Over the past half-century, Optimal Power Flow (OPF) has become one of the most important and widely studied nonlinear optimization problems. In general, OPF seeks to optimize the operation of electric power generation, transmission, and distribution networks subject to system constraints and control limits. Within this framework, however, there is an extremely wide variety of OPF formulations and solution methods. Moreover, the nature of OPF continues to evolve due to modern electricity markets and renewable resource integration. In this two-part survey, we survey both the classical and recent OPF literature in order to provide a sound context for the state of the art in OPF formulation and solution methods. The survey contributes a comprehensive discussion of specific optimization techniques that have been applied to OPF, with an emphasis on the advantages, disadvantages, and computational characteristics of each. Part I of the survey (this article) provides an introduction and surveys the deterministic optimization methods that have been applied to OPF. Part II of the survey examines the recent trend towards stochastic, or non-deterministic, search techniques and hybrid methods for OPF.

Optimal power flow: a bibliographic survey I

DC power flow is a commonly used tool for contingency analysis. Recently, due to its simplicity and robustness, it also becomes increasingly used for the real-time dispatch and techno-economic analysis of power systems. It is a simplification of a full power flow looking only at active power. Aspects such as voltage support and reactive power management are possible to analyse. However, such simplifications cannot always be justified and sometimes lead to unrealistic results. Especially the implementation of power flow controlling devices is not trivial since standard DC power flow fundamentally neglects their effects. Until recently, this was not an issue as the application of power flow controlling devices in the European grid was limited. However, with the liberalisation of European electricity market and the introduction of large wind energy systems, the need for real power flow control has emerged and therefore, the use of these devices has been reconsidered. Several phase shifting transformers (PST) are being installed or planned in order to control flows. Therefore, it is important to fundamentally re-validate the fast, but less accurate, DC power flow method. In this paper the assumptions of DC power flow are analysed, and its validity is assessed by comparing the results of power flow simulations using both the DC and AC approaches on a modified IEEE 300 bus system with PSTs.

Usefulness of DC power flow for active power flow analysis with flow controlling devices

https://www.qualenergia.it/sites/default/files/articolo-doc/Studio_Imperial_College_wind_farms.pdf

How does wind farm performance decline with age

Fast acting static synchronous compensator (STATCOM), a representative of FACTS family, is a promising technology being extensively used as the state-of-the-art dynamic shunt compensator for reactive power control in transmission and distribution system. Over the last couple of decades, researchers and engineers have made path-breaking research on this technology and by virtue of which, many STATCOM controllers based on the self-commutating solid-state voltage-source converter (VSC) have been developed and commercially put in operation to control system dynamics under stressed conditions. Because of its many attributes, STATCOM has emerged as a qualitatively superior controller relative to the line commutating static VAR compensator (SVC). This controller is called with different terminologies as STATic COMpensator advanced static VAR compensator, advanced static VAR generator or static VAR generator, STATic CONdenser, synchronous solid-state VAR compensator, VSC-based SVC or self-commutated SVC or static synchronous compensator (SSC or S2C). The development of STATCOM controller employing various solid-state converter topologies, magnetics configurations, control algorithms, switching techniques and so on, has been well reported in literature with its versatile applications in power system. A review on the state-of-the-art STATCOM technology and further research potential are presented classifying more than 300 research publications.

Static synchronous compensators (STATCOM): a review

Optimal sizing of PV/wind/diesel hybrid microgrid system using multi-objective self-adaptive differential evolution algorithm

Preface. Introduction. Modelling of FACTS Controllers. Modelling of Conventional Power Plant. Conventional Power Flow. Power Flow including FACTS Controllers. Three--phase Power Flow. Optimal Power Flow. Power Flow Tracing. Appendix A: Jacobian Elements for FACTS Controllers in Positive Sequence Power Flow. Appendix B: Gradient and Hessian Elements for Optimal Power Flow Newtona s Method. Appendix C: Matlab(R) Computer Program for Optimal Power Flow Solutions using Newtona s Method. Index.

FACTS: Modelling and Simulation in Power Networks

The aim of this paper is the analysis of the methodologies and extrapolation laws subsequently used in the calculation of wind speed profiles. It also highlights the disadvantages of using low-sized measurements for creating the wind profile. It also demonstrates how to obtain different speed profiles at the same site and for the same month of a different year. This arrangement allows for the compilation of different roughness and friction coefficients for the same site. This paper also entails a full study case presentation for the site located in the Mexican state of Zacatecas and where the wind speed measurements were extrapolated with a view to estimate the wind power at a specific height.

Analysis and validation of the methodology used in the extrapolation of wind speed data at different heights

For many centuries to date, wind energy has been used as a source of power for a whole host of purposes. In early days it was used for sailing, irrigation, grain grinding, etc. At the onset of the 20th century, wind energy was put to work on a different use: power generation and electricity-generating wind turbines were produced. Wind turbines do convert the wind renewable energy into electricity, thus becoming a clean and sustainable power generation alternative. There is a large number and wide assortment of wind turbines which, over time, have evolved in its two key areas: capacity and efficiency. The evolution of wind turbines has been boosted thanks to the growing awareness on environmental issues which in turn stems from an equally growing concern over conventional fossil fuel energy sources. Furthermore, high oil prices and other financial incentives are also bearing their respective weights on the issue. Large scale wind turbines in the range 4 to 10 MW are now being developed and used for equipping large-scale wind farms worldwide. The power developed with wind generators depends on several factors with the noteworthy ones being the height above the ground level, the humidity rating and the geographic features of the area but the chief factor is the wind speed. Therefore, the first step in ascertaining the energy that can be produced and the effects of a wind farm on the overall electricity network calls for a thorough understanding of wind itself. There are different methods used in estimating the wind potential. This paper is aimed at presenting the impact of various methods and models used for extrapolating wind speed measurements and generate a relevant wind speed profile. The results are compared against the real life wind speed readings. Wind resource maps come as a plus factor.

/pdf/methodologies-used-in-the-extrapolation-of-wind-speed-data-gkzt1r665z.pdf

Methodologies Used in the Extrapolation of Wind Speed Data at Different Heights and Its Impact in the Wind Energy Resource Assessment in a Region

Models for high voltage DC-voltage source converter (HVDC-VSC) controllers suitable for direct incorporation into Newton-Raphson power flow algorithms are presented. The models are developed from first principles, starting with a simple VSC model and progressing to encompass the full HVDC-VSC link model. The applied modelling approach is modular in nature and in addition to the shunt-connected voltage source model, which may be used to represent a STATCOM, a series-connected voltage source model is also developed. This enables significant modelling flexibility since by suitably combining shunt and/or series voltage sources several VSC-based flexible AC transmission system (FACTS) controller models are realised quite straightforwardly, namely the back-to-back HVDC-VSC, the full HVDC-VSC link and the unified power flow controller. Attention is focused on the HVDC-VSC models. The models are implemented into an existing OOP power flow computer program written in C++ that incorporates a wide portfolio of FACTS models. The models are tested for reliability towards the convergence and accuracy of results using several power systems with varying degrees of operational complexity and power flow control requirements.

Inclusion of a high voltage DC-voltage source converter model in a Newton-Raphson power flow algorithm

http://www.scielo.org.mx/pdf/jart/v15n1/2448-6736-jart-15-01-36.pdf

César Angeles-Camacho

Papers

FACTS: Modelling and Simulation in Power Networks

Analysis and validation of the methodology used in the extrapolation of wind speed data at different heights

Methodologies Used in the Extrapolation of Wind Speed Data at Different Heights and Its Impact in the Wind Energy Resource Assessment in a Region

Inclusion of a high voltage DC-voltage source converter model in a Newton-Raphson power flow algorithm

Technical comparison of FACTS controllers in parallel connection