Dynamic Load Variations Research Articles

Research on bridge spatial deformation monitoring using light poles and displacement-relay theory

The growing traffic on municipal bridges demands effective methods for monitoring spatial deformations to ensure structural safety. Traditional measurement techniques often fall short in terms of efficiency and precision. This study presents an innovative bridge deformation measurement system that employs light poles and displacement-relay theory, integrated with high-resolution optical cameras, sub-pixel image recognition algorithms, and IMU data. Laboratory experiments involved chain camera units and multiple data processing methods, including sub-pixel recognition and wavelet denoising. Results showed that sub-pixel recognition with four-layer wavelet denoising achieved the highest accuracy, aligning closely matching the performance of commercial equipment. Field tests on the Xinwuyi and Dinghuaimen Bridges under varying traffic conditions confirmed the system’s reliability. The study concludes that the system effectively captures dynamic load variations, enhancing the accuracy of spatial deformation measurements. Future work will refine error analysis and data processing methods to further enhance the system’s practical applicability.

A Novel Linear-Based Closed-Loop Control and Analysis of Solid-State Transformer

In this paper, a new linear-based closed-loop control method for a Solid-State Transformer (SST) has been proposed. In this new control method, individual current and voltage loops for each of the power conversion stages (AC-DC, DC-DC, DC-AC) are implemented. The feedback between the input and output control signals for each loop is achieved through the voltage on the DC link capacitors and the current transferred between the converters. This enables the SST to be controlled easily in a linear-based closed-loop manner without the need for complex computations. In order to evaluate the performance analysis of the proposed control system, a simulation of an SST with approximately 10 kVA apparent power was performed. Based on the obtained simulation results, the response time of the proposed control method for dynamic load variations was proved to be in the range of 40 milliseconds, and it has been observed that this method allows electrical power to be transferred from the load to the grid. The power factor value of SST under inductive load is measured to be approximately 99%, and the overall system efficiency is 96% and above, indicating that this proposed new control method has very high performance.

Power Flow Control between the Grid and Distributed Generation for Dynamic Load Variation with VSC Converter

Power Flow Control between the Grid and Distributed Generation for Dynamic Load Variation with VSC Converter

Study on the dynamic characteristics, control strategies and load variation rates of the concentrated solar power plant

As more and more wind power and photovoltaic power are connected to the electrical power system, it brings great challenges to the stability of power grid. Concentrated solar power (CSP) plant with thermal energy storage (TES) can undertake the task of load regulation and frequency regulation in power grid by balancing the electricity demand and generation. However, the maximum load variation rates of the CSP plant are not known, which restricts sufficient utilization of its advantages. In this study, a dynamic simulation model of CSP plant was built by using the APROS, and the dynamic characteristics were investigated by applying the step disturbances to molten salt flowrate, molten salt temperature, and the opening of steam regulating valve. Based on the results of dynamic characteristics, the control strategies were developed with the consideration of thermal storage in system and the feedforward signal of setting load and load variation rate. Then, the maximum load increase and reduction rates within different load ranges were studied. The results indicated that steam regulating valve, molten salt flowrate and molten salt temperature could be used to control turbine power, steam pressure and steam temperature, respectively. The designed control system could effectively follow the load variation with load deviation less than 0.3 MW and steam temperature deviation less than 1.2 °C in the condition of load variation rate at 3% Pe·min−1, which was superior to the conventional control strategy not considering the thermal storage in system. The maximum load increase and reduction rates were 11.57% Pe·min−1 and 8.94% Pe·min−1 within the load range of 75%THA-100%THA, and they were 10.42% Pe·min−1 and 7.46% Pe·min−1 within the load range of 50%THA-75%THA, respectively. The above load variation rates were first demonstrated for CSP plant, which could provide important guidance for plant operation in load regulation task and the load dispatching on grid side.

Power quality improvement of grid interfaced solar PV system using an improved least mean square‐based unified control technique

SummaryThis article presents an improved least mean square (LMS) algorithm‐based control approach for a three‐phase grid interfaced solar photovoltaic (GISPV) system for smart building applications. The SPV is primarily utilized to supply household loads, and the absence or intermittency of SPV is curbed by utilizing power from the grid. The majority of household loads are nonlinear loads that affect the grid power quality (PQ). However, the effects of both linear and nonlinear loads on grid PQ have been analyzed in this article. This article proposes a Gaussian Kernel function‐based normalized LMS (GKNLMS) algorithm to calculate the active peak weight component of the load current, thereby utilizing it to obtain a sinusoidal reference current. Considering a higher step size and utilizing the Gaussian Kernel function for reduced mean square error (MSE) improves both the convergence rate and accuracy of estimation in the conventional LMS. The proposed control technique effectively addresses system anomalies caused by dynamic solar irradiance, load variation, and unbalanced loading conditions. Furthermore, the system response with the GKNLMS algorithm is assessed in MATLAB/Simulink and validated by developing a laboratory setup of the system for experimentation.

A New 29-Level Switched-Diode Multilevel Inverter with Optimal Device Count

A novel single-phase 29-level asymmetrical switched-diode multilevel inverter (MLI) topology is presented in this paper with a reduced number of components. The developed topology can able to generate a maximum of 29-levels of output voltage using unequal DC sources. The basic 15-level MLI is developed and then further developed to 29-levels. The proposed topology reduces the circuit components, size and cost of the system. Apart from the several benefits of MLIs, reliability and accuracy plays a vital role because of the existence of more components count to reduce THD value. This can be considered as a major challenge employed to boost reliability without altering the best THD value. Various parameters are realized for both basic 15-level and the proposed 29-level switched-diode MLIs like total standing voltage (TSV), power loss, efficiency and cost function (CF). As the proposed MLI is undergone in dynamic load variations, the experimental results show the variations from R-load to L-load and L-load to R-load and it is found that the inverter is found to be stable throughout its operation. Experimental THD is represented, which is similar to the simulation THD which is under IEEE standards. TSV and cost factor of the proposed MLI is determined and is compared with several existing topologies and is observed to be cost-effective. A precise comparison is made on various parameters using graphical depiction. . The simulation for the proposed topology is done in MATLAB/Simulink and the experimental verification is done using the hardware prototype model under several conditions.

Study on numerical simulation method and dynamic force of dropper of a catenary system

The dropper through bends and bears dynamic impact load before and after the train passes in actual service, which has an important impact on the fatigue life of the dropper. In this paper, a simulation model which can simulate the interaction between pantograph and catenary is established by using the numerical simulation method. A dropper model which can simulate the dynamic stress of the dropper is established through the beam-link combination element. The simulation result shows that among the six droppers in a span, the dynamic force of No. 1 and No. 6 droppers is the smallest, and the dynamic force of No. 3 and No. 4 droppers is the largest. The dynamic load variation characteristics of the dropper are characterized by the dynamic coefficient. When the front and rear pantograph pass through, the maximum dynamic force of the dropper appears when the rear pantograph passes through. The maximum dynamic force is located in the middle of the dropper. Through the research of this paper, the simulation method of catenary and dropper is established, and the dynamic stress process of dropper is analyzed, which lays a technical foundation for the subsequent research on the fatigue failure mechanism of dropper.

Design and implementation of a novel 35-level inverter topology with reduced switch count

• A novel 35-level multilevel inverter is designed with reduced switch count. • Experimental investigation is carried out with dynamic load changes. • Performance of the proposed inverter is evaluated with various parameters. • The proposed inverter is cost-effective with lower total standing voltage. • The proposed inverter has reduced power losses with improved efficiency of 93.37%. This paper projects a novel topology for the 35-level MLI. The proposed topology aims to generate 35-levels at the output with a reduced total harmonic distortion (THD). The developed topology requires a lesser number of switches with fewer switching losses compared with other similar topologies. As the proposed MLI consists of a lesser switch count, the respective driver circuits and the total number of components of the circuit becomes less, hence the size and cost of the MLI get reduced. The modulation scheme incorporated in the proposed MLI is the staircase modulation technique. The developed MLI is tested for various loads such as R, L and combinational loads like R-L and l -R, also the MLI is tested with dynamic load variations and found to be stable throughout the operation of the MLI. The simulation of the developed MLI is done using MATLAB/Simulink and the experimental results are validated with a hardware prototype with a dSPACE RTI1104. The outcomes of the proposed 35-level MLI are compared with the several conventional and existing modern topologies with various parameters and found to be efficient in its operation. The suggested 35-level inverter is quite suitable for Hybrid /Full electric vehicles (HEV) and medium or high voltage/power applications.

Wind-Driven DFIG–Battery–PV-Based System With Advance DSOSF-FLL Control

In this article, a wind-driven doubly fed induction generator (DFIG), battery, and photovoltaic (PV) array-based system with advanced discrete second-order sequence filter-frequency locked loop control for grid-side converter (GSC) is presented. The improved grid-side control provides the reactive power demand of load connected at the point of common coupling. The GSC control provides active and reactive power sharing and mitigates the power quality issues at unbalanced and nonlinear load conditions. Moreover, it gives a satisfactory performance during the dynamic wind speeds and load variation. The maximum wind power is extracted using the tip speed ratio algorithm. The necessary quantity of reactive power for DFIG is delivered by the rotor-side converter (RSC). The battery with a bidirectional converter is connected to the common dc link of the DFIG. The battery is used to maintain the dc-link voltage between RSC and GSC and it stores the power in light-load conditions. It provides the load demand during lower wind speed and solar irradiation. The maximum solar power is extracted by well-established incremental conductance (InC) algorithm, which provides optimum performance during the high dynamic variation of solar irradiation. Moreover, the InC algorithm increases the system's stability and reduces costs. It is easy to implement and handle nonlinearity. The feedforward PV component is added with the active load current component to improve the dynamic behavior of the system. Simulated and test results show the performance of the developed system in different dynamic conditions, such as load unbalancing, changes in PV insolation, and change in speed from the cut-in to cut-out speeds of the wind turbine. Moreover, obtained results show the battery behavior during different dynamic conditions.

An Inverse Dynamics-Based Control Approach for Compliant Control of Pneumatic Artificial Muscles

Rehabilitation is an area of robotics in which human–robot collaboration occurs, requiring adaptation and compliance. Pneumatic artificial muscles (PAM) are soft actuators that have built-in compliance making them usable for rehabilitation robots. Conversely, compliance arises from nonlinear characteristics and generates obstructions in modeling and controlling actions. It is a critical issue limiting the use of PAM. In this work, multi-input single-output (MISO) inverse modeling and inverse dynamics model learning approaches are combined to obtain a novel nonlinear adaptive control scheme for single PAM-actuated 1-DoF rehabilitation devices, for instance, continuous passive motion (CPM) devices. The objective of the proposed system is to bring an alternative solution to the compliant operation of PAM while performing exercise trajectories, to satisfy requirements such as larger range of motion (ROM) and adaptability to external load impedance variations. The control system combines the operation of a nonlinear autoregressive network with exogenous inputs (NARX)-based inverse dynamics estimator used as a global range controller and cascade PIDs for local position and pressure loops. Implementation results demonstrated the efficacy of the introduced method in terms of compliant operation for dynamic external load variations as well as a stable operation in case of impulsive disturbances. To summarize, a simple but efficient method is illustrated to facilitate the common use of PAM.

Model predictive control of solar photovoltaic‐based microgrid with composite energy storage

SummaryThe renewable energy (e.g., solar photovoltaic)‐based grid‐connected microgrid (MG) with composite energy storage system (CESS) is feasible to ensure sustainable and quality power to the commercial and domestic load demands. Effective control systems provide the dynamic performance of such deployed MGs. This paper investigates the application of the finite control‐set model predictive controller (FCS‐MPC) for solar photovoltaic‐based grid‐connected MGs with composite energy storage. FCS‐MPC considers the discrete nature of interfacing (DC–AC and DC–DC) converters into the control algorithm to predict the optimal control command for reference current tracking. Compared to classical control approaches, FCS‐MPC provides a fast‐dynamic response, discards the modulation stage, and effectively handles the effects of dynamic source and load variations and nonlinear loads. The control system encapsulates a proportional–integral (PI) controller, low‐pass filter (LPF), power management algorithm (PMA) unit, and followed by the FCS‐MPC approach. The CESS unit consists of a battery and supercapacitor storage system. The efficacy of the FCS‐MPC approach is verified through the MATLAB/Simulink results. Solar photovoltaic variation due to irradiance, utility grid availability, electricity pricing, and dynamic load variations are considered in the implementation. Furthermore, real‐time simulation of the proposed method is validated using OPAL‐RT OP4510 real‐time simulator.

Design of protection and control scheme for hybrid nanogrid

Nanogrid is “The new ray of hope” for people living in remote isolated locations as well as where power supply reliability is poor. A nanogrid is a small power capacity distribution system with the ability to operate standalone or with a utility grid. It consists of local power production supplying local loads and energy storage systems. In this paper, an innovative inverter design is presented, which converts the power in a single stage. It is superior to the traditional two-stage inverter system and can supply hybrid loads (AC and DC loads) with a single input. System AC and DC bus voltages are regulated under both steady-state and dynamic load variation conditions in the nanogrid. Simulation results are presented which confirm the suitability of the inverter and its control strategy for a hybrid nanogrid system.

Optimal allocation of Multiple Distributed Generators and Shunt Capacitors in a Distribution System using Political Optimization Algorithm

To meet the increasing real & reactive power demand of a distribution system (DS), it is essential to allocate the Distributed Generators (DGs) and Shunt capacitors (SCs) optimally. In this article, multiple DGs and SCs are allocated simultaneously in the DS aiming minimal power loss (PL), improved voltage stability index (VSI) and voltage profile of the system. A combined approach considering loss sensitivity factor (LSF) and political optimization algorithm (POA) is proposed to solve the allocation and sizing of DGs and SCs. The analysis is performed on an IEEE 33 bus system considering 9 different scenarios and results are compared with other Meta heuristic techniques. The analysis is extended for a 24 hour case study to prove the efficacy of the proposed combined approach. From all the performed simulations it can be observed that the combined approach helps in minimizing power loss and improving voltage profile and VSI for dynamic load variations effectively.

A Modified Control Method for Grid Connected Multiple Rooftop Solar Power Plants

This article proposes an enhanced control strategy for a microgrid consisting of multiple rooftop solar photovoltaic sources. These sources are of different power ratings and intermittent in nature. The microgrid is flexible to function either in islanded mode or in grid connected mode. It affects power management and hampers the power quality in microgrid. The proposed control scheme enhances the power quality of the microgrid by providing reactive power compensation to local loads. Thus, it reduces the burden on utility grid. The proposed control technique establishes a priority-based policy for reactive and active power compensation under local demand variance. A smooth and automated transition of microgrid between islanded and grid connected modes is achieved. This seamless transition of the system between two modes avoids the transient in the system. In islanded mode, the proposed control scheme ensures improved voltage regulation under dynamic load demand. It also ensures a minimum burden on the voltage source. Also, the proposed control scheme maintains the power factor of the system near to unity. The system performance is validated experimentally under a number of various operating conditions such as dynamic load variation, grid condition, automated transition, intermittent power generation in real time simulator.

A SIMPLE SHAKING TABLE TEST TO MEASURE LIQUEFACTION POTENTIAL OF PRAMBANAN AREA, YOGYAKARTA, INDONESIA

This paper presents the experimental study of liquefaction potential for sandy soil in Prambanan Area, Yogyakarta, Indonesia, which underwent liquefaction due to the Mw 6.3 Jogja Earthquake on May 27, 2006. Shaking table tests considering the variation of acceleration and shaking duration were performed to investigate the liquefaction potential of sand. The liquefaction time stages including time to start liquefaction, time to start pore pressure dissipation, and liquefaction duration were observed. The percentage of liquefaction duration increase, the excess pore water pressure ratio and the required time to generate liquefaction, and the effect of applied acceleration to cyclic stress ratio, were also presented. The results showed that the sand could undergo liquefaction under the variation of dynamic load. The variation of dynamic load significantly influenced the time stages of liquefaction, the increase of liquefaction duration percentage and cyclic stress ratio. The results also exhibited that the larger applied acceleration and the longer shaking duration means the longer liquefaction duration and the larger liquefaction potential. In general, the result could bring the recommendation to the liquefaction countermeasure for Prambanan Area.

Development of a cost‐effective circuit hardware architecture for brushless direct current motor driver

SummaryA dual‐duty digital pulse‐width modulation (DDPWM) technique‐based cost‐effective control hardware architecture for brushless DC (BLDC) motor drive is reported in this paper. DDPWM control technique involves reduced computational complexity, which is beneficial in on‐chip area and power dissipation reduction. Simple Hall sensor‐based speed calculation and commutation circuits were also incorporated in the hardware to reduce the chip area further. The edge detection‐based speed calculation circuit was designed to be tolerant of any external noise or glitch in the Hall sensor signal. The proposed hardware architecture was implemented on the field‐programmable gate array (FPGA) and application‐specific integrated circuit (ASIC) platform using TSMC 180‐nm technology library. The ability of the integrated circuit (IC) for resource utilization reduction was validated by comparing the FPGA‐implemented architecture with the existing literature. The FPGA‐implemented architecture was also examined in real‐time using an experimental prototype BLDC motor setup. The drive response with dynamic load and speed variations, speed control precision, and glitch tolerant speed calculation is reported in the paper. The ASIC implementation demonstrates that the developed architecture sampled at 50 MHz is highly effective in the gate count and power dissipation reduction compared to the standard PI controller‐based width modulated pulse generation hardware architecture.

A hybrid evolutionary algorithm for stability analysis of 2-area multi-non-conventional system with communication delay and energy storage

The integration of renewable energy with the grid is essential given the environmental and economic constraints. In this work, the dynamic performance of Automatic Generation Control (AGC) was studied with a dynamic steam turbine and renewable sources. A 2-area multi-non-conventional source (Thermal-Hydro-Solar-wind-Gas-battery storage) system with communication time delay (τ) is implemented with the proposed cascaded PID (C-PID) controller scheme. The parameters of the C-PID controller were tuned by a hybrid Improved Teaching Learning Based Optimization and Differential Evolution (hITLBO-DE).Root locus, Bode plot, and eigenvalue analysis were used to demonstrate the stability of the system. Various controllers (i.e. I, PI, PID, and C-PID) were implemented with the designed system under varying operating conditions of step (1% to 10%) and dynamic load variation (1%, ±1%). The C-PID controller is able to maintain a stable system response even for τ of 4 s. Finally, the obtained Amelioration (%) of 55.93%, 49.03%, and 72.84% for Over Shoot emphases the efficacy of the proposed C-PID controller and hITLBO-DE algorithm.

A Novel Asymmetrical 21-Level Inverter for Solar PV Energy System With Reduced Switch Count

This article presents a novel asymmetrical 21-level multilevel inverter topology for solar PV application. The proposed topology achieves 21-level output voltage without H-bridge using asymmetric DC sources. This reduces the devices, cost and size. The PV standalone system needs a constant DC voltage magnitude from the solar panels, maximum power point tracking (MPPT) technique used for getting a stable output by using perturb and observe (P&O) algorithm. The PV voltage is boosted over the DC link voltage using a three-level DC-DC boost converter interfaced in between the solar panels and the inverter. The inverter is tested experimentally with various combinational loads and under dynamic load variations with sudden load disturbances. Total standing voltage with a cost function for the proposed MLI is calculated and compared with multiple topologies published recently and found to be cost-effective. A detailed comparison is made in terms of switches count, and sources count, gate driver boards, the number of diodes and capacitor count and component count level factor with the same and other levels of multilevel inverter and found to be the proposed topology is helpful in terms of its less TSV value, devices count, efficient and cost-effective. In both simulation and experimental results, total harmonic distortion (THD) is observed to be the same and is lower than 5% which is under IEEE standards. A hardware prototype is implemented in the laboratory and verified experimentally under dynamic load variations, whereas the simulations are done in MATLAB/Simulink.

Design and Implementation of 31-Level Asymmetrical Inverter With Reduced Components

This paper presents a novel topology for the single-phase 31-level asymmetrical multilevel inverter accomplished with reduced components count. The proposed topology generates maximum 31-level output voltage with asymmetric DC sources with an H-bridge. The fundamental 13-level multilevel inverter (MLI) topology is realized, and further, the topology is developed for 31-level can be used for renewable energy applications. This reduces the overall components count, cost and size of the system. Rather than the many advantages of MLIs, reliability issues play a significant role due to higher components count to reduce THD. This is a vital challenge for the researchers to increase the reliability with less THD. Several parameters are analyzed for both fundamental 13-level and developed 31-level MLIs such as total standing voltage (TSV), cost function (CF) and power loss. The inverter is tested experimentally with various combinational loads and under dynamic load variations with sudden load disturbances. Total standing voltage with the cost function for the proposed MLI is compared with various topologies published recently and is cost-effective. A detailed comparison of several parameters with graphical representation is made. Less TSV and components requirement is observed for the proposed MLI. The obtained total harmonic distortion (THD) is under IEEE standards. The topology is simulated in MATLAB/Simulink and verified experimentally with a hardware prototype under various conditions.

Seven Level T-Type Switched Capacitor Inverter Topology for PV Applications

The conventional neutral point clamped (NPC) multilevel inverter topology needs voltage balancing circuits to balance the dc-link capacitor, the number of component count is high and output voltage is half of the input voltage which increase the size of the source side dc/dc converter in PV applications. In this paper, a new topology of seven level neutral point clamped inverter is developed. The proposed inverter has a self-voltage boosting capability using a floating capacitor to boost the output voltage one and half of the input voltage. In this proposed topology, no additional sensors are required for the floating capacitor voltage stability, which results in minimizing the complexity of designing the inverter. The direct link between the neutral point and the mid-point of the dc-link capacitors significantly reduces the leakage current and common mode voltage in this inverter. A thorough comparison between the developed topology and recent suggested topologies is carried out which set the benchmark for the proposed one due to its lower switch count and higher voltage gain. The proposed topology is verified in simulation and prototype hardware model and results are discussed with dynamic load variations. The efficiency of the inverter is 97.1% @200W and low as 88.1 % @ inductive load. The voltage THD is 17.01% for simulation and 19.3% I for experimental is results.