scholarly journals Stability Criteria for Input Filter Design in Converters with CPL: Applications in Sliding Mode Controlled Power Systems

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4048 ◽  
Author(s):  
Jorge Luis Anderson Azzano ◽  
Jerónimo J. Moré ◽  
Paul F. Puleston

Microgrids are versatile systems for integration of renewable energy sources and non-conventional storage devices. Sliding Mode techniques grant excellent features of robustness controlling power conditioning systems, making them highly suitable for microgrid applications. However, problems may arise when a converter is set to behave as a Constant Power Load (CPL). These issues manifest in the stability of internal dynamics (or Zero Dynamics), which is determined by the input filter of the power module. In this paper, a special Lyapunov analysis is conducted to address the nonlinear internal dynamics of SM controlled power modules with CPL. It takes advantage of a Liérnad-type description, establishing stability conditions and providing a secure operation region. These conditions are translated into conductance and invariant region diagrams, turning them into tools for the design of power module filters.

Author(s):  
Roghieh Abdollahi Biroon ◽  
Pierluigi Pisu ◽  
David Schoenwald

The increasing penetration of renewable energy sources in power grids highlights the role of battery energy stor- age systems (BESSs) in enhancing the stability and reliability of electricity. A key challenge with the renewables’, specially the BESSs, integration into the power system is the lack of proper dynamic model for stability analysis. Moreover, a proper control design for the power system is a complicated issue due to its complexity and inter-connectivity. Thus, the application of decentralized control to improve the stability of a large- scale power system is inevitable, especially in distributed energy sources (DERs). This paper presents an optimal distributed hybrid control design for the interconnected systems to suppress the effects of small disturbances in the power system employing utility-scale batteries based on existing battery models. The results show that i) the smart scheduling of the batteries’ output reduces the inter-area oscillations and improves the stability of the power systems; ii) the hybrid model of the battery is more user-friendly compared to the Western electricity coordinating council (WECC) model in power system analysis.


2019 ◽  
Vol 116 ◽  
pp. 00042
Author(s):  
Małgorzata Kwestarz ◽  
Maciej Chaczykowski

The power systems in European Union operate under energy policies where the greenhouse gases reduction, the increase of the share of renewable energy sources (RES) and the improvements in energy efficiency are the main objectives. Polish energy sector is currently based on inefficient usage of coal and must be transformed according to the requirements of EU energy and climate policy. A policy framework for climate and energy in the period from 2020 to 2030 established the target of 27% of share of RES in energy consumption. With the continuing increase in the use of RES, it is likely that more and more generation will have to be curtailed to maintain the stability of the power system which was not originally designed to integrate renewable generation. In this context, the conversion of renewable electricity to heat in connection with its storage in district heating systems, known as Power-to-Heat (PtH) can be considered as a viable option in increasing the share of RES and facilitating the stability of the power system. In this paper an attempt is made to estimate the potential of PtH technology for Poland up to 2030, including the high RES share scenario for the energy mix development.


Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5605
Author(s):  
Roghieh Abdollahi Biroon ◽  
Pierluigi Pisu ◽  
David Schoenwald

The increasing penetration of renewable energy sources in power grids highlights the role of battery energy storage systems (BESSs) in enhancing the stability and reliability of electricity. A key challenge with the renewables’, specially the BESSs, integration into the power system is the lack of proper dynamic models and their application in power system analyses. The control design strategy mainly depends on the system dynamics which underlines the importance of the system accurate dynamic modeling. Moreover, control design for the power system is a complicated issue due to its complexity and inter-connectivity, which makes the application of distributed control to improve the stability of a large-scale power system inevitable. This paper presents an optimal distributed control design for the interconnected systems to suppress the effects of small disturbances in the power system employing utility-scale batteries based on existing battery models. The control strategy is applied to two dynamic models of the battery: hybrid model and Western electricity coordinating council (WECC) model. The results show that (i) the smart scheduling of the batteries’ output reduces the inter-area oscillations and improves the stability of the power systems; (ii) the hybrid model of the battery is more user-friendly compared to the WECC model in power system analyses.


Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5786
Author(s):  
Stefanos Ntomalis ◽  
Petros Iliadis ◽  
Konstantinos Atsonios ◽  
Athanasios Nesiadis ◽  
Nikos Nikolopoulos ◽  
...  

The defossilization of power generation is a prerequisite goal in order to reduce greenhouse gas emissions and transit for a sustainable economy. Achieving this goal requires increasing the penetration of renewable energy sources (RESs) such as solar and wind power. The gradual shrinking of conventional generation units in an energy map introduces new challenges to the stability of power systems as there is a considerable reduction of stored rotational energy in the synchronous generators (SGs) and the capability to control their power output, which has been taken for granted until today. Inertia and primary reserve reduction have a substantial effect on the ability of the power system to maintain its security and self-resilience during contingency events. Such issues become more evident in the case of non-interconnected islands (NII) as they have unique features associated with their small size and low inertia. The present study examines in depth the NII system of Madeira, which is composed of thermal, hydro, solid-waste, wind and solar generation units, and additional RES integration is planned for the near future. Electromagnetic transient (EMT) simulations are performed for both the current and future states of the system, including the installation of planned variable RES capacities. To alleviate the stability issues that occurred in the high-RES scenario, the introduction of a utility-scale battery energy storage system (BESS), capable of mitigating the active power imbalance due to the power system’s disturbances resultant of RES penetration, is examined. In addition, a comparison between a flywheel energy storage system (FESS) and BESS is shortly investigated. The grid has been modeled and simulated utilizing the open-source, object-oriented modeling language Modelica. The dynamic simulation results proved that battery storage is a promising technology that can be a solution for transitioning to a sustainable power system, maintaining its self-resilience under severe disturbances such as rapid load changes, the tripping of generation units and short-circuits.


Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2288
Author(s):  
Zhenghao Wang ◽  
Yonghui Liu ◽  
Zihao Yang ◽  
Wanhao Yang

In recent years, wind power systems have been used extensively, which not only improve the efficiency of current conventional power generation systems, but also can save traditional fossil fuel resources. However, considering the instability of wind power, after being grid connected, it can easily cause an impact on the stability of the grid operation. Considering the above problems, this paper considers to make full use of the energy storage part of electric vehicles (EVs) to increase the stability of grid operation. Based on the mathematical model, this paper studies the load frequency control (LFC) problem of a multi-region interconnected power system with wind power and EVs. First, since the system states are difficult to be monitored, a state observer is designed to estimate the state. Based on this, the integral sliding mode controller (SMC) is designed to realize the LFC of the interconnected power system. Meanwhile, to obtain better control performance, this paper further analyzes and optimizes the controller parameters based on Lyapunov stability theory. At last, simulations are carried out for the power systems with two regions in Simulink. The results show that the designed controllers are effective to compensate the load demand disturbances. In addition, it is demonstrated that the battery storage of EVs can play the role of peak-shaving and valley-filling in LFC.


Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 751 ◽  
Author(s):  
Flavio Balsamo ◽  
Davide Lauria ◽  
Fabio Mottola

This paper deals with the design and control aspects of modern ship power systems within the paradigm of an all-electric ship. The widespread use of power electronic converters is central in this context due to the technological advances in automation systems and the integration of the electrical propulsion systems and other components, such as electrical energy storage systems and renewable energy sources. The issue to address in this scenario is related to the request of increased performances in dynamic operation while pursuing advantages in terms of energy savings and overall system security. In addition, the presence of large load changes requires providing robustness of the control in terms of system stability. This paper is focused on medium voltage direct current (MVDC) ship power systems and the design and control of coupled inductor DC–DC converters. The load is handled in terms of a constant power model, which generally is considered the most critical case for testing the stability of the system. The robustness of the design procedure, which is verified numerically against large and rapid load variations, allowed us to confirm the feasibility and the attractiveness of the design and the control proposal.


1996 ◽  
Vol 11 (3) ◽  
pp. 472-479 ◽  
Author(s):  
M. Florez-Lizarraga ◽  
A.F. Witulski

2020 ◽  
Vol 12 (8) ◽  
pp. 3469 ◽  
Author(s):  
Dohyuk Kim ◽  
Hwanhee Cho ◽  
Bohyun Park ◽  
Byongjun Lee

The penetration of renewable energy sources (RESs) equipped with inverter-based control systems such as wind and solar plants are increasing. Therefore, the speed of the voltage controllers associated with inverter-based resources (IBRs) has a substantial impact on the stability of the interconnected grid. System strength evaluation is one of the important concerns in the integration of IBRs, and this strength is often evaluated in terms of the short circuit ratio (SCR) index. When IBRs are installed in an adjacent location, system strength can be weaker than evaluation by SCR. This study proposes an inverter interaction level short circuit ratio (IILSCR) method by tracing IBRs output flow. The IILSCR can accurately estimate system strength, wherein IBRs are connected in adjacent spots, by reflecting the interaction level between IBRs. The study also demonstrates the efficiency of IILSCR by applying this method to Institute of Electrical and Electronics Engineers (IEEE) 39 bus test system and future Korea power systems.


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