A survey on fopid controllers for lfo damping in power systems using synchronous generators, facts devices and inverter-based power plants

In recent decades, various types of control techniques have been proposed for use in power systems. Among them, the use of a proportional–integral–derivative (PID) controller is widely recognized as an effective technique. The generalized type of this controller is the fractional-order PID (FOPID) controller. This type of controller provides a wider range of stability area due to the fractional orders of integrals and derivatives. These types of controllers have been significantly considered as a new approach in power engineering that can enhance the operation and stability of power systems. This paper represents a comprehensive overview of the FOPID controller and its applications in modern power systems for enhancing low-frequency oscillation (LFO) damping. In addition, the performance of this type of controller has been evaluated in a benchmark test system. It can be a driver for the development of FOPID controller applications in modern power systems. Investigation of different pieces of research shows that FOPID controllers, as robust controllers, can play an efficient role in modern power systems

Design of a Computer Code To Evaluate the Influence of the Harmonics in the Electrical Networks

This paper aims to present the design of a computer code (HPFCODE), forcalculate a power flow and power losses in power systems under theinfluence of harmonics, using the GUI in MATLAB. After described theprogram was run for two networks IEEE 6 nodes and IEEE 14 nodes. Thepower flow by Newton-Raphson method was calculated as the losses ofactive and reactive power in the lines, respectively, where the loads arelinear and nonlinear (Static Var Compensator(SVC), Thyristor controlledReactor(TCR), and Unified Power Flow Controller ((UPFC)), The resultswere almost consistent and show the influence of higher harmonics onpower losses in electrical networks.DOI:http://dx.doi.org/10.11591/ijece.v2i5.146

Phase domain modelling and simulation of large-scale power systems with VSC-based FACTS equipment

Most of the analysis techniques available for planning and operation of multiphase power systems are based upon the assumption that the network operates under perfectly balanced conditions. The advantage of this assumption from the modelling view point is that only one phase of the three phase system needs to be considered for analysis, resulting in a reduced size of the problem at hand. However, the phase frame of reference offers a more general representation for the solution of power system problems than the frame of reference provided by the sequences. The former can accommodate networks containing any degree of unbalance whilst the latter is only applicable to power networks exhibiting perfect or near-perfect impedance balance between phases. The thesis reports on the development of steady state and time domain models of Flexible AC Transmission System (FACTS) controllers in the natural framework of electric systems, i.e. namely the phase co-ordinates domain. The FACTS equipment selected for analytical development in this research are: the static synchronous compensator (STATCOM), the static synchronous series compensator (SSSC), the unified power flow controller (UPFC) and the high-voltage direct current (HVDC). These power electronics-based controllers have the voltage source converter as their main constituent. The combined solution of both steady state and dynamic power flow equations pertaining to the VSC-based FACTS controllers and the power network are fully described in the thesis. The steady-state mathematical models of VSC-based FACTS controllers are formulated in nodal form using the frame of reference of the phases. Guidelines for their implementation into two distinct power flows algorithm namely, the Newton-Raphson in polar co-ordinates and the Newton-Raphson in rectangular coordinates are given. For the purpose of long-term dynamic assessment, a simultaneous solution using implicit trapezoidal integration method with Newton iteration is used to solve the set of differential-algebraic equations of generating plants and network components. In order to assess both the steady state and the dynamic behaviour of the models developed, a comprehensive, newly developed integrated software environment is used

A novel single-phase inverter with distribution static compensator capability for wind applications

The modular multilevel converter (MMC) is an attractive topology for HVDC/FACTS systems. In this paper a new single-phase MMC-based D-STATCOM inverter for grid connection is proposed. The proposed inverter is designed for grid-connected wind turbines in the small- to mid-sized (10kW-20kW) range using the most advanced multi-level inverter topology. The proposed MMC D-STATCOM inverter controls the DC link voltage as well as the active and reactive power transferred between the renewable energy source, specifically wind turbine, and the grid in order to regulate the power factor (PF) of the grid regardless of the input active power from wind turbine. The goal of this paper is to present a new inverter with FACTS capability in a single unit without any additional cost. The 5-level D-STATCOM inverter is simulated and the results are presented to verify the operation of the proposed system. The simulation studies are carried out in the MATLAB/Simulink environment. To validate the simulation results, an experimental configuration of a 5-Level MMC D-STATCOM inverter has been built and tested

A novel approach for coordinated design of TCSC controller and PSS for improving dynamic stability in power systems

The purpose of this article is to present a novel strategy for the coordinated design of the Thyristor Controlled Series Compensator (TCSC) controller and the Power System Stabilizer (PSS). A time domain objective function that is based on an optimization problem has been defined. This objective function takes into account not only the influence that disturbances have on the mechanical power, but also, and this is more accurately the case, the impact that disturbances have on the reference voltage. When the objective function is minimized, potential disturbances are quickly mitigated, and the deviation of the speed of the generator's rotor is limited; as a result, the system's stability is ultimately improved. Particle Swarm Optimization (PSO) and the Shuffled Frog Leaping Algorithm are both components of a composite strategy that is utilized in the process of determining the optimal controller parameters. (SFLA). An independent controller design as well as a collaborative controller design utilizing PSS and TCSC are developed, which enables a direct evaluation of the functions performed by each. The presentation of the eigenvalue analysis and the findings of the nonlinear simulation can help to provide a better understanding of the efficacy of the outcomes. The findings indicate that the coordinated design is able to successfully damp low-frequency oscillations that are caused by a variety of disturbances, such as changes in the mechanical power input and the setting of the reference voltage, and significantly enhance system stability in power systems that are connected weekly

Analysis and robust decentralized control of power systems using FACTS devices

Today\u27s changing electric power systems create a growing need for flexible, reliable, fast responding, and accurate answers to questions of analysis, simulation, and design in the fields of electric power generation, transmission, distribution, and consumption. The Flexible Alternating Current Transmission Systems (FACTS) technology program utilizes power electronics components to replace conventional mechanical elements yielding increased flexibility in controlling the electric power system. Benefits include decreased response times and improved overall dynamic system behavior. FACTS devices allow the design of new control strategies, e.g., independent control of active and reactive power flows, which were not realizable a decade ago. However, FACTS components also create uncertainties. Besides the choice of the FACTS devices available, decisions concerning the location, rating, and operating scheme must be made. All of them require reliable numerical tools with appropriate stability, accuracy, and validity of results. This dissertation develops methods to model and control electric power systems including FACTS devices on the transmission level as well as the application of the software tools created to simulate, analyze, and improve the transient stability of electric power systems.;The Power Analysis Toolbox (PAT) developed is embedded in the MATLAB/Simulink environment. The toolbox provides numerous models for the different components of a power system and utilizes an advanced data structure that not only increases data organization and transparency but also simplifies the efforts necessary to incorporate new elements. The functions provided facilitate the computation of steady-state solutions and perform steady-state voltage stability analysis, nonlinear dynamic studies, as well as linearization around a chosen operating point.;Applying intelligent control design in the form of a fuzzy power system damping scheme applied to the Unified Power Flow Controller (UPFC) is proposed. Supplementary damping signals are generated based on local active power flow measurements guaranteeing feasibility. The effectiveness of this controller for longitudinal power systems under dynamic conditions is shown using a Two Area - Four Machine system. When large disturbances are applied, simulation results show that this design can enhance power system operation and damping characteristics. Investigations of meshed power systems such as the New England - New York power system are performed to gain further insight into adverse controller effects

Research on the power grid operation improvement by static VAR compensators

U radu je istražen utjecaj statičkog VAR kompenzatora na naponske prilike i tokove jalovih snaga u Hrvatskoj prijenosnoj mreži. Istraživanje je provedeno između TS Melina–RHE Velebit–TS Konjsko i to u uvjetima niskih i visokih opterećenja sustava, te su utvrđene mogućnosti povećanja prijenosne moći postojećih visokonaponskih vodova kroz regulaciju i upravljanje tokova jalovih snaga u mreži. Današnji stupanj industrijalizacije i razvoja životnog standarda stanovništva iziskuje izrazito velike količine električne energije, što predstavlja veliki problem postojećim prijenosnim sustavima kao nedovoljno snažnim da zadovolje rastuće potrebe i zahtjeve kupaca. Ključni parametri za rješavanje navedenih problema su prijenosna moć voda, stabilnost napona i kompenzacija jalove snage, a povećanje i regulaciju istih moguće je ostvariti uz pomoć SVC uređaja.The paper investigates the impact of a static VAR compensator on voltage circumstances and reactive power flows in a Croatian power transmission grid. The research has been conducted between Melina SS–reversible Velebit HEPP–Konjsko SS under low- and high-load conditions of the system. During the research, the possibility of higher transfer capability of the existing HV overhead lines was identified through the reactive power flow control on the grid. Today\u27s degree of industrialization and the living standards require exceptionally high quantities of electric energy, which is a great problem for the existing transmission systems having insufficient capacity to meet the increasing needs and demands of customers. The key parameters for solving the problems are the line transfer capability, voltage stability and reactive power compensation, which could be improved in terms of their high capabilities and better control by means of SVC devices

Lost-Phase and Short-Circuit Impacts on Electrical Network Managed by a Dual IPCs 30P15

This work evaluates the impact of short-circuit and the phase-lost in a particular transmission network located in south division in Cameroon (Central Africa). This network is precisely located between two towns called Songloulou and Logbaba (douala Town). The chosen network is modelled in Matlab Simulink software. Further, the network currents and voltages undergo non periodical distortions when short-circuit and phase lost come into play. Those distortions are deleted when dual controllers’ system is introduced and the network is stabilized. It appears that dual IPCs (interphase power controllers) present good results. However, the dual system which is a combination of two IPCs improves the network stability. The investigation of dual IPCs’ system uses the phase shift method

Five-Level Flying Capacitor Converter used as a Static Compensator for Current Unbalances in Three-Phase Distribution Systems

This thesis presents and evaluates a solution for unbalanced current loading in three-phase distribution systems. The proposed solution uses the flying capacitor multilevel converter as its main topology for an application known as Unbalanced Current Static Compensator. The fundamental theory, controller design and prototype construction will be presented along with the experimental results. The Unbalanced Current Static Compensator main objective is the balancing of the up-stream currents from the installation point to eliminate the negative- and zero-sequence currents originated by unbalanced single-phase loads. Three separate single-phase flying capacitor converters are controlled independently using a d-q rotating reference frame algorithm to allow easier compensation of reactive power. Simulations of the system were developed in MATLAB/SIMULINK™ in order to validate the design parameters; then, testing of the UCSC prototype was performed to confirm the control algorithm functionality. Finally, experimental result are presented and analyzed