scholarly journals A Novel Control Strategy for Large-Capacity Energy Storage Systems Based on Virtual Synchronous Generator

Author(s):  
Zhipeng Wu ◽  
Ping Yang ◽  
Dongyang Rui ◽  
Xinyu Jiang
Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2240
Author(s):  
Guangqing Bao ◽  
Hongtao Tan ◽  
Kun Ding ◽  
Ming Ma ◽  
Ningbo Wang

Photovoltaic virtual synchronous generator (PV-VSG) technology, by way of simulating the external characteristics of a synchronous generator (SG), gives the PV energy integrated into the power grid through the power electronic equipment the characteristics of inertial response and active frequency response (FR)—this attracts much attention. Due to the high volatility and low adjustability of PV energy output, it does not have the characteristics of a prime mover (PM), so it must be equipped with energy storage systems (ESSs) in the DC or AC side to realize the PV-VSG technology. However, excessive reliance on ESSs will inevitably affect the application of VSG technology in practical PV power plants (PV-PPs). In view of this, this paper proposes the PV power reserve control type VSG (PV-PRC-VSG) control strategy. By reducing the active power output of part of the PV-PPs, the internal PV-PPs can maintain a part of the active power up/down-regulation ability in real time, instead of relying on external ESSs. By adjusting the active reserve power of this part, the output of the PV-PPs can be controlled within a certain range, and the PV-PPs can better simulate the PM characteristics and realize the FR of the grid by combining the VSG technology. At the same time, the factors affecting the reserve ratio are analyzed, and the position of the voltage operating point in PRC mode is deduced. Finally, the simulation results show that the proposed control strategy is effective and correct.


Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2388 ◽  
Author(s):  
Ting Yang ◽  
Yajian Zhang ◽  
Zhaoxia Wang ◽  
Haibo Pen

With the increasing proportion of renewable energy in microgrids (MGs), its stochastic fluctuation of output power has posed challenges to system safety and operation, especially frequency stability. Virtual synchronous generator (VSG) technology, as one effective method, was used to smoothen frequency fluctuation and improve the system’s dynamic performance, which can simulate the inertia and damping of the traditional synchronous generator. This study outlines the integration of VSG-controlled energy storage systems (ESSs) and traditional synchronous generators so they jointly participate in secondary frequency regulation in an independent MG. Firstly, a new uncertain state-space model for secondary frequency control is established, considering the measurement noises and modelling error. Then, an improved linear quadratic Gaussian (LQG) controller is designed based on stochastic optimal control theory, in which the dynamic performance index weighting matrices are optimized by combining loop transfer recovery (LTR) technology and the distribution estimation algorithm. On the issue of secondary frequency devices’ output power allocation, the dynamic participation factors based on the ESS’s current state of charge (SOC) are proposed to prevent the batteries’ overcharging and overdischarging problems. The energy storage devices’ service life can be prolonged and OPEX (operational expenditure) decreased. Multiple experimental scenarios with real parameters of MGs are employed to evaluate the performance of the proposed algorithm. The results show that, compared with the lead-compensated-proportional-integral-derivative (LC-PID) control and robust μ-control algorithms, the proposed stochastic optimal control method has a faster dynamic response and is more robust, and the fluctuations from renewable energy and power loads can be smoothened more effectively.


Author(s):  
Angelos I. Nousdilis ◽  
Georgios C. Kryonidis ◽  
Eleftherios O. Kontis ◽  
Georgios Christos Christoforidis ◽  
Grigoris K. Papagiannis

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1261
Author(s):  
Dina Emara ◽  
Mohamed Ezzat ◽  
Almoataz Y. Abdelaziz ◽  
Karar Mahmoud ◽  
Matti Lehtonen ◽  
...  

Recently, the penetration of energy storage systems and photovoltaics has been significantly expanded worldwide. In this regard, this paper presents the enhanced operation and control of DC microgrid systems, which are based on photovoltaic modules, battery storage systems, and DC load. DC–DC and DC–AC converters are coordinated and controlled to achieve DC voltage stability in the microgrid. To achieve such an ambitious target, the system is widely operated in two different modes: stand-alone and grid-connected modes. The novel control strategy enables maximum power generation from the photovoltaic system across different techniques for operating the microgrid. Six different cases are simulated and analyzed using the MATLAB/Simulink platform while varying irradiance levels and consequently varying photovoltaic generation. The proposed system achieves voltage and power stability at different load demands. It is illustrated that the grid-tied mode of operation regulated by voltage source converter control offers more stability than the islanded mode. In general, the proposed battery converter control introduces a stable operation and regulated DC voltage but with few voltage spikes. The merit of the integrated DC microgrid with batteries is to attain further flexibility and reliability through balancing power demand and generation. The simulation results also show the system can operate properly in normal or abnormal cases, thanks to the proposed control strategy, which can regulate the voltage stability of the DC bus in the microgrid with energy storage systems and photovoltaics.


Energies ◽  
2017 ◽  
Vol 10 (2) ◽  
pp. 215 ◽  
Author(s):  
Rui Hou ◽  
Thai-Thanh Nguyen ◽  
Hak-Man Kim ◽  
Huihui Song ◽  
Yanbin Qu

2021 ◽  
Author(s):  
Hooman Samani

This Master’s thesis project introduces a micro-grid system that includes a hybrid power storage backup system and photovoltaic module power generation system, which is connected to the grid and supports the hybrid backup system. The first section presents a solution or algorithm to an existing problem in an energy flow management strategy for the hybrid energy storage system. In the second section, power is provided from the photovoltaic arrays by the convenience of the Maximum Power Point Tracking (MPPT) for each photovoltaic module. The generated power will charge the storage backup system. The micro-grid is capable of selling the surplus power to the utility grid. A master controller optimizes integration, dispatching and control over the whole micro-grid operation. There have been many different control strategies and topologies presented over the years to manage the energy flow for hybrid energy storage systems; however, there are some aspects that differentiate some from others, such as real-time prediction, cumbersome architecture, full spectrum control over recourses, and cost-effectiveness. The first section of this thesis proposes a control strategy on hybrid energy storage systems based on fundamental electrical principles. The low volume and simple algorithm make the controller easy to perform on the embedded systems and quickly responds within a tiny space. The control strategy is equipped with a load prediction method, which provides a fast response at the time of load current surge. The controller architect provides the full control over all the resources. The presented controller is cost-effective by increasing the battery life and by minimizing the power loss in the hybrid storage backup system. The simulation results in two different experiments validate the efficiency and performance of the offered control strategy for hybrid backup system.


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