Unified Power Flow Controller Controller Research Articles

Power quality enhancement in the wind energy distribution system using HHO algorithm based UPFC

ABSTRACT This study proposes using a Wind Energy Conversion System (WECS) to power a Unified Power Flow Controller (UPFC) Direct Current (DC) capacitor, maintaining appropriate voltage levels. This arrangement allows UPFC adjustment to improve Power Quality (PQ). The main issue rapid growth of nonlinear loads causes sudden variations in source voltage, resulting in a reduction in power quality within seconds. UPFC is used to address these concerns. This work uses the Harris Hawks Optimizer (HHO) to improve the performance of the UPFC. To begin, the aim function parameters are defined, including voltage, current, active power, and reactive power. Thus, these characteristics are used to generate control pulses for the series and shunt active power filters. HHO is used to find the best solution and predict the ideal UPFC control signal. Additionally, voltage instability and power dissipation decrease under different load conditions. Thus, system power supply quality improves. To evaluate the effectiveness of the proposed technique, two scenarios were identified: fault circumstances and engine speed changes. MATLAB/Simulink was used to implement the suggested strategy and compare it to established methodologies like Grey Wolf Optimization (GWO), Modified Particle Swarm Optimization (MPSO), and Whale Optimization Algorithm (WOA).

OPTIMAL LOCATION OF AN IDEAL TRANSFORMER UPFC MODEL USING OPF FIRST-ORDER SENSITIVITIES

This paper presents a screening technique for greatly reducing the computation involved in determining the optimal location of a unified power flow controller (UPFC) in a power system. The first-order sensitivities of the generation cost with respect to UPFC control parameters are derived. This technique requires running only one optimal power flow (OPF) to obtain UPFC sensitivities for all possible transmission lines. To implement a sensitivity-based screening technique for guidance in optimally locating a single UPFC in a power system, we propose a new UPFC model, wrach consists of an ideal transformer with a complex turns ratio and a variable shunt admittance. In this model, the UPFC control variables do not depend explicitly on UPFC input and output currents and voltages. Accordingly, this model does not require adding extra buses for UPFC input and output terminals. IEEE five-, 14- and 30-bus systems were used to frustrate the technique. Index Terms-Flexible ac transmission systems (FACTS), FACTS location, first-order sensitivity, optimal power flow (OPF), screening technique, unified power flow controller (UPFC), UPFC ideal transformer model, UPFC placement, UPFC uncoupled model. This study focuses on the development of an Ideal Transformer Unified Power Flow Controller (UPFC) model and its integration with Optimal Power Flow (OPF) first-order sensitivities analysis for determining optimal UPFC locations in power systems. The abstract outlines the significance of UPFCs in enhancing power system stability and efficiency by controlling voltage and power flow. It highlights the objectives of the research, including the development of the UPFC model, analysis of OPF first-order sensitivities, and their combined application for screening optimal UPFC locations. The study aims to contribute to the improvement of power system operation and control through strategic UPFC placement. The abstract provides a concise overview of the study, summarizing the key aspects of the research. It outlines the development of an ideal transformer Unified Power Flow Controller (UPFC) model, the analysis of Optimal Power Flow (OPF) first-order sensitivities, and their application in determining optimal locations for UPFC installation in power systems

Control and Protection of Medium Voltage Distribution Network Based on Unified Power Flow Controller

The integration of diverse load types, such as large-scale distributed generators and charging stations, presents considerable challenges to distribution networks. The Unified Power Flow Controller (UPFC) provides multiple benefits, including its compact dimensions, cost efficiency, seamless regulation, and swift response. When deployed in distribution networks, the UPFC facilitates the creation of a Distribution Unified Power Flow Controller (DUPFC) system. The DUPFC system enhances medium voltage distribution network regulation but also affects power quality, fault characteristics, and relay protection accuracy. To address these issues, a power flow equivalent circuit model for the medium voltage distribution loop network was developed. The operating principle and steady-state model of the UPFC were investigated, based on distribution loop network parameters and power flow distribution characteristics. A UPFC control strategy was designed to create a suitable DUPFC system for the medium voltage distribution loop network, ensuring coordination between UPFC protection and the distribution system’s protection mechanisms. This system accomplishes rapid fault isolation and automatic load transfer. Finally, a simulation model based on a typical 20 kV distribution loop network structure was selected to validate the effectiveness of the UPFC control strategy and the DUPFC protection system in MATLAB/Simulink.

Non-Linear Synergetic Control of UPFC for Efficient Damping of Local and Inter-Area Oscillations

This paper suggests a novel non-linear synergetic control for a unified power flow controller (UPFC). UPFC is a member of flexible AC transmission system devices, that controls power flow and regulates the voltage by enhancing the transient stability of the power system. UPFC comprises of two voltage source converters (VSCs). Equations of VSC are inherently non-linear. In this paper, we propose a non-linear approach to control the UPFC based on the synergetic control technique. It is simple to implement and valid for a variety of operations. It is also effective in suppressing inter-area oscillations. To verify the effectiveness of the proposed controller, various case studies are simulated and the results are compared with the traditional linear and non-linear controllers.

Novel approach for modeling and attenuation of power waves in large – scale power systems

In this paper modeling and attenuation of electromechanical power waves in large – scale power systems are discussed. Mathematical model of power wave is derived using Euler – Lagrange equation. The proposed modeling procedure is based on kinetic and potential energies of the system, as well as system’s dissipation power. A novel method for incorporation of spatially dependent power losses into Euler – Lagrange equation is defined as well. The obtained mathematical model is simple for derivation, straightforward and practical for use, so it can easily be applied to derive wave equation of other technical systems or natural phenomena as well, which is an additional advantage compared to the existing models. Based on the developed model, an appropriate control system is proposed. The main idea for control system synthesis is to reduce transmitted waves inside the system. It is shown that the series power line impedance and voltage amplitude have the greatest impact on the wave transmission coefficient. Since unified power flow controller (UPFC) is capable of simultaneously modulating both these parameters, this device is chosen to perform control tasks in proposed operation mode. The effectiveness of the proposed solution has been verified by thorough computer simulations on artificial generator array and IEEE benchmark simplified Australian system. The results show significant power wave reduction. Some future works such as derivation of the mathematical model of inverter array or incorporation of artificial intelligence algorithms in UPFC control system based on transmission coefficient reduction might rely on this work.

A hybrid DMO-RERNN based UPFC controller for transient stability analysis in grid connected wind-diesel-PV hybrid system

AbstractIn this paper, a novel hybrid technique is proposed for transient stability analysis on grid connected Wind-Diesel-PV hybrid system. The proposed hybrid methodology is combination of the dwarf mongoose optimization algorithm (DMO) and the recalling enhanced recurrent neural network (RERNN) named DMO-RERNN. The main purpose of this work is to consider various elements on hybrid system for the analysis of transient stability according to different conditions. The voltage profile of hybrid system is enhanced using the proposed unified power flow controller (UPFC), which also has higher performance improving transient performance compared to the conventional ANN, PI and fuzzy-sliding mode controller. Considering the proposed technique, DMO is used to find the optimal global solution for the fault predicted by the RERNN approach. The proposed system is executed on MATLAB work platform; its performance with existing systems is analyzed. The result proves that the proposed hybrid technique based UPFC controller provides better results compared with other existing technique. The efficiency of the PI is 82.136, ANN is 77, Fuzzy Sliding Mode is 65.097% and proposed technique is 97.99038%.

Performance Analysis of Marine-Predator-Algorithm-Based Optimum PI Controller with Unified Power Flow Controller for Loss Reduction in Wind–Solar Integrated System

Transmission line losses are a crucial and essential issue in stable power system operation. Numerous methodologies and techniques prevail for minimizing losses. Subsequently, Flexible Alternating Current Transmission Systems (FACTSs) efficiently reduce transmission losses, and the Unified Power Flow Controller (UPFC) is a reactive power compensation controller. The parameter strength of the proportional–integral (PI) controller was calibrated with the Marine Predator Algorithm (MPA), a recent metaheuristic algorithm. An MPA-based optimum PI controller with a UPFC evaluates the optimal location of the UPFC and PI controller parameters to accomplish the desired research objective. The power rating of the UPFC was determined depending on the voltage collapse rating and power loss and an evaluated performance analysis of the MPA–PI-controlled UPFC on a modified IEEE-30 bus transmission network in MATLAB Simulink code. The Newton–Raphson method was used to perform the load flow analysis. Hence, the proposed MPA–PI controller was examined in contrast to preferred heuristic algorithms, the Artificial Bee Colony (ABC) and Moth Flame Optimization algorithms (MFO); the results showed that the MPA–PI controller exhibited better performance with an improved voltage profile and surpasses active power losses with the optimal placement of the UPFC device under different loading conditions. The active power loss, considering a UPFC with the proposed algorithm, reduced from 0.0622 p.u to 0.0301 p.u; consequently, the voltage profile was improved in the respective buses, and the loss percentage reduction during a 100% base load was 68.39%, which was comparatively better than the ABC and MFO algorithms.

Comparison of Intelligent Control Methods Performance in the UPFC Controllers Design for Power Flow Reference Tracking

The Unified Power Flow Controller (UPFC) is one of such emerging FACTS devices that can manage the power flow in Transportation System. Based on the control system associated with the management of UPFC, both the controllers of shunt and series converters of UPFC are controlled conventionally using PIs controllers. However, the PI system alone cannot control the UPFC in the presence of uncertainty of system parameters and disturbances. For this reason, the use of novel robust techniques based on artificial intelligence theory in the design control of UPFC is very efficient for improving its performances. In this regard, four approaches have been used in this study to replace the conventional PI controller and enhance the performance of the UPFC for power flow reference tracking. In the first approach, the fuzzy logic technique (Mamdani and Sugeno types) has been employed to provide dynamic control of series and shunt converters of UPFC, whereas in the second method, the controllers of UPFC are performed through the optimization techniques such as: PSO, PSO_SQP, and GA techniques. The proposed techniques based UPFC are tested in MATLAB/Simulink software by using UPFC with a 48-pulse voltage source converter (VSC) equipping a High Voltage (HV) electrical network. In terms of dynamic performance, the simulations’ results and the comparative analysis clearly show the superiority of the intelligent controllers regardless of the variation of powers that affecting the model plant. Compared to PI controller, they ensure good performance in terms of tracking and decoupling.

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.

The use of numerical method in an electric grid coupled to a wind farm to compare different kinds of flexible AC transmission systems

The PSAT software was used in this study to analyse and compare the performance of hybrid compensators such as SSSC-STATCOM (controllers), TCSC-SVC (compensators), and UPFC in an electric grid coupled to a wind farm. The flexible AC transmission system (FACTS) technology is used to provide a continual power flow and to provide new ways to control the electric system network. In the FACTS devices, the UPFC (Unified Power Flow Controller) is one of the most adaptable, flexible, and complicated power electric devices. The active and reactive power flows and the local voltage on the bus can be regulated by UPFC; it can also resolve the problem of harmonics. The TCSC (Thyristor-Controlled Series Capacitor) consists as a series-compensating capacitor shunted by a thyristor-controlled reactor. The SVC (Static Var Compensator) is the first shunt generation FACTS controller. We can observe that the UPFC controller has an effective power flow control, shorter setting time and a shorter overshoot. The UPFC obtained a well-known reputation for high controllability in power systems. The multilevel Unified Power Flow Controller can be operated in Static Synchronous Compensator (STATCOM), in Static Synchronous Series Compensator SSSC and exactly in the UPFC compensator. The results of this research compare the hybrid controllers and investigate the effects of TCSC-SVC, SSSC-STATCOM, and UPFC on voltage, phase angle stability, and the active and reactive power in the tested system. The purpose of this comparison is to improve dynamic voltage regulation, especially when the utilisation of nonlinear loads and the presence of fault and breaker rise. These hybrid controllers have been shown to outperform series or shunt compensators; however, when compared to hybrid compensators SSSC-STATCOM, TCSC-SVC, and UPFC, the results employing the numerical method in the UPFC are more significant. The UPFC is the best hybrid controller in this study, and the compensators SSSC-STATCOM outperform the controllers TCSC-SVC.

Model Predictive Controlled Four‐Bus System Employing Hybrid Power Flow Controller

A fuzzy logic‐ (FL‐) based control technique for unified power flow controller (UPFC) to resolve the power quality issues in transmission network is presented in this paper. MATLAB/Simulink is used to design the FL‐based controllers for shunt and series converters of UPFC, which is validated on 4‐bus system. In addition, the performance of the suggested FL‐based UPFC is compared with PI (proportional integral), HC (hysteresis controller), MPC (model predictive controller), and FLC (fuzzy logic controller), and the outcomes are compared in terms of settling time and steady‐state error. The consequences characterize that the higher enactment of closed loop hybrid power flow controller (HPFC) 4‐bus system with FLC UPFC controller’s (FL based) robustness is ensured from the simulation results as it has overcome the power quality issues like reactive power compensation, voltage sag mitigation, and THD reduction of transmission line current below 5% as per IEEE standard. Settling time of CL FBS is abridged from 0.87 to 0.62 sec, and steady‐state error of voltage in CL FBS is abridged from 0.9 to 0.1 V using FLC.

Novel non‐linear control of DFIG and UPFC for transient stability increment of power system

This paper offers novel non-linear control of a doubly fed induction generator (DFIG) and unified power flow controller (UPFC) for transient stability increment with transient energy function (TEF) and sliding mode observer in a power system. First, the TEF technique is considered for the damping control in a power system with a synchronous generator (SG), DFIG, and UPFC, and then the controller time-derivative signals are estimated by a second-order sliding mode observer. The importance of the issue is in the employ of a complete UPFC model. Also, a one-axis model is used for DFIG that is similar to the SG model. Another characteristic of the novel non-linear technique is robust versus system topology changes and variable time delay of the control signals. To evaluate the performance of the novel non-linear control method for increment transient stability, simulation studies are performed on a two-machine connected to an infinite bus (TMIB), the IEEE 9-bus, and the New England Standard 39-bus power system. The results determine that the novel non-linear control method decreases the first swing of fluctuations admissibly and enhancement stability margins considerably.

Optimal Power Flow Calculation of Active Distribution Network Based on Improved Comprehensive Technology

Comprehensive unified power flow controller ( UPFC ) technology can calculate voltage control parameters of UPFC, but it increases the nonlinearity of Newton power flow calculation. When the comprehensive technology is combined with the intelligent algorithm, the control parameters can only be optimized through the active and reactive power of UPFC on the branch, which makes the optimization convergence worse. Therefore, an optimal power flow calculation method for active distribution network based on improved comprehensive technology is proposed. First, based on the analysis of the influence of UPFC on branch power flow, an improved UPFC model is proposed. The accuracy of UPFC control parameters is enhanced by adjusting the voltage phase angle and regulation radius of series side transformer. Second, the optimal control model considering UPFC is established. Finally, the corresponding self-admittance and mutual admittance elements are extracted from the constructed UPFC model and introduced into the Jacobian matrix, so that while the comprehensive technology maintains the dimension of the Jacobian matrix, the intelligent algorithm can directly optimize the control parameters to reduce the search space. The IEEE33 bus system is used for example simulation, the results before and after the improvement are compared, and the Monte Carlo method is used to calculate the two algorithms 50 times respectively based on the installation number of UPFC, which verifies that the proposed optimization method has better convergence and operation speed.

Fault identification scheme for UPFC compensated transmission line based on characteristic voltage active injection

When a fault occurs at Unified Power Flow Controller (UPFC) compensated transmission line, the traditional auto reclosing scheme cannot identify the fault characteristics, and thus reclosing on a permanent fault would cause the second strike on the power system within a short period. To solve this problem, this paper proposes a fault identification scheme based on the active injection of the characteristic voltage by the control of UPFC. Firstly, after the circuit breakers on both sides of the faulty line have tripped, the converter on the series side of the UPFC is switched to the additional control mode. Then, the characteristic voltage is actively injected into the faulty line through the series transformer. Based on the active injection, the fault characteristics can be identified through the difference of characteristic voltages and currents under different faults. Therefore, this scheme could prevent the circuit breaker from reclosing on permanent faults and thus enhance the stability and safety of the system. Finally, the simulation results in PSCAD/EMTDC verify the robustness and effectiveness of the proposed scheme.

Transient stability improvement of power system with UPFC control by using transient energy function and sliding mode observer based on locally measurable information

This paper proposes a non-linear technique to improve the transient stability of power systems with a unified power flow controller (UPFC) based on locally measurable information. The proposed method is developed by applying the direct Lyapunov function. The whole control system contains both elementary control approach and an additional control scheme. In the elementary control, the TEF method is investigated for modeling the damping control of the power system with UPFC. In the additional control, the time-derivative signals of the controller are estimated with a 2nd order SMO. The significance of the study is in the use of a complete UPFC model. The other main feature of the proposed method is its robustness properties against changes in the system topology. The simulation results in the case of a single machine connected to an infinite bus, the IEEE 14-bus, and the IEEE 9-bus power system illustrate the efficiency of the proposed control technique under severe disturbances. The results reveal that the proposed control technique for UPFC reduces the first swing of oscillations acceptably and increases stability margins significantly.

Investigation of advanced control for unified power flow controller (UPFC) to improve the performance of power system

Recently, global power demand has significantly increased. As this demand does not have proportional impact with transmission capacity and power generation. The new techniques are used to improve power system performance. The Flexible Alternating Current Transmission System (FACTS) devices are applied to improve the existing transmission network capacity. The Unified Power Flow Controller (UPFC) has been selected in this study to control power flow in transmission networks and improve the power system operation. In this paper, the Artificial Neural Network Controller (ANN) proposed to overcome the problems of the existing UPFC controller and tested using the IEEE-14 bus system with various test cases. The results showed that the proposed ANN has improved the efficiency of UPFC successfully by increasing the active power flow, reducing reactive power, and improving the voltage profile. The performance of proposed ANN-based UPFC has also been compared with Proportional Integral (PI) based UPFC and with Fuzzy Logic Controller (FLC) based UPFC shows its effectiveness. The simulation results have shown that the proposed ANN-based UPFC proved its robustness in improving all power system parameters compared to PI-based UPFC.

Investigation of advanced control for unified power flow controller (UPFC) to improve the performance of power system

Recently, global power demand has significantly increased. As this demand does not have proportional impact with transmission capacity and power generation. The new techniques are used to improve power system performance. The Flexible Alternating Current Transmission System (FACTS) devices are applied to improve the existing transmission network capacity. The Unified Power Flow Controller (UPFC) has been selected in this study to control power flow in transmission networks and improve the power system operation. In this paper, the Artificial Neural Network Controller (ANN) proposed to overcome the problems of the existing UPFC controller and tested using the IEEE-14 bus system with various test cases. The results showed that the proposed ANN has improved the efficiency of UPFC successfully by increasing the active power flow, reducing reactive power, and improving the voltage profile. The performance of proposed ANN-based UPFC has also been compared with Proportional Integral (PI) based UPFC and with Fuzzy Logic Controller (FLC) based UPFC shows its effectiveness. The simulation results have shown that the proposed ANN-based UPFC proved its robustness in improving all power system parameters compared to PI-based UPFC.

Hybrid Reference Current Generation Theory for Solar Fed UPFC System

The extensive usage of power electronic components creates harmonics in the voltage and current, because of which, the quality of delivered power gets affected. Therefore, it is essential to improve the quality of power, as we reveal in this paper. The problems of load voltage, source current, and power factors are mitigated by utilizing the unified power flow controller (UPFC), in which a combination of series and shunt converters are combined through a DC-link capacitor. To retain the link voltage and to maximize the delivered power, a PV module is introduced with a high gain converter, named the switched clamped diode boost (SCDB) converter, in which the grey wolf optimization (GWO) algorithm is instigated for tracking the maximum power. To retain the link-voltage of the capacitor, the artificial neural network (ANN) is implemented. A proper control of UPFC is highly essential, which is achieved by the reference current generation with the aid of a hybrid algorithm. A genetic algorithm, hybridized with the radial basis function neural network (RBFNN), is utilized for the generation of a switching sequence, and the generated pulse has been given to both the series and shunt converters through the PWM generator. Thus, the source current and load voltage harmonics are mitigated with reactive power compensation, which results in attaining a unity power factor. The projected methodology is simulated by MATLAB and it is perceived that the total harmonic distortion (THD) of 0.84% is attained, with almost a unity power factor, and this is validated with FPGA Spartan 6E hardware.

Comparison of (SVC/TCSC) - (STATCOM/SSSC) compensators and UPFC controller in network coupled to wind farm using Jacobian matrix in Newton-Raphson algorithm

In recent years, the fast progress in the field and the application of the electronic system transmission plays an important role to make the system more reliable, controllable and efficient. It opened new opportunities for the application of the FACTS devices. The Flexible Alternating Current Transmissions System technology (FACTS) is used to have an optimal continuous power flow and open up new opportunities for controlling the electric system network. The UPFC (Unified Power Flow Controller) is one of the most versatile and complex power electric devices in the FACTS family. UPFC can control the active and the reactive power flow, a local bus voltage, it can also result a problem due to harmonics. In that regard, this paper presents a case study in which the PSAT software was implemented to comparing and analyzing the performance of the hybrid compensators namely (SVC/TCSC), (STATCOM/SSSC) and the UPFC in network coupled to wind farm. The Static Var Compensator (SVC) is a first shunt generation FACTS controller. TCSC (thyristor Controlled Series Capacitor) is consisted as a series compensating capacitor shunted by a thyristor controlled reactor. We can see that the UPFC controller has an effective power flow control, less setting time and less overshoot. The UPFC obtained a well known reputation for high controllability in power systems. The multilevel UPFC can be operated in STATCOM (Static Synchronous Compensator), in SSSC (Static Synchronous Series Compensator) and exactly in the UPFC mode. The results using Jacobian matrix in Newton-Raphson algorithm of UPFC are more significant compared to the hybrid (SVC/TCSC) and the (STATCOM/SSSC) controllers.

IEC 61850 Modeling of UPFC and XMPP Communication for Power Management in Microgrids

Integration of distributed renewable energy sources in microgrids presents many challenges to grid such as voltage, stability and power management issues. In literature different control strategies to improve the performance of microgrids integrated with renewable energy sources proposed. FACTS based controller such as Unified Power Flow Controller (UPFC) has also been employed in microgrids to improve the power management and transient stability. Coordinated control strategies between UPFC controller and DERs have been developed. However, the underlying communication for realizing these strategies has not been discussed. This paper presents IEC 61850 and XMPP based communication for coordinating UPFC and DERs in microgrid for its stable operation. IEC 61850 information model for UPFC controller is developed. Furthermore, the XMPP protocol is utilized to provide the scalability for communication network in microgrids with high penetration of DERs. Additionally, XMPP also provides improved security along with the scalability. IEC 61850 message exchanges over XMPP communication between different components of microgrid for power management is demonstrated.