Simplified voltage and frequency controller based on droop control for the dynamic analysis of a Microgrid (original) (raw)
Related papers
Controlling Voltage and Frequency of a Power Network with Microgrid Using Droop Method
Global Journal of Research In Engineering, 2011
Microgrids (MG) are new concept of electric power networks consisting of distributed generation (DG), renewable energy resources and sensitive loads. The goal of microgrid operation is to provide reliable and high-quality electric power regardless of faults or abnormal operating conditions. Many control methods have been employed to regulate the output power of DGs used in MGs. This paper presents a control scheme for DGs of a power system, especially with voltage source inverter (VSI) interface, for both grid connected and islanded modes. A comprehensive study has been performed through PSCAD simulations of the inverter-fed MG behavior under both islanding and connected operation for different load conditions. The simulation results prove the droop method efficiency in controlling the voltage and frequency of the inverter output which is connected to the loads.
International Journal of Renewable Energy Research, 2019
Conventional droop-control scheme shares the load amongst energy sources in proportion to their ratings. The scheme suffers from the issue of ineffective utilization of the sources when performance of some of the sources is dependent on environmental conditions. Hence, a modified droop-control strategy is proposed for a microgrid comprising of photovoltaic (PV) based distributed generators (DG) operating in parallel with other DGs. Dynamic nature applied to the droop characteristic by the primary control unit (PCU) sets the frequency reference such that the PV sources operate at their maximum power point and the energy demanded from the auxiliary source is the minimum. The margin available after supplying the active power is used to allocate the references for reactive power sharing. The reactive power sharing algorithm employed in secondary control unit (SCU) ensures that the standard deviation of the percentage utilization of the inverters is kept the minimum. Even in case of the failure of the communication between the PCU and SCU, a reasonably good performance is ensured as the control shifts to the master-slave control having dynamic droop adjustment feature. The effectiveness of the proposed strategy against other approaches is justified through the simulation results obtained in MATLAB/Simulink.
Comparative Analysis of Droop Control and PWM with VSI for Islanded Microgrid
2019
Present energy demands are supplied by fossil fuel. It has negative impact on environment, therefore the renewable sources are the best solution for energy supplies. PV array and VS I can employed in distributed manner to collect energy from solar irradiation. It can design at small scale according to site requirement. Collection of distributed generators build microgrid. Microgrid is able to supply power to local area, and it can supply power to the main grid or receive power from the main grid. Main issue with microgrid is power regulation. Communication based system is able to regulate microgrid power, but it is suffered from single point failure. VS I can control through PWM technique, but its performance is not compatible with system. Droop Control can control system parameter and improve system performance, and it control each VS I individually. In faulty condition controller cut off only faulty unit from system. Model is design and simulated in MATLAB/S imulink 2017a and results are discussed.
Voltage and frequency of microgrids (MGs) are strongly impressionable from the active and reactive load fluctuations. Often, there are several voltage source inverters (VSIs) based distributed generations (DGs) with a specific local droop characteristic for each DG in a MG. A load change in a MG may lead to imbalance between generation and consumption and it changes the output voltage and frequency of the VSIs according to the droop characteristics. If the load change is adequately large, the DGs may be unable to stabilize the MG. In the present paper, following a brief survey on the conventional voltage/frequency droop control, a generalized droop control (GDC) scheme for a wide range of load change scenarios is developed. Then to remove its dependency to the line parameters and to propose a model-free based GDC, a new framework based on adaptive neuro-fuzzy inference system (ANFIS) is developed. It is shown that the proposed intelligent control structure carefully tracks the GDC dynamic behavior, and exhibits high performance and desirable response for different load change scenarios. It is also shown that the ANFIS controller can be effectively used instead of the GDC. The proposed methodology is examined on several MG test systems.
An Overview on Microgrid Control Strategies
—In response to the ever increasing energy demand, integrating distributed energy resource-based microgrid will be the most promising power system improvement in the near future. Microgrid system implementation provides significant advantages for both electric utility provider and end customer user. This paper performs a comprehensive literature review on the current key issues on control strategies of microgrid islanded mode operation. Brief descriptions are provided for typical microgrid control methods, PQ control, droop control, voltage/frequency control, and current control, which are associated with microgrid mode of operation. This review also covers microgrid control issues such as islanded mode, stability, and unbalanced voltages to provide adequate power quality. In addition, this paper discusses the challenges of microgrid islanded mode issues, such as load sharing, distributed generation losses, and non-linear /unbalanced load. Finally, research conclusions of the important microgrid control requirements for future development are also described.
An improved control scheme based in droop characteristic for microgrid converters
Electric Power Systems Research, 2010
Power-quality a b s t r a c t In the present work, an improved version of the conventional-droop control for microgrid converter is presented. The modifications added to the control are based on a feed-forward current control that allows the converter to work in several modes, both when it is grid connected or in island. The use of this control represents the main contribution of this paper, permitting the inverter to work as a grid supporting source or ancillary services provider when it works grid connected. In this mode the converter varies the injected active and reactive power with the variation of voltage module and frequency using the same main control loop as when it is working in island mode.
IEEE Transactions on Smart Grid, 2015
power management on islanded microgrid -Proportional power sharing in hierarchical droop control," IEEE Trans. Smart Grid, 2015, IEEE early access. Abstract -A microgrid (MG) is a local energy system consisting a number of energy sources (e.g. wind turbine or solar panels among others), energy storage units and loads that operate connected to the main electrical grid or autonomously. MGs provide flexibility, reduce the main electricity grid dependence and contribute to change the large centralized production paradigm to local and distributed generation. However, such energy systems require complex management, advanced control and optimization. Moreover, the power electronics converters have to be used to correct energy conversion and interconnected through common control structure is necessary. Classical Droop Control system is often implemented in microgrid. It allows to the correct operation of parallel voltage source converters (VSI) in grid connected as well as islanded mode of operation. However, it requires complex power management algorithms, especially in islanded microgrids, which balances system, improves reliability. The novel reactive power sharing algorithm is developed, which takes into account the converters parameters as apparent power limit and maximum active power. The developed solution is verified in simulation and compared with other known reactive power control methods.
Enhanced Droop Control Technique for Parallel Distributed Generations in AC Microgrid
2021
In a microgrid, distributed generations (DGs) such as solar photovoltaic and energy storages(ESs) are interfaced with the AC network through power electronic-based inverters. Due to the low inertia of the solar photovoltaic system, the inverter controls become crucial for improving the power quality. State-of-the art conventional droop control in the inverters face problems such as large voltage and frequency deviations and improper reactive power sharing during various contingencies. This paper presents a simulation model of a stand-alone microgrid with solar photovoltaic source with an enhanced droop control technique which is able to mitigate the constraints of conventional droop control. In order to improve the transient response and appropriate reactive power sharing, proposed control technique explores the addition of derivative of active power for the frequency droop control and the rms output voltage from the inverter for the reactive power control. The simulation results of the proposed controller are obtained and compared with the conventional droop control methods using MATLAB/Simulink.
An Improved Droop Control Method to Enhance Dynamic Performance of AC Microgrid
2018 20th National Power Systems Conference (NPSC), 2018
The sources, interfaced with the microgrid using power electronic converters have inherently low physical inertia. With step variation in load demand, voltage and frequency difference are created among the sources during transient and the low frequency oscillations appear in the power supplied through the interconnecting lines. This may even lead to false triggering of fault protection system. To suppress these transient in powers and to improve dynamic response of microgrid in islanded mode, a modified droop controller which uses dynamic variation in droop gains of active power frequency (P − ω) characteristics is proposed. The variation of droop gains is based on the rate of change of active power supplied by the corresponding source. Key advantages offered by the modified droop controller are improved dynamic response with reduced peaks in power supplied by the sources during step change in load power demand. The effectiveness of the proposed technique is demonstrated using linearized model derived for microgrid taking into account the dynamics of proposed controller, loads and distribution network. The root loci plots are used to study the behavior of the ac microgrid with respect to variation in parameters of proposed controller. The effectiveness of the controller is validated using simulation study in Simulink/Matlab for a microgrid test model.
IRJET, 2021
Recent climatic changes have led to the increase in utilization of sustainable Distributed Generation (DG) resources such as fuel cells using natural or biogas, wind, solar etc. To meet the ever increasing energy requirement, society is moving to renewable sources like solar energy, wind energy etc, as it is pollution free, clean and available in plenty. In this paper , a micro grid model is designed using PV cell by using two different control strategies have been analyased. Droop control and advanced dynamic droop control methods have been explained in this paper In both these techniques, there is no need of communication line and maximum power is extracted from solar panel using Perturb and Observe method. The LC filters are designed to eliminate harmonic current. The conventional droop control has poor voltage regulation at heavy load condition and poor power sharing performance at light load condition. The conventional P-Q droop methods shares the active power based on fixed droop coefficient irrespective of available energy from non conventional energy source. The disadvantages of the conventional droop control can be reduced with the use of advanced dynamic droop control. PV models with droop control and advanced dynamic droop control have been designed and compared using matlab/simulink models