On Grid Codes

If $A_{i}$ is finite alphabet for $i=1,...,n$, the Manhattan distance is defined in $\prod_{i=1}^{n}A_{i}$. A grid code is introduced as a subset of $\prod_{i=1}^{n}A_{i}$. Alternative versions of the Hamming and Gilbert-Varshamov bounds are presented for grid codes. If $A_{i}$ is a cyclic group for $i=1,...,n$, some bounds for the minimum Manhattan distance of codes that are cyclic subgroups of $\prod_{i=1}^{n}A_{i}$ are determined in terms of their minimum Hamming and Lee distances. Examples illustrating the main results are provided

Active power control in a hybrid PV-storage power plant for frequency support

The recent increase of intermittent power generation plants connected to the electric power grids may stress the operation of power systems. So, grid codes started considering these power plants should con- tribute to the grid support functions. Recently, a power ramp rate limitation is being included in several grid codes, which is a challenge for photovoltaic installations due to the lack of inertia. This paper pre- sents a method to deal with the main grid code requirements considering a PV plant with an energy stor- age device, where a strict two-second time window ramp rate restriction is applied. A direct ramp rate control strategy is used, which includes a dynamic SOC control and battery support functionality for active power setpoint compliance. The control strategy is validated by simulations.Postprint (published version

Review of grid codes: Ranges of frequency variation

This article contains a review of grid codes throughout the world. Although grid codes addresses many issues, only four aspects related to generator-grid interaction are the most important: ranges of frequency variation, ranges of voltage variation, fault ride through capability, reactive power capability

Development of a generic future grid code regarding wind power in Europe

Present grid codes might not be a suitable reference for future-oriented research. The diversity of grid codes by different transmission system operators makes it challenging to get a clear and compact general overview on grid code requirements. ENTSO-E aims to develop a uniform grid code framework for Europe, which at present, however, still leaves many key aspects unspecified, referring instead to regulation by the relevant transmission system operator. To enable for general assessment of grid code compliance in future scenarios, a generic future grid code is required for academic research purposes, hence the compliance test is generalised and future-oriented rather than examining it with actual grid codes of today. The generic grid code under development provides fault ride through voltage profile and the required response, as well as frequency and rate of change of frequency requirements and the demanded power-frequency response. The specifications are inspired by the European grid codes, by ENTSO-E and the Irish grid code, which is seen by many as progressive when it comes to wind power integration

Reducing noise in moving-grid codes with strongly-centroidal Lloyd mesh regularization

A method for improving the accuracy of hydrodynamical codes that use a moving Voronoi mesh is described. Our scheme is based on a new regularization scheme that constrains the mesh to be centroidal to high precision while still allowing the cells to move approximately with the local fluid velocity, thereby retaining the quasi-Lagrangian nature of the approach. Our regularization technique significantly reduces mesh noise that is attributed to changes in mesh topology and deviations from mesh regularity. We demonstrate the advantages of our method on various test problems, and note in particular improvements obtained in handling shear instabilities, mixing, and in angular momentum conservation. Calculations of adiabatic jets in which shear excites Kelvin Helmholtz instability show reduction of mesh noise and entropy generation. In contrast, simulations of the collapse and formation of an isolated disc galaxy are nearly unaffected, showing that numerical errors due to the choice of regularization do not impact the outcome in this case.Comment: 9 pages, 14 figures, MNRAS submitte

Application of SMES unit to improve the performance of wind turbine conversion system

The amount of wind turbine connected to the power grid has significantly increased during the last decade. This has resulted in essential need to establish grid codes. Previously, wind turbine generators (WTGs) were allowed to be disconnected from the network during any disturbance at the grid side to avoid WTGs from being damaged. However, lately, the transmission system operators (TSOs) require WTGs to be stayed connected to provide support to the grid during fault. This new requirement has been regulated in the new grid codes. In this paper, the super conducting magnetic energy storage (SMES) unit is used to enhance the high voltage ride through (HVRT) capability of DFIG based WTG during voltage swell events at the grid side. Two new grid codes are used to verify the ability of the SMES unit to avoid the WTG from being disconnected from the grid

Mapping of grid faults and grid codes

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