrical expressions for the powers in particular. The paper shows the equivalence of the modern theory of Currents׳ Physical Components to the Conservative Power Theory, and its formulation, for being applicable to various grid monitoring and energy control applications. A corrected computation for the reactive power by means of time-domain Conservative Power Theory is proposed as well. Moreover, equivalence in single phase systems between Buchholz apparent power and geometric apparent power is shown, which indicate the suitability of using apparent power definitions to grid manufacturing and modern distribution systems design. [ABSTRACT FROM AUTHOR]

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The dynamic performance of the local control of single-phase voltage source inverters (VSIs) can be degraded when supplying to nonlinear loads (NLLs) in microgrids. When this control is based on the droop principles, a proper calculation of the active and reactive averaged powers (P–Q) is essential for a proficient dynamic response against abrupt NLL changes. In this work, a VSI supplying to an NLL was studied, focusing the attention on the P–Q calculation stage. This stage first generated the direct and in-quadrature signals from the measured load current through a second-order generalized integrator (SOGI). Then, the instantaneous power quantities were obtained by multiplying each filtered current by the output voltage, and filtered later by utilizing a SOGI to acquire the averaged P–Q parameters. The proposed algorithm was compared with previous proposals, while keeping the active power steady-state ripple constant, which resulted in a faster calculation of the averaged active power. In this case, the steady-state averaged reactive power presented less ripple than the best proposal to which it was compared. When reducing the velocity of the proposed algorithm for the active power, it also showed a reduction in its steady-state ripple. Simulations, hardware-in-the-loop, and experimental tests were carried out to verify the effectiveness of the proposal. [ABSTRACT FROM AUTHOR]