DC Bus Voltage Regulation Strategy for Modular Super Capacitor Energy Storage Based on Extended State Observer

Author(s):  
Bi Kaitao ◽  
Yang Chuan ◽  
Duan Jiandong ◽  
Sun Li ◽  
An Quntao
2018 ◽  
Vol 8 (9) ◽  
pp. 1525
Author(s):  
Ahmad M. A. Malkawi ◽  
Luiz A. C. Lopes

DC bus voltage signaling (DBS) and droop control are frequently employed in DC nano and microgrids with distributed energy resources (DERs) operating in a decentralized way. This approach is effective in enforcing the desired contributions of power sources and energy storage systems (ESSs) in steady-state conditions. The use of supercapacitors (SCs) along with batteries in a hybrid energy storage system (HESS) can mitigate the impact of high and fast current variations on the losses and lifetime of the battery units. However, by controlling the HESS as a single unit, one forfeits the potential contribution of the SC and its high power capabilities to dynamically improve voltage regulation in a DC nanogrid. This paper discusses an approach where the SC interface is controlled independently from the battery interface, with a small droop factor and a high pass filter (HPF), to produce high and short current pulses and smooth DC bus voltage variations due to sudden power imbalances in the DC nanogrid. Experimental results are presented to show that, unlike in a conventional HESS, the SC unit can be used to improve the dynamic voltage regulation of the DC nanogrid and, indirectly, mitigate the high and fast current variations in the battery.


2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Dejun Liu ◽  
Jinfei Xu ◽  
Ruonan Xue ◽  
Chao Song ◽  
Zhenxiong Zhou

In the photovoltaic inverter grid-connected power generation system, the output power of photovoltaic panels is affected by illumination and temperature. The change of output power of photovoltaic panels will lead to the fluctuation of DC bus voltage. If the control is improper, it will directly affect the regular operation of the system. In order to improve the performance of the grid-connected inverter system, an active disturbance rejection control method based on adaptive extended state observer (ESO) is proposed. Firstly, a feedforward PI current inner loop controller is designed, which simplifies the structure of the control system and improves the tracking performance of the current. Then, the DC bus voltage outer loop ADRC is designed, and a conversion method that ignores the essential difference between nonlinear/time-varying and time-varying/linear is proposed. Through the conversion of time-invariant nonlinear system and time-varying linear system, the stability of the extended state observer is proved by the Routh criterion. Secondly, to solve the problem of mutual restriction between the stability and observation accuracy of the extended state observer, an adaptive function online automatic tuning ESO parameter method is proposed. Finally, the simulation results show that the proposed method has better dynamic and static performance, and the grid-connected voltage and current harmonics are small, which proves the correctness and effectiveness of the proposed method.


2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Muhamad Zalani Daud ◽  
Azah Mohamed ◽  
M. A. Hannan

This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods.


Electronics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1470
Author(s):  
Mahdi Shahparasti ◽  
Amirhossein Rajaei ◽  
Andres Tarraso ◽  
Jose David Vidal Leon Romay ◽  
Alvaro Luna

This paper presents a proposal for potential bioelectrochemical power to gas stations. It consists of a two-level voltage source converter interfacing the electrical grid on the AC side and an electromethanogenesis based bioelectrochemical system (EMG-BES) working as a stacked module on the DC side. The proposed system converts CO2 and electrical energy into methane, using wastewater as the additional chemical energy input. This energy storage system can contribute to dampening the variability of renewables in the electrical network, provide even flexibility and grid services by controlling the active and reactive power exchanged and is an interesting alternative technology in the market of energy storage for big energy applications. The big challenge for controlling this system lays in the fact that the DC bus voltage of the converter has to be changed in order to regulate the exchanged active power with the grid. This paper presents a cascade approach to control such a system by means of combining external control loops with fast inner loops. The outer power loop, with a proportional-integral (PI) controller with special limitation values and anti-windup capability, is used to generate DC bus voltage reference. An intermediate loop is used for DC bus voltage regulation and current reference generation. A new proportional resonant controller is used to track the current reference. The proposed scheme has been validated through real-time simulation in OPAL OP4510.


2021 ◽  
pp. 002029402110286
Author(s):  
Pu Yang ◽  
Peng Liu ◽  
ChenWan Wen ◽  
Huilin Geng

This paper focuses on fast terminal sliding mode fault-tolerant control for a class of n-order nonlinear systems. Firstly, when the actuator fault occurs, the extended state observer (ESO) is used to estimate the lumped uncertainty and its derivative of the system, so that the fault boundary is not needed to know. The convergence of ESO is proved theoretically. Secondly, a new type of fast terminal sliding surface is designed to achieve global fast convergence, non-singular control law and chattering reduction, and the Lyapunov stability criterion is used to prove that the system states converge to the origin of the sliding mode surface in finite time, which ensures the stability of the closed-loop system. Finally, the effectiveness and superiority of the proposed algorithm are verified by two simulation experiments of different order systems.


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