Browsing by Author "Pouresmaeil, Edris"

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  • An Adaptive Parameter-based Control Technique of Virtual Synchronous Generator for Smooth Transient between Islanded and Grid-connected Mode of Operation
    (2021-10) Pouresmaeil, Mobina; Sangrody, Reza; Taheri, Shamsodin; Pouresmaeil, Edris
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This paper deals with the development of a control technique for the control of voltage source converters (VSCs) as an interface between renewable energy sources (RESs) and power grids. The lack of inertia in converter-based generators and their unconventional dynamic behavior increase the negative impacts on the power grid, unlike the operation of the conventional synchronous generators (SGs). In this sense, the proposed control technique emulates the behavior of SGs in the control loop of the interfaced converter acting as a grid-forming power generator. Thus, supportive functionalities for enhancing electric grid stability (e.g., frequency oscillation damping) will be provided by interfaced converter as a virtual synchronous generator (VSG). The main targets of the proposed control technique include virtual inertia emulation, frequency oscillation damping, primary and secondary frequency regulation, and voltage regulation. The main contribution of this work over the existing methods is that the optimal values for swing equation parameters are employed to ensure well-designed damping feature of the VSG-based converter which adapts grid-connected and islanded operating modes, enabling a smooth resynchronizing to the grid as its plug-and-play capability requirement. The control structure is evaluated through simulation in MATLAB/Simulink.
  • Adjustable unbalanced current controller for tranformerless PV generation to suppress DC voltage ripples of inverter in low-voltage ride-through (LVRT) operation
    (2022-04-27) Kadri, Afshin; Ebrahimi, Reza; Pouresmaeil, Edris
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Low voltage ride-trough (LVRT) feature is compulsory for each grid-connected inverter to support the grid by injecting reactive power in low voltage conditions. It is well known that the operation of an inverter in a normal grid condition is different from its operation in a faulty one. One of the detrimental effects of working in a faulty grid is ripples in the DC bus voltage due to the active power oscillation caused by unbalance voltages. Here, a new control system based on unbalance current injection is proposed to eliminate these ripples. For the analysis, a four-leg inverter is considered in a transformerless microgrid. Then, instantaneous power constraints, which are imposed by the capacity of the inverter, and low voltage ride-through necessities are considered to achieve the required reference currents. In addition, constant power strategy is used as a power control method and essential reference currents for this condition are presented. Moreover, the required reference currents are achieved to eliminate the ripples in the DC bus voltage when the constant power strategy cannot be performed because of current limitation restriction. Finally, simulation results are presented to prove the effectiveness of the proposed controller in different conditions.
  • Analysis of electrical behaviour of PV arrays covered with nonuniform snow
    (2020-02-20) Hosseini, S.; Taheri, S.; Pouresmaeil, Edris; Taheri, H.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Snowfall during cold months impacts the performance of photovoltaic (PV) installations. In real field operations, different ambient conditions often cause non-uniform snow accretion on PV panels. This can have a considerable effect on PV power production depending on array configuration, the pattern of snow coverage, and bypass diodes included in a PV system. The electrical behaviour of snow-covered PV cells is experimentally characterised. Then, the true impact of non-uniform snow accretion on PV system performance is investigated. Effect of employing bypass diodes on a PV string power generation is also verified. Different PV array layouts are studied to improve the PV harvest efficiency in cold climate regions. This research may be regarded as a practical tool for the design and selection of PV modules subjected to snowfall.
  • Angular Frequency Dynamic-Based Control Technique of a Grid-Interfaced Converter Emulated by a Synchronous Generator
    (2018) Mehrasa, Majid; Sepehr, Amir; Pouresmaeil, Edris; Kyyrä, Jorma; Marzband, Mousa; Catalão, João P.S.
     A4 Artikkeli konferenssijulkaisussa
    In this paper, an angular frequency dynamic-based control technique is proposed to control interfaced converters between the power grid and renewable energy sources. The proposed control technique can guarantee a stable operation of power grid under high penetration of renewable energy resources through providing the required inertia properties. The synchronous generator characteristics combined with the basic dynamic model of the interfaced converter can shape a second order derivative of the grid angular frequency consisting of converter power and virtual mechanical power derivative with embedded virtual inertia to prevent instability from the power grid as well as to generate active and reactive power with appropriate inertia. Simulation analyses are performed in Matlab/Simulink to attest the high performance of the proposed control technique.
  • An Approach Utilizing Converters for Locating Faults in LV Distribution Grids
    (2021-10-25) Pitkäniemi, Sami; Routimo, Mikko; Kukkola, Jarno; Pirsto, Ville; Pouresmaeil, Edris
     A4 Artikkeli konferenssijulkaisussa
    This paper proposes an approach for locating faults in a distribution grid by utilizing data measured and gathered by distributed converters. The data, comprising grid voltages and impedances from multiple locations, is processed using multinomial logistic regression, a machine learning algorithm, to classify a fault location in the grid. The algorithm is first trained with simulation data, followed by evaluation of its predictive performance using a set of test data previously unseen by the algorithm. The fault location accuracy of the proposed approach is found resonable and encourages further studies of the unused potential in the converters.
  • An Asymmetrical Step-Up Multilevel Inverter Based on Switched-Capacitor Network
    (2019-06-02) Taghvaie, Amir; Alijani, Ahmad; Adabi, M. Ebrahim; Rezanejad, Mohammad; Adabi, Jafar; Rouzbehi, Kumars; Pouresmaeil, Edris
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This paper presents a transformerless step-up multilevel inverter based on a switched-capacitor structure. One of the main contributions of the proposed topology is replacing the separated DC voltage source with capacitors which are charged at predetermined time intervals. Therefore, a high-level staircase voltage waveform can be achieved by discharging some of these capacitors on the load. The other contribution of the proposed structure is to eliminate the magnetic elements which traditionally boost the input DC voltage. In addition, asymmetrical or unequal amounts of capacitor voltages create more voltage levels, which enable voltage level increments without increasing the number of semiconductor devices. This paper introduces a self-balanced boost Switched-Capacitors Multilevel Inverter (SCMLI) which is able to create a nearly sinusoidal voltage waveform with a maximum voltage of up to 45 times that of the input voltage DC source. Higher level output voltage levels are also achievable by extending the circuit topology. After determination of the switching angles and selecting the proper switching states for each level, an offline NLC method is used for modulation, which eases the control implementation. Analysis, simulation and experiments are carried out for a 91-level inverter (45 levels for positive and negative voltages and one for zero voltage) are presented.
  • Bidirectional Dual-Input Single-Output DC-DC Converter Based on Passivity Control Strategy
    (2024) Abdolahi, Mohsen; Hosseinnataj, Saeed; Norouzian, Majid; Adabi, Jafar; Pouresmaeil, Edris
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The increasing popularity of Electric Vehicles (EVs) can be attributed to recent advancements in highly efficient power conversion technology, as well as a desire to reduce reliance on fossil fuels. As a result, bidirectional DC-DC converters have gained significant interest and importance in the field of electric vehicle applications. This paper introduces an enhanced DC-DC converter, the Bidirectional Dual-Input Single-Output (BDISO) converter for the Electrical Vehicle application, which combines multiple energy sources for efficient power delivery to a load. The converter offers versatile operational modes and employs a Passivity-Based Control (PBC) strategy for stable closed-loop control. A mathematical model is developed and analyzed to understand its behavior. In addition, rigorous evaluations of reliability and efficiency demonstrate robust performance and high operational efficiency across various conditions in comparison with exciting systems. Finally, the proposed converter with its controller is validated through simulation and experimental results.
  • A Centralized Smart Decision-Making Hierarchical Interactive Architecture for Multiple Home Microgrids in Retail Electricity Market
    (2018) Javadi, Masoumeh; Marzband, Mousa; Akorede, Mudathir Funsho; Godina, Radu; Saad Al-Sumaiti, Ameena; Pouresmaeil, Edris
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The principal aim of this study is to devise a combined market operator and a distribution network operator structure for multiple home-microgrids (MH-MGs) connected to an upstream grid. Here, there are three distinct types of players with opposite intentions that can participate as a consumer and/or prosumer (as a buyer or seller) in the market. All players that are price makers can compete with each other to obtain much more possible profitability while consumers aim to minimize the market-clearing price. For modeling the interactions among partakers and implementing this comprehensive structure, a multi-objective function problem is solved by using a static, non-cooperative game theory. The propounded structure is a hierarchical bi-level controller, and its accomplishment in the optimal control of MH-MGs with distributed energy resources has been evaluated. The outcome of this algorithm provides the best and most suitable power allocation among different players in the market while satisfying each player’sgoals. Furthermore, the amount of profit gained by each player is ascertained. Simulation results demonstrate 169% increase in the total payoff compared to the imperialist competition algorithm. This percentage proves the effectiveness, extensibility and flexibility of the presented approach in encouraging participants to join the market and boost their profits.
  • Characterization, Calibration and Verification of Upper-Atmosphere Weather Instruments
    (2024-01-22) Paaso, Pauli
     Sähkötekniikan korkeakoulu | Master's thesis
    Upper atmosphere weather instrumentation measurements have a pivotal role in advancing the understanding of atmospheric dynamics and refining weather prediction methodologies. However, there exists various conditions which introduce errors to the values measured by the instruments. These conditions range from solar radiation heating to extreme cold and low pressure. This thesis examines one such instrument in its late development phase, Skyfora StreamSonde radiosonde, for improvements regarding calibration, characterization, and verification processes. While Skyfora StreamSonde is capable of measuring a plethora of measurands, the focus of the thesis is on Pressure, Temperature and Humidity (PTU) measurements. The Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) is an international collaborative initiative that provides a robust framework and guides the research towards innovative solutions and optimization strategies for measurement procedures. Skyfora StreamSonde seeks to reach GRUAN sounding standards and thus, the procedures described in this aim to elevate the measurements of Skyfora StreamSonde to reach GRUAN standards. The PTU instruments of Skyfora StreamSonde are analysed based on test soundings and laboratory tests for areas of improvements. Based on the analysis, a procedure that enhances the capabilities of the instrument is introduced and implemented for each measurand. These procedures are: Time-lag correction, temperature calibration, and GNSS based pressure calculation. The results are empirically validated whenever applicable.
  • Circuit Configuration and Modulation of a Seven-Level Switched-Capacitor Inverter
    (2020-11-06) Khodaparast, Aryorad; Hassani, Mohammadjavad; Azimi, Erfan; Adabi, M. Ebrahim; Adabi, Jafar; Pouresmaeil, Edris
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In this article, a step-up seven-level inverter supplied by a single dc source suitable for renewable energy application is presented. Forming the desired output is realized by charging capacitors and synthesizing them based on a switched-capacitor concept. This structure is praised for the ability of sensorless voltage balancing of the capacitors, reducing control complexity to produce a bipolar staircase waveform. It also benefits from regenerative performance, avoiding unwanted capacitors overvoltage. A phase disposition pulsewidth modulation (PD-PWM) technique is utilized to control the circuit operation. Furthermore, a comparison with other recent topologies reveals that losses, number of semiconductor devices, and gate driver circuits are reduced. Theoretical analysis is verified through a laboratory prototype implementation. Experimental results under various types of loads approve the performance of the proposed inverter and validity of the design. Finally, maximum experimental efficiency of 94.3% (115 V, 250 W load) was reached.
  • Circulating Current Elimination of Grid-Connected Modular Multilevel Converters
    (2018) Shahnazian, Fatemeh; Adabi, Jafar; Pouresmaeil, Edris; Mehrasa, Majid; Catalão, João P.S.
     A4 Artikkeli konferenssijulkaisussa
    This paper presents an analytical dynamic model of a modular multilevel converter (MMC) in grid-connected operating mode. The proposed model is then efficiently used to design a circulating current controller. The proposed controller can accurately study the dynamic and steady-state performance of the converter through harmonic evaluations. Based on this configuration, the modulation is accomplished so that the stable performance of the converter in the network is obtained, which is considered as the foremost novelty of the proposed control method over existing control methods. In order to mitigate the circulating currents, the proposed controller inserts an estimated second harmonic component into modulation indices, which is considered as the second novelty of the proposed control method. The functionality and capability of the proposed control method are validated using detailed theoretical analysis and simulations with MATLAB/Simulink.
  • A Compound Current Limiter and Circuit Breaker
    (2019-05-01) Heidary, Amir; Radmanesh, Hamid; Bakhshi, Ali; Rouzbehi, Kumars; Pouresmaeil, Edris
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The protection of sensitive loads against voltage drop is a concern for the power system. A fast fault current limiter and circuit breaker can be a solution for rapid voltage recovery of sensitive loads. This paper proposes a compound type of current limiter and circuit breaker (CLCB) which can limit fault current and fast break to adjust voltage sags at the protected buses. In addition, it can act as a circuit breaker to open the faulty line. The proposed CLCB is based on a series L-C resonance, which contains a resonant transformer and a series capacitor bank. Moreover, the CLCB includes two anti-parallel power electronic switches (a diode and an IGBT) connected in series with bus couplers. In order to perform an analysis of CLCB performance, the proposed structure was simulated using MATLAB. In addition, an experimental prototype was built, tested, and the experimental results were reported. Comparisons show that experimental results were in fair agreement with the simulation results and confirm CLCB’s ability to act as a fault current limiter and a circuit breaker.
  • Computational Intelligence Based PEVs Aggregator Scheduling with Support for Photovoltaic Power Penetrated Distribution Grid Under Snow Conditions
    (2023-01-01) Hashemi, Behzad; Taheri, Shamsodin; Cretu, Ana-Maria; Pouresmaeil, Edris
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This paper addresses the issue of optimal day-ahead scheduling of a plug-in electric vehicles (PEVs) aggregator that participates in the electricity market and offers an out-of-market balancing service to the local renewable power penetrated distribution system in a snow-prone area. The proposed balancing service provides a reliable source of flexibility for the extra real-time energy demand of the distribution system operator (DSO) which originates from the difference between its day-ahead bids and the actual demand. The problem is investigated on a snowy day when the DSO's day-ahead decisions encounter more uncertainty due to the considerable effect of snow loss on the DSO's photovoltaic plant performance. The aggregator's scheduling is formulated as two-stage stochastic programming which minimizes the PEVs’ charging cost. Monte Carlo simulation and K-means clustering are implemented to generate scenarios of driving patterns and real-time energy market prices, respectively. Offering the balancing service requires day-ahead predictions of the photovoltaic power and the grid load demand which are modeled using long short-term memory networks. The problem is formulated as mixed-integer linear programming. The results show that the proposed scheduling approach reduces the PEVs’ charging cost by 53% and guarantees the grid normal operation. Moreover, the balancing service can reduce the expected PEVs’ charging cost and the DSO's real-time cost by 12% and 14%, respectively.
  • Control of Grid-Tied Converters for Integration of Renewable Energy Sources into the Weak Grids
    (2019) Sepehr, Amir; Pouresmaeil, Edris; Saeedian, Meysam; Routimo, Mikko; Godina, Radu; Yousefi-Talouki, Arzhang
     A4 Artikkeli konferenssijulkaisussa
    This paper proposes a developed control technique for integration of renewable energy sources into the weak grids. The developed controller alleviates the negative impact of weak grid operating condition on the stability of interface converters by mean of impedance reshaping technique. Furthermore, the proposed controller provides virtual inertia to support the power grid stability. Satisfactory and stable operation of the interface converter as well as providing virtual inertia under weak grid condition with high penetration level of RESs, are the main contributions of this paper. Comparative simulation results are presented to demonstrate and verify the effectiveness of the proposed control technique.
  • Control of MMC-Based STATCOM as an Effective Interface between Energy Sources and the Power Grid
    (2019) Shahnazian, Fatemeh; Adabi, M. Ebrahim; Adabi, Jafar; Pouresmaeil, Edris; Rouzbehi, Kumars; Rodrigues, Eduardo M.G.; Catalão, João P.S.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This paper presents a dynamic model of modular multilevel converters (MMCs), which are considered as an effective interface between energy sources and the power grid. By improving the converter performance, appropriate reactive power compensation is guaranteed. Modulation indices are calculated based on detailed harmonic evaluations of both dynamic and steady-state operation modes, which is considered as the main contribution of this paper in comparison with other methods. As another novelty of this paper, circulating current control is accomplished by embedding an additional second harmonic component in the modulation process. The proposed control method leads to an effective reduction in capacitor voltage fluctuation and losses. Finally, converter’s maximum stable operation range is modified, which provides efficiency enhancements and also stability assurance. The proficiency and functionality of the proposed controller are demonstrated through detailed theoretical analysis and simulations with MATLAB/Simulink.
  • Control of Modular Multilevel Converters Under Loading Variations in Distributed Generation Applications
    (2018) Pouresmaeil, Edris; Mehrasa, Majid; Rodrigues, Eduardo M.G.; Godina, Radu; Catalão, João P.S.
     A4 Artikkeli konferenssijulkaisussa
    In this paper, a function-based modulation control strategy for modular multilevel converters (MMCs) in a distributed generation (DG) system is proposed. Two novel modulation functions are introduced in this paper for the switching state functions of the lower and upper sub-modules of the interfaced MMC, which is considered as the main contribution of this control technique over other control methods. The amplitude and phase angle of the output current of the interfaced MMC can be easily applied to the proposed modulation functions to prepare a specific active and reactive power injection into the demand side. In addition, the equivalent capacitors of the lower and upper submodules are defined by taking into account the introduced modulation functions to guarantee an appropriate operation for the interfaced MMC in DG systems. Simulation results validate the capability of the proposed control method for MMCs under load variations.
  • Control of Multilevel Converters for High Penetration of Renewable Energies
    (2021-06-28) Pouresmaeil, Mobina; Sepehr, Amir; Sangrody, Reza; Taheri, Shamsodin; Pouresmaeil, Edris
     A4 Artikkeli konferenssijulkaisussa
    Increasing integration of converter-interfaced renewable power generation challenges the stability of the frequency in the modern power systems due to the lack of inertia in this type of generators. In this regard, this paper establishes a control method for controlling multilevel converters as an interface between renewable power generation and the power grid, which enables them to operate as voltage-controlled sources, thus grid-forming capabilities like conventional synchronous generators (SGs). In fact, the proposed control technique mimics the behavior of synchronous generators in the control loop of the neutral point clamped (NPC) converter. Consequently, supportive functionalities for frequency stability i.e., inertia and frequency/power oscillation damping will be provided by the multilevel converter as a virtual synchronous generator (VSG). Simulation results in Matlab/Simulink verifies the well-designed inertia and damping features for the interfaced converter as well as appropriate performance of multilevel converter in reducing total harmonic distortion (THD).
  • Control of Power Converters for the Integration of Battery Storage Systems into Power Grids
    (2024-05-29) Komulainen, Veera
     Sähkötekniikan korkeakoulu | Master's thesis
    The future of electrical networks worldwide is increasingly reliant on renewable energy sources (RES), driven by their capacity to reduce carbon footprints, enhance long-term energy security, and extend energy access to diverse consumers, especially in the developing world. However, the integration of large-scale renewable energies poses substantial challenges to the stability and reliability of power grids. RES such as solar photovoltaic (PV) and wind turbines, present stochastic and variable output behavior, providing real-time balancing challenges to power systems. This variability necessitates an increase in power reserves from conventional power stations to maintain grid stability. Additionally, the power electronic converters used to connect RES to power grids operate differently from the synchronous nature of power grids, lacking inertia and exhibiting unique transient dynamics that can adversely impact power system operation. Contrary to conventional synchronous generators, these challenges hinder the seamless integration of renewable energies into the power grid. To overcome these hurdles, the integration of battery storage systems (BSS) has emerged as a crucial solution. BSS helps mitigate the intermittency of RES and provides the required inertia for power grids. Achieving this requires the implementation of precise control mechanisms in interfaced converters between energy sources and power grids. This thesis delves in the investigation of control strategies employed in grid-connected converters and their key role in overcoming challenges associated with RES integration. Simulations will be conducted to explore the behavior of grid-connected converters under various conditions. The study involves considerations of different modulation methods, simulations of converters operation as an active power filter, and the mitigation of total harmonic distortion in grid currents under different operating conditions. Simulations will further evaluate the capability of feeding specific active and reactive power into loads, estimating grid frequency, and implementing virtual inertia within converter-based power generators for the grid supports. These aspects collectively contribute to a comprehensive understanding of the performance of converter-based generators and their potential impact on grid stability within the context of RES and BSS integration.
  • Control of power electronics-based synchronous generator for the integration of renewable energies into the power grid
    (2019) Mehrasa, Majid; Pouresmaeil, Edris; Sepehr, Amir; Pournazarian, Bahram; Catalão, João P.S.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This paper addresses a single synchronous controller (SSC) for interfaced converters with high penetration of renewable energy resources (RERs) into a low inertia power grid. The SSC is modelled based on a comprehensive dependence between each operative feature of a synchronous generator (SG) and a power electronics converter. This can properly improve the performance of the power grid in such scenarios in which large-scale penetration of RERs are detected. The main contribution of this paper is representing an exhaustive relation between active components of the proposed SSC and SG features which enables the proposed SSC-based interfaced converter to more accurately mimic the behaviour of SGs during active power generating along with providing controllable inertia. Due to containing sufficient decoupling, both components of the proposed SSC have no impact on each other, also the proposed SSC has a superior operational flexibility within a wide range of inertia from very low to high values. Thus, two closed-loop control systems are considered to separately analyse the characteristic effects of SGs in active and reactive power sharing apart from the power grid stability challenges. In addition, the impacts of active power variations on reactive power are subsequently evaluated. To further analyse the operation of the system, the effects of the virtual mechanical power (VMP) error embedded in the SSC are considered as an alternative option for assessing the power grid stability. Also, the variations of the virtual angular frequency (VAF) error are carefully deliberated for more considerations associated with the active and reactive power performance of the SSC. Simulation results are presented to demonstrate the high performance of the SSC in the control of the power electronics-based SG when high-penetration renewable energy sources are integrated into the low inertia power grid.This paper addresses a single synchronous controller (SSC) for interfaced converters with high penetration of renewable energy resources (RERs) into a low inertia power grid. The SSC is modelled based on a comprehensive dependence between each operative feature of a synchronous generator (SG) and a power electronics converter. This can properly improve the performance of the power grid in such scenarios in which large-scale penetration of RERs are detected. The main contribution of this paper is representing an exhaustive relation between active components of the proposed SSC and SG features which enables the proposed SSC-based interfaced converter to more accurately mimic the behaviour of SGs during active power generating along with providing controllable inertia. Due to containing sufficient decoupling, both components of the proposed SSC have no impact on each other, also the proposed SSC has a superior operational flexibility within a wide range of inertia from very low to high values. Thus, two closed-loop control systems are considered to separately analyse the characteristic effects of SGs in active and reactive power sharing apart from the power grid stability challenges. In addition, the impacts of active power variations on reactive power are subsequently evaluated. To further analyse the operation of the system, the effects of the virtual mechanical power (VMP) error embedded in the SSC are considered as an alternative option for assessing the power grid stability. Also, the variations of the virtual angular frequency (VAF) error are carefully deliberated for more considerations associated with the active and reactive power performance of the SSC. Simulation results are presented to demonstrate the high performance of the SSC in the control of the power electronics-based SG when high-penetration renewable energy sources are integrated into the low inertia power grid.This paper addresses a single synchronous controller (SSC) for interfaced converters with high penetration of renewable energy resources (RERs) into a low inertia power grid. The SSC is modelled based on a comprehensive dependence between each operative feature of a synchronous generator (SG) and a power electronics converter. This can properly improve the performance of the power grid in such scenarios in which large-scale penetration of RERs are detected. The main contribution of this paper is representing an exhaustive relation between active components of the proposed SSC and SG features which enables the proposed SSC-based interfaced converter to more accurately mimic the behaviour of SGs during active power generating along with providing controllable inertia. Due to containing sufficient decoupling, both components of the proposed SSC have no impact on each other, also the proposed SSC has a superior operational flexibility within a wide range of inertia from very low to high values. Thus, two closed-loop control systems are considered to separately analyse the characteristic effects of SGs in active and reactive power sharing apart from the power grid stability challenges. In addition, the impacts of active power variations on reactive power are subsequently evaluated. To further analyse the operation of the system, the effects of the virtual mechanical power (VMP) error embedded in the SSC are considered as an alternative option for assessing the power grid stability. Also, the variations of the virtual angular frequency (VAF) error are carefully deliberated for more considerations associated with the active and reactive power performance of the SSC. Simulation results are presented to demonstrate the high performance of the SSC in the control of the power electronics-based SG when high-penetration renewable energy sources are integrated into the low inertia power grid.This paper addresses a single synchronous controller (SSC) for interfaced converters with high penetration of renewable energy resources (RERs) into a low inertia power grid. The SSC is modelled based on a comprehensive dependence between each operative feature of a synchronous generator (SG) and a power electronics converter. This can properly improve the performance of the power grid in such scenarios in which large-scale penetration of RERs are detected. The main contribution of this paper is representing an exhaustive relation between active components of the proposed SSC and SG features which enables the proposed SSC-based interfaced converter to more accurately mimic the behaviour of SGs during active power generating along with providing controllable inertia. Due to containing sufficient decoupling, both components of the proposed SSC have no impact on each other, also the proposed SSC has a superior operational flexibility within a wide range of inertia from very low to high values. Thus, two closed-loop control systems are considered to separately analyse the characteristic effects of SGs in active and reactive power sharing apart from the power grid stability challenges. In addition, the impacts of active power variations on reactive power are subsequently evaluated. To further analyse the operation of the system, the effects of the virtual mechanical power (VMP) error embedded in the SSC are considered as an alternative option for assessing the power grid stability. Also, the variations of the virtual angular frequency (VAF) error are carefully deliberated for more considerations associated with the active and reactive power performance of the SSC. Simulation results are presented to demonstrate the high performance of the SSC in the control of the power electronics-based SG when high-penetration renewable energy sources are integrated into the low inertia power grid.
  • A control strategy based on the upper and lower's arms modulation functions of MMC in HVDC applications
    (2018-04-27) Mehrasa, Majid; Sharifzadeh, Mohammad; Sheikholeslami, Abdolreza; Pouresmaeil, Edris; Catalao, Joao P.S.; Al-Haddad, Kamal
     A4 Artikkeli konferenssijulkaisussa
    A control strategy Is proposed In this paper based on considering the upper and lower's arms modulation functions of a MMC in HVDC applications. The designed modulation-functions-based controller is consisted of the modulation index and phase that are accurately evaluated according to ac-side voltage, MMC voltage and current components in a-b-c reference frame. Two main contributions of the proposed control strategy over the other existing control techniques are robust against the MMC parameter variations and simplicity operation that causes MMC to perform the ac/DC conversion for the HVDC applications. The simulation results verify the ability of the proposed control strategy at approaching to the stable performance of MMC under various operating conditions.