Power Penetration Research Articles

Power quality disturbance mitigation in grid connected photovoltaic distributed generation with plug-in hybrid electric vehicle

In the last twenty years, electric vehicles have gained significant popularity in domestic transportation. The introduction of fast charging technology forecasts increased the use of plug-in hybrid electric vehicle and electric vehicles (PHEVs). Reduced total harmonic distortion (THD) is essential for a distributed power generation system during the electric vehicle (EV) power penetration. This paper develops a combined controller for synchronizing photovoltaic (PV) to the grid and bidirectional power transfer between EVs and the grid. With grid synchronization of PV power generation, this paper uses two control loops. One controls EV battery charging and the other mitigates power quality disturbances. On the grid connected converter, a multicarrier space vector pulse width modulation approach (12-switch, three-phase inverter) is used to mitigate power quality disturbances. A Simulink model for the PV-EV-grid setup has been developed, for evaluating voltage and current THD percentages under linear and non-linear and PHEV load conditions and finding that the THD values are well within the IEEE 519 standards.

Improved measurement of the glue layer in composite material by using sparse deconvolution.

Due to its powerful penetration, and greater spatial resolution than microwaves and ultrasonic waves, the terahertz technique stands out as being particularly useful in identifying thin glue layers in multilayered materials. However, the arrival times of echoes are challenging to pinpoint from the experimental data because of the temporal form of the incident pulse and the system noise. Here, two terahertz signal sparse deconvolution algorithms are studied to more accurately identify the times of the echoes. Using the circulant structure of the convolution matrix, the method's computation time can be lowered to hundreds of milliseconds. In addition, a method based on group velocity dispersion is investigated to reduce the impact of time-varying pulses with minimal computational expense. The presented algorithms have the potential to be employed in real-time inspection in production lines due to their quick speed and high confidence.

Advanced Intelligent Approach for Solar PV Power Forecasting Using Meteorological Parameters for Qassim Region, Saudi Arabia

Solar photovoltaic (SPV) power penetration in dispersed generation systems is constantly rising. Due to the elevated SPV penetration causing a lot of problems to power system stability, sustainability, reliable electricity production, and power quality, it is critical to forecast SPV power using climatic parameters. The suggested model is built with meteorological conditions as input parameters, and the effects of such variables on predicted SPV power have been studied. The primary goal of this study is to examine the effectiveness of optimization-based SPV power forecasting models based on meteorological conditions using the novel salp swarm algorithm due to its excellent ability for exploration and exploitation. To forecast SPV power, a recently designed approach that is based on the salp swarm algorithm (SSA) is used. The performance of the suggested optimization model is estimated in terms of statistical parameters which include Root Mean Square Error (RMSE), Mean Square Error (MSE), and Training Time (TT). To test the reliability and validity, the proposed algorithm is compared to grey wolf optimization (GWO) and the Levenberg–Marquardt-based artificial neural network algorithm. The values of RMSE and MSE obtained using the proposed SSA algorithm come out as 1.45% and 2.12% which are lesser when compared with other algorithms. Likewise, the TT for SSA is 12.46 s which is less than that of GWO by 8.15 s. The proposed model outperforms other intelligent techniques in terms of performance and robustness. The suggested method is applicable for load management operations in a microgrid environment. Moreover, the proposed study may serve as a road map for the Saudi government’s Vision 2030.

An unprecedented control of 3‐phase grid tied solar photovoltaic‐hydrogen/bromine‐supercapacitor composite storage microgrid for pulse power load regulation under nonideal grid conditions

AbstractPhotovoltaic (PV) power penetration into the distribution grid has increased. PV power fluctuations, abrupt load changes, nonlinear loading, growing usage of portable electronic devices, electric cars low average power and comparatively high pulse power needs, and other factors translate into severe grid instability. As a result, in these circumstances, power exchange between PV and the utility grid becomes a difficult task. Therefore, this article proposes a hydrogen/bromine (H2/Br2) redox flow battery and supercapacitor composite energy storage for a three phase grid tied PV system with multifunctional active power filter support to ensure grid codes. Further, the system is equipped with an unprecedented control technique that encompasses: an adaptive frequency tuned complex coefficient filter‐phase locked loop that provides grid frequency and phase angle information under adverse grid conditions, a modified sparrow search algorithm tuned tilt integral derivative with filter plus double integral controllers are employed to regulate the control errors under various system dynamic and disturbance conditions, fractional order incremental conductance maximum power point tracking is incorporated to efficiently track the PV peak power irrespective of atmospheric variations, a holistic fast‐acting power based energy management control employed for efficient regulation of load power and smooth out the PV power variation, and PV feedforward control dynamics to enhances system dynamics by reducing oscillations under various atmospheric conditions. The aim is to attain a smooth power transition with the grid at the unit power factor under normal and nonideal grid conditions. With reactive power injection, the control also maintains the voltage profile. During all these operations, no trade‐off occurs with the system power quality. Matlab simulations and the real time simulation test bench results under unfavorable grid circumstances demonstrate the effectiveness of the proposed method, and system harmonics are well within bounds in all the scenarios undertaken.

Facile fabrication of large-area BN films for thermal management in flexible electronics

Flexible electronics, as an emerging and exciting research field, have brought infinite varieties for their powerful penetration into many areas of smart electronics. Simultaneously, significant challenges were generated and continued to grow in the thermal management of flexible electronics. The flexible substrate is the main pathway to remove excess energy from electronics to the outside, thus facile strategies to integrate fillers with high thermal conductivity (k) in substrates are needed. Here, large-area and foldable boron nitride nanosheets (BNNS)-based films are fabricated via the combination of electrospinning and hot-pressing. Due to the satisfactory microscopic orientation and dense stacking of BNNS, the obtained film exhibits an outstanding in-plane k (32.3 Wm−1K−1) and good electrical insulation. We further demonstrate the practical application of the film as a flexible substrate for printed electrodes. Our study contributes new ideas for fabricating large-area, highly thermally conductive flexible substrates and performance regulation of filler-based macroscopic assemblies.

Planning of Flexible Generators and Energy Storages under High Penetration of Renewable Power in Taiwan Power System

The proportion of renewable power generation in the world has been increasing in recent years. However, the fluctuations and uncertainties of renewable power generation bring a considerable challenge to future unit scheduling. Therefore, the generation flexibility in power systems becomes more critical as a large amount of renewable generation is integrated into power systems. The use of flexible generators with energy storage systems is one of the most efficient methods of improving power system flexibility. The primary purpose of this study is to explore the effect of generation flexibility on the cost of unit scheduling. A flexibility index is used to evaluate the generation flexibility in the Taiwan power system, and a multi-scenario analysis for renewable power integration is considered. This study also considers various system constraints, such as the unit commitment of actual hydro and thermal units, the scheduling of flexible internal combustion engines (ICEs) and energy storage systems, and possible curtailments of renewable power generation. According to the seasonable characteristics of renewable power generation, this study provides a suitable capacity for flexible ICE units and energy storage systems. Furthermore, this study demonstrates that the cost of unit scheduling is effectively reduced by increasing flexible ICE units and energy storage systems. The results of this study can be used as a reference for power systems in preparing flexible generating units and energy storage systems under the integration of a large amount of renewable power generation in the future.

The State of Israel: Toward a Renewable Low‐Carbon Energy Production

Israel is located within the global solar belt, having high population density, a small share of rural population, while industry makes up a great part of the gross domestic product. As such, Israel is an excellent practice test site for identifying the best approaches to increase photovoltaic (PV) power penetration into the economies of developed countries. The core of the new distributed renewable power friendly paradigm is local prosumer‐to‐prosumer microgrids, which are aggregated into secondary supergrids, which may be, in turn, aggregated into ternary supergrids. Besides, the approach is also promising from the social point of view, transferring the power management to the people. The comment dwells into the challenges and possible solutions, which Israel is facing toward zero carbon energy production. Resolving these issues will affect the way of future sustainable energy supply growth and management. The comment written here refers also to the paradigm of battery technology for storing the PV energy, pointing on a possible misunderstanding within the battery community, which addresses the number of cycles a battery system can provide, rather than the expected service life of the system itself. In this aspect, it is proposed to focus the efforts of the researchers and developers into an alternative battery system.

Two-Stage Chance-Constrained Coordinated Operation of an Integrated Gas–Electric System

Under the background that the high penetration of renewable energy generation, which mainly consists of wind power, will have a significant impact on electric power systems due to the volatility and uncertainty of renewable energy, energy systems with gas–electric coupling and interconnections have been widely studied to accommodate renewable energy generation. This paper proposes a two-stage chance-constrained coordinated operation model of an integrated gas–electric system and fully considers the uncertainty and high penetration of wind power. The Taylor series expansion method is used to linearize the Weymouth gas flow equation of a natural gas system and finally obtains a mixed integer linear programming model. Case studies show the effectiveness of the integrated energy system for peak shaving, valley filling, and promoting wind power accommodation. The proposed model ensures the consumption of wind power generation and also reduces the operation cost by about 0.7%.

A Solution Method for Many-Objective Security-Constrained Unit Commitment Considering Flexibility

With the increasing penetration of wind power into power systems and the random fluctuation of the wind farm (WF) output, system flexibility must be considered in the optimal generation dispatch. Based on the extreme scenarios of the WF output, we proposed a flexibility risk index to evaluate the system flexibility of each time interval. We established a five-objective security-constrained unit commitment (SCUC) model of a power system with WFs, thermal generation plants, battery energy storage stations, and pumped storage hydro stations. The objectives were to minimize the system flexibility risk, total network loss, operation cost, power purchase cost, and pollutant gas emissions. To obtain the Pareto optimal solutions of the model, based on the objective selection and ε-constraint methods, we proposed two methods to reduce the dimension of objectives and transformed the five-objective optimization model into a series of three-objective optimization models. Then, we used the normalized normal constraint method to solve the Pareto frontier surface of each three-objective optimization model. We used a color column to represent the value change of the two upper layer objectives and visualized the Pareto frontier of the five-objective SCUC model in the three-dimensional ordinate space. Case studies on the modified IEEE-9 bus system and an actual power grid demonstrated the effectiveness and high computational efficiency of the proposed method.

Research on the Amplitude–Phase Motion Equation for the Modeling of Wind Power System

The increasing penetration of wind power together with its high volatility could significantly impact the transient stability of the power grid. To quickly evaluate this impact, current engineering practice is primarily relying on time-domain simulation, which is computationally expensive despite that the results are more accurate. To solve this computational complexity issue, the amplitude–phase motion method is proposed to establish the electromechanical transient simulation model of the double-fed induction generator (DFIG) for wind energy. However, the traditional amplitude–phase motion equation (APME) suffers from the instability control from the abrupt change of terminal voltage induced by the system changes or flickers. To improve the transient stability of DFIG, this study firstly incorporates the q-axis current together with the amplitude change of terminal voltage into the phase error of the phase-locked loop (PLL). Then, the output phase of the terminal voltage of DFIG is highly combined with the q-axis current and the amplitude of terminal voltage to improve the internal control effect of the typical APME. The simulation results in the four-machine two-area power system with one wind farm demonstrate that the proposed method is able to maintain a stable operation of the wind farm and the power grid when experiencing a sharp disturbance of wind speed.

CFD Investigation on The Jet-Engine Inspired Wind Turbine

The Malaysian Government has set a more ambitious target to achieve higher penetration of Renewable Energy (RE) in the Malaysian energy mix which was 31% by 2025. Compared to the penetration of solar and wind power specifically in the European region, whose sharing was more than 50% of total generation, Malaysia currently only has 2% of its energy coming from RE generation sources, which mostly was provided by solar photovoltaic. In Malaysia’s energy sources point of view, wind RE-based power generation system was foreseen a promising potential provided the technology was suitably designed for low wind conditions. Therefore, the potentiality of the Jet-Engine inspired Wind Turbine operating under low-speed wind environment by mean of Computational Fluid Dynamics (CFD) numerical approach were explored in This study. The main objectives were to develop a reliable numerical model for accessing the capability of the Jet-Engine inspired Wind Turbine and to regulate its performance with influence of curly shroud on the induced flow. The conventional shrouded Wind Turbine has been modified which consist of a stator and a rotor blade covered by curly-shaped shroud adapting the concept of Jet-Engine. A constant wind speed of 5 m/s which was the average wind speed in Malaysia, and tip speed ratio (TSR) varies from 2 to 6 were specified in the simulation. The investigation discovered that the curly-shaped shroud gave an impact to the performance of the Wind Turbine as it can be reviewed from the comparison of the power coefficient on the Jet-Engine inspired Wind Turbine with shroud and without shroud. It was found that the shrouded Wind Turbine improved the power coefficient by 8.6% which was from 0.35 to 0.38. The effect of the curly shroud was also analysed by obtained the velocity and pressure contour from the ANSYS Fluent, where there was a swirl formation at the shroud as the air mixed at different angle, which causes the pressure drop and inlet velocity increased.

Modeling of solar photovoltaic power using a two-stage forecasting system with operation and weather parameters

ABSTRACT The integration of solar photovoltaic (SPV) system to the grid has introduced a new source of intermittency in the grid, and the grid has to react smartly to the changes that occur in the penetration of SPV power. Accurate modeling of weather-dependent SPV power will be helpful in forecasting the penetration of SPV power into the grid. An SPV power output forecasting model has been developed based on artificial neural network (ANN) approach. Two forecasters, namely ANN forecaster and two-stage hybrid-ANN forecaster, are developed with operational and weather parameters. The historical data of SPV power (P), hours of operation of SPV system (to), daily global solar radiation (H), and ambient temperature(T) are used as modeling parameters. The combination of modeling parameters {P, H, T, to} is identified as the best combination that influences the forecasting of day-ahead power output. A relative root mean square error (RRMSE) of 5.74% was obtained with the combination of {P, H, T, to}. An RRMSE of 6.04% was observed with the combination of {P, H, T} as inputs, and the hours of operation of the SPV plant could be ignored in the model. The historical power data of the SPV plant is identified as the crucial parameter in the SPV power forecast model and has given an RRMSE of 7.25%. The models developed with temperature and radiation as modeling parameters have resulted in good forecasting accuracy, which could be best suitable for feasibility studies of SPV plant at a particular location. Solar radiation prediction models are used in the development of hybrid-ANN forecaster. It has produced an RRMSE of 7.35% with four inputs. The hybrid-ANN forecaster with predicted radiations as modeling input will eliminate the need of a costly pyranometer. The models developed in the present study have utilized readily available parameters as modeling parameters, thereby cost of the forecasting system has been decreased. The developed models will be useful for energy scheduling and energy management in the smart grid. Abbreviations: GSR, Global Solar Radiation; ANN, Artificial Neural networks; SPV, Solar Photovoltaics; MAPE, Mean Absolute Percentage Error; RRMSE, Relative Root Mean Square Error; MSE, Mean Square Error.

Operation Risk Assessment of Hydroelectric Energy Storage Based on Data Visualization and Convolutional Neural Network

Hydroelectric energy storage, that is, pumped storage hydropower (PSH) is considered as the essential solution for grid reliability with high penetration of renewable power, due to its advantages of cost-effectiveness for grid energy storage as well as supporting ancillary services. However, the operation modes of the main transformer unit in PSH are way more complex than the conventional power transformer, which makes the condition monitoring and fault detection of PSH becoming a technical challenge. In this article, an operation status recognition model of main transformers in PSH based on artificial visualization of mechanical vibration signals and deep learning is proposed. The vibration signals on a series of 500 kV/360 MVA main transformers of PSH are monitored periodically by contacting sensor arrays. These vibration signals are processed into nephograms by using linear interpolation fitting and 1D to 2D data mapping. A deep learning method based on the convolutional neural network (CNN) is used to classify nephograms obtained under different operation modes, that is, no load, full load, DC bias, and short circuit. The proposed status prediction algorithm was trained and tested through 150 sets of vibration nephogram samples, which ensures the feasibility of the nephogram generation method and the performance of the classifier. The testing results show that the overall status prediction accuracy for the proposed algorithm achieves 89.7% when the network structure is optimized. It is indicated that the mechanical vibration of the main transformer has a pattern matching relationship with the operating state of PSH. In practice, the operating status of PSH can be diagnosed remotely by embedded IoT sensors; the health index of PSH can also be estimated by weighed analysis of the changing trend of vibration data obtained in the life cycle.

Analysis of Multi-Frequency Oscillation Stability in a Prosumer Power Network

Multi-frequency oscillation is a new type of electromagnetic oscillation issue in power systems caused by the increasing penetration of renewable power and power electronic devices. This study investigates the risks and influencing factors of multi-frequency oscillation in a prosumer power network where a variety of converter-based resources exists. For the feasibility of analysis, the internal and external stability of the study system are defined and analyzed based on sequence impedance models. Analysis results show the impacts of control parameters of prosumers, length of cables, transformer ratios, local grid strength, and power and capacity of prosumers on the risks of oscillation. Accordingly, despite the poorly tuned control parameters, the study system has higher risks of multi-frequency oscillation with longer cables, lower-rated voltage of cables, larger capacity, and inductive power consumption of the neighboring prosumers. Frequency-domain analysis results are demonstrated by EMTDC/PSCAD simulations.

Supervisory Power Coordination Scheme to Mitigate Power Curtailment in the Application of a Microgrid

There are cases where the output of renewable eappennergy (RE) is curtailed due to an increase in the share of RE. Typically, wind power (WP) is curtailed due to oversupply and low loads at midnight. However, there are cases where the output of WP is limited during the daytime due to the increase in the share of photovoltaics (PV). In the current electricity market, as the share of PV is increased, the curtailments of WP will be increased further, which will add to the difficulties experienced by wind farm operators. This paper proposes a supervisory power coordination scheme. The main purposes are to prevent the penetration of extra power from REs into the grid; thus, the curtailments can be prevented. In order to make it feasible, the proposed scheme is to design a grid-connected microgrid system to be operated only in response to loads and virtual power plant (VPP) requests. The effectiveness of the proposed scheme was verified by simulation studies conducted in the MATLAB/Simulink environment. The verification was conducted based on the voltage criteria, such as the AC voltage regulation between ±6% of the rated AC voltage, the DC voltage regulation between ±10% of the rated DC voltage, the power balance according to variations in the loads, and VPP requests for power. The simulation showed that the proposed scheme is feasible and justifiable, not only to mitigate the power curtailment problem but also to apply different system configurations.

Microwave power penetration enhancement inside an inhomogeneous human head

The penetration of microwave power inside a human head model is improved by employing a dielectric loaded rectangular waveguide as the transmission source. A multi-layer reflection model is investigated to evaluate the combined material characteristics of different lossy human head tissues at 2.45 GHz. A waveguide loaded with a calculated permittivity of 3.62 is shown to maximise the microwave power penetration at the desired frequency. A Quartz (SiO2) loaded rectangular waveguide fed by a microstrip antenna is designed to validate the power penetration improvement inside an inhomogeneous human head phantom. A measured 1.33 dB power penetration increment is observed for the dielectric loaded waveguide over a standard rectangular waveguide at 50 mm inside the head, with an 81.9% reduction in the size of the transmission source.

Coordinated Frequency Regulation of Smart Grid by Demand Side Response and Variable Speed Wind Turbines

Frequency stability of the power system is impacted by the increasing penetration of wind power because the wind power is intermittent. Meanwhile, sometimes the demand side loads increase quickly to require more power than total power produced. So balancing the active power in the power system to maintain the frequency is the main challenge of the high penetration of wind power to the smart grid. This paper proposes coordination rotor speed control (RSC), pitch angle control (PAC) and inertial control (IC) to control wind turbines, together with demand side response (DSR) participating in frequency regulation to balance active power in the power system. Firstly, the model of a single area load frequency control (LFC) system is obtained, which includes variable-speed wind turbines (VSWT) and DSR containing aggregated air conditioners and plug-in electric vehicles (PEVs). Then the RSC, PAC and IC, which controls wind turbines participating in frequency regulation in the power system, are introduced, respectively. Finally, the coordination of these three methods for wind turbines in different wind speeds is proposed. Case studies are carried out for the single area LFC system with a wind farm and DSR supported grid frequency. Coordination RSC and PAC combined IC are used to control wind turbines with DSR to balance active power in the power system. The proposed method used in the power system with high penetration of wind power and fluctuation of demand load is tested, respectively. Coordinated RSC or PAC with DSR can increase penetration of wind power and reduce peak load.

Grid impact and power quality assessment of wave energy parks: Different layouts and power penetrations using energy storage

Power fluctuations induced by wave energy converters (WECs) may reflect negative impact on the power quality of the power grid. Assessing their impact is an important step to ensure the grid compliance level of the energy park. The IEC 61000-4-15 standard classifies the allowable disturbances in the grid. This study analysed and assessed the grid impact in terms of flicker, harmonic distortion and voltage variations. The assessments were performed without energy storage and compared when using the energy storage. A single WEC is emulated as an irregular power output of a real WEC using a combined model of power take-off in the Simulink model. Time series based on data obtained in earlier offshore experiments, conducted at the Lysekil research site in Sweden, is used to emulate a wave energy park (WEP) power in a land-based test rig in real-time power hardware-in-the-loop simulations. A total of three and ten WECs are emulated by introducing a time delay in the time series to investigate the grid impact in each layout. Flicker emissions, voltage variations, individual and total harmonics of the voltage at the connection point in each layout are studied and compared with the limits to be grid compliant for layouts of the WEP. In addition, voltage and current harmonics for the single WEC and individual harmonics in each phase of the voltage are measured and analysed to assess the compliance level of the WEP.

Evaluation of DFIGs’ Primary Frequency Regulation Capability for Power Systems with High Penetration of Wind Power

Accompanying the continuous increase in wind power penetration, the power system inertia is reduced, and the system frequency regulation performance deteriorates. Wind turbine generators are required to participate in primary frequency regulation (PFR) to support system frequency. Here, the PFR capability of the widely-used doubly-fed induction generator (DFIG) is evaluated to estimate the participation of the DFIG in system frequency control. The frequency regulation model of the DFIG is established and briefly discussed. The equivalent PFR droop coefficient is then deduced from the model using a small signal increment method to evaluate the DFIG’s PFR capability. Key factors affecting the equivalent droop coefficient are studied, and the droop control is optimized to keep the equivalent droop coefficient in the desired range. The proposed method is verified utilizing a provincial power grid model of China.

Voltage stability improvement with coordinated ULTC–STATCOM controller and VSC-HVDC in high wind penetration cases

In recent years, implementing renewable energy systems such as wind power systems into interconnected grids play a vital role in energy management and production. Besides the good aspects of this energy policy, there may be some undesirable cases if not controlled. Increasing penetration of wind generation into the electricity grid negatively affects the power system stability and the required reactive power that might cause serious voltage stability problems. In order to overcome this problem, especially in the weakest areas of the system with respect to voltage stability, it is necessary to support the reactive power reserve. In this study, a coordinated ULTC–STATCOM controller has been designed to improve the reactive power reserve and enhance voltage stability by the penetration of wind power through the VSC-HVDC wind farm system into weak area of the AC system. The novelty of the proposed coordination control than the classical coordination approaches is changing the tap position of the ULTC especially at high penetration levels and thus to maintain the reactive power reserve of STATCOM. The proposed approach is tested in a two-bus sample system and adapted to the weakest area of the IEEE 10-machine 39-bus test system that simulations are conducted in DIgSILENT PowerFactory 15.0 software. Comparative simulation results show that the proposed approach has enhanced both reactive power reserve and voltage stability margin of the test systems.