skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Stability-oriented Optimization and Consensus Control for Inverter-based Microgrid
In this paper, the small-signal model and stability-oriented consensus control scheme for inverter-based microgrid systems is proposed. By perturbating four identified dominant control parameters of inverter-based microgrid intentionally, the corresponding incremental matrix of microgrid system can be formed. Then, Matrix Perturbation Theory is employed in this paper to reduce the computational burden caused by repetitive calculations of system eigenvalues during stability analysis. Furthermore, the objective function is formulated based on the small-signal stability index and consensus index of microgrid system. Finally, the optimal control algorithm based on the joint application of Matrix Perturbation Theory and Artificial Fish Swarm Algorithm is introduced in this paper so that the stability and consensus rate of microgrid can be ensured. Besides, the effectiveness of proposed method can be verified in Matlab/Simulation results.  more » « less
Award ID(s):
1711951
PAR ID:
10202316
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
2018 North American Power Symposium (NAPS)
Page Range / eLocation ID:
1 to 6
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    With the increasing integration of renewable energy, the problems associated with deteriorating grid frequency profile and potential power system instability have become more significant. In this paper, the inertial control algorithm using Virtual Synchronous Generator (VSG) is implemented on type-4 Permanent Magnet Synchronous Generator (PMSG) - wind turbine generator (WTG). The overall nonlinear dynamic model and its small-signal linearization of PMSG-WTG using VSG is established and comprehensively analyzed. Inevitably, the direct application of VSG introduces large inertia which causes conflict between the fast-varying of available wind power and inverter control with slow dynamics, particularly in region 2 of wind turbine. Aiming to address such issue, VSG with multiple virtual rotating masses is proposed in order to improve the active power tracking performance as well as to boost inertial control of a VSG. The inertial responses are verified in a modified 10MVA IEEE 14 bus microgrid system. The assessment of the simulation results demonstrates the applicability of VSG on renewable energy generation units. 
    more » « less
  2. null (Ed.)
    Microgrid systems can provide extensive information using their measurement units to the operators. As microgrid systems become more pervasive, there will be a need to adjust the information an operator requires to provide an optimized user-interface. In this paper, a combinatorial optimization strategy is used to provide an optimal user-interface for the microgrid operator that selects information for display depending on the operator's trust level in the system, and the assigned task. We employ a method based on sensor placement by capturing elements of the interface as different sensors, that find an optimal set of sensors via combinatorial optimization. However, the typical inverter-based microgrid model poses challenges for the combinatorial optimization due to its poor conditioning. To combat the poor conditioning, we decompose the model into its slow and fast dynamics, and focus solely on the slow dynamics, which are more well conditioned. We presume the operator is tasked with monitoring phase angle and active and reactive power control of inverter-based distributed generators. We synthesize user-interface for each of these tasks under a wide range of trust levels, ranging from full trust to no trust. We found that, as expected, more information must be included in the interface when the operator has low trust. Further, this approach exploits the dynamics of the underlying microgrid to minimize information content (to avoid overwhelming the operator). The effectiveness of proposed approach is verified by modeling an inverter-based microgrid in Matlab. 
    more » « less
  3. In this work, a synchronous model for grid-connected and islanded microgrids is presented. The grid-connected model is based on the premise that the reference frame is synchronized with the AC bus. The quadrature component of the AC bus voltage can be cancelled, which allows to express output power as a linear equation for nominal values in the AC bus amplitude voltage. The model for the islanded microgrid is developed by integrating all the inverter dynamics using a state-space model for the load currents. This model is presented in a comprehensive way such that it could be scalable to any number of inverter-based generators using inductor–capacitor–inductor (LCL) output filters. The use of these models allows designers to assess microgrid stability and robustness using modern control methods such as eigenvalue analysis and singular value diagrams. Both models were tested and validated in an experimental setup to demonstrate their accuracy in describing microgrid dynamics. In addition, three scenarios are presented: non-controlled model, Linear-Quadratic Integrator (LQI) power control, and Power-Voltage (PQ/Vdq) droop–boost controller. Experimental results demonstrate the effectiveness of the control strategies and the accuracy of the models to describe microgrid dynamics. 
    more » « less
  4. This paper proposes a methodology to increase the lifetime of the central battery energy storage system (CBESS) in an islanded building-level DC microgrid (MG) and enhance the voltage quality of the system by employing the supercapacitor (SC) of electric vehicles (EVs) that utilize battery-SC hybrid energy storage systems. To this end, an adaptive filtration-based (FB) current-sharing strategy is proposed in the voltage feedback control loop of the MG that smooths the CBESS current to increase its lifetime by allocating a portion of the high-frequency current variations to the EV charger. The bandwidth of this filter is adjusted using a data-driven algorithm to guarantee that only the EV's SC absorbs the high-frequency current variations, thereby enabling the EV's battery energy storage system (BESS) to follow its standard constant current-constant voltage (CC-CV) charging profile. Therefore, the EV's SC can coordinate with the CBESS without impacting the charging profile of the EV's BESS. Also, a small-signal stability analysis is provided indicating that the proposed approach improves the marginal voltage stability of the DC MG leading to better transient response and higher voltage quality. Finally, the performance of the proposed EV charging is validated using MATLAB/Simulink and hardware-in-the-loop (HIL) testing. 
    more » « less
  5. Conventional perturbation-based extremum seeking control (ESC) employs a slow time-dependent periodic signal to find an optimum of an unknown plant. To ensure stability of the overall system, the ESC parameters are selected such that there is sufficient time-scale separation between the plant and the ESC dynamics. This approach is suitable when the plant operates at a fixed time-scale. In case the plant slows down during operation, the time-scale separation can be violated. As a result, the stability and performance of the overall system can no longer be guaranteed. In this paper, we propose an ESC for periodic systems, where the external time-dependent dither signal in conventional ESC is replaced with the periodic signals present in the plant, thereby making ESC time-invariant in nature. The advantage of using a state-based dither is that it inherently contains the information about the rate of the rhythmic task under control. Thus, in addition to maintaining time-scale separation at different plant speeds, the adaptation speed of a time-invariant ESC automatically changes, without changing the ESC parameters. We illustrate the effectiveness of the proposed time-invariant ESC with a Van der Pol oscillator example and present a stability analysis using averaging and singular perturbation theory. 
    more » « less