STATCOM Research Articles

A Non-singular Fast Terminal Sliding Mode Approach to Improve the Network Stability of Wind Rich Power Grids

The increased penetration of wind energy conversion systems (WECS) into the grid creates many challenges for maintaining grid stability, reliability and efficiency. This paper proposes an approach that integrates the robustness and fast convergence capability of non-singular fast terminal sliding mode control (NFTSMC) with the fast current support of static synchronous compensators (STATCOM) to improve the dynamic stability of wind energy systems during network disturbances. The NFTSMC control approach is designed for the inner current control loop of a STATCOM with voltage source inverter topology. Its main objective is to support both the active and reactive currents and thereby effectively regulate the system's frequency and bus voltage. The proposed approach was implemented to a WECS-based test microgrid subject to sudden load variations and mismatched disturbances. The obtained results confirmed its effectiveness in properly mitigating dynamic instabilities stemming from grid disturbances and maintaining the voltage and frequency within their rated values. Further comparison between the performance of the proposed NFTSMC and that of a standard SMC approach showed better performance and reduced chattering compared to the standard SMC.

Digital Control of DSTATCOM using TI-C2000 Processor and MATLAB/ Simulink for Sustainable Power System Network

This paper describes the detailed digital control of a Distribution Static Synchronous shunt Compensator (DSTATCOM) using a MATLAB embedded coder for compensation to be in command of Voltage Source Converter (VSC) input voltage, reactive power compensation and the power factor improvement of a secondary radial distribution system with a voltage rating of 11kV/415V and with a capacity of 750 kW. The model has been simulated and tested in MATLAB/Simulink using the Simscape tool block set version of MATLAB R2019a. The same is achieved using a 32-bit DSP TMS320F2812 controller programmed with CCS V 6.1 software and tested with MATLAB embedded coder generation using Texas Instrument C2000 processors. Using this embedded code is developed and dumped into the CCS V 6.1. Real and Reactive power control (PQ) and Back Propagation Control Algorithm (BPCA) are the control methods. BPCA controller is based on the elementary extracted biased value of Reactive Power (Q) and Active Power (P) components of load currents. These current values are necessary for the reference source's current estimation. The reference source currents are estimated from the available source currents to generate firing pulses for the PQ and BPCA controllers. The real and reactive power controller is based on the transformation of synchronously rotating load currents in alpha and beta frames. The BPCA-based DSTATCOM is simulated for linear and non-linear load circumstances and that helps in restoring the power system networks sustainability.

Optimal fractional SSSC damping action for variable wind penetrations

An optimal fractional SSSC based control action has been proposed in this work for enhancing small signal stability of power system pertaining to intermittent variations in wind penetrations. The parameters of controllers are tuned by sailfish algorithm and ITAE based objective function has been chosen for minimization problem. A three machine system has been considered in this work with different operating conditions and step with random variations in wind penetrations have been executed with different machines and subject to which the system response and eigen values are analyzed. Based on system response it is observed that subject to intermittent variations in wind source the small signal stability is hampered due to increased power system oscillations and by properly tuning the fractional lead-lag control action based on static synchronous series compensator. These oscillations can be damped efficiently. The performance of proposed sailfish algorithm (SFA) tuned SSSC controlled action has been compared with PSO and DE algorithms subject to different case studies.

Modeling and Simulation of DVR and D-STATCOM in Presence of Wind Energy System

The present study suggests that series voltage injection is more effective than parallel current injection to improve voltage quality on the load side. The line voltage can be accurately symmetrized at the connection point by creating and controlling a series voltage component in each phase. This is more reliable and effective than parallel current injection. A dynamic voltage restorer (DVR) and a distribution static synchronous compensator (DSTATCOM) were utilized to provide the required power. The DVR is an effective and modern device utilized in parallel within the grid and can protect sensitive loads from voltage problems in the grid by injecting voltage. The DVR and D-STATCOM were used to improve voltage stability in faults. A standard 13-bus system was studied in the presence of a wind farm. The simulation results demonstrated that single and three-phase overloads dramatically altered the voltage of the system, making it necessary to use compensators to improve voltage stability. The DVR and D-STATCOM showed similar performance under normal conditions and somewhat improved grid voltage unbalance. However, the DVR outperformed D-STATCOM under asymmetric faults conditions and led to lower voltage variations.

Metaheuristic for the Allocation and Sizing of PV-STATCOMs for Ancillary Service Provision

In addition to active power generation, photovoltaic inverters can be used to provide ancillary services to grids, including reactive power compensation. This paper proposes a metaheuristic approach based on particle swarm optimization for the allocation and sizing of photovoltaic inverters that perform the complementary functions of static synchronous compensator (PV-STATCOM) units. The objective of the aforementioned approach is to reduce the initial investment cost in the acquisition of PV-STATCOM units. The proposed methodology considers both the daily load curve and generation and is applied to a 33-bus test system. The methodology is validated based on an exhaustive search algorithm and tested over 1000 consecutive simulations for the same problem; consequently, the methodology produces low standard deviations and errors, indicating its robustness. The methodology demonstrates an improved grid voltage profile throughout the day when applied to the 33-bus test system. Furthermore, the photovoltaic inverter efficiently performs its main function of active power generation. As a major contribution, the proposed methodology may assist investors in determining the allocation and sizing of PV-STATCOM units to perform the ancillary service of reactive power compensation in grids

Exploring the Enhanced Performance of a Static Synchronous Compensator with a Super-Capacitor in Power Networks

The use of a super-capacitor as a storage device integrated with a Voltage source converter-based shunt-connected Static Synchronous Compensator (STATCOM) is proposed for improving the STATCOM performance during sudden large disturbances in a power network. The super-capacitor was applied across the STATCOM capacitor during the disturbance condition. MATLAB simulations were carried out for the verification of a secondary function of the STATCOM like oscillation damping, transient stability improvement, and security of the power network with the storage device. The validation of the proposed super-capacitor was carried out in MATLAB.

Reactive power compensation using STATCOM in a PV grid connected system with a modified MPPT method

Commonly Static Synchronous Compensators (STATCOMs) are employed extensively as voltage regulators and VAR compensators in transmission networks in power systems. This research proposes the integration of STATCOMs in distribution networks, particularly in PV grid-connected systems that use distributed energy resources to reduce active and reactive power demand from the grid by supplying variable reactive power from an alternative supply which adapts to the load demand. This decreases the dependence on the utility power supply and promotes the integration of STATCOMs with renewables. Complete case studies between the differences in application of a fixed reactive power compensating condenser and STATCOM for dynamic VAR compensation to loads connected at the point of common coupling in a grid connected Photo-Voltaic (PV) system is presented. The scope of this research is to examine the behavior of dynamic loads, such as an induction motor, at steady state operation when the reactive power demand from the supply increases, as well as the effect of this demand variation on the network that supplies such loads. Complete system modeling and analysis for both scenarios, the fixed reactive power compensator and the STATCOM, supplying various load demands, have been developed. The simulation is based on a 100-kW rated PV grid-connected system to simulate behavior and performance of such study. Adaptive Neuro Fuzzy Inference System with Particle Swarm Optimization was used to extract the maximum power point of the PV array proceeded by a sliding mode controller. MATLAB/ Simulink was developed for modelling and analysis. Various load dynamics with varying solar irradiance and increasing reactive power demand of the associated load were simulated to evaluate various challenges and disturbances on the power supply.

Comparative Performance of DVR and STATCOM for Voltage Regulation in Radial Microgrid with High Penetration of RES

In recent years, the penetration of renewable energy sources (RES) in microgrids and distribution system feeders has increased manifold. Moreover, the advancement of power electronics-based devices in the distribution system has significantly increased the number of sensitive loads. Variations in the voltage under intermittent RES create functional problems with sensitive loads, necessitating voltage regulators (VR) installation. In this paper, two custom power devices: dynamic voltage restorer (DVR) and static synchronous compensator (STATCOM), used for voltage regulation in a microgrid, are investigated under different operating conditions. The efficacy of DVR and STATCOM for voltage regulation in an 11-node radial microgrid with high penetration of RES is simulated under a MATLAB Simulink environment. Furthermore, the simulated microgrid voltage profile results are analyzed to evaluate the efficacy of both voltage regulators.

Small-Signal Stability Assessment of Multi- Converter-Based-Renewable Systems With STATCOMs Based on Generalized Short-Circuit Ratio

The increasing integration of renewable resources (such as wind and solar) through grid-following converters is shifting the modern power system into a multi-converter-based- renewable (multi-CBR) system. In such a multi-CBR system, the dynamic interaction between CBRs and the power network may cause small-signal stability issues, especially under low short-circuit strength conditions. While static synchronous compensators (STATCOMs) are integrated into the multi-CBR system for providing voltage support, their dynamics also influence the small-signal stability. However, it has not been theoretically revealed how STATCOMs affect the small-signal stability, especially for low short-circuit strength systems. To fill this gap, this paper proposes a method to analyze small-signal stability of a multi-CBR system with STATCOMs based on grid strength analysis, wherein the grid strength is represented by short-circuit ratio (SCR) for a single-CBR system and generalized SCR (gSCR) for a multi-CBR system. Firstly, we analyze the relationship between small-signal stability and SCR in a single-CBR single-STATCOM system. Then, we study the relationship between the small-signal stability and gSCR in a multi-CBR system with STATCOMs. On this basis, a gSCR-based method is proposed for assessing the small-signal stability of a multi-CBR system with STATCOMs. The proposed method is validated through eigenvalue analysis, electromagnetic transient simulations and hardware-in-loop simulations.

Admittance Decomposition for Assessment of APF and STATCOM Impact on the Low-Frequency Stability of Railway Vehicle-Grid Systems

Dynamic compensators, such as active power filter (APF) and static synchronous compensator (STATCOM), can be used to mitigate the low-frequency oscillations (LFO) in high-speed railway vehicle-grid systems. However, the small-signal impedances of APF and STATCOM are affected by that of vehicles, which makes it challenging to characterize the impedance of these devices directly and ensure stable operation. The traditional stability analysis is based on terminal impedances of source and load subsystems, which does not always provide sufficient insight into LFO suppression. In this article, a novel idea based on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> -frame admittance decomposition is proposed to investigate the impact of APF and STATCOM on the system stability. The proposed approach is demonstrated in simulation and experimental results. It is shown that the control paths of the APF and STATCOM for measuring the vehicle current introduce their coupling with the vehicle. The resulting coupling admittance of these devices plays a significant role in the load admittance reshaping and determining their ability to enhance the system stability and suppress the LFO.

Impact of static synchronous compensator STATCOM installation in power quality improvement

&lt;span lang="EN-US"&gt;The present work investigates the flexible AC transmission system (FACTS) device's role to improve the voltage stability for a distribution network of various types of loads. Our analysis was based on using a static synchronous compensator (STATCOM) device over a test distribution system. Firstly, a detailed description of the mathematical model used in our system is presented. Then we studied the effect of inductive and capacitive loads with and without STATCOM. To investigate the efficacy and robustness of using STATCOM in a distribution network, a test system is developed using MATLAB/Simulink, where we analyzed the voltage profile in different cases. The results of the simulation demonstrate that the STATCOM plays a critical role in optimizing the voltage profiles of distribution systems, either capacitive or inductive.&lt;/span&gt;

Wide-area damping control system for large wind generation with multiple operational uncertainty

• Illustrates the contribution of wind generation, and investigates the influence of the grid-forming mode-based VSWT-DFIGs. • Coordinated design of wide-area damping controller for utility-scale wind generation power plants considering time delays uncertainty. • Optimization is used to optimize the parameters of damping controller. • Contains case studies on a large power system, including FACTS, and wind generation. • MATLAB/Simulink-based nonlinear simulations are performed, for variable wind speed, 3-phase faults, and dynamic load model. The large integration of wind generation resources into power systems may causes low-frequency oscillations and deterioration in power system stability. This paper presents a novel coordinated approach-based Wide-Area Damping Control System (WADCS) for large wind generation integrated power system, while taking into consideration of the operational uncertainties. The coordinated WADCS approach is used to enhance the damping of inter-area oscillations while maintaining the voltage and frequency in the prescribed range. In a coordinated WADCS, a wide-area damping controller is coordinated with the rotor side converter model of wind generation resources (WGRs). The Static compensator (STATCOM) is used to enhance voltage and reactive power support for WGRs. To provide the additional damping, a static synchronous series compensator (SSSC) is also employed with the WADCS. The geometric measures of controllability/observability and residues method is utilized to select the appropriate input control signals and optimal location of wide-area damping controller. A multi-objective grey wolf optimizer (MOGWO) algorithm is used to optimize the parameters of the wide-area damping controller to enhance the damping. MATLAB/Simulink-based nonlinear simulations are performed considering operational uncertainties such as variable wind speed, 3-phase faults, variable load, and time delays to demonstrate the efficacy of the proposed coordinated control for modified WGRs integrated test power system.

Power System Stability Enhancement Using Robust FACTS-Based Stabilizer Designed by a Hybrid Optimization Algorithm

Improving the stability of power systems using FACT devices is an important and effective method. This paper uses a static synchronous series compensator (SSSC) installed in a power system to smooth out inter-area oscillations. A meta-heuristic optimization method is proposed to design the supplementary damping controller and its installation control channel within the SSSC. In this method, two control channels, phase and magnitude have been investigated for installing a damping controller to improve maximum stability and resistance in different operating conditions. An effective control channel has been selected. The objective function considered in this optimization method is multi-objective, using the sum of weighted coefficients method. The first function aims to minimize the control gain of the damping controller to the reduction of control cost, and the second objective function moves the critical modes to improve stability. It is defined as the minimum phase within the design constraints of the controller. A hybrid of two well-known meta-heuristic methods, the genetic algorithm (GA) and grey wolf optimizer (GWO) algorithm have been used to design this controller. The proposed method in this paper has been applied to develop a robust damping controller with an optimal control channel based on SSSC for two standard test systems of 4 and 50 IEEE machines. The results obtained from the analysis of eigenvalues and nonlinear simulation of the power system study show the improvement in the stability of the power system as well as the robust performance of the damping in the phase control channel.

Higher order sliding mode reactive power control of a hybrid power system with wind power and parameter uncertainty

Reactive power management and voltage control are the critical problems to be dealt with in hybrid power systems, considering the frequent changes in load and wind power along with parameter uncertainties. Therefore, in this work, the load-side converter with a doubly-fed induction generator is controlled and operated as a static synchronous compensator to provide reactive power support to the system. A higher order sliding mode controller with a super-twisting feature is proposed as a robust controller for the load-side converter operation to regulate the reactive power balance and improve the voltage response of the system. The asymptotic stability of the applied control scheme is guaranteed using the Lyapunov stability analysis. MATLAB-based computer simulation studies are conducted to show the efficacy of the proposed control structure while considering the disturbances in load, wind power, and parameter uncertainties.

Transient stability increase of multi-machine power system by using SSSC and DFIG control with TEF technique and super twisting differentiator

This paper suggests a nonlinear controller of a Static Synchronous Series Compensator (SSSC) and a doubly-fed induction generator (DFIG) for transient stability enhancement by transient energy function (TEF) technique and super-twisting differentiator in the multi-machine power system. Initially, the TEF approach is employed to damping control and stability enhancement in a multi-machine power system including an SSSC, DFIG, and synchronous generator (SG). Then, the signals of time-derivative in the controller with a super-twisting differentiator are estimated. The significance and novelty of this work are the employs of the TEF method obtained for the multi-machine power system containing DFIG and SG. Another novelty is the use of the DFIG and SSSC simultaneous control whose uncertain parameters are estimated with a super-twisting differentiator. The feature of the nonlinear control approach is robust versus modifications in the topology of the system. Simulation is performed on the IEEE 9-bus system to appraise the operation of the nonlinear controller approach compared to back-stepping and sliding mode control. The simulation results demonstrate that the nonlinear controller approach satisfactorily reduces the first swing of oscillations.

Impact of D-STATCOM and OLTC with Integrated Volt/var Control in Distribution System for Power Loss Minimization and Voltage Control

ABSTRACT Voltage control and power loss minimization are some of the crucial issues in distribution system energy management. Finding the best strategy for Voltage control and power loss reduction is a critical task for the distribution network operator (DNO). The main contributions of the proposed work are (i) determination of size and location of the Distribution Static Synchronous Compensator (DSTATCOM) with (OLTC). (ii) to minimize the power loss and Voltage deviation with the Volt/var control strategy. (iii) To obtain the impact of single and multiple D-STATCOM units with and without OLTC. The proposed method is tested on two test systems: (i) IEEE-69 RDS and (ii) IEEE-25 bus three-phase unbalanced system. The benefits of the proposed results are addressed in the reduction of power loss, enhancement of the Voltage profile, and the annual cost of saving for the DNO. The results are tabulated, verified, and compared with other methods. The power loss is reduced to 39.25%, 38.04% for 69 bus and 25 bus test systems. The minimum Voltage profile is enhanced from 0.90918 pu to 0.9619 pu for 69 bus RDS and from 0.922559 pu to 0.9747 pu for 25 bus three-phase system.

Reconsideration on Capacitor Ripple Voltage of CHB-StatCom: Observation, Modeling, Analysis, and Application of Ripple Effect From Design Perspective

The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ripple effect</i> phenomenon wherein the capacitor ripple voltage generates the fundamental-frequency output ac voltage of a cascaded H-bridge-based static synchronous compensator (CHB-StatCom) is revealed and investigated in this work. First, an observation method of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ripple effect</i> for the CHB-StatCom is presented. Then, the reason why CHB-StatCom has a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ripple effect</i> is explained. Subsequently, the accurate mathematical model of the CHB-StatCom considering <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ripple effect</i> is reformulated. Based on the remodeled mathematical model, the cognition inaccuracy of the conventional design of a CHB-StatCom is analyzed, and a new cost-majorization-oriented (CMO) design principle is proposed to optimize the cost of CHB-StatCom. The proposed CMO design needs a lower dc-link voltage to generate the same maximum fundamental-frequency output ac voltage compared with the conventional design, thereby reducing the cost of CHB-StatCom. The simulation and experimental results validate the correctness and effectiveness of the analysis.

Optimization Placement and Sizing of Static Synchronous Compensator

ABSTRAK Pertumbuhan ekonomi di indonesia berbanding lurus dengan permintaan energi listrik di masyarakat yang terus meningkat. Dampaknya adalah sistem tenaga listrik akan menimbulkan berbagai masalah dalam penyaluran energi listrik, seperti drop tegangan diluar batas yang diijinkan, dan rugi rugi daya bertambah besar pada saluran. Salah satu solusi yang dapat dilaksankan untuk mengurangi masalah rugi rugi daya pada saluran dan memperbaiki profil tegangan adalah menggunakan Flexible AC Transmission System (FACTS) devices. Penelitian ini melakukan analisis Static Synchronous Compensator (STATCOM) sebagai salah satu jenis FACTS yang akan diimplementasikan pada sistem tenaga listrik Sumatera Bagian Utara (SUMBAGUT) 150 kV tahun 2020 untuk memperbaruhi profil tegangan dan meminimalisir rugi daya dengan menggunakan metode optimasi Artificial Bee Colony Hasil simulasi diperoleh bahwa pemasangan satu buah STATCOM dapat memperbaiki profil tegangan sistem yang awalnya terdapat 18 bus diluar batas yang diijinkan SPLN menjadi 5 bus. Selain itu, terjadi penurunan rugi daya aktif dari 131,40 MW menjadi 121,56 MW. Kata kunci: ABC algorithm, STATCOM, SUMBAGUT, FACTS, rugi-rugi daya, profil tegangan ABSTRACT Indonesia's economic growth is directly proportional to the increasing demand for electrical energy in society. The electric power system causes various electrical energy distribution problems, such as voltage drops outside the allowable limits, greater power losses on the line, and even unbalanced loads. One solution to the problem of power losses and improving the voltage profile is to use Flexible AC Transmission System (FACTS) devices. In this research, an analysis of Static Synchronous Compensator (STATCOM) is implemented in the 150 kV North Sumatera (SUMBAGUT) electric power system to improve the voltage profile and minimize power loss by using the Artificial Bee Colony optimization method (ABC) Algorithm. The simulation results show that installing one STATCOM can improve the system voltage profile. In addition, there was a decrease in active power loss from 131.40 MW to 121.56 MW. Keywords: ABC algorithm, STATCOM, SUMBAGUT, FACTS, power losses, voltage profile.

Design and Analysis of FOPID-Based Damping Controllers Using a Modified Grey Wolf Optimization Algorithm

This study proposes a novel modified grey-wolf optimization algorithm (MGWOA) to enhance power system stability. The power system stabilizer and static synchronous series compensator (SSSC) are used as damping controllers. Additionally, fractional-order PID (FOPID) controller is used to handle the system nonlinearities and thus achieve better performance. The control parameters are tuned using the proposed MGWOA method which has been verified on unimodal and multimodal functions. Single-machine infinite bus (SMIB) and multimachine power system (MMPS) are taken as case studies to analyze the efficacy of the proposed controller. Minimization of rotor speed deviation is considered an objective function. The results obtained from the MGWOA-tuned FOPID-based damping controllers are compared with those obtained using recently developed efficient and competitive heuristic algorithms. It was observed that the MGWOA method is well-suited for damping low-frequency oscillations. Furthermore, statistical analysis is performed on the obtained results to justify the superiority of the MGWOA method. The simulation results suggest that the MGWOA exhibits superior performance characteristics when applied to a real power system.

Analysis of Power Quality Problems on Nigerian 330 kV Power System Using Statcom with Voltage Sensitivity Index

Transmission system is the transportation of electrical energy from generating stations to load centers. However, increase usage of non-linear loads from the consumers has led to electrical Power Quality (PQ) problems which have negative impacts on the operation of the power system especially Nigerian power system. This research analyzed the PQ problem on Nigerian 330 kV power system. Newton-Raphson (NR) iterative method was used to performed load flow analysis on Nigerian 28-bus transmission systems. Then power injection model of the Static Synchronous Compensator (STATCOM) was incorporated to modify the NR mathematical model. The suitable placement for the STATCOM in the system was determined using Voltage Sensitivity Index (VSI) and simulation was done in MATLAB/SIMULINK. The results showed that, the suitable placements of STATCOM controller in the power system were buses 5, 8, 12 and 16. The corresponding STATCOM reactive power, sag voltage and sag duration for buses 5, 8, 12 and 16 were 72.56 MVar, 0.77454 p.u, 0.7336s; 65.35 Mvar, 0.7464 p.u, 0.7419 s; 50.86 Mvar, 0.7615 p.u, 0.6512 s and 53.75 MVar, 0.7442 p.u. 0.5972 s, respectively. Therefore, the results have established the importance of STATCOM with VSI in obtaining suitable solution for PQ problems on electrical power system. Keywords: Transmission System, Electrical Energy, Non-linear Load, Power Quality, Newton-Raphson, STATCOM, Voltage Stability Index. DOI: 10.7176/ISDE/12-6-03 Publication date: October 31 st 2022