Power Flow Controller Research Articles

Hierarchical Energy Management of Networked Flexible Traction Substations for Efficient RBE and PV Energy Utilization Within ERs

The particular split-phase traction power system of AC electrified railways (ERs) restricts its regenerative braking energy (RBE) utilization and photovoltaic (PV) penetration. Networked flexible traction substation (FTSS) operation is a promising paradigm to address this restriction. Therefore, this paper proposes a networked FTSS system architecture that ties adjacent FTSSs via unified power flow controllers (UPFC) at sectioning posts (SPs), which matches the technical characteristics of split-phase ERs obtaining the lower capacity requirement. Correspondingly, a real-time hierarchical energy management strategy is designed. The networked FTSS management level optimizes the energy cooperation among FTSSs, i.e., the exchange power at SPs. It aims at maximizing the global RBE and PV energy utilization and shaving the maximum demand of each FTSS. At the individual FTSS management level, each FTSS autonomously regulates the power outputs of the local back-to-back converter and energy storage system to maximize the local RBE and PV energy utilization and improve the local power quality issues. These two energy management levels operate independently with different time scales, making the networked FTSS system have good extensibility and reliability. Finally, the performance of the proposed scheme is verified via hardware-in-the-loop tests.

Implementation of Grid-Connected Wind Energy during Fault Analysis Using Moth Flame Optimization with Firebug Swarm Optimization

In modern trends, the voltage profile has become increasingly critical when incorporating wind turbine energy sources because of changes in fault ride-through capabilities throughout voltage reaction. Ripple, voltage magnitude changes, and injected harmonics due to conversion switches are power quality issues for grid-integrated doubly fed induction generators (DFIG) wind sources. In this study, FACTS (flexible alternating current transmission system) devices like the static VAR compensator (SVC), thyristor controlled series compensator (TCSC), unified power flow controllers (UPFC), and static synchronous compensators (STATCOM) are used to stabilise wind energy with DFIGs. The simulation test cases using MATLAB also analyse three lines to ground fault (LLL-G) of fault measures, which showed a 9 MW that transferred to utility grid. Therefore, it is suggested to inject or absorb reactive power to stabilise the system using moth flame optimization with firebug swarm optimization (MFO-FSO). The simulation results clearly demonstrate that the proposed MFOFSO based STATCOM devices outperform the current nonlinear generalized predictive control based STATCOM, which only achieves 0.9815 per unit voltage stability, by achieving a higher voltage profile of 0.9925 per unit voltage stability with a reactive power injection of 1.82 MVAR.

Reliability Improvement of Composite Power System using UPFC

Together with quality power supply criteria, Composite Power System (CPS) reliability is also one of the important aspects of deciding the security of the CPS for a given load demand. In the current paper, the reliability of CPS is evaluated. The Newton Raphson (NR) approach is implemented in Power System Simulation for Engineering (PSSE) software to take into account, the load flows, then the power available to the load points, to evaluate the reliability of CPS. Newton Raphson NR Method was implemented by considering different contingencies of the CPS. Power available to the load points obtained by the NR method is critical in identifying the successful operating state of the CPS. Expected Load Curtailment (ELC), Number of Load Curtailment (NLC), Expected Energy Not Supplied (EENS), and Severity Index (SI) are the crucial dependability indices that are assessed. The main objective of the Reliability evaluation of the CPS is to investigate the scope for the improvement of reliability and explore the possible schemes to improve CPS reliability. The Unified Power Flow Controller (UPFC) one of the Flexible AC Transmission Systems is incorporated into the CPS to analyze the improvement in the reliability of the system. Further, the effect of UPFC on the power-carrying capacity of the lines under contingency conditions, resulting in the failure mode of CPS operation is examined. Improvement in the reliability indices of the system is observed due to UPFC incorporation.

Enhancing power system security using soft computing and machine learning

Purpose. To guarantee proper operation of the system, the suggested method infers the loss of a single transmission line in order to calculate a contingency rating. Methods. The proposed mathematical model with the machine learning with particle swarm optimization algorithm has been used to observe the stability analysis with and without the unified power flow controller and interline power flow controller, as well as the associated costs. This allows for rapid prediction of the most affected transmission line and the location for compensation. Results. Many contingency conditions, such as the failure of a single transmission line and change in the load, are built into the power system. The single transmission line outage and load fluctuation used to determine the contingency ranking are the primary emphasis of this work. Practical value. In order to set up a safe transmission power system, the suggested stability analysis has been quite helpful.

An accurate power control strategy for electromagnetic rotary power controllers

AbstractWith the rapid development of active distribution networks, the “petal”‐type distribution network has become the mainstream power supply structure. Power control methods for active distribution networks should be further studied to ensure the safe and reliable power supply of a distribution system. An electromagnetic rotary power flow controller (RPFC) is a feasible solution for controlling power in active distribution networks. However, when testing the effectiveness of the PQ decoupled control method for RPFC based on instantaneous reactive power theory, difficulties were encountered with the synchronous control of the rotor position angle of two rotating‐phase transformers, and the accuracy of power control was unsatisfactory. Given this condition, PQ control is improved in three ways. First, the system's periodic oscillation problem is solved via variable speed control. Second, the servo motor‐rotary phase‐shifting transformer synchronous rotation scheme, which reduces power control error and improves stability, is designed. Third, the overshoot phenomenon in power control is improved using the variable‐domain fuzzy proportional‐integral adaptive method. Experimental results show that the proposed advanced control scheme exhibits good dynamic and static performance in power control scenarios and achieves effective improvement in RPFC.

Power quality enhancement of solar–wind grid connected system employing genetic-based ANFIS controller

Abstract The demand for electricity globally has led to the search for renewable energy resources for power generation and attaining it in an eco-friendly manner. The solar photovoltaic systems and wind-based generators of power are regarded as primary resources of renewable energy and are called Distributed Generation units as they are scattered in nature. These are operated with bidirectional converters by providing auxiliary services at grid side and load side in either mode of microgrid operation. Besides, the DC power generation units’ integration gets converted into AC system by means of inverters. These types of systems not only increase voltage and current harmonics and power frequency deviations but also drive the distribution system to risky operating zone. This emphasizes the stipulation of advanced control schemes for microgrid architecture. Consequently, power electronic converters introduce harmonics in the system and affect system performance. To report these expanded issues, the authors recognized an advanced custom power device entitled Distributed Power Flow Controller (DPFC). In this study, the proposed system on solar–wind-based hybrid energy approach has been examined primarily through the strategy of DPFC mechanism. Later, the system has been examined with Genetic Algorithm (GA)-based fuzzy logic controller and GA-based adaptive neuro fuzzy inference system controller for shunt control of context built with DPFC mechanism. Furthermore, the validated results are verified using MATLAB/Simulink software.

DER integrated BTB-VSI based DSTATCOM for PQ enhancement

ABSTRACT This article demonstrates the performance of back-to-back connected voltage source inverter (BTB-VSI)-based distribution static compensator (DSTATCOM). In the proposed system, a three-phase three wire electrical utility system (EUS) is integrated with distributed energy resources (DER) through BTB-VSI. It has drawn more attention due to enhanced active power filtering, simple design procedure and performs reliable operation. The objectives of the research work is to provide clean power for weak EUS with improved power quality (PQ) such as, better voltage regulation, improved power factor (P.F), reduced total harmonic distortion (THD), balanced voltage at point of common coupling (PCC) and better optimal active power flow control (OAPFC), and so on. An artificial neurocontrol technique Kernel Hebbian Least Mean Square (KHLMS) is chosen to determine the accurate reference source current for operation of voltage source inverter (VSI). The BTB-VSI performance is investigated on both shunt compensation and OAPFC. The proposed system is converted to a simulation model and hardware unit using MATLAB/Simulink software and SPARTAN−6 field programmable gate arrays (FPGA) controller. Finally, the Simulation and experimental results illustrate that the shunt compensating ability with OAPFC of BTB-VSI performs better over VSI as per IEEE Std 1159–2019 grid code.

An intelligent fault detection and classification technique based on variational mode decomposition-CNN for transmission lines installed with UPFC and wind farm

The output voltage and current signals of grid-connected doubly-fed induction generator (DFIG)-based wind turbine generators (WTGs) are significantly modulated during grid disturbances. Consequently, the performance of conventionally used distance relaying-based transmission line (TL) protection schemes are affected. The problem becomes further complicated when the interconnected TLs are compensated with unified power flow controller (UPFC). In this paper, an intelligent relaying scheme is proposed for efficient detection and classification of faults in such crucial TLs. In the proposed method, the suitable features are extracted from the locally measured current signals using variational mode decomposition (VMD). The main advantage of VMD is that it can extract the different frequency components of a faulted current signal adaptively with fast convergence. The extracted gray-scale images through VMD are utilized further by the deep convolution neural network (CNN) classifier for effective classification of faults. The efficacy of the proposed relaying algorithm is evaluated on 12000 fault and 120 non-fault cases generated on a system comprising of DFIG-wind farm and UPFC compensation using MATLAB/Simulink® and real time digital simulation platform (OP4510). The fast fault detection time (¡10 ms), high accuracies in the fault detection and classification (100% and 99.86%) justify the merits of the proposed relaying scheme.

Design and simulation of monarch butterfly optimized SP-UPFC for power quality compensation

The super smart gridsare a kind of broad-area transmission network, which makes use of Flexible AC transmission system (FACTS)and helps to reduce greenhouse gas emissions while also maintaining the electricity infrastructure of various nations. The six-phase unified power flow controller (SP-UPFC) is a FACTS device that offers total stability to power system networks in the form of series and shunt compensations. The power quality compensation (PQC) operation using SP-UPFC is achieved by adopting the monarch butterfly optimization (MBO) algorithm. Here, shunt converters and series converters of parallel and series connection units are kept in sync with the help of master-slave synchronization. In addition, a coordination strategy is created for the SP-UPFC control protection system and the power grid protection, which improves the ride-through capability during a failure. In comparison to state-of-the-art methods, the simulation results reveal that the proposed MBO-optimizedSP-UPFC decreases total harmonic distortion (THD) and increases power factor.

Optimized Power Flow Control to Minimize Congestion in a Modern Power System

The growing integration of renewable energy sources (RES) into the power system causes congestion to occur more frequently. In order to reduce congestion in the short term and to make the utilization of the power system more efficient in the long term, power flow control (PFC) in the transmission system has been proposed. However, exemplary studies show that congestion will increase also in the distribution system if the transmission system is expanded. For this reason, the potential of PFC to reduce congestion in a model of a real 110 kV distribution system is investigated. Several Unified Power Flow Controller (UPFC) devices are optimized in terms of their number and placement in the power system, their size, control parameters, and costs, by using a Parallel Tempering approach as well as a greedy algorithm. Two optimization variants are considered, one reducing the number of degrees of freedom by integrating system knowledge while the other does not. It is found that near a critical grid state and disregarding costs, PFC can reduce congestion significantly (99.13%). When costs of the UPFCs are taken into account, PFC can reduce congestion by 73.2%. A basic economic analysis of the costs reveals that the usage of UPFCs is profitable. Furthermore, it is found that the reduction in the solution space of the optimization problem leads to better results faster and that, contrary to expectations, the optimization problem is simple to solve. The developed methods allow not only for the determination of the optimal use of UPFCs to minimize congestion, but also to estimate their profitability.

Loss reduction of transmission lines using PSO-based optimum performance of UPFC

Transmission line losses are one of the essential topics and issues in power systems research. Several methods and techniques have been used to reduce these losses, and one of these modern techniques is flexible alternating current transmission systems (FACTS). In this paper, one of the most important types of this technology, the unified power flow controller (UPFC), was used to reduce losses in the Iraqi national grid (ING) 400 kV. This paper presents an efficient method for minimizing losses of transmission lines in the ING system (400 kV) 46-bus approach. A particle swarm optimization (PSO)-based optimum proportional-integral (PI) controller with UPFC was proposed to obtain the optimal location of UPFC and optimum parameters of the PI controller to achieve the objective function of the research. MATLAB coded the algorithm. The Newton-Raphson method was employed to perform load flow analysis. The results showed that the best place for UPFC is buses (14-17) named BGE4 (Baghdad)-AMN4 (Baghdad), and the total active power and reactive power losses decreased from 727.4593 to 579.3874 MW and from 5155.9 to 3971.1 MVAR, respectively and also led to voltage regulation.

Optimal design and performance analysis of Rotating Power Flow Controller

In this paper, a scheme of rotating power flow controller (RPFC) is proposed, which can flexibly and effectively reduce the voltage deviation under the disturbance of distributed generation and load side. Firstly, based on the prototype of a new rotating power flow controller (RPFC) with a rated capacity of 40 kVA, a two-dimensional finite element model based on the core component RPST is established. Then the optimal parameter combination in RPST is determined by the Taguchi experiment method and weight calculation. Finally, Matlab, Maxwell, and Simplorer are used to realize the joint simulation of field-circuit coupling. The results show that the voltage regulation efficiency and power factors of RPFC are increased by 1.4% and 2.7% respectively under the optimal parameter combination, which provides a reference for the design and engineering application of large-capacity RPFC.

Power Flow Improvement by Designing and Simulating a Unified Power Flow Controller with Solar Power: A Case Study

Power Flow Improvement by Designing and Simulating a Unified Power Flow Controller with Solar Power: A Case Study

Performance Enhancement of Grid-Connected Renewable Energy Systems Using UPFC

No one denies the importance of renewable energy sources in modern power systems in terms of sustainability and environmental conservation. However, due to their reliance on environmental change, they are unreliable systems. This paper uses a Unified Power Flow Controller (UPFC) to enhance the reliability and performance of grid-tied renewable energy systems. This system consists of two renewable sources, namely photovoltaic cells (PV) and wind turbines (WTs). The UPFC was selected for its unique advantage in both active and reactive power control. The UPFC is controlled with an optimized Fractional Order Proportional–Integral–Derivative (FOPID) controller. The parameters of this controller were tuned using an Atomic Search Optimization (ASO) algorithm. Simulation results confirm the efficiency of the suggested controller in supporting the reliability and performance of the hybrid power system during some disturbance events including voltage sag, swell, and unbalanced loading. In addition, power quality can be improved through reducing the total harmonic distortion. It is worth mentioning that two maximum point tracking techniques had been included for the PV and WT systems separately. MATLAB/SIMULINK 2021a software was used to model the system.

Congestion Management of Power Systems by Optimal Allocation of FACTS devices using Hybrid Techniques

For system operators, Congestion management is a difficult task as the market’s security and reliability are protected by this methodology. As the magnitude of an electric transmission system is extremely dynamic, limits must be estimated much beforehand, in order to manage the congestion issues at the right time. Flexible AC transmission systems (FACTS) are used to control voltage fluctuation by adjusting the system's real and reactive power. A combination of Improved Remora Optimization (IRO) and Improved Radial Basis Function (IRBF) is used to allocate positions and sizes of the FACTS devices. In this study, Static Synchronous Compensator (STATCOM), Interlink Power Flow Controllers (IPFC) and Unified Power Flow Controllers (UPFC) are among the FACTS devices used. In the proposed hybrid IRO-IRBF technique, following are the functional aims calculated: build-on-expenditure, Line Loading (LL), Total Voltage Deviation (TVD) and real power loss. Additionally, the hybrid IRO-IRBF technique is used to confirm the proper location using the IEEE 30 bus structure. TVD, power loss, installation costs, and line loading are the measurements used to assess the implementation performance of the hybrid IRO-IRBF approach. From the result analysis, the hybrid IRO-IRBF achieved a real power loss of 0.1591 p.u., and TVD of 0.02 p.u., which is lesser than the existing Whale Optimization Algorithm and Mayfly Optimization Algorithm.

Investigation of the impact of PSO, ABC, BFO and Cuckoo search optimization techniques on UPFC device for sustainable voltage stability margin improvement

This paper investigates the enhancement of voltage stability margin using Unified Power Flow Control (UPFC) device tuned with Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC), Bacterial Foraging Optimization (BFO) and Cuckoo Search techniques (CS) on Nigerian 330 kV 56-bus practical network. In order to have a voltage stable power system, it is good to keep voltages within the acceptable limits. This is achieved using continuation power flow embedded in Power System Analysis Toolbox (PSAT). The optimal location and tuning of the UPFC device is determined using line stability index and the met-heuristics techniques. The effects of UPFC and the proposed optimizing techniques on voltage stability margin are examined. The results so obtained for tuning PSO, ABC, BFO and Cuckoo Search with UPFC device are compared to know the technique that yields the best loading parameter for Nigerian 56- bus power system for voltage stability margin enhancement. It is found that UPFC tuned with Cuckoo Search outperforms the other techniques in terms of the increased loading parameter of the Nigerian power system with margin improvement of 86.6%, 90% and 88.6% for Adiabor (Bus 45), Jalingo (Bus 34) and Jos (Bus 13). The tuned UPFC device has proved beyond reasonable doubt that it can improve voltage stability margin of the entire Nigerian 330 kV Network as envisaged from results before and after optimization.

Two-area power system stability analysis by frequency controller with UPFC synchronization and energy storage systems by optimization approach

AbstractAn optimization approach for two-area power system with Unified Power Flow Controller (UPFC) is proposed in this paper. The proposed method is the Atomic Orbital Search (AOS) approach. The proposed approach is applied to achieve full utilization of UPFC and keeps the parameters uncertain. The multivariable PI controller is utilized to control the system controller and eliminates the negative interaction of the controllers. The proposed approach combines the two subsystems by converting algebraic subsystem using differential approximation, which leads to a nonlinear system. The proposed approach provides efficient voltage regulation and quicker damping of inter-area mode oscillations. The proposed UPFC controller eliminates generator oscillation and fault condition, which guarantee the stability of the system as well as provides dynamic power flow control under the tie-line. At last, the proposed method is simulated on MATLAB platform and compared with existing methods. From this comparison, it is shown that the proposed approach provides less oscillation than the existing approach.

Stability analysis of improved combined-mode power converter and power flow control using FPGA

ABSTRACT An improved combined-mode power converter (CMPC) for a solar photovoltaic (SPV) system is presented in this paper. Ten-power electronic switches are utilised for the functioning of the converter. The proposed converter has four modes of operation: buck, boost, inverter, and mixed mode. The new CMPC topology provides a unique and complex switching sequence for implementing the mixed-mode operation. This work uses a field-programmable gate array (FPGA) for mode selection and to create PWM (MS-PWM) signals. A digital MS-PWM controller is configured to switch between improved stepped perturb and observe (ISPO) maximum-power point tracking (MPPT) and sine wave PWM (SPWM). The ISPO provides the appropriate duty cycle for buck/boost operation, while the SPWM controls the inverter operation. This work’s new digital PWM control algorithm supports mode selection, PWM generation, and reconfiguring PWM generation timings. The whole framework for constructing the MS-PWM controller employs a very high-speed integrated circuit hardware description language (VHDL). Simulation and experimental results are presented, proving that the digital MS-PWM controller uses fewer resources with improved accuracy.

A Multiport DC Power Flow Controller Embedded in Modular Multilevel DC Transformer

Meshed dc or hybrid ac/dc distribution grids have attracted increasing interest lately and their power flow control is a major topic of study. Since the dc grids implemented with existing power converters lack sufficient control freedoms for proper power flow adjustment, it is necessary to develop new dc power flow controllers (DCPFCs) to effectively mitigate power flow congestion and line losses by optimizing the power flow of the connected feeders. Unlike previously introduced solutions, this paper proposes a DCPFC directly integrated in a modular multilevel dc transformer (M²DCT). The proposed DCPFC does not require external power supply and high-voltage isolation transformer, and features a simple structure, convenience for multiport extension and bidirectional power flow adjustment capability. The power flow control strategy and its energy balance scheme based on phase-shifted modulation are elaborated. The proposed topology and its performance are verified through a scaled-down experimental platform under typical operating conditions.

Comprehensive review on control schemes and stability investigation of hybrid AC-DC microgrid

The utility grid integration of distributed generation units is seen as one of the most accomplished through the use of microgrid. Control methods and stability analyses in the microgrid are continuously being investigated in the field of hybrid microgrid. The most reviewed control method is hierarchical control, consisting of primary, secondary, and tertiary layers. This paper reviews multiple schemes of primary control for current or voltage regulation, secondary control for voltage or current error correction, power-sharing in microgrid, and tertiary control for power flow and energy management in a hybrid microgrid system. Additionally, this study examines the benefits and drawbacks of several control architectures that function as distributed, centralized, and decentralized controls. The principle of operation and effectiveness of each microgrid architecture control method have been discussed. Specific control factors are investigated in this paper, including mode transition and coordinated control between numerous interlinking converter and energy storage systems. System stability is the main concern of microgrid for system engineer thorough knowledge of control strategies is the upmost requirement. Thus, this paper highlights control strategies, rotor angle, voltage and frequency instability in power systems, and methods for improving stability in microgrid are also reviewed.