This article proposes a dual-active-bridge control to support the fast synthetic inertial action in DC microgrids. First of all, the selection of the isolated DC/DC converter to link an energy storage system with the DC bus in a microgrid is analyzed and the advantages of the dual-active-bridge converter controlled by a single-phase shift modulation justify its selection. An active front-end can be then adapted to connect the DC bus with an AC grid. Secondly, this paper presents the design of a discrete PI controller for supporting fast synthetic inertial action. In particular, a discrete dual-active-bridge model based on the transferred power between both converter bridges, which overcomes the approximations of the output current linearization model, is proposed. Moreover, the article introduces a novel equation set to directly and dynamically tune discrete PI parameters to fulfill the design frequency specifications based on the inversion formulae method. In this way, during the volt... [more]

The fuel cell engine mechanism model is used to research fault diagnosis based on a data-driven method to identify the failure of proton exchange membrane fuel cells in the process of operation, which leads to the degradation of system performance and other problems. In this paper, an extreme learning machine and a support vector machine are applied to classify the usual faults of fuel cells, including air compressor faults, air supply pipe and return pipe leaks, stack flooding faults and temperature controller faults. The accuracy of fault classification was 78.67% and 83.33% respectively. In order to improve the efficiency of fault classification, a genetic algorithm is used to optimize the parameters of the support vector machine. The simulation results show that the accuracy of fault classification was improved to 94% after optimization.

For most of the technical community, rotary flow dividers are known for synchronization of two or more hydraulic actuators. However, there is also a possibility to use them for pressure multiplication, flow regeneration, or speed control. For those applications, there is a need to describe the behavior of its quantities. This article reveals a new evaluation methodology for rotary flow dividers when they are unconventionally used as pressure multipliers and also reveals a new quantity-pressure multiplying efficiency. Then, there is an experiment provided between two rotary flow dividers with different designs, where there is a new evaluation methodology used. On the base of that, it is possible to compare and decide which divider is more likely to be used in multiplying circuits and more suitable for further investigation from the perspective of new designs. With this evaluation methodology, it is possible to compare much more than two different dividers. It is possible to run more tes... [more]

This paper presents a filterless sensorless control scheme with an optimized time sequence based on high-frequency (HF) square-wave voltage injection for a five-phase interior permanent magnet machine (IPMSM) drive. To avoid the utilization of low-pass filters (LPFs) in signal processing, an effective method without filters is proposed in this paper. Moreover, the cross-coupling magnetic saturation is analyzed and the online position error compensation is applied based on the offline measurements and finite-element analysis (FEA). Besides, compared with the conventional time sequence of senseorless control, the proposed optimized time sequence can eliminate the additional position estimation error caused by the time delay in digital implementation. Numerical simulations and experiments with a 2-kW five-phase IPMSM are carried out. The results verify the feasibility and effectiveness of the proposed sensorless control scheme with an optimized time sequence adopted by the IPMSM drives.

Achieving a fully integrated energy market under the EU electricity target model constitutes an ongoing process. Given that the integration of spot markets is already at a mature stage, the next step forward is the successful integration of the balancing markets across European control areas. An analytical review of all the aspects governing the European balancing market integration is presented in this paper, providing a detailed description on the European regulatory framework on this topic. In addition, the design variables that need to be harmonized among national balancing markets as well as the available balancing market arrangements for the exchange of cross-border balancing services are presented. Numerical examples of the essence of the balancing market integration are provided, and the implementation projects initiated by European transmission system operators (TSOs) towards this direction are described. The review concludes that balancing market integration may indeed lead t... [more]

Hydrogen is increasingly being viewed as a significant fuel for future industrial processes as it offers pathways to zero emission. The UK sees hydrogen as one of a handful of low-carbon solutions for transition to net zero. Currently, most hydrogen production is from steam reforming of natural gas or coal gasification, both of which involve the release of carbon dioxide. Hydrogen production from mini decentralised grids via a thermochemical process, coupled with electricity production, could offer favourable economics for small modular reactors (SMRs), whereby demand or grid management as a solution would include redirecting the power for hydrogen production when electricity demand is low. It also offers a clean-energy alternative to the aforementioned means. SMRs could offer favourable economics due to their flexible power system as part of the dual-output function. This study objective is to investigate the critical performance parameters associated with the nuclear power plant (NPP... [more]

As part of the RFCS project, which aimed to improve transport safety in mines, ITG KOMAG proposed a system for monitoring loads and geometric of arch support. The system’s function is to control safety, mainly during suspended monorail runs. This paper presents a hardware model and a measurement method based on the use of vibrating wire strain gauges and draw-wire sensors. The challenge was to properly adapt the vibrating wire strain gauge operation to the requirements of the ATEX directive on the safe use of electrical equipment in underground mines. The signal transducer algorithm and potential mounting locations for the proposed sensors were discussed. The results of tests carried out using the ŁP arc support are presented, reflecting the actual behavior of the casing during loading in accordance with the test methodology proposed by the Central Mining Institute. In order to compare the results with another measurement method, film strain gauges were additionally applied. The result... [more]

With the development of power electronic technology, adding bidirectional DC/DC to the DC side of the motor controller has become an effective way to broaden the speed of motors. However, the motor drive system integrated with bidirectional DC/DC increases the switching loss and current harmonics of the inverter. Therefore, in this paper, a method based on fixed space vector pulse width modulation (SVPWM) modulation index and voltage instruction compensation are proposed, In this method, by considering the back electromotive force of the motor and the security margin of the weak magnetic region, the output voltage command amplitude of the current loop and the limit value of the inverter output is judged, and the optimal inverter input voltage is obtained, which effectively reduces the switching loss of the inverter, broadens the high efficient area of motor operation, and improves the efficiency of the controller. At the same time, the standardized benchmark composed of motor parameter... [more]

Green innovation has become an important support to promote the strategic goals of peak carbon dioxide emission and high-quality economic development. This paper systematically examines whether internal control can effectively drive enterprise green innovation and achieve the “win−win” result of enterprise economic development and environmental protection. We found that internal control can significantly improve the green innovation level of enterprises, which is mainly reflected in the mandatory disclosure stage of internal control information and the other four elements of internal control, except the control environment. The mechanism test found that internal control can promote green innovation by reducing enterprise risks, alleviating agency conflicts, relieving financing constraints, and improving the rationality of innovation investment. The heterogeneity test found that the promotion effect of internal control on green innovation is more significant in large enterprises and pri... [more]

This paper presents a two-stage grid-connected PV system with reactive power management capability. The proposed model can send phase-shifted current to the grid during a low-voltage ride through (LVRT) to recover the voltage levels of the grid’s feeders. The novelty of the proposed algorithm, unlike the common methods, is that it does not need to disable the maximum power point tracking (MPPT) state while managing active and reactive power injection simultaneously. Moreover, the new method promotes a safety factor by offering overcurrent protection to the PV inverter. The phase-locked loop based on the synchronous reference frame (SRF-PLL) is optimized using a genetic algorithm (GA). The settling time of SRF-PLL’s step response is minimized, and the frequency dynamics are improved to enhance synchronization during LVRT. The system’s performance is tested and verified using MATLAB/Simulink simulations. The obtained results prove the effectiveness of the proposed control algorithm in ma... [more]

In view of the problems associated with coal powder production in the development of Coalbed Methane (CBM), a fiber fracturing fluid technology is proposed to control pulverized coal production. Based on a force analysis of coal powder in the fracture and the microstructure of fiber-proppant, a critical intercepted particle size model of coal powder is established. This model is primarily related to fiber properties, proppant particle size and flow rate. To verify this, an FCES-100 device (Nantong Yichuang Experimental Instrument Co., Ltd., Nantong, China) was used to study the influence of fibers on the transportation of pulverized coal in the proppant pack. Five groups of comparative experiments were set up using no fiber, 0.25 g undegraded fiber, 0.25 g degradable fiber, 0.5 g undegraded fiber and 0.5 g degraded fiber, with the flow rate and closure pressures controlled, and, finally, particle size analysis of the discharged pulverized coal was performed using a laser particle size... [more]

The implementation of pro-ecological projects, including those in the field of renewable energy sources, should bring the desired effects, not only environmental or social, but also economic and financial. Although the latter should not prejudge the implementation of such projects, investors, who are primarily enterprises, need information on whether financing the project from specific, available sources is effective and when the incurred financial expenses will pay off. The publication presents a model that reflects the procedure in the analysis of financing opportunities for pro-ecological projects, aimed at maximizing their financial effects, with a consideration of specific risk factors and limitations. The result of the application of this model is information that supports making rational decisions about the implementation of a specific pro-ecological project. The model was positively verified within a case study concerning the purchase and assembly of a photovoltaic installation... [more]

Recently, the integration of optimal battery dispatch and demand response has received much attention in improving DC microgrid operation under uncertainties in the grid-connect condition and distributed generations. However, the majority of prior studies on demand response considered the characteristics of global frequency variable instead of the local voltage for adjusting loads, which has led to obstacles in operating DC microgrids in the context of increasingly rising power electronic loads. Moreover, the consideration of voltage-dependent demand response and optimal battery dispatch has posed challenges for the traditional planning methods, such as stochastic programming, because of nonlinear constraints. Considering these facts, this paper proposes a model predictive control-based integrated voltage-based demand response and batteries’ optimal dispatch operation for minimizing the entire DC microgrid’s operating cost. In the proposed model predictive control approach, the binary... [more]

Modular multilevel converters are playing a key role in the present and future development of topologies for medium−to−high−power applications. Among this category of power converters, there is a direct AC−AC modular multilevel converter called “Hexverter”, which is well suited to connect three−phase AC systems operating at different frequencies. This topology is the subject of study in this manuscript. The complete Hexverter system is composed of an Hexverter power converter and several control layers, namely, a “virtual VC2 controller”, a branch current controller in a two−frequency dq reference frame, a modulator, and a voltage balancing algorithm. The paper presents a thorough description and analysis of the entire Hexverter system, providing research contributions in three key aspects: (i) modeling and control in a unified two−frequency dq framework; (ii) developing a “virtual VC2 controller” to dynamically account for Hexverter’s active power losses allowing to achieve active pow... [more]

A considerable increase of seismicity has occurred in the USA in the last decade (2009−2020) with an annual average of 345 M3+ earthquakes. Numerous field cases have shown that excessive well pressure due to a high injection rate may have triggered seismic events. This study defines conditions for inducing a seismic event by excessive injection in the well’s pressure that may cause geomechanical damage to the rock. Introduced here is an analytical model and method for predicting pressure increase during injection of produced water contaminated with oil. The model calculates time-dependent advancement of the captured oil saturation causing the well’s injectivity damage and pressure increase. Critical conditions for a seismic event are set by defining rock failure when well pressure exceeds the fracturing pressure of the wellbore or when the increased pore pressure reduces the effective normal stress at the “weak” interface inside the rock, computed with a geomechanical model. This conce... [more]

Mobile machines using a hydrostatic transmission is highly efficient under lower working-speed condition but less capable at higher transport velocities. To enhance overall efficiency, we have improved the powertrain design by combining a hydrostatic transmission with a dual-clutch transmission (DCT). Compared with other mechanical gearboxes, the DCT avoids the interruption of torque transmission in the process of shifting without sacrificing more transmission efficiency. However, there are some problems of unstable torque transmission during the shifting process, and an excessive torque drop occurring at the end of the gear shift, which result in a poor drive comfort. To enhance the performance of the novel structural possibility of powertrain design, we designed a novel control strategy, which maintains the sliding in the torque phase and reduces the difference before and after the engagement, for the motor torque and the clutch torques during the shifting process, and then validated... [more]

This paper proposes an extended structure of a programmable low-pass filter (PLPF) for direct filtering of three-phase variables in automotive AC drives. The PLPF adjusts its cut-off frequency according to the synchronous frequency of the AC motors. Moreover, it compensates gain attenuation and phase delay of the fundamental component signal. The conventional PLPF can only be applied to variables in the stationary reference frame. In order to obtain filtered three-phase variables, an inverse reference frame transformation is required. However, the extended structure, which includes reference frame transformations, can be directly applied to three-phase variables and remove the noise in the earlier stage before transformation. The extended PLPF is more useful for making signal flows clear and intuitive when organizing an algorithm that directly requires three-phase variables. The extended PLPF requires a moderate computational load corresponding with that of the conventional PLPF becaus... [more]

The transport characteristics and kinetics of moisture in hot-pressing are crucial to controlling the insulated paperboard drying process. The effects of operating temperature (110, 120, and 130 °C) on moisture transfer characteristics of an insulated paperboard were investigated. The results showed that the hot-pressing process consists of four successive stages, i.e., the warm-up stage, the boiling-point temperature stabilization stage, the temperature slowly rising stage, and the constant temperature stage. It was observed that a higher temperature mainly affected the medium and later stages of the hot-pressing process. When the operating temperature increased from 110 to 130 °C, the maximum value of the drying rate increased by 16.04%, and the drying time decreased by 62.50% consequently. Furthermore, a new mathematical model used to describe the moisture transfer kinetics for the insulated paperboard hot-pressing was developed in this paper. The results from the proposed new model... [more]

In recent years, aerial infrared thermography (aIRT), as a cost-efficient inspection method, has been demonstrated to be a reliable technique for failure detection in photovoltaic (PV) systems. This method aims to quickly perform a comprehensive monitoring of PV power plants, from the commissioning phase through its entire operational lifetime. This paper provides a review of reported methods in the literature for automating different tasks of the aIRT framework for PV system inspection. The related studies were reviewed for digital image processing (DIP), classification and deep learning techniques. Most of these studies were focused on autonomous fault detection and classification of PV plants using visual, IRT and aIRT images with accuracies up to 90%. On the other hand, only a few studies explored the automation of other parts of the procedure of aIRT, such as the optimal path planning, the orthomosaicking of the acquired images and the detection of soiling over the modules. Algori... [more]

This paper presents a modulated model predictive control (M2PC) strategy for a nine-switch inverter (NSI) based electrification system to improve the steady-state performance. The model predictive control method has gained significant interest due to its straightforward structure. However, the traditional finite control set model predictive control (FCS-MPC) imposes a high computational burden that is problematic in practical applications. This prevents reaching the high sampling frequencies due to an excessive increase in algorithm run-time. Selecting a low sampling frequency causes an unpleasant distortion in the control variable or poor power quality. An M2PC method for the NSI is proposed in this work to remove this trade-off. One zero vector and two active vectors are selected by evaluating a cost function for each allowed switching state of the NSI. The duty cycles of these vectors are calculated by assessing the cost function employing current error terms. An optimized sequence... [more]

A control system for a piezoelectric beam actuator, which had one or two control inputs, was a subject of numerical and laboratory research. The actuator had a prismatic shape with a rectangular cross-section and consisted of one layer of carrying substrate made from PCB-FR4 and two patches of Macro Fiber Composite of P1 type. MFC patches were glued on both sides of the carrying substrate. An article presents a comparison of the control quality of piezoelectric actuator with one control signal (one-input actuator) and the control quality of piezoelectric actuator with two control signals (two-input actuator). An application of two-input actuator led to a reduction of control voltage compared to the control voltage of one-input actuator. The decrease in the maximum voltage was approximately from 30% to 39% in conducted laboratory experiments. An application of two-input actuator causes a reduction of an overshoot value compared to one-input actuator. An application of limit of maximum c... [more]

Over the last few years, the number of grid-connected photovoltaic systems (GCPVS) has expanded substantially. The increase in GCPVS integration may lead to operational issues for the grid. Thus, modern GCPVS control mechanisms should be used to improve grid efficiency, reliability, and stability. In terms of frequency stability, conventional generating units usually have a governor control that regulates the primary load frequency in cases of imbalance situations. This control should be activated immediately to avoid a significant frequency variation. Recently, renewable distribution generators such as PV power plants (PVPPs) are steadily replacing conventional generators. However, these generators do not contribute to system inertia or frequency stability. This paper proposes a control strategy for a GCPVS with active power control (APC) to support the grid and frequency stability. The APC enables the PVPP to withstand grid disturbances and maintain frequency within a normal range. A... [more]

The method of operative determination of active power losses (both loading and crown) in alternating current lines has been improved. The proposed technique allows monitoring of active power losses in lines. Based on the comparative analysis of different approximation methods, the most effective method of analytical representation of regression dependences of active power losses on the corona on voltage for different weather conditions is proposed. The validity and reliability of scientific statements, conclusions, and recommendations given in the dissertation are confirmed by the analysis of the results of comparative calculations performed for different models. The efficiency of the developed algorithms and programs was tested on control examples with reference source data, where the results of the calculations were compared with the results obtained by standard programs. The developed technique of operative determination of losses of active power (loading and on a crown) allows one... [more]

Concerns about climate change, air pollution, and the depletion of oil resources have prompted authorities to enforce increasingly strict rules in the automotive sector. There are several benefits to implementing fuel cell hybrid vehicles (FCHV) in the transportation sector, including the ability to assist in reducing greenhouse gas emissions by replacing fossil fuels with hydrogen as energy carriers. This paper examines different control strategies for optimizing the power split between the battery and PEM fuel cell in order to maximize the PEM fuel cell system efficiency and reduce fuel consumption. First, the vehicle and fuel cell system models are described. A forward approach is considered to model the vehicle dynamics, while a semi-empirical and quasi-static model is used for the PEM fuel cell. Then, different rule-based control strategies are analyzed with the aim of maximizing fuel cell system efficiency while ensuring a constant battery state of charge (SOC). The different met... [more]

Light electric vehicles are alternative solutions to passenger cars in terms their lower costs and space saving in city traffic. Narrow tilting vehicles (NTV), known also as three−wheeled vehicles, can be equipped with an active tilting stability controller that tilts the vehicle automatically during cornering to enable lateral stability. There are mainly direct tilt control (DTC), steering tilt control (STC), and combined DTC−STC methods described in the literature. The DTC method is typically applied up to 10 km/h vehicle speeds. Considering city traffic and frequent start−stop cycles, the DTC method needs to be improved in terms of lower actuator torque and energy consumption. DTC can be designed by using either hydraulic or servo motor actuators. In state of the art, the servo motor actuator has not been studied in detail considering its integration and application aspects. Mostly, the actuator has been considered as a black box model. Proposed control method in this study enables... [more]