Query: Frequency regulation inverter  Modulation methods for Frequency regulation of photovoltaic systems

Candidate papers:

abstract: In this study, a new multi input high step up inverter, based on isolated soft switching DC DC converter blocks is proposed. Each of these blocks can provide zero voltage and zero current switching for its semiconductors, which improve power efficiency. The interesting feature of this DC DC converter is using bidirectional switches to generate both positive and negative output voltage levels in each DC DC block with an appropriate control scheme. Each DC DC converter operates by simple pulse width modulation control through fixed frequency and has two degrees of freedom, which provide the capability of output voltage regulation or maximum power point tracking. The proposed inverter consists of the cascaded connection of these DC DC converters at their output terminal. This inverter can operate with high voltage gain, where the output voltage of each DC DC converter is regulated. Furthermore, it can generate more output voltage levels with less number of DC DC blocks. All these advantages make the proposed inverter suitable for photovoltaic power conditioning systems. In this study, the theoretical analysis with steady state waveforms, design constraints, resonant tank analysis and comparison study are given. Then, experimental results of both the proposed inverter and its DC DC blocks are presented.
author_names: Ebrahim Babaei

Hadi Tarzamni

Farzad Tahami

Hossein Khoun Jahan

Mohammad Bagher Bannae Sharifian
title: Multi input high step up inverter with soft switching capability, applicable in photovoltaic systems
year: 2020

abstract: To ensure the reliable delivery of AC power to consumers from renewable energy sources, the photovoltaic inverter has to ensure that the frequency and magnitude of the generated AC voltage are within acceptable limits. This paper develops models and control strategies for the DC AC converter to ensure that the sinusoidal waveform of the desired frequency voltage and magnitude generated for both single phase and three phase operation depend on the robustness of the inverter control system. The paper reviews various topologies and modulation approaches for photovoltaic inverters in both single phase and three phase operational modes. Finally, a proposed control strategy is presented to ensure frequency and voltage regulation.
author_names: Shayan Ebrahimi

Ali Moghassemi

Javad Olamaei
title: PV Inverters and Modulation Strategies: A Review and A Proposed Control Strategy for Frequency and Voltage Regulation
year: 2020

abstract: In the era of world transition, it is vital to redefine the means of energy generation in order to obtain affordable low carbon energy and to overcome deregulation of electricity. One of the best solutions is to utilize the renewable energy sources (Chambers et al. 2001; Jenkins et al. 2010) such as photovoltaic (PV) wind turbine and fuel cell technology (Roomi et al. 2014; Roomi et al. 2015; Roomi et al. 2016) However, PV and wind systems are prone to environmental factors. In the case of PV systems, intermittency and unpredictability of solar energy due to weather make the system unreliable. Variations in wind speed lead to uncertain and randomly fluctuating power from the wind power generator. Even though fuel cells are not prone to the fluctuations observed in PV or wind, low power generation remains a major downside. Hence, renewable energy sources require buffering elements such as energy storage systems and power electronic conditioning circuits before connecting to the utility mains or a power grid. Additionally, these systems experience problems with efficiency. Therefore, energy regulation is indispensable during the interfacing stage to provide efficient energy usage. With recent developments in power electronics, the aforementioned hurdles can be ameliorated. Power electronic regulators consist of a power controller and a power converter and play a vital role in energy regulation. The power controller performs maximum power point tracking, grid synchronization and fast dynamic response in the system. The magnitude, frequency and electrical phase conversions are performed by the power converters. Energy conversion for applications involving ac motor drives (Banerjee and Ranganathan, 2009; Levi
author_names: Muhammad M Roomi
title: Roomi An Overview of Carrier based Modulation Methods for Z Source Inverter 1
year: 2019

abstract: Distributed photovoltaic could not respond to frequency deviation, and the photovoltaic modules, connected to the grid through the inverter, are non rotating static component, which means that it does not have the rotary inertia of the synchronous generator. When distributed photovoltaic is connected to the grid in a dense manner, it will reduce the system inertia. Under the same boundary conditions, the system frequency may drop even lower. To solve this problem, this paper proposes to add energy storage system on the DC side to satisfy the frequency regulation requirements. By adopting the virtual synchronous generator control strategy, the solar photovoltaic energy storage hybrid system is equivalent to a voltage source on the DC side. And it has similar characteristics to the synchronous generator on the AC side. This improves the stability of the external output power of photovoltaic, and also enables the distributed photovoltaic to respond to frequency deviation. the effectiveness of the proposed control strategy is verified in MATLAB/Simulink.
author_names: Liu Yunxin

Liao Siyang

Sun Yuan-zhang

Xu Jian

Ghamgeen Izat Rashed

Ke Deping

Yao Liangzhong

Yang Jun

Wu Di

Tang Wei

Yang Cheng
title: Primary Frequency Modulation of Solar Photovoltaic energy Storage Hybrid System Based on Virtual Synchronous Generator
venue: 2019 International Conference on Power Generation Systems and Renewable Energy Technologies (PGSRET)
year: 2019

abstract: Power inverter adopting virtual synchronous generator (VSG) control can provide inertia support for distributed generation systems. However, it cannot take into account the dynamic regulation characteristics of frequency. Thus, when the system encounters a sudden change in load or disturbance, the dynamic process of frequency regulation will be greatly influenced. In view of this issue, an improved VSG control strategy based on a coordinated self adaptive (CSA) method is proposed. The time domain analysis method is used to study the influences of virtual inertia and damping parameter perturbation on the system steady and dynamic performances. Further, in order to make the control strategy suitable for large load changes and suppress frequency variation beyond the limit, the secondary frequency modulation is introduced into the control loop. Through the coordinated adaptive control of virtual inertia, virtual damping and frequency modulation, the dynamic performance of VSG frequency regulation can be improved obviously. Simulation and experiment results have verified the effectiveness of the proposed CSA control strategy.
title: Improved virtual synchronous generator control for frequency regulation with a coordinated self adaptive method
year: 2020

abstract: Purpose The specific modulation methods are used to control different kind of single phase, as well as three phase, inverters to ensure flexibility and high quality of the output waveform. This paper aims to present a combination of two classical methods, namely, pulse width modulation method and direct digital synthesis modulation method. Design/methodology/approach The total harmonic distortion of output waveforms of single phase inverter based on elaborated modulation method has been determined by means of fast Fourier transform analysis. Tests have been carried out by using standard low frequency application and also a wireless resonant energy link system. Findings Applying appropriate timer parameters of microcontroller enables to obtain a waveform for given output parameters (amplitude, frequency, frequency modulation index, etc. The only limitation is the computing power of a microcontroller. Originality/value The elaborated method can be successfully used in both low and high frequency application ensuring high level of output waveform quality. Additional signal generators and the control of amplitude modulation ratio are no longer indispensable, what simplify immensely a control system.
author_names: Wojciech Pietrowski

Wojciech Ludowicz

Rafal Wojciechowski
title: The wide range of output frequency regulation method for the inverter using the combination of PWM and DDS
venue: COMPEL The international journal for computation and mathematics in electrical and electronic engineering
year: 2019

abstract: Abstract The future power system is developing to an inverter based system from a machine dominated power system due to a large integration of renewable energy sources (RESs) Lack of inertial part and intermittency of the RESs causes frequency instability in the power system. The virtual synchronous generator (VSG) development has been made to add inertial control to the power system for controlling the frequency deviation caused by the integration of the photovoltaic system. The VSG system comprised of power electronics components having a droop control mechanism like the conventional synchronous generator, which provides the necessary frequency stability to the power system. In this paper, three parallel VSG based photovoltaic systems integrated with battery storage systems are used to analyze the frequency response and its stability. Moreover, an advanced genetic algorithm optimization method is used to get the optimal values of parameters of the droop controller used in VSG. Furthermore, two different cases with respect to variation in supply and load power of the system are analyzed in detail. Additionally, an IEEE 14 bus system is utilized to validate the proposed system in MATLAB/Simulink. Evident improvements are observed in the simulation results presented through the suggested GA based VSG control technique.
author_names: Haseeb ur Rehman

Xiangwu Yan

Mohamed Abdelkarim Abdelbaky

Mishkat Ullah Jan

Sheeraz Iqbal
title: An advanced virtual synchronous generator control technique for frequency regulation of grid connected PV system
year: 2021

abstract: Abstrac Due to their intermittent features and poorer inertial response, distributed energy resources (DERs) such as photovoltaic (PV) systems and fuel cell systems have increased the complexity of the power system. This reorganization of the power system has a significant impact on the system's transient responsiveness, resulting in inter area oscillations, less synchronised coupling, and power swings. Furthermore, the idea of being dispersed and generating electricity from many points in the electrical system exacerbates the transitory impact of DERs by introducing difficulties like reverse power flows. This technique proposed the effects of changing power system characteristics that are impeding large scale DER integration. In addition, by introducing virtual inertia to inverter based DERs in the electricity system, a method to enhance the system's inertial responsiveness is addressed. The suggested control increased the stability margin and allowed the system to follow its rated frequency. By increasing the rate of change of frequency, the injected synchronized active power to the system avoids the protective relays from tripping. The suggested system functioning is tested experimentally using the MATLAB 2015 simulation system on a sample power grid that includes generation, transmission, and distribution with solar pv and fuel cell system integration.
author_names: Danish Khan

Chetan M Bobade
title: Frequency Regulation of the Bulk Power System for Distributed Energy Resources
year: 2021

abstract: The future of the machine controlled power system is advancing to an inverter based power system with a huge integration of renewable energy sources (RES) like photovoltaic (PV) and wind energy. The penetration of RES leads to instability of frequency due to the lack of inertia. Recent development has been made in inverter's based virtual inertia control for frequency regulation in virtual synchronous generator based systems. Inverters connecting to the microgrid are provided with virtual inertia and droop control by the virtual synchronous generator (VSG) system. In this study, three parallel VSGs based PV systems are used to investigate the frequency response and voltage stability. An advanced genetic algorithm (GA) optimization method is utilized to attain the optimum parameters of the droop control used in the VSGs. Furthermore, two different case studies with respect to load change are analyzed in detail with comparisons with the classical droop controller. The simulation results observed many improvements of the proposed controller over the classical controller.
author_names: Haseeb Ur Rehman

Xiangwu Yan

Mohamed Abdelkarim Abdelbaky

Mishkat Ullah Jan

Ahmed Rabee Sayed

Sayed A Zaki

Sheeraz Iqbal
title: Frequency Regulation and optimization of Microgrid System with Multi PV VSG using Advanced Droop Controller
venue: 2020 IEEE 4th Conference on Energy Internet and Energy System Integration (EI2)
year: 2020

abstract: The main objective of this paper is to develop a simulation model of stand alone solar photovoltaic (PV) system based on mathematical models. A maximum power point tracking (MPPT) algorithm based on incremental conductance method is applied to extract the maximum power from solar PV energy conversion system. A DC/DC boost converter allows the MPPT to control the intermediate voltage. To regulate to voltage at load side a voltage source converter (VSC) based controller is applied to generate the pulse signal for three phase inverter. The frequency regulation controller is developed based on conventional phase locked loop (PLL) system along with resistive dumping loads. A simulation model based on mathematical model is constructed using Matlab (r) /Simulink (r) /SimPower (r) interface. Results from simulation are stated to demonstrate the behaviour of stand alone solar PV energy conversion system.
author_names: Md Aminul Islam

Adel Merabet

Rachid Beguenane

Hussein Ibrahim

Hafiz Ahmed
title: Simulation based study of Maximum Power Point Tracking and Frequency Regulation for Stand alone Solar Photovoltaic Systems
year: 2014