This article proposes a novel distributed event-triggered secondary control approach subject to i... more This article proposes a novel distributed event-triggered secondary control approach subject to input saturation and time delay in communication links among distributed generators (DGs) to achieve both voltage restoration and proportional current sharing in islanded DC microgrids (MGs). In contrast to periodic communication, sampled-data exchanges only occur when the triggering condition is satisfied. Therefore, communication instants and computation burdens will be reduced significantly. Compared with the existing event-triggered mechanism, this article investigates conditions for achieving consensus in the presence of both input saturation and time delay constraints. The Lyapunov synthesis is employed to derive the stability and convergence analysis of the proposed event-triggering condition and ensure the Zeno-free of the system. Finally, the effectiveness of the proposed controller is validated by simulating its performance under various scenarios in an islanded DC MG using the MATLAB/SimPowerSystems Toolbox.
2018 9th Annual Power Electronics, Drives Systems and Technologies Conference (PEDSTC)
This paper presents a 4th order CLCL resonant converter that has a simple and unique design, and ... more This paper presents a 4th order CLCL resonant converter that has a simple and unique design, and also it has the constant current power supply characteristic that is used for many constant current applications in various laboratories and industries. This converter is designed with Immittance two inductors and two capacitors, to property for constant current power supply. A detailed analysis, design and control process of a 200w converter is given, and simulation results are verified with results of a constructed converter. This converter with its unique structure, a combination of series and parallel resonant converter, has the advantages of both. As a constant current supply, CLCL resonant converter has the advantages of rigidity against short circuit even without a controller, easy operation in parallel mode, low circulating currents and high efficiency due to its soft switching operation. For this converter, leakage and magnetizing inductance of a transformer can be used as a part in the resonance network, and it decreases the converter size. Furthermore, series capacitor, eliminates the DC component and prevents the transformer saturation in unbalance conditions. With fixed-frequency performance, filter design also will be easier. Considering these advantages, the proposed topology can be used in a variety of applications such as magnetic power supplies, capacitor charging power supplies and agitator for laser diodes.
2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC)
In this study, a new cascaded multilevel inverter with low number of power transistors is propose... more In this study, a new cascaded multilevel inverter with low number of power transistors is proposed. The presented topology has a low voltage stress across the switches, and can inherently produce all of the negative voltage levels. The proposed structure uses two types of module, namely, MI-module and LI-module. The LI-module uses a capacitor-based circuit to increase the number of level in which balancing of the capacitors' voltage is done automatically. The structure of each module, the derived cascaded structure, and the associated relationships are described and presented. The operation of the proposed structure is studied via simulation with MATLAB/SIMULINK and the simulation results are presented. Finally, to demonstrate the advantages of the proposed topology, a comparison between the proposed topology and other topologies is accomplished.
In this paper, a hierarchical control strategy is introduced to control a new three-port multidir... more In this paper, a hierarchical control strategy is introduced to control a new three-port multidirectional DC-DC converter for integrating an energy storage system (ESS) to a bipolar DC microgrid (BPDCMG). The proposed converter provides a voltage-balancing function for the BPDCMG and adjusts the states of charge (SoC) of the ESS. Previous studies tend to balance the voltage of the BPDCMG buses with active sources or by transferring power from one bus to another. Furthermore, the batteries available in BPDCMGs were charged equally by both buses. However, this power sharing method does not guarantee efficient operation of the whole system. In order to achieve a higher efficiency and lower energy losses, a triple-layer hierarchical control strategy, including a primary droop controller, a secondary voltage restoration controller and a tertiary optimization controller are proposed. Thanks to the multi-functional operation of the proposed converter, its conversion stages are reduced. Furthermore, the efficiency and weight of the system are both improved. Therefore, this converter has a significant capability to be used in portable BPDCMGs such as electric DC ships. The converter modes are analyzed and small-signal models of the converter are extracted. Comprehensive simulation studies are carried out and a BPDCMG laboratory setup is implemented in order to validate the effectiveness of the proposed converter and its hierarchical control strategy. Simulation and experimental results show that using the proposed converter mitigates voltage imbalances. As a result, the system efficiency is improved by using the hierarchical optimal power flow control.
In this paper, we propose a multi-purpose controllableelectrochemical impedance spectroscopy (MP-... more In this paper, we propose a multi-purpose controllableelectrochemical impedance spectroscopy (MP-cEIS) devicefor online and offline battery monitoring and testing duringcharge and discharge processes.
2019 10th International Power Electronics, Drive Systems and Technologies Conference (PEDSTC), 2019
A novel transformerless single-phase inverter suitable for photovoltaic applications is introduce... more A novel transformerless single-phase inverter suitable for photovoltaic applications is introduced in this paper. The common-ground feature of this topology provided for both the input and output terminals leads to elimination of leakage current in the photovoltaic systems. Compared to the single-phase semi-Z-source and switched-coupled-inductor Z-source inverters, the proposed inverter guarantees the higher voltage gain. In design procedure of the presented topology, the capacitors are selected small enough to satisfy the reliability and the economic issues. The operation principles of the inverter are discussed which finally the obtained simulation results confirm the validity of the proposed topology performance.
2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC), 2020
A unified power quality conditioner (UPQC) is introduced and designed in this paper, which is cap... more A unified power quality conditioner (UPQC) is introduced and designed in this paper, which is capable of dealing with multiple power quality issues simultaneously. The mentioned UPQC consists of two active power filters (APF), one of which is placed series with the line, and the other one is parallel to it. Two control systems are developed for each of the UPQC sections. The series APF is controlled by a carrier-based pulse width modulation (PWM) generator, which enables it to follow the reference voltage. Furthermore, a direct-quadrature-zero (dq0) transformation is utilized to generate the most proper current reference signal in order to minimize harmonics in the current waveform and maximize the power factor. Then, a hysteresis controller is used to build command signals for shunt APF. The proper functionality of introduced UPQC and its control system is verified in cases of most common power quality problems such as voltage sag, voltage swell, single-phase fault, three-phase fault, reactive power compensation, current harmonic compensation of nonlinear loads, and unbalanced load by performing extensive simulations in MATLAB Simulink.
2019 27th Iranian Conference on Electrical Engineering (ICEE), 2019
This paper presents a cooperative control strategy to reduce the power consumption based on the c... more This paper presents a cooperative control strategy to reduce the power consumption based on the concept of conservation voltage reduction (CVR) in an islanded DC microgrid. It is expected that each islanded DC microgrid supplies its loads autonomously; however, owing to the unexpected power demand, it is possible that the microgrid experiences power deficiency. In conventional power systems, the CVR is one of the cheapest technologies for demand-side management that the utilities lower the voltage of end-use loads within the permissible range in hope that the power demand is reduced. However, in the islanded DC microgrids, the employment of CVR for demand-side management has not received sufficient attention so far. Therefore, this paper presents a CVR based distributed cooperative control scheme which, carries out demand-side management by voltage regulation. The efficiency of the proposed control scheme in comparison to the well-known hierarchical distributed cooperative control is illustrated. A complete set of simulation studies is carried out in PLECS to verify the effectiveness of the proposed control scheme.
2020 28th Iranian Conference on Electrical Engineering (ICEE), 2020
This study proposes a new topology of DC-DC converter which its voltage gain is a quadratic form ... more This study proposes a new topology of DC-DC converter which its voltage gain is a quadratic form of the conventional boost circuit. The proposed converter has been consisted of combining conventional cuk and boost converters which makes it possible to obtain high output voltages without the high value of the duty cycle. The voltage ratio of proposed topology has been compared with conventional topologies and modified structures of literature. Continuous input current is another brilliant feature of the introduced converter. Operating details and steady state operation have been analyzed in continuous conduction motor (CCM). Small signal analysis and bode plots which are essential for control system design have been reported. Finally, simulation results which have been done by PELECS are reported.
2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC), 2020
Although the traditional power network is capable of making the instantaneous balance between pow... more Although the traditional power network is capable of making the instantaneous balance between power generation and consumption, it still faces many problems such as energy crisis, and environmental pollution. Considering these problems, much effort went into developing Microgrids. Microgrids consist of loads and distributed generation units which operate as a single controllable system. This paper includes the step by step controlling and modeling of voltage-source converters and DSTATCOM and modeling of constant impedance and constant power loads. The results of this paper are simulated and analyzed using modal analysis. This mathematical model is verified by the simulation, Then, by using the introduced models, the small-signal stability of microgrid is studied (a) with and (b) without the existence of DSTATCOM by the eigenvalues analysis method.
iranian journal of electrical and electronic engineering, 2017
This paper proposes a decentralized control technique to minimize the total operation cost of a D... more This paper proposes a decentralized control technique to minimize the total operation cost of a DC microgrid in both grid-connected and islanded modes. In this study, a cost-based droop control scheme based on the hourly bids of all participant distributed generators (DGs) and the hourly energy price of the utility is presented. An economic power sharing technique among various types of DG units is adopted to appropriately minimize the daily total operation cost of DC microgrid without a microgrid central controller. The DC microgrid may include non-dispatchable DG units (such as photovoltaic systems) and dispatchable generation units. Unlike other energy management techniques, the proposed method suffers neither from forecasting errors for both load demand and renewable energy power prediction modules, nor from complicated optimization techniques. In the proposed method, all DGs and the utility are classified in a sorting rule based on their hourly bids and open market price, and t...
In this paper, the improvement of small signal stability of islanded inverter-based microgrids by... more In this paper, the improvement of small signal stability of islanded inverter-based microgrids by selective dynamic gains of droop are discussed. An acceptable improvement must be reached by using the possible minimum number of voltage source inverters in order to adding the proper dynamic gains to their droop characteristic. First, using the linearized equations of inverter-based islanded microgrids, a state-space equation of islanded microgrids is presented. Then, a microgrid test system is considered and a sensitivity analysis is applyied to its low-frequency eigenvalues wih a low damping factor. Using the sensitivity analysis, the more effective voltage source inverters are identifiyed such that the addition of proper dynamic gains only to their droop characteristic can increase the damping of low-frequency power oscillations of microgrid. A simulation study is carried out in order to verify the effectiveness of selective dynamic gains of droop in PLECS software.
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
In this paper, it is shown that by increasing the number of Micro-Inverters (MIs), the performanc... more In this paper, it is shown that by increasing the number of Micro-Inverters (MIs), the performance of their harmonic compensators, may be deteriorated. Therfore, to design harmonic compensators for a large number of parallel MIs, it is not enough to consider the performance of only one MI. The analysis show that, in the design of harmonic compensators, presence of filter capacitor, can cause the MIs to have capacitive behaviors. On the other hand, by increasing the number of MIs, the probable interaction frequency between the MIs and the grid, drifts down to the lower frequency range and close to the harmonic frequencies. In this situation, the interaction among the inductive grid and the capacitive MIs, at harmonic frequencies, is inevitable. As a solution, in this paper, the modified design of harmonic compensators is proposed. A complete set of simulations is also provided to evaluate the effectiveness of the proposed analysis.
Abstract This paper presents a comprehensive small-signal stability analysis for synchronous gene... more Abstract This paper presents a comprehensive small-signal stability analysis for synchronous generator (SG)-based microgrids (MGs) considering the control type of SGs and wide range of loading condition. The original aim is to evaluate the effect of loading conditions on the small-signal stability of droop-controlled and PQ-controlled SGs which has not been adequately addressed in the literature. To this purpose, complete state–space small-signal model of a typical medium voltage AC MG involving both droop-controlled and PQ-controlled SGs is developed. This facilitates stability studies by means of eigenvalue analysis. Results show that the small-signal stability behavior of droop-controlled SGs is different from that of PQ-controlled SGs. It is found that droop-controlled SGs show weaker stability or even instability in light loading condition. It is found that operation of PQ-controlled SGs in the presence of droop-controlled SGs can result in better stability of SG-based MG at light loading conditions. Effect of reference powers of PQ-controlled SGs on small-signal stability is also investigated. Moreover, the effect of Power System Stabilizer (PSS) on the damping of the weak stability or instability observed in low loading conditions of droop-controlled SG-based MGs is investigated. Time-domain simulations are used in order to verify the proposed theoretical analysis.
2019 27th Iranian Conference on Electrical Engineering (ICEE), 2019
This paper introduces a novel topology of buck-boost converter. In comparison to the traditional ... more This paper introduces a novel topology of buck-boost converter. In comparison to the traditional buck-boost converter, the voltage ratio of the proposed topology is high. Despite the high voltage gain of the quadratic buck-boost converters in step-up mode, the voltage ratio of the proposed converter in a specified duty cycle is approximately 2 times of the quadratic buck-boost converters in step up mode. Continuity of the input current is the other advantages of the proposed converter. Thus, the proposed topology is appropriate for renewable applications. Moreover, the output current of the proposed converter is continuous. The introduced topology is functioning in continuous current mode (CCM); hence, all principle operations and steady state analysis are discussed in CCM. Eventually, a simulation studies is carried out in PLECS to verify performances of the offered topology.
This article proposes a novel distributed event-triggered secondary control approach subject to i... more This article proposes a novel distributed event-triggered secondary control approach subject to input saturation and time delay in communication links among distributed generators (DGs) to achieve both voltage restoration and proportional current sharing in islanded DC microgrids (MGs). In contrast to periodic communication, sampled-data exchanges only occur when the triggering condition is satisfied. Therefore, communication instants and computation burdens will be reduced significantly. Compared with the existing event-triggered mechanism, this article investigates conditions for achieving consensus in the presence of both input saturation and time delay constraints. The Lyapunov synthesis is employed to derive the stability and convergence analysis of the proposed event-triggering condition and ensure the Zeno-free of the system. Finally, the effectiveness of the proposed controller is validated by simulating its performance under various scenarios in an islanded DC MG using the MATLAB/SimPowerSystems Toolbox.
2018 9th Annual Power Electronics, Drives Systems and Technologies Conference (PEDSTC)
This paper presents a 4th order CLCL resonant converter that has a simple and unique design, and ... more This paper presents a 4th order CLCL resonant converter that has a simple and unique design, and also it has the constant current power supply characteristic that is used for many constant current applications in various laboratories and industries. This converter is designed with Immittance two inductors and two capacitors, to property for constant current power supply. A detailed analysis, design and control process of a 200w converter is given, and simulation results are verified with results of a constructed converter. This converter with its unique structure, a combination of series and parallel resonant converter, has the advantages of both. As a constant current supply, CLCL resonant converter has the advantages of rigidity against short circuit even without a controller, easy operation in parallel mode, low circulating currents and high efficiency due to its soft switching operation. For this converter, leakage and magnetizing inductance of a transformer can be used as a part in the resonance network, and it decreases the converter size. Furthermore, series capacitor, eliminates the DC component and prevents the transformer saturation in unbalance conditions. With fixed-frequency performance, filter design also will be easier. Considering these advantages, the proposed topology can be used in a variety of applications such as magnetic power supplies, capacitor charging power supplies and agitator for laser diodes.
2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC)
In this study, a new cascaded multilevel inverter with low number of power transistors is propose... more In this study, a new cascaded multilevel inverter with low number of power transistors is proposed. The presented topology has a low voltage stress across the switches, and can inherently produce all of the negative voltage levels. The proposed structure uses two types of module, namely, MI-module and LI-module. The LI-module uses a capacitor-based circuit to increase the number of level in which balancing of the capacitors' voltage is done automatically. The structure of each module, the derived cascaded structure, and the associated relationships are described and presented. The operation of the proposed structure is studied via simulation with MATLAB/SIMULINK and the simulation results are presented. Finally, to demonstrate the advantages of the proposed topology, a comparison between the proposed topology and other topologies is accomplished.
In this paper, a hierarchical control strategy is introduced to control a new three-port multidir... more In this paper, a hierarchical control strategy is introduced to control a new three-port multidirectional DC-DC converter for integrating an energy storage system (ESS) to a bipolar DC microgrid (BPDCMG). The proposed converter provides a voltage-balancing function for the BPDCMG and adjusts the states of charge (SoC) of the ESS. Previous studies tend to balance the voltage of the BPDCMG buses with active sources or by transferring power from one bus to another. Furthermore, the batteries available in BPDCMGs were charged equally by both buses. However, this power sharing method does not guarantee efficient operation of the whole system. In order to achieve a higher efficiency and lower energy losses, a triple-layer hierarchical control strategy, including a primary droop controller, a secondary voltage restoration controller and a tertiary optimization controller are proposed. Thanks to the multi-functional operation of the proposed converter, its conversion stages are reduced. Furthermore, the efficiency and weight of the system are both improved. Therefore, this converter has a significant capability to be used in portable BPDCMGs such as electric DC ships. The converter modes are analyzed and small-signal models of the converter are extracted. Comprehensive simulation studies are carried out and a BPDCMG laboratory setup is implemented in order to validate the effectiveness of the proposed converter and its hierarchical control strategy. Simulation and experimental results show that using the proposed converter mitigates voltage imbalances. As a result, the system efficiency is improved by using the hierarchical optimal power flow control.
In this paper, we propose a multi-purpose controllableelectrochemical impedance spectroscopy (MP-... more In this paper, we propose a multi-purpose controllableelectrochemical impedance spectroscopy (MP-cEIS) devicefor online and offline battery monitoring and testing duringcharge and discharge processes.
2019 10th International Power Electronics, Drive Systems and Technologies Conference (PEDSTC), 2019
A novel transformerless single-phase inverter suitable for photovoltaic applications is introduce... more A novel transformerless single-phase inverter suitable for photovoltaic applications is introduced in this paper. The common-ground feature of this topology provided for both the input and output terminals leads to elimination of leakage current in the photovoltaic systems. Compared to the single-phase semi-Z-source and switched-coupled-inductor Z-source inverters, the proposed inverter guarantees the higher voltage gain. In design procedure of the presented topology, the capacitors are selected small enough to satisfy the reliability and the economic issues. The operation principles of the inverter are discussed which finally the obtained simulation results confirm the validity of the proposed topology performance.
2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC), 2020
A unified power quality conditioner (UPQC) is introduced and designed in this paper, which is cap... more A unified power quality conditioner (UPQC) is introduced and designed in this paper, which is capable of dealing with multiple power quality issues simultaneously. The mentioned UPQC consists of two active power filters (APF), one of which is placed series with the line, and the other one is parallel to it. Two control systems are developed for each of the UPQC sections. The series APF is controlled by a carrier-based pulse width modulation (PWM) generator, which enables it to follow the reference voltage. Furthermore, a direct-quadrature-zero (dq0) transformation is utilized to generate the most proper current reference signal in order to minimize harmonics in the current waveform and maximize the power factor. Then, a hysteresis controller is used to build command signals for shunt APF. The proper functionality of introduced UPQC and its control system is verified in cases of most common power quality problems such as voltage sag, voltage swell, single-phase fault, three-phase fault, reactive power compensation, current harmonic compensation of nonlinear loads, and unbalanced load by performing extensive simulations in MATLAB Simulink.
2019 27th Iranian Conference on Electrical Engineering (ICEE), 2019
This paper presents a cooperative control strategy to reduce the power consumption based on the c... more This paper presents a cooperative control strategy to reduce the power consumption based on the concept of conservation voltage reduction (CVR) in an islanded DC microgrid. It is expected that each islanded DC microgrid supplies its loads autonomously; however, owing to the unexpected power demand, it is possible that the microgrid experiences power deficiency. In conventional power systems, the CVR is one of the cheapest technologies for demand-side management that the utilities lower the voltage of end-use loads within the permissible range in hope that the power demand is reduced. However, in the islanded DC microgrids, the employment of CVR for demand-side management has not received sufficient attention so far. Therefore, this paper presents a CVR based distributed cooperative control scheme which, carries out demand-side management by voltage regulation. The efficiency of the proposed control scheme in comparison to the well-known hierarchical distributed cooperative control is illustrated. A complete set of simulation studies is carried out in PLECS to verify the effectiveness of the proposed control scheme.
2020 28th Iranian Conference on Electrical Engineering (ICEE), 2020
This study proposes a new topology of DC-DC converter which its voltage gain is a quadratic form ... more This study proposes a new topology of DC-DC converter which its voltage gain is a quadratic form of the conventional boost circuit. The proposed converter has been consisted of combining conventional cuk and boost converters which makes it possible to obtain high output voltages without the high value of the duty cycle. The voltage ratio of proposed topology has been compared with conventional topologies and modified structures of literature. Continuous input current is another brilliant feature of the introduced converter. Operating details and steady state operation have been analyzed in continuous conduction motor (CCM). Small signal analysis and bode plots which are essential for control system design have been reported. Finally, simulation results which have been done by PELECS are reported.
2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC), 2020
Although the traditional power network is capable of making the instantaneous balance between pow... more Although the traditional power network is capable of making the instantaneous balance between power generation and consumption, it still faces many problems such as energy crisis, and environmental pollution. Considering these problems, much effort went into developing Microgrids. Microgrids consist of loads and distributed generation units which operate as a single controllable system. This paper includes the step by step controlling and modeling of voltage-source converters and DSTATCOM and modeling of constant impedance and constant power loads. The results of this paper are simulated and analyzed using modal analysis. This mathematical model is verified by the simulation, Then, by using the introduced models, the small-signal stability of microgrid is studied (a) with and (b) without the existence of DSTATCOM by the eigenvalues analysis method.
iranian journal of electrical and electronic engineering, 2017
This paper proposes a decentralized control technique to minimize the total operation cost of a D... more This paper proposes a decentralized control technique to minimize the total operation cost of a DC microgrid in both grid-connected and islanded modes. In this study, a cost-based droop control scheme based on the hourly bids of all participant distributed generators (DGs) and the hourly energy price of the utility is presented. An economic power sharing technique among various types of DG units is adopted to appropriately minimize the daily total operation cost of DC microgrid without a microgrid central controller. The DC microgrid may include non-dispatchable DG units (such as photovoltaic systems) and dispatchable generation units. Unlike other energy management techniques, the proposed method suffers neither from forecasting errors for both load demand and renewable energy power prediction modules, nor from complicated optimization techniques. In the proposed method, all DGs and the utility are classified in a sorting rule based on their hourly bids and open market price, and t...
In this paper, the improvement of small signal stability of islanded inverter-based microgrids by... more In this paper, the improvement of small signal stability of islanded inverter-based microgrids by selective dynamic gains of droop are discussed. An acceptable improvement must be reached by using the possible minimum number of voltage source inverters in order to adding the proper dynamic gains to their droop characteristic. First, using the linearized equations of inverter-based islanded microgrids, a state-space equation of islanded microgrids is presented. Then, a microgrid test system is considered and a sensitivity analysis is applyied to its low-frequency eigenvalues wih a low damping factor. Using the sensitivity analysis, the more effective voltage source inverters are identifiyed such that the addition of proper dynamic gains only to their droop characteristic can increase the damping of low-frequency power oscillations of microgrid. A simulation study is carried out in order to verify the effectiveness of selective dynamic gains of droop in PLECS software.
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
In this paper, it is shown that by increasing the number of Micro-Inverters (MIs), the performanc... more In this paper, it is shown that by increasing the number of Micro-Inverters (MIs), the performance of their harmonic compensators, may be deteriorated. Therfore, to design harmonic compensators for a large number of parallel MIs, it is not enough to consider the performance of only one MI. The analysis show that, in the design of harmonic compensators, presence of filter capacitor, can cause the MIs to have capacitive behaviors. On the other hand, by increasing the number of MIs, the probable interaction frequency between the MIs and the grid, drifts down to the lower frequency range and close to the harmonic frequencies. In this situation, the interaction among the inductive grid and the capacitive MIs, at harmonic frequencies, is inevitable. As a solution, in this paper, the modified design of harmonic compensators is proposed. A complete set of simulations is also provided to evaluate the effectiveness of the proposed analysis.
Abstract This paper presents a comprehensive small-signal stability analysis for synchronous gene... more Abstract This paper presents a comprehensive small-signal stability analysis for synchronous generator (SG)-based microgrids (MGs) considering the control type of SGs and wide range of loading condition. The original aim is to evaluate the effect of loading conditions on the small-signal stability of droop-controlled and PQ-controlled SGs which has not been adequately addressed in the literature. To this purpose, complete state–space small-signal model of a typical medium voltage AC MG involving both droop-controlled and PQ-controlled SGs is developed. This facilitates stability studies by means of eigenvalue analysis. Results show that the small-signal stability behavior of droop-controlled SGs is different from that of PQ-controlled SGs. It is found that droop-controlled SGs show weaker stability or even instability in light loading condition. It is found that operation of PQ-controlled SGs in the presence of droop-controlled SGs can result in better stability of SG-based MG at light loading conditions. Effect of reference powers of PQ-controlled SGs on small-signal stability is also investigated. Moreover, the effect of Power System Stabilizer (PSS) on the damping of the weak stability or instability observed in low loading conditions of droop-controlled SG-based MGs is investigated. Time-domain simulations are used in order to verify the proposed theoretical analysis.
2019 27th Iranian Conference on Electrical Engineering (ICEE), 2019
This paper introduces a novel topology of buck-boost converter. In comparison to the traditional ... more This paper introduces a novel topology of buck-boost converter. In comparison to the traditional buck-boost converter, the voltage ratio of the proposed topology is high. Despite the high voltage gain of the quadratic buck-boost converters in step-up mode, the voltage ratio of the proposed converter in a specified duty cycle is approximately 2 times of the quadratic buck-boost converters in step up mode. Continuity of the input current is the other advantages of the proposed converter. Thus, the proposed topology is appropriate for renewable applications. Moreover, the output current of the proposed converter is continuous. The introduced topology is functioning in continuous current mode (CCM); hence, all principle operations and steady state analysis are discussed in CCM. Eventually, a simulation studies is carried out in PLECS to verify performances of the offered topology.
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Papers by Mohsen Hamzeh