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Energy storage systems are widely used for compensation of intermittent renewable energy sources and restoration of system frequency and voltage. In a conventional operation, all distributed energy storage systems are clustered into one fixed virtual power plant and their state of charges are maintained at a common value. In this article, it is proposed to dynamically cluster the energy storage systems into several virtual power plants based on the energy storage systems’ power demands and capacities. This results in reduced network power losses. The proposed dynamic clustering algorithm enables to cluster agents (energy storage systems) based on their preselected feature states (local power demands and energy storage capacities). To determine the clusters, the distance of the agents’ current feature states from the average estimates of the states is determined in all clusters. The algorithm also provides average estimates of designated auxiliary states that can be used for control purposes. Presented RTDS-based real-time implementation results verify that clustering energy storage systems (batteries) into dynamic virtual power plants can reduce the network power losses.

In this article, the effect of large double frequency capacitor voltage ripple (CVR) on harmonic performance, efficiency, and capacitor lifetime in the cascaded H-bridge low capacitance static reactive power compensator (StatCom) (LC-StatCom) is analytically determined. With insight provided by the analysis, an LC-StatCom with modular switched capacitors is proposed that provides a degree of freedom to control the CVR magnitude. The premise of the operation is to keep redundant capacitor modules in standby mode when operating with lower currents. In addition, it is shown that by distributing losses between additional dc-side switches and the main H-bridge switches, the proposed concept provides opportunities for choosing an optimal hybrid combination of semiconductor technologies. The proposed concept is evaluated using a simulated 8.5 MVA StatCom and feasibility of the proposed system is confirmed by experiments on a seven-level 0.8 kVA single-phase LC-StatCom prototype.

This paper presents the application of information gap decision theory (IGDT) to deal with uncertainties associated with load forecasting in dynamic, environment constrained, coordinated generation and transmission expansion planning. Traditionally, the gaseous emissions are constrained over the whole system. Conventional methods cannot guarantee a practical expansion plan since huge emissions can still occur on some buses in the power system. This paper introduces a per-bus emission limit to avoid extreme emissions in highly populated areas. The effect of nodal emission limits is fully discussed and compared to a conventional method. The model is kept linear using the big M approach to decrease the model computational burden. Reliability is considered by limiting the estimated load not served in each year over the planning horizon. The cost of fuel transportation and fuel limits are considered in order to make the model more realistic and practical. The effectiveness of the proposed model is verified by implementation on Garver 6 bus, IEEE 30 bus, and 118 bus test systems.

This paper presents a new framework, utilizing information-gap decision theory (IGDT), for multiobjective robust security-constrained unit commitment of generating units in the presence of wind farms and gridable vehicles. Both the wind power and load demand uncertainties are considered, and modeled using a biobjective model. As the main advantage, the framework enables the system operator to take an appropriate operational decision with respect to the extremity of each uncertainty. The proposed problem is solved using a normal boundary intersection technique. Subsequently, VIsekriterijumska optimizacija i KOmpromisno Resenje (VIKOR), a decision-making tool, is utilized to choose the best Pareto optimal solution. Finally, the IGDT-based framework presented in this paper is validated using a six-bus test system, the IEEE Reliability Test System with 24 buses, and the IEEE 118-bus system.

This paper proposes an aperiodic sampled and time delayed data based distributed control system for frequency restoration, state of charge balancing and voltage restoration in a microgrid with distributed batteries and PV systems. Lyapunov–Krasovskii functionals and linear matrix inequalities are used to calculate the control system parameters and ensure its stability. The proposed control method is scalable since the stability depends only on the largest and smallest/second smallest eigenvalues of the communication graph Laplacian matrices. Real-time digital simulator is used to verify the proposed control method on an IEEE 13 node test feeder with variable loads.

This paper expands a previous study regarding application of modular variable filter inductor in a cascaded H-bridge low-capacitance StatCom (LC-StatCom). In this paper, the benefit of having such a filter to expand the operating capability of the LC-StatCom into the inductive region is demonstrated. A comparison between the modular filter inductor and thyristor bypassed series inductor solutions is performed through derivation of analytic expressions. The added capacity to operate in the inductive region is also validated via experimental results.

There is increasing interest in understanding residential inverter behavior, particularly due to the growth of roof-top photovoltaic (PV) system installations and the impact behavior has on the distribution system. The response of a single PV inverter or a simulated model does not represent the actual behavior of several inverters integrated with the distribution network. In this research, 28 off-the-shelf residential PV inverters experimental responses to voltage phase angle jumps are analyzed. Statistical analysis is performed to demonstrate the impact of the behavior of the installed roof-top PV inverters under such disturbances on the Australian National Electricity Market. Undesired curtailment and disconnections were observed, threatening the power system’s stability where a high penetration of solar PV generation exists. The main objective of this study is to provide a statistical analysis method to identify the potential power system response under massive disconnection and power curtailment of inverters. Another aim is to assist in future Standards development and a proper contextual investigation for high penetrated areas of roof-top PV systems.

This paper proposes a distributed fixed-time multiagent control strategy for the frequency restoration, voltage regulation, state of charge balancing, and proportional reactive power sharing between photovoltaic battery systems distributed in a microgrid with communication time delays. First, the feedback linearization method is applied to find the direct relationships between explicit states and control inputs. Then, based on the model, the distributed fixed-time cooperative control system restores the frequency, regulates the average voltage to the nominal value, and achieves accurate power sharing. For the state of charge balancing, a fixed-time observer is proposed to estimate the average state of charge of a battery using only information from neighbors. Based on the estimated value, a local fixed-time sliding mode control is applied to achieve the balanced state of charge. Due to robustness of the fixed-time control strategy, the balanced state of charge can be maintained despite intermittent photovoltaic generation and variable loads. The Artstein's transformation is applied to ensure the stability of the time delayed system. The dynamic performance is verified with an RTDS Technologies real-time digital simulator, using switching converter models, nonlinear lead-acid battery models, photovoltaic generation, and communication delays in a European benchmark microgrid.

This paper proposes a distributed coordination control strategy for load sharing and energy balancing between heterogeneous energy storages. These control objectives are satisfied through a two-level control structure. At the primary level, the decentralized virtual impedance control, without the requirement of communication links, allocates the low frequency component of the loads to batteries, while the high frequency component is allocated to ultracapacitors. Distributed control strategy, introduced at the secondary level over a sparse communication network, achieves battery state of charge balancing and regulation of the local bus voltages. Two sets of data are exchanged via the communication links, the local bus voltages, and state of charges of batteries. The distributed controller for the restoration of local bus voltages implements an average consensus protocol, while the controller for energy balancing uses a cooperative protocol. In addition, the ultracapacitor voltages are locally restored at a slower time-scale. The proposed control strategy is resilient to communication link failures and features plug-and-play capability. Presented results demonstrate performance of the proposed control strategy for an islanded 380 VDC datacenter with variable loads. Different operating conditions are verified through the RTDS Technologies real-time digital power system simulator using switching converter models and nonlinear battery models.

This paper proposes a novel distributed multi-agent finite-time control strategy with time delays for the state of charge balancing and voltage restoration in a dc microgrid with distributed battery energy storage systems. The delays can be different and theoretically unbounded for each battery system. Feedback linearization method is applied to convert the state of charge balancing and voltage restoration problems to double-integrator and single-integrator systems with input time delays, respectively. Then, the Artstein transformation is applied to reduce the time delayed systems to delay-free systems. Based on the reduced models, the finite-time control is modified to achieve the state of charge balancing and voltage restoration. Only the state of charge and its derivative and voltage information are required to be transmitted over a sparse communication network to generate the control signals. The finite-time Lyapunov method ensures accurate convergence and finite-time stability. The proposed secondary control strategy can be integrated with conventional primary droop control. The proposed control strategy is resilient to communication link failures and features plug-and-play capability. The performance is verified with an RTDS Technologies real-time digital simulator, using switching converter models and nonlinear lead-acid battery models.

In this paper, a cascaded H-bridge low-capacitance StatCom (LC-StatCom) with a modular inductive filter is introduced. Replacing the fixed-value filter inductors with thyristor-switched reactors, a well-developed member of the static VAR compensators family, reduces the overall energy storage capacity and voltage rating of the LC-StatCom without violating standard limits on current quality. The proposed modular inductive filter takes advantage of LC-StatCom's ability to synthesize high-quality ac voltage to reduce the overall energy storage requirement of the filter inductance. The proposed modular filter inductor concept adds an additional degree of freedom to control the maximum voltage drop on the filter inductor by changing the inductance value. This additional capability decreases the overall voltage rating of the converter. The effects of adding the modular inductor unit on the I-V characteristic of the LC-StatCom are evaluated. The effectiveness of the proposed solution is demonstrated by experimental results on a seven-level 0.7-kVA LC-StatCom. MOE (Min. of Education, S’pore)

This paper proposes a robust framework for the security-constrained unit commitment (SCUC) of generating units, in the presence of lithium-ion battery energy storage units, using the information-gap decision theory (IGDT) technique. In the suggested model, the degradation cost of the battery storage units has been considered in the objective function as a highly influencing factor in the operation of such storage units. The framework is independent of probability density functions or membership of sets and enables the system operator to adjust the conservatism of the operating strategy (between overconservative and reckless) against the load demand uncertainty. In this respect, the SCUC model has been presented within a day-ahead scheduling problem on the hourly basis using mixed-integer linear programming. Finally, the proposed framework has been simulated on a typical 6-bus test system as well as IEEE 24-bus and IEEE 118-bus systems to verify the efficiency and the effectiveness of the model using the IGDT technique.

This article presents a predictive home energy management system (HEMS) for a residential building with integration of a plug-in electric vehicle (PEV), a photovoltaic array, and a heat pump. A stochastic model predictive control (MPC) strategy is applied in the HEMS in order to minimize the home's electricity cost and reduce the PEV battery degradation cost. Moreover, the MPC ensures that home load demand, PEV battery charging requirements, and household thermal comfort conditions are met. The MPC operates in real-time and thus minimizes the effects of gap between the forecasted and real data on the HEMS performance by updating its control decisions and the forecast data as the stochastic parameters are realized in each time step. The obtained simulation results demonstrate that the proposed control strategy reaches 96% to 97% of ideal performance achieved by off-line optimization counterpart with perfect data.

Microgrid is a power system incorporating renewable energy sources and energy storage systems in a small geographic area. Since the microgrid covers small area its voltage rating is low. Therefore, the low voltage microgrid has highly resistive line impedances unlike a conventional power system with highly inductive line impedances. Thus, the power decoupling assumption based on the highly inductive power lines is no longer valid and the primary level droop control and higher level controls have to be redesigned. This paper proposes a bi-level control structure, combining the secondary level control with the primary level droop control, for the highly resistive low voltage microgrids with distributed photovoltaic generation sources and energy storage systems. The primary level droop control implements P −V and Q − f strategy. Then, the primary level droop control frequency and voltage references are set by the secondary level control for the frequency and average voltage restorations, state of charge balancing and reactive power sharing between renewable energy sources and energy storage systems. Presented simulation results carried out on the RTDS real-time digital simulator verify the proposed control structure on a microgrid with switching level converter models.

This paper proposes a new approach for preventive/corrective voltage control in smart power systems. Previous research works, which were based on deterministic methods, cannot be applied in the presence of high uncertainty caused by renewable generation and loads. Hence, new frameworks are required to handle the stochastic space of the problem. In this research, a robust approach based on the information gap decision theory is used to handle the uncertain space using the risk averse (RA) and opportunity seeker (OS) strategies. The RA strategy can provide an operation schedule for a given uncertainty budget in real time and with a required loading margin. The OS strategy helps us to decrease the operating costs in view of possible uncertainties. The proposed method was implemented according to the IEEE reliability test system. The results of this approach give the flexibility to select a degree of robustness considering the desired uncertainty budget.

This paper proposes a new convex model predictive control strategy for dynamic optimal power flow between battery energy storage systems distributed in an AC microgrid. The proposed control strategy uses a new problem formulation, based on a linear d-q reference frame voltage-current model and linearised power flow approximations. This allows the optimal power flows to be solved as a convex optimisation problem, for which fast and robust solvers exist. The proposed method does not assume real and reactive power flows are decoupled, allowing line losses, voltage constraints and converter current constraints to be addressed. In addition, non-linear variations in the charge and discharge efficiencies of lithium ion batteries are analysed and included in the control strategy. Real-time digital simulations were carried out for an islanded microgrid based on the IEEE 13 bus prototypical feeder, with distributed battery energy storage systems and intermittent photovoltaic generation. It is shown that the proposed control strategy approaches the performance of a strategy based on non-convex optimisation, while reducing the required computation time by a factor of 1000, making it suitable for a real-time model predictive control implementation.

This paper proposes a novel centralized switching controller for the state of charge balancing of battery energy storage systems distributed in a DC microgrid. The main advantage of the proposed controller is that it can tolerate non-uniform and time-varying delays in the communication links between a central processor and each battery energy storage system. The central processor generates predictive estimates of the renewable energy generation/load and state of charge of each battery energy storage. The switching controller uses the predictive estimates to generate participation rates of battery energy storage systems. The proposed control strategy is integrated with the primary droop control and the secondary voltage control for the power sharing and microgrid voltage restoration. In addition, the proposed control method guarantees that the active battery energy storage systems are either charging or discharging thus eliminating circulating currents. RTDS real-time simulator is used to verify the proposed large time delay tolerant control scheme on a DC microgrid with four distributed battery energy storage systems, loads and a PV generation. Moreover, mathematically rigorous analysis of the proposed control scheme is given.

Currently, communication-based distributed cooperative control strategies are employed to control energy storage systems in an islanded DC datacentre microgrid. This paper proposes a fully decentralized, communication-less control strategy for heterogeneous energy storage devices distributed in the DC datacentre. In the proposed strategy, decentralized virtual resistance based control allocates the low frequency component of loads to batteries while the high frequency component is allocated to ultracapacitors with the virtual capacitive droop control. Furthermore, the proposed control system balances the batteries’ state of charges to a common value. During operation, the microgrid local bus voltages are regulated within 360–400 V range in accordance with the ETSI EN 300 132-3-1 standard. The proposed control approach offers advantages in terms of reliability and flexibility, as it does not require any communication infrastructure. Performance of the proposed decentralized control strategy is demonstrated on an islanded 380 VDC datacentre microgrid with variable loads, using Real-Time Digital Simulator (RTDS) with detailed switching converter models and nonlinear battery models.

Filter-based battery–supercapacitor hybrid energy storage systems (HESSs) are popular as a way of extending battery lifetime by diverging the high-frequency power variations to the supercapacitor. However, when a traditional supercapacitor voltage controller (SCVC) is employed in the filter-based HESS, precise sizing of the supercapacitor as well as finding filter parameters for the power allocation are challenging due to nonlinearities. These problems can be circumvented by using a supercapacitor energy controller (SCEC) proposed in this paper. The paper presents a method for selection of the SCEC and filter parameters as well as precise sizing of the supercapacitor for a given application. The proposed method is experimentally verified on a single-phase grid-connected HESS used to smooth the power delivered to the grid at the point of common coupling. It is also shown that the size of the supercapacitor when using the SCEC is significantly lower than the one estimated for the traditional SCVC.

Battery energy storage systems (BESS) are becoming common with the increasing penetration of renewable energy sources. Real-time simulations (RTS) can provide an effective approach in the studies of BESS by reducing initial experimental cost and increasing model and test flexibility. Therefore, the need for developing accurate models of BESS for RTS is rising. This paper develops three RTS models for BESS with detailed power electronics, including ripple-port inverter, boost inverter and H-bridge with series-connected flyback converter. Moreover, the second harmonic current (SHC) affects the battery lifetime. To prolong the lifetime of BESS, the topologies and corresponding control schemes are designed to mitigate the SHC in battery. The operation of the real-time models and the effectiveness of the three topologies is demonstrated through RTS results that also show how the topologies and implementated control schemes can reduce the SHC significantly.

In the conventional integrated reconfigurable converter (IRC) topology, the battery modules charging mode was implemented using a unidirectional DC/DC buck converter supplied by an external DC source. This paper proposes an enhanced IRC configuration which allows bidirectional energy transfer between the battery modules and the AC grid. The bidirectional energy transfer is facilitated by the IRC DC/DC converter and an H-bridge. During the ‘battery to grid’ mode the active/reactive power control is realized by cooperation of the DC/DC converter operating in the boost mode and the H-bridge in the inverting mode. Conversely, during the ‘grid to battery’ mode, the DC/DC converter operates in the buck mode and the H-bridge as a rectifier. The proposed configuration is compact as the same inductor can be shared between all IRC operating modes. A scaled down prototype of the IRC is implemented with three series-connected battery modules. Presented experimental results verify viability of the proposed configuration.

There are various studies related to the advantages of implementing home energy management system (HEMS) for residential buildings to minimize the cost of energy consumption and improve user’s comfort level. However, there is still a lack of comprehensive study to evaluate benefits of utilizing HEMS technologies in various residential buildings with different insulation quality (highly or poorly insulated buildings, which can be determined by energy labels). Therefore, in this paper, a concise yet comprehensive comparative analysis is conducted to investigate the operating profits of using HEMS technologies in residential buildings with different energy labels. Moreover, this comparative analysis is performed with two different heat emission systems: radiator only system and a combination of floor–radiator system. The HEMS performance results are presented and compared for both the heating systems in terms of minimizing the cost of energy and the user’s comfort. Also, the results for each building are compared with a baseline case (without HEMS technology) for both heating systems to prove the HEMS performance effectiveness. The simulation results demonstrate that the HEMS operating profits increase as the building insulation quality rises. For example, the HEMS can minimize the cost of energy by 41% in a building with label “A” (highly insulated building), while in a building with label “G”, the energy cost minimization is 26% under the same conditions. Finally, it is proved that the HEMS is more effective with floor-radiator combination heat emission system rather than the radiator only system.

Multi-energy integrated sources are increasingly being used as the bundling-sale for electric systems. Estimating the power supply reliability and regulation performance of the fixed-speed Pumped-Storage Generation Systems (PSGSs) in suppressing power fluctuations of intermittent energy is essential to the operational safety and reliability of a system. However, the regulation process relates to the coupling fluctuations of hydraulic-mechanical-electrical factors, leading to a multiple time-scale effect to the whole hybrid power system. This makes the PSGS’s power response lagging behind the wind power fluctuation and further impacts the power supply reliability of the hybrid power system. To enable the analysis, a numerical model which describes operating states of the presented integrated system, including wind energy and PSGS, is developed in MATLAB/Simulink. Then, ten wind scenarios are selected to study complementation and regulation ability of the PSGS based on a framework of evaluation indicators. The results show that longer power response delay and larger guide vane distance opening result in weaker complementary response of PSGS to wind disturbances. It is also shown that the PSGS provides good complementary capability at lower random wind standard deviation (0.5 vs 1.5), larger wind speed mean value (15 m/s vs 13 m/s) and lower wind speed deviation (5 m/s vs 12 m/s). Furthermore, an unexpected regulation behavior is demonstrated: fast settling and peak times coincide with large variation in overshoot, undershoot and peak value of the power response. This presents a challenge in assessing performance of the integrated generation system. The proposed evaluation method and presented results are important steps to increasing the national power grid capability to accept high integration of multiple energy sources.

In modern power systems, renewable energy, such as solar and wind, has been increasingly exploited to replace traditional fossil fuels in hope of resolving the issue of energy crisis. Normally, the renewable generators are integrated into the power grid through power converters. A common issue with the photovoltaic (PV) powered single-phase inverter systems is that the performance and lifespan of the dc source might be undermined by the second-order current ripple (SCR) due to the double line frequency instantaneous power oscillating at the ac side. This issue tends to exacerbate when the inverter interfaces more complicated nonlinear loads, where the input current is adulterated with multiple low-frequency ripple components besides SCR. To solve this issue, this paper presents a repetitive controller based dual-mode control method for PV powered single-phase buck-boost inverter under nonlinear load scenario. Without introducing any additional circuit or passive electrical components, the proposed method manages to significantly mitigate ripple components in the input current with the reduced dc-link capacitance. Finally, simulated results are demonstrated to verify its effectiveness in current ripple reduction.

Battery-supercapacitor hybrid energy storage systems (HESSs) are popular as a way of extending the battery lifetime by reducing the battery current fluctuations. In this paper, a current sensor reduction method for a recently proposed interleaved boost inverter based battery-supercapacitor HESS is proposed. A pulse width modulation (PWM) and inductor current reconstruction scheme is developed to achieve the current sensor reduction for the HESS. The method is able to measure four inductor current waveforms using two current sensors while ensuring the interleaved operation of the boost converter legs.

This paper proposes an improved method for voltage restoration in DC microgrid without using communication lines. Due to nature of traditional droop control, the voltage of the microgrid droops a small amount to achieve load sharing. However, in some situations the load requires high quality power supply and the voltage deviation is unacceptable. This can be solved by using a secondary control to generate a correction signal based on real-time measurement. However, this control structure requires a low bandwidth communication links; therefore the most significant advantage of the droop method is compromised. A washout filter-based control method has been recently proposed to solve the drooping without communication lines, however it suffers from the tradeoff between system stability and restoration speed. A fuzzy logic based compensator proposed in this paper improves the transient response of the washout filter based method without affecting the power sharing and stability.

This paper proposes a cooperative control for power sharing and energy balancing between heterogeneous energy storage devices, improving reliability, flexibility, and scalability. The batteries are controlled in a distributed fashion, over a sparse communication network, while decentralized control is used for the ultracapacitors. The virtual impedance control strategy allocates the high frequency component of the loads to the ultracapacitors and the low frequency component to the batteries, without using filters. Presented simulation results verify the performance of the proposed strategy for an islanded DC microgrid with variable loads.

The proliferation of photovoltaic (PV) generation in low- and medium-voltage distribution networks is expected to continue. Qualified studies can quantify adverse impacts of high PV penetration on distribution networks and assist utilities in decision making. This paper proposes an index-based methodology for assessing the impact of high solar PV generation, considering the reverse power flow and voltage rise phenomena. Indices are defined that link these two phenomena and their impact on the voltage profile across the feeder. This assessment relies on detailed modeling of the network and the solar PV generation components, which are performed over a 24-h window. Results are presented for a modified 13-bus IEEE test network, emulating a weak network with three-phase balanced loads. This methodology can only be applied to three-phase balanced networks. Actual insolation levels and load profiles are used to confirm the effectiveness of the proposed indices. This paper derives the acceptable range of the proposed indices and safe margin, which have been compared with the basic active power curtailment method with no constraint, in order to avoid voltage rise. The IEEE 69-bus network is also modified and assessed for voltage rise due to reverse power flow and compared before and after applying the proposed methodology.

Model-based temperature estimation has been widely studied and applied in many applications, including for power/energy storage applications such as batteries or supercapacitors (SCs). In this paper, sensors placement for a temperature monitoring and diagnostic system is studied, with respect not only to the state estimation during normal condition but also abnormal overheating detection. The abnormal overheating is modelled as an unknown additional disturbance. Several measures based on the cross Gramian matrix are used as the basis for the optimal sensors placement for the overheating detectability, and the placement selection is evaluated from different overheating simulation scenarios. A “naive” sensor placement which intuitively places the sensors in an evenly distributed manner along the string is also included to confirm the usefulness of the cross Gramian measure-based sensors placement.

We propose a compensator-based strategy for design of a track-seeking and track-following control system for a dual-stage servo actuator in hard disk drives. A well-known decoupling structure is employed to disconnect the control of the primary voice coil motor (VCM) actuator from the loop for a secondary high-bandwidth actuator. The compensator is placed in the secondary loop and suitably combined with a saturation nonlinearity in order to obtain actuator signal boundedness. The design procedure consists of four steps: 1) design of an established nonlinear seek-settle-track following controller for the VCM; 2) design of a linear track following controller for the secondary actuator; 3) observer design; and 4) design of a compensator to retain global stability and to improve performance. The proposed control system improves performance of both long-span seeking (proximate-time-optimal controller) and short-span seeking. In addition, it achieves high-bandwidth track following performance. The experimental results show good track-following performance, and short-span/long-span-seeking performance with fast settling time. The overshoot during track seeking can be made negligible for a suitably tuned VCM-actuator control loop.

Adjustable balancers are useful in applications where rotational imbalance is frequently varied. For example, in media level servo track writers used in the hard disk drive industry, a set of blank disks is loaded on a spindle motor for the purpose of servo writing. Since servo writing is performed at high speeds, imbalance introduced by disks and spacers results in significant vibrations that can affect the quality of the servo writing process. This paper proposes a new configuration of adjustable balancer that enables to compensate for rotational imbalance each time a new set of blank disks is loaded into the servo track writing machine. The adjustable balancer is ring shaped with a number of grooves displaced around axis of rotation. Steel balls are placed inside the grooves and held by permanent magnets. Imbalance compensation is achieved by electromagnetically activated release of the steel balls. The main advantage of the proposed configuration is its large compensation range. Presented three-dimensional finite-element analysis results and experimental results demonstrate and prove the effectiveness of this novel configuration.

Temperature measurement in battery strings is most critical not just for safety reasons but also to restrain operating conditions that would reduce the battery lifetime. However, placing a thermal sensor in each individual battery cell within a battery string implies cost and space. In this paper, the optimal number and location of thermal sensors in a forced-cooled battery string is discussed. Different observability Gramian-based observability criteria are used to evaluate and compare observability degree of placement of different number and different combinations of sensors locations in the battery string. The observability degree is further verified by evaluating the observer performance for the different sensor locations. The most suitable observability criteria to ascertain the optimal location of such thermal sensors are recommended.

We present a method for improving the short-span seeking performance of a recently proposed compensator-based control system for a dual-stage servo actuator. The method consists of replacing a constant saturation nonlinearity in the secondary loop of the dual-stage control system by a dynamic saturation nonlinearity. This results in a significantly faster response of the secondary actuator and hence faster seeking times. The improvement in seeking times is greatest for short-range seeks that are within the range of the secondary actuator. We also present experimental results comparing the performance of a dual-stage servo actuator with constant and with dynamic saturation in the secondary loop.

We derive an objective function which instead of mapping/placing application task graphs in a compact manner onto reconfigurable devices, dilates the mappings as much as the available latencies on critical connections allow. The objective function is then optimized using simulated annealing. The main advantage of the dilated placement of the task graphs is that the unused resources between an application's configured components can be used to provide additional flexibility when the configuration needs to change. We present results of applying the dilated placement to one synthetic case and one real case. The presented results show successful and meaningful graph dilation.

Unlike synchronous generators, renewable generators, e.g. photovoltaic (PV) arrays and wind turbines, cannot provide rotating inertia when connected to the grid through power converters. As a result, excessive grid frequency deviations are likely to occur in the event of generator tripping and/or load shedding. An effective approach to increase inertia is achieved by proportionally associating the dc-link voltage of grid-connected power converters with the grid frequency, allowing power converters to generate a fixed amount of virtual inertia for frequency support. To further develop this idea, this paper proposes a frequency deadband-based virtual inertia controller for power converters to perform inertia responses during frequency events. The proposed controller enables the increase of inertia in a shorter time duration, leading to an improved frequency nadir and a reduction of the energy required for inertia emulation. Finally, simulated and experimental results are presented to verify its effectiveness.

This paper proposes aperiodically sampled and time delayed data based distributed control system for frequency restoration, state of charge balancing and voltage restoration, in a microgrid with distributed batteries. Lyapunov-Krasovskii functionals and linear matrix inequalities are used to calculate the control system parameters. Real-time simulations using RTDS are used to verify the proposed control method on a European benchmark microgrid.