A novel control method for voltage regulation and island detection of a DC microgrid connected photo voltaic converter system

Author(s):  
K. Anoop ◽  
M. Nandakumar
Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1622 ◽  
Author(s):  
Haochen Hua ◽  
Yuchao Qin ◽  
Hanxuan Xu ◽  
Chuantong Hao ◽  
Junwei Cao

The energy internet (EI) is a wide area power network that efficiently combines new energy technology and information technology, resulting in bidirectional on-demand power transmission and rational utilization of distributed energy resources (DERs). Since the stability of local network is a prerequisite for the normal operation of the entire EI, the direct current (DC) bus voltage stabilization for each individual DC microgrid (MG) is a core issue. In this paper, the dynamics of the EI system is modeled with a continuous stochastic system, which simultaneously considers related time-varying delays and norm-bounded modeling uncertainty. Meanwhile, the voltage stabilization issue is converted into a robust H ∞ control problem solved via a linear matrix inequality approach. To avoid the situation of over-control, constraints are set in controllers. The problem of finding a balance between voltage regulation performance and constraints for the controllers was also extensively investigated. Finally, the efficacy of the proposed methods is evaluated with numerical simulations.


2020 ◽  
Author(s):  
Saman Dadjo Tavakoli

<div>This paper presents a decentralized control scheme for voltage balancing and power sharing in bipolar dc</div><div>microgrids. This relies on utilizing a converter topology which offers three levels of output voltage availability with the key features of boosting the input voltage and balancing the output voltages. This converter makes it possible to further improve the structure of bipolar dc microgrids as it does not require a central voltage balancer. Small-signal analysis is done and system transfer functions are derived. Based on the RGA concept the highly coupled input-output pairs are found which helps with replacing the MIMO control system of the converter by two SISO systems. The appropriate voltage and current controllers are designed based on SISO principles. Moreover, a double droop control method is proposed which fulfills the simultaneous power sharing and voltage regulation of DG units in the host microgrid. The effectiveness of the proposed control strategy is demonstrated through simulation studies conducted on an</div><div>islanded bipolar dc microgrid involving unbalanced loads, while the voltage balancing of the bipolar dc microgrid and the power sharing accuracy are evaluated.</div>


2020 ◽  
Author(s):  
Saman Dadjo Tavakoli

<div>This paper presents a decentralized control scheme for voltage balancing and power sharing in bipolar dc</div><div>microgrids. This relies on utilizing a converter topology which offers three levels of output voltage availability with the key features of boosting the input voltage and balancing the output voltages. This converter makes it possible to further improve the structure of bipolar dc microgrids as it does not require a central voltage balancer. Small-signal analysis is done and system transfer functions are derived. Based on the RGA concept the highly coupled input-output pairs are found which helps with replacing the MIMO control system of the converter by two SISO systems. The appropriate voltage and current controllers are designed based on SISO principles. Moreover, a double droop control method is proposed which fulfills the simultaneous power sharing and voltage regulation of DG units in the host microgrid. The effectiveness of the proposed control strategy is demonstrated through simulation studies conducted on an</div><div>islanded bipolar dc microgrid involving unbalanced loads, while the voltage balancing of the bipolar dc microgrid and the power sharing accuracy are evaluated.</div>


Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2793 ◽  
Author(s):  
Tao Wu ◽  
Yanghong Xia ◽  
Liang Wang ◽  
Wei Wei

Based on the droop control, voltage regulation at the secondary control is required to eliminate the deviation of the average voltage across the microgrid. Meanwhile, to prevent any of energy storage (ESs) from over-charging or over-discharging, State-of-Charge (SoC) balancing should be added in the secondary control. This paper proposes a distributed secondary control in the DC microgrid based on the multiagent system (MAS). This controller consists of voltage regulation and time-oriented SoC balancing. In voltage regulation, a PI controller adjusts the droop parameters according to the discrepancy between the average voltage and the reference voltage. In SoC balancing, controller operates in charging mode or discharging mode according to changes of the global average SoC. Being different from the conventional method, the time-oriented SoC balancing method is designed to balance charge/discharge time rather than to balance SoC directly. Thus, SoCs reach a consensus only at the last moment when all ES nodes charge or discharge completely. Furthermore, characteristics, global dynamic model, and steady-state analysis of the proposed control method are studied. Finally, MATLAB/Simulink simulations are performed to verify the effectiveness of the proposed control.


2018 ◽  
Vol 7 (1.8) ◽  
pp. 153 ◽  
Author(s):  
G Srinivasa Rao ◽  
K Harinadha Reddy ◽  
B Ravi Teja ◽  
B Devasahayam ◽  
Shaik Khaleel

DC microgrids are playing an important role in remote area power applications like power supply to off-grid tele communication towers, off-grid data centres, rural electrification etc. and moreover these are extensively used, as these appear as solutions for integrating two or more renewable energy resources. In this paper, photovoltaic (PV) and wind energy systems have been integrated along with batteries and a load to form an autonomous DC microgrid with high reliability and stability.  The primary aspects which are to be taken into consideration in a standalone DC microgrid are voltage regulation, load sharing and battery management. In this paper, an energy management strategy is proposed which includes maximum power point tracking (MPPT) algorithms and voltage droop control method. This strategy ensures optimal power sharing among the sources and increases reliability and stability profile of the microgrid. The operation of the microgrid in different modes and the behaviour of the system at different operating conditions is studied by varying the solar irradiance and wind speed for specific time periods. The simulation is done in Matlab Simulink software and the results are obtained. 


Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5356
Author(s):  
Prudhvi Kumar Gorijeevaram Reddy ◽  
Sattianadan Dasarathan ◽  
Vijayakumar Krishnasamy

In a DC microgrid, droop control is the most common and widely used strategy for managing the power flow from sources to loads. Conventional droop control has some limitations such as poor voltage regulation and improper load sharing between converters during unequal source voltages, different cable resistances, and load variations. This paper addressed the limitations of conventional droop control by proposing a simple adaptive droop control technique. The proposed adaptive droop control method was designed based on mathematical calculations, adjusting the droop parameters accordingly. The primary objective of the proposed adaptive droop controller was to improve the performance of the low-voltage DC microgrid by maintaining proper load sharing, reduced circulating current, and better voltage regulation. The effectiveness of the proposed methodology was verified by conducting simulation and experimental studies.


Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 404
Author(s):  
Sara J. Ríos ◽  
Daniel J. Pagano ◽  
Kevin E. Lucas

Currently, high-performance power conversion requirements are of increasing interest in microgrid applications. In fact, isolated bidirectional dc-dc converters are widely used in modern dc distribution systems. The dual active bridge (DAB) dc-dc converter is identified as one of the most promising converter topology for the mentioned applications, due to its benefits of high power density, electrical isolation, bidirectional power flow, zero-voltage switching, and symmetrical structure. This study presents a power management control scheme in order to ensure the power balance of a dc microgrid in stand-alone operation, where the renewable energy source (RES) and the battery energy storage (BES) unit are interfaced by DAB converters. The power management algorithm, as introduced in this work, selects the proper operation of the RES system and BES system, based on load/generation power and state-of-charge of the battery conditions. Moreover, a nonlinear robust control strategy is proposed when the DAB converters are in voltage-mode-control in order to enhance the dynamic performance and robustness of the common dc-bus voltage, in addition to overcoming the instability problems that are caused by constant power loads and the dynamic interactions of power electronic converters. The simulation platform is developed in MATLAB/Simulink, where a photovoltaic system and battery system are selected as the typical RES and BES, respectively. Assessments on the performance of the proposed control scheme are conducted. Comparisons with the other control method are also provided.


Sign in / Sign up

Export Citation Format

Share Document