Frequency and State-of-Charge Restoration Method in a Secondary Control of an Islanded Microgrid without Communication

2020 ◽  
Vol 10 (5) ◽  
pp. 1558
Author(s):  
Jin-Oh Lee ◽  
Yun-Su Kim
Keyword(s):  
Distributed Generation ◽  
Control Method ◽  
State Of Charge ◽  
Secondary Control ◽  
Communication Devices ◽  
State Frequency ◽  
Integral Controller ◽  
Islanded Microgrid ◽  
Restoration Method ◽  
System Frequency

This paper presents a control method for inverter-interfaced distributed generation (DG) and energy storage systems (ESSs) in an islanded microgrid. The proposed method is focused on secondary control, particularly frequency restoration and maintaining the ESSs’ state of charge (SOC). To recover frequency deviation due to load change, an ESS is used as a droop-controlled grid-forming source. However, the grid-forming ESS cannot manage its own SOC, since it cannot control its own output power; hence, grid-feeding DGs are used to maintain the SOC within a desired range. Management of the SOC, as well as frequency restoration, is conducted by using local controllers without any communication devices, since dependency on communication may deteriorate system reliability in the case of failure. The proposed method for maintaining SOC can be realized by adjusting the system frequency, which is the only value that can be measured locally with almost the same value at every node in a steady state. Frequency restoration can be achieved by a simple ON/OFF scheme of the integral controller with a hysteresis loop to solve problems caused by differences between frequency measurements or set points among DGs.

Analysis and Modeling of Droop Control in Micro-Source for Islanded Micro-Grid

2014 ◽  
Vol 960-961 ◽  
pp. 1151-1155 ◽  
Author(s):  
Wei Lin Zhang ◽  
Jing Xiong ◽  
Yu Jiong Gu ◽  
Ping Zhu
Keyword(s):  
Distributed Generation ◽  
Control Method ◽  
Controller Design ◽  
Power Sharing ◽  
Droop Control ◽  
Simulation Data ◽  
Storage Devices ◽  
Load Power ◽  
Micro Grid ◽  
System Frequency

Considering decentralization of the micro-source units and loads in the micro-grid and concentrating on generation types and models of the storage devices,droop controlstrategy is used in controller design for the distributed generation units. The generation units adopting droop control method based on the droop characteristics can facilitate load power sharing when the powers of loads vary, and can also maintain the system frequency when a unit fault occurs and the micro-grid islands. Then, the operation variations of the micro-grid are analyzed when it runs with load changes in islanding mode and runs with the load power of micro-source varied suddenly. The corresponding rules of the active power, voltage and current for each micro-source and the frequency for the micro-grid are obtained. The simulation data results show the correctness and validity of the droop control strategy.

scholarly journals New Adaptive Control Strategy for a Wind Turbine Permanent Magnet Synchronous Generator (PMSG)

Inventions ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 3
Author(s):  
Wenping Cao ◽  
Ning Xing ◽  
Yan Wen ◽  
Xiangping Chen ◽  
Dong Wang
Keyword(s):  
Adaptive Control ◽  
Wind Turbine ◽  
Permanent Magnet ◽  
Control Method ◽  
Synchronous Generator ◽  
Permanent Magnet Synchronous Generator ◽  
Model Reference ◽  
Integral Controller ◽  
Proportional Integral Controller ◽  
Model Reference Adaptive

Wind energy conversion systems have become a key technology to harvest wind energy worldwide. In permanent magnet synchronous generator-based wind turbine systems, the rotor position is needed for variable speed control and it uses an encoder or a speed sensor. However, these sensors lead to some obstacles, such as additional weight and cost, increased noise, complexity and reliability issues. For these reasons, the development of new sensorless control methods has become critically important for wind turbine generators. This paper aims to develop a new sensorless and adaptive control method for a surface-mounted permanent magnet synchronous generator. The proposed method includes a new model reference adaptive system, which is used to estimate the rotor position and speed as an observer. Adaptive control is implemented in the pulse-width modulated current source converter. In the conventional model reference adaptive system, the proportional-integral controller is used in the adaptation mechanism. Moreover, the proportional-integral controller is generally tuned by the trial and error method, which is tedious and inaccurate. In contrast, the proposed method is based on model predictive control which eliminates the use of speed and position sensors and also improves the performance of model reference adaptive control systems. In this paper, the proposed predictive controller is modelled in MATLAB/SIMULINK and validated experimentally on a 6-kW wind turbine generator. Test results prove the effectiveness of the control strategy in terms of energy efficiency and dynamical adaptation to the wind turbine operational conditions. The experimental results also show that the control method has good dynamic response to parameter variations and external disturbances. Therefore, the developed technique will help increase the uptake of permanent magnet synchronous generators and model predictive control methods in the wind power industry.

Control Strategy of Wind Photovoltaic and Energy Storage System Stability Running

2013 ◽  
Vol 336-338 ◽  
pp. 547-550
Author(s):  
Ji Hong Zhang ◽  
Zhen Kui Wu ◽  
Hua Li ◽  
Han Shan Li
Keyword(s):  
Energy Storage ◽  
Distributed Generation ◽  
Control Strategy ◽  
Control Method ◽  
Storage System ◽  
Energy Storage System ◽  
System Stability ◽  
Mathematics Model ◽  
Generation Efficiency ◽  
Micro Grid

Micro grid may exert adequately distributed generation efficiency, and that wind Photovoltaic and Energy Storage is a key equipment in the micro grid. Aiming at the distributed generation existing intermittence and randomicity characteristic, the paper discussed the micro grid P/Q control method under the connection grid state and the micro grid U/F control method under the disconnection grid state. It also studied the distributed generation parameters variational law under the micro grid different run mode, and built the correlative mathematics model and tested by simulation. The results show: the control strategy ensured the mice grid running stably, and achieved the system anticipative design request, and offered theory foundation for the distributed generation extend application.

scholarly journals Research on Control Method of Microgrid Based on Multi Distributed Generation

2021 ◽  
Vol 2083 (2) ◽  
pp. 022099
Author(s):  
Chengyi Yue ◽  
Binbin Bei
Keyword(s):  
Distributed Generation ◽  
Control Strategy ◽  
Power Supply ◽  
Control Method ◽  
Peer To Peer ◽  
Strategy Method ◽  
Distributed Power ◽  
Simulink Simulation ◽  
Efficient Control ◽  
Peer Control

Abstract Reducing the dependence of microgrid upon the communication system and realizing the efficient control of multiple distributed generation of the microgrid are problems that need to be solved urgently. Through the research, based on multiple microgrid operation modes, the peer-to-peer control strategy in microgrid is investigated, and the peer-to-peer control strategy method of microgrid is given for a variety of complex control problems of distributed power According to the peer-to-peer control strategy method, distributed power supply adopts droop control in adjusting distributed power supply in output voltage and frequency; the droop controller has P-f and Q-U droop characteristics. This paper establishes a peer-to-peer control microgrid simulation model, adopts the droop controller designed in this paper to island mode and grid-connected mode, and investigates how the microgrid switches between the two modes. In accordance with Matlab/Simulink simulation outcomes, the research examines frequency, voltage and power changes in distributed generation in the microgrid, and verifies the validity and feasibility of microgrid peer-to-peer control strategy.

scholarly journals Distributed Secondary Control Method for Islanded Microgrids With Communication Constraints

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 5812-5821 ◽  
Author(s):  
Wenfa Kang ◽  
Qiang Li ◽  
Mengkai Gao ◽  
Xingxin Li ◽  
Jianguo Wang ◽  
...  
Keyword(s):  
Control Method ◽  
Communication Constraints ◽  
Secondary Control

scholarly journals Secondary Control for Storage Power Converters in Isolated Nanogrids to Allow Peer-to-Peer Power Sharing

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 140 ◽  
Author(s):  
Eva González-Romera ◽  
Enrique Romero-Cadaval ◽  
Carlos Roncero-Clemente ◽  
Mercedes Ruiz-Cortés ◽  
Fermín Barrero-González ◽  
...  
Keyword(s):  
Power Flow ◽  
Control Method ◽  
Low Voltage ◽  
Hierarchical Control ◽  
Power Converter ◽  
Power Sharing ◽  
Primary Control ◽  
Secondary Control ◽  
Control Loops ◽  
Energy Interchange

It is usual in literature that power sharing among grid-forming sources of an isolated microgrid obeys their energy rating, instead of economic agreements between stakeholders, and circulating energy among them is usually avoided. However, these energy interchanges make strong sense and classical power sharing methods must be reformulated in the context of prosumer-based microgrids. This paper proposes a secondary control method for a prosumer-based low-voltage nanogrid that allows for energy interchange between prosumers, where storage systems, together with PV generators, are the controllable grid-forming sources. A power flow technique adapted to islanded microgrids is used for secondary control algorithm and the whole hierarchical control strategy for the prosumer converter is simulated and validated. This hierarchical control consists of three stages: tertiary control plans the energy interchange among prosumers, secondary obtains different voltage and power setpoints for each of the grid-forming sources, and, finally, primary control guarantees stable voltage and frequency values within the nanogrid with droop rules. Inner control loops for the power converter are also defined to track setpoints and assure stable performance. Simulation tests are carried out, which prove the stability of the proposed methods and the accuracy of the setpoint tracking.

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