scholarly journals An Enhanced Control Strategy for Mitigation of State-Transition Oscillation Phenomena in Grid-Forming Self-Synchronized Converter System with Islanded Power System

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8453
Author(s):  
Ki Ryong Kim ◽  
Sangjung Lee ◽  
Jong-Pil Lee ◽  
Jaesik Kang
Keyword(s):  
Power System ◽  
Control Strategy ◽  
State Transition ◽  
Reactive Power ◽  
Phase Synchronization ◽  
Control Method ◽  
System Stability ◽  
Electromagnetic Transient ◽  
Point Of Common Coupling ◽  
Hardware In Loop

This paper proposes an enhanced control strategy for mitigating state-transition oscillations in active and reactive power responses of self-synchronized converter system to secure the islanded power system stability. The self-synchronized converter is well known for “grid-forming” that is able to operate to stand-alone mode (SAM) providing grid voltage and frequency without phase synchronization units. Although the grid-forming (GFM) is self-synchronized, the inherent synchronization principle causes system degradation in which should maintain a point of common coupling (PCC) voltage for critical loads as well as transitions from grid-connected mode (GCM) to SAM and vice versa. Therefore, this paper focuses on resolving the inherent oscillatory issues in GFM self-synchronized converter system (especially adopted ‘synchronverter’ principle), and proposes a control strategy for controllability improvement based on stability analysis for smooth state-transition under islanded power system. The efficacy of the proposed control method is verified through a high-fidelity electromagnetic transient (EMT) simulation with case studies on 30kW synchronverter system and further experimental hardware-in-loop system (HILS) test with Opal-RT (OP-5707) platform.

Coordination Control Strategy for Active and Reactive Power of DFIG Based on Exact Feedback Linearization under Grid Fault Condition

2011 ◽  
Vol 48-49 ◽  
pp. 335-344
Author(s):  
Meng Zeng Cheng ◽  
Zhen Lan Dou ◽  
Xu Cai
Keyword(s):  
Nonlinear Control ◽  
Power System ◽  
Control Strategy ◽  
Feedback Linearization ◽  
Transient Stability ◽  
Reactive Power ◽  
Control Method ◽  
Linear Quadratic Regulator ◽  
Linear Quadratic ◽  
Nonlinear Control Method

In this paper, a control strategy for operation of rotor side converter (RSC) of Doubly Fed Induction Generators (DFIG) is developed by injecting reactive power into the grid in order to support the grid voltage during and after grid fault events. The novel nonlinear control method is based on differential geometry theory, and exact feedback linearization is applied for control system design of DFIG. Then the optimal control for the linearized system is obtained through introducing the linear quadratic regulator (LQR) design method. Simulation results on a single machine infinite bus power system show that the proposed nonlinear control method can inject reactive power to fault grid rapidly, reduce the oscillation of active power and improve the transient stability of power system.

Co-ordinated and real time voltage control of DSTS-biomass based isolated hybrid power system using Grey Wolf optimization

2020 ◽  
pp. 002072092096587
Author(s):  
M Mynavathi ◽  
J Devi Shree ◽  
K Saranya
Keyword(s):  
Power System ◽  
Real Time ◽  
Control Strategy ◽  
Reactive Power ◽  
System Stability ◽  
Grey Wolf ◽  
Grey Wolf Optimization ◽  
Hybrid Power System ◽  
Hybrid Power ◽  
Voltage Deviation

This paper proposes a co-ordinated reactive power control strategy analysis in Line Side Converter (LSC) of Doubly Fed induction generator (DFIG) and in the Automatic voltage regulator (AVR) of synchronous generator (SG) in isolated Dish Stirling solar Thermal(DSTS) – Biomass hybrid power system. This co-ordinated control strategy greatly maintains the autonomous hybrid power system voltage deviation by adjusting the reactive power imbalance caused due to the impulsive reactive power nature of DFIG coupled with the DSTS and load. Gain values of Integral Order Proportional Integral (IO-PI) controller in LSC and AVR are optimized to maintain the system voltage stability. Modern and simple Grey wolf optimization algorithm has been used to extract the superior PI gain values to maintain system stability with less reaction time. The proposed co-ordinated control strategy has been tested with various load disturbance and with dynamic input power feed from DSTS to validate the system robustness. Also, the optimized gain value based voltage deviation values are validated in real time with dSPACE.

scholarly journals Investigation on Control Strategies for a Single-Phase Photovoltaic Inverter Using PSCAD/EMTDC Software

2021 ◽  
Vol 6 (1) ◽  
pp. 75-99
Author(s):  
Cristiano Luiz Henz ◽  
Fabiano Perin Gasparin
Keyword(s):  
Power System ◽  
Power Electronics ◽  
Control Strategy ◽  
Single Phase ◽  
Reactive Power ◽  
Control Strategies ◽  
Simulation Software ◽  
Photovoltaic Systems ◽  
Electromagnetic Transient ◽  
Q Theory

Abstract In the last decades, electric power produced through photovoltaic conversion has been increasing because of the need to reduce fossil fuel burning. Recently, photovoltaic systems have become more competitive and their role in the renewable energies market share is steadily gaining in importance. Improvements in the power electronics employed in the DC/AC conversion are topics of interest in the quest for more efficient and eventually reduced-cost inverters. The goal of this paper is to perform an investigation of control strategies and propose a topology for a single-phase DC/AC converter for photovoltaic arrays using the simulation software Power System Computer Aided Design/ Electromagnetic Transient Design and Control (PSCAD/EMTDC). The circuit proposed in this paper employs an isolating transformer to a grid-connected photovoltaic inverter. The control strategy proposed uses the instantaneous reactive power theory (p–q theory) and phase-locked loop (PLL). The p-q theory uses two virtual axes in the Park Transformation, which provide to the control system a good dynamic response, accuracy, and decoupling between the control and power system. Computer simulations using the electromagnetic transient software PSCAD show the efficiency of the proposed strategy for a single-phase inverter. The control strategy and topology are quite simple and easy to implement in the future using a Digital Signal Processor (DSP). The results provide insights into new power electronics solutions, which can improve the efficiency and efficacy of the current available in DC/AC converters for photovoltaic systems.

scholarly journals A Novel Autonomous Current-Sharing Control Strategy for Multiple Paralleled DC–DC Converters in Islanded DC Microgrid

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3951 ◽  
Author(s):  
Zhang ◽  
Zhuang ◽  
Liu ◽  
Wang ◽  
Guo
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Control Method ◽  
Controller Design ◽  
Voltage Drop ◽  
Low Frequency ◽  
System Stability ◽  
Current Sharing ◽  
Current Sharing Control ◽  
Droop Characteristic

Due to the existence of line impedances and low-bandwidth communication, the traditional peer-to-peer control method based on droop control has difficult meeting the requirements of current sharing and voltage stability in islanded DC microgrids at the same time. In this paper, a novel current-sharing control strategy based on injected small ac voltage with low frequency and low amplitude is proposed for multiple paralleled DC–DC converters. The small ac voltage is superimposed onto the output voltage of each converter. Then, the reactive circulating power is generated and used to regulate the output DC voltage of each converter. Under the droop characteristic between the injected frequency and output DC current, a feedback mechanism is generated to realize the accurate current sharing. On this basis, a reactive power-voltage limiter link and virtual negative impedance are added. Under the interaction of the two links, the bus voltage drop caused by line impedances can be almost completely eliminated. This method does not need any communication or to change the hardware structure. The controller design process is presented in detail along with a system stability analysis. Finally, the feasibility and effectiveness of the proposed control strategy are validated by the results obtained from simulations and experiments.

Control Strategy of Wind Photovoltaic and Energy Storage System Stability Running

2013 ◽  
Vol 336-338 ◽  
pp. 547-550
Author(s):  
Ji Hong Zhang ◽  
Zhen Kui Wu ◽  
Hua Li ◽  
Han Shan Li
Keyword(s):  
Energy Storage ◽  
Distributed Generation ◽  
Control Strategy ◽  
Control Method ◽  
Storage System ◽  
Energy Storage System ◽  
System Stability ◽  
Mathematics Model ◽  
Generation Efficiency ◽  
Micro Grid

Micro grid may exert adequately distributed generation efficiency, and that wind Photovoltaic and Energy Storage is a key equipment in the micro grid. Aiming at the distributed generation existing intermittence and randomicity characteristic, the paper discussed the micro grid P/Q control method under the connection grid state and the micro grid U/F control method under the disconnection grid state. It also studied the distributed generation parameters variational law under the micro grid different run mode, and built the correlative mathematics model and tested by simulation. The results show: the control strategy ensured the mice grid running stably, and achieved the system anticipative design request, and offered theory foundation for the distributed generation extend application.

A New Iterative Identification and Control Method of Closed-Loop Power System Based on Ambient Signals

2015 ◽  
Vol 798 ◽  
pp. 261-265
Author(s):  
Miao Yu ◽  
Chao Lu
Keyword(s):  
Power System ◽  
Closed Loop ◽  
Control Method ◽  
Controller Design ◽  
Design Method ◽  
Stability Margin ◽  
System Stability ◽  
Iterative Identification ◽  
Effective Performance ◽  
And Control

Identification and control are important problems of power system based on ambient signals. In order to avoid the model error influence of the controller design, a new iterative identification and control method is proposed in this paper. This method can solve model set and controller design of closed-loop power system. First, an uncertain model of power system is established. Then, according to the stability margin of power system, stability theorem is put forward. And then controller design method and the whole algorithm procedure are given. Simulation results show the effective performance of the proposed method based on the four-machine-two-region system.

A Novel Control Strategy for Three-Phase Four-Wire STATCOM

2012 ◽  
Vol 516-517 ◽  
pp. 1722-1727 ◽  
Author(s):  
Wei Jun Yun ◽  
Gang Yao ◽  
Li Dan Zhou ◽  
Chen Chen ◽  
Jun Min Pan
Keyword(s):  
Control Strategy ◽  
Power Distribution ◽  
Distribution System ◽  
Reactive Power ◽  
Control Method ◽  
Loop Control ◽  
Power Distribution System ◽  
Imbalance Problem ◽  
Three Phase ◽  
Close Loop Control

Nowadays Static Synchronous Compensator (STATCOM) has gradually become one of the representative techniques in the field of dynamic reactive power compensation in the power distribution system. This paper analyzed the topology and the voltage imbalance problem of the up and down capacitors on DC side of the three-phase four-wire STATCOM. In allusion to the imbalance problem of neutral point, a novel control strategy based on the control of zero-sequence current was proposed. By the triple close-loop control strategy, the STATCOM can achieve great control accuracy and dynamic performance. Simulation result proves that the proposed control method is effective.

scholarly journals Modeling of Multiple Master–Slave Control under Island Microgrid and Stability Analysis Based on Control Parameter Configuration

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2223 ◽  
Author(s):  
Haifeng Liang ◽  
Yue Dong ◽  
Yuxi Huang ◽  
Can Zheng ◽  
Peng Li
Keyword(s):  
Reactive Power ◽  
Control Method ◽  
Mutual Influence ◽  
Renewable Energy Sources ◽  
System Stability ◽  
Voltage Source ◽  
Stable Operation ◽  
Parameter Configuration ◽  
Islanded Mode ◽  
Virtual Impedance

The stable operation of a microgrid is crucial to the integration of renewable energy sources. However, with the expansion of scale in electronic devices applied in the microgrid, the interaction between voltage source converters poses a great threat to system stability. In this paper, the model of a three-source microgrid with a multi master–slave control method in islanded mode is built first of all. Two sources out of three use droop control as the main control source, and another is a subordinate one with constant power control which is also known as real and reactive power (PQ) control. Then, the small signal decoupling control model and its stability discriminant equation are established combined with “virtual impedance”. To delve deeper into the interaction between converters, mutual influence of paralleled converters of two main control micro sources and their effect on system stability is explored from the perspective of control parameters. Finally, simulation and analysis are launched and the study serves as a reference for parameter setting of converters in a microgrid.

A Control Strategy for Transient Stability Improvement of Doubly-Fed Wind Power Generation System

2014 ◽  
Vol 953-954 ◽  
pp. 337-341
Author(s):  
Chao Xu ◽  
Jin Ling Lu ◽  
Jin Long Zhou
Keyword(s):  
Control Strategy ◽  
Wind Farm ◽  
Transient Stability ◽  
Reactive Power ◽  
System Stability ◽  
Control Loop ◽  
Reactive Control ◽  
Voltage Control Strategy ◽  
Transient Voltage ◽  
Doubly Fed

A novel inverter control strategy to enhance the transient stability of grid-connected wind farm based on doubly-fed induction generator (DFIG) is presented. Adding transient angle control strategy in the rotor side converter active control loop, this can dissipate the system unbalancing energy and restrain the system oscillations by the variation of wind turbine speed. Adding transient voltage control strategy in reactive control loop, this can provide fast reactive power compensation and support the restoration and reconstruction of the grid voltage when fault occurred. The control strategy which can improve the transient Angle stability and transient voltage stability at the same time is put forward. Finally, a testing system including a DFIG-based wind farm is realized using DigSILENT/Power Factory, the strategy validation and the contribution to power system stability enhancement are verified by simulation.

Coordinated Reactive Power and Voltage Control Based on Doubly-Fed Wind Farm Cluster

2014 ◽  
Vol 1070-1072 ◽  
pp. 224-227
Author(s):  
Li Lin ◽  
Kai Li
Keyword(s):  
Control Strategy ◽  
Voltage Stability ◽  
Wind Farm ◽  
Optimal Allocation ◽  
Reactive Power ◽  
Coordinated Control ◽  
Current Control ◽  
Separate Control ◽  
Point Of Common Coupling ◽  
Doubly Fed

Current control strategy of reactive power and voltage for wind power integration is separate control of single wind farm (WF), which cannot achieve the optimal allocation of reactive power and is not beneficial for the optimization of voltage stability and network loss. In this paper, a coordinated control strategy of reactive power and voltage for wind farm cluster is proposed, which takes the voltage stability at point of common coupling (PCC) and economic operation as the optimization goals. The coordinated control strategy is realized through the platform of Cybercontrol industrial configuration, and the application testing verifies the effectiveness of the proposed strategy.

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