scholarly journals Islanded Mode Response Verification of AC Microgrid under Symmetrical and Non-symmetrical Short Circuits

2019 ◽  
Vol 115 ◽  
pp. 01002
Author(s):  
Maruf A. Aminu
Keyword(s):  
Wind Turbines ◽  
Reactive Power ◽  
Control Strategies ◽  
Short Circuit ◽  
Islanded Mode ◽  
Short Circuits ◽  
Detection And Diagnosis ◽  
And Performance ◽  
Mode Response ◽  
Optimization And Performance

The assumptions and parameters required in modeling a microgrid depend on the platform, among other variables. It is therefore pertinent to verify the response of a modeled testbed to establish its validity. This work reports on verification of the response of a wind turbines-based microgrid to symmetrical and non-symmetrical short circuits. The testbed consists of 2 units of 5.5 kW 400 V wind turbines capable of connecting to the utility. Short circuits are introduced at 6.00 second and withdrawn at 8.00 second, measuring the dynamic response of the testbed while the microgrid is in islanded mode alternately under voltage and reactive power control strategies. The response is shown to be consistent, symptomatic of the type of short circuit and therefore suitable for short circuit detection and diagnosis, verifying validity of the microgrid testbed. The testbed can therefore be used for short circuit related studies, design optimization and performance prediction.

scholarly journals Research on Serial VSC-LCC Hybrid HVdc Control Strategy and Filter Design Scheme

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2260
Author(s):  
Fan Cheng ◽  
Lijun Xie ◽  
Zhibing Wang
Keyword(s):  
Reactive Power ◽  
Filter Design ◽  
Control Strategies ◽  
Short Circuit ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Level Control ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Design Scheme

This paper investigated the characteristics of a novel type of hybrid high voltage direct current (HVdc) converter, which is composed by line commutated converter series with voltage source converter. The system and valve level control strategies are introduced, which can provide ac system voltage support. A novel filter design scheme composed by resonant filers for hybrid HVdc are also proposed, which can decrease the capacity of reactive power compensation equipment without deteriorate harmonic characteristics. The ac voltage of HVdc fluctuation level caused by transmitted power variation will be effectively reduced, with the coordination between filter design scheme and converter control. In addition, the influence of ac grid strength is also analyzed by equivalent source internal impedance represented by short circuit ratio (SCR). Finally, the +800 kV/1600 MW hybrid HVdc system connecting two ac grids under different SCR cases are studied, and the PSCAD/EMTDC simulation results have validated the effectiveness for proposed strategy.

scholarly journals Fuzzy Logic based H-bridge STATCOM Controller to compensate Unbalanced Voltages

2020 ◽  
Vol 6 (7) ◽  
pp. 135-139
Author(s):  
G Mahesh P Ankineedu Prasad
Keyword(s):  
Fuzzy Logic ◽  
Reactive Power ◽  
Control Strategies ◽  
Current System ◽  
Voltage Regulation ◽  
Large Current ◽  
Railway Traction ◽  
And Performance ◽  
Shunt Compensation ◽  
Traction Power Supply

In this paper a new method four-leg topology is suggested for shunt compensation, the H-bridge multilevel converters based on the half-bridge converters, to achieve higher performance as a STATCOM in a distorted and unbalanced medium-voltage large-current system. Further, an extended Fuzzy based STATCOM is proposed in order to manage more accurate compensation for high-power applications. Both proposals can be controlled for various purposes such as reactive power and unbalance compensation, voltage regulation, and harmonic cancellation. One interesting application for the Fuzzy logic based STATCOM could be the improvement in power quality and performance of the electrified railway traction power supply system. Both the H-bridge based STATCOM along with their proposed control strategies were simulated.

scholarly journals Grid-connected Response Verification of AC Microgrid under Single Line-to-ground Short Circuit

2019 ◽  
pp. 1-10
Author(s):  
Maruf A. Aminu
Keyword(s):  
Power Systems ◽  
Reactive Power ◽  
Short Circuit ◽  
Synchronous Generator ◽  
Dynamic Responses ◽  
Single Line ◽  
Physical Systems ◽  
Short Circuits ◽  
Power System Performance ◽  
Grid Interconnection

In design of power systems, assumptions are made to model the physical systems. The assumptions may not sufficiently reflect the behavior of the system under normal and faulted conditions. Under short circuit conditions, system parameters vary significantly, particularly in microgrids with grid interconnection capabilities. This paper presents the result of validating the response of a microgrid which is capable of grid interconnection and islanding under voltage and reactive power control regimes. The microgrid is modeled to incorporate two wind turbines, each rated 5.5 kW, 400 V. The utility has synchronous generator rated 100 MW, 13.8 kV. Both the utility and microgrid are capable of exchanging active power and reactive power. Single line-to-ground short circuits are introduced and withdrawn at 30.00 s and 32.00 s, respectively. The dynamic responses of the testbed are captured pre-, during- and post-short circuit in grid-connected mode under both control regimes. The response of the testbed is verified to be consistent with established short circuit theory, verifying the validity of the system for short circuit detection and analysis. The testbed can therefore be used for short circuit and related studies, design optimization and power system performance prediction.

Active and Reactive Power Droop Controller Design for Reliable and Optimal Control of Renewable-Based Micro-Grid

2021 ◽  
Vol 41 ◽  
pp. 111-136
Author(s):  
Peter Anuoluwapo Gbadega ◽  
Olufunke Abolaji Balogun
Keyword(s):  
Reactive Power ◽  
Controller Design ◽  
Control Strategies ◽  
Operation Mode ◽  
Pv System ◽  
Distributed Generations ◽  
Potential Benefits ◽  
Islanded Mode ◽  
Micro Grid ◽  
Micro Grids

Technical concerns about micro-grid dynamics, particularly in autonomous (island) mode necessitate revision of current paradigms in control of energy systems. Advanced control techniques are imperative segments for micro-grid realization. In general, micro-grids and the integration of distributed energy resources (DER) units introduce a number of operational challenges that required to be addressed in the control design and protection systems such that the reliability and stability levels are not affected significantly and subsequently ensured that the distributed generations (DGs) potential benefits are wholly harnessed. In this paper, the micro-grid coordination strategy was investigated by simply analysing the present micro-grid situation and various control strategies. More so, active-reactive power (P/Q) and droop controller based on proportional-integral (PI) and model predictive control (MPC) were designed to control the inverter output of the micro-sources. A micro-grid model, which has two photovoltaic (PV) and one wind turbine (WT) blocks, were built in MATLAB/Simulink to simulate the following three cases in this study. The three cases are as follows, the switching of operation mode between the grid connected and islanded mode, increasing and decreasing of loads in islanded mode and the disconnection of one PV system at a certain time in islanded mode. Therefore, through the simulation analyses, the MPC controller utilized in this micro-grid as compared to the PI controller, achieved desirable efficiency of the inverter’s power control and shared the load power effectively.

scholarly journals An Active/Reactive Power Control Strategy for Renewable Generation Systems

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1061
Author(s):  
Iván Andrade ◽  
Rubén Pena ◽  
Ramón Blasco-Gimenez ◽  
Javier Riedemann ◽  
Werner Jara ◽  
...  
Keyword(s):  
Control Strategy ◽  
Power Flow ◽  
Reactive Power ◽  
Control Strategies ◽  
Voltage Source ◽  
Renewable Generation ◽  
Frequency Reference ◽  
Active And Reactive Power ◽  
Reactive Power Flow ◽  
Islanded Mode

The development of distributed generation, mainly based on renewable energies, requires the design of control strategies to allow the regulation of electrical variables, such as power, voltage (V), and frequency (f), and the coordination of multiple generation units in microgrids or islanded systems. This paper presents a strategy to control the active and reactive power flow in the Point of Common Connection (PCC) of a renewable generation system operating in islanded mode. Voltage Source Converters (VSCs) are connected between individual generation units and the PCC to control the voltage and frequency. The voltage and frequency reference values are obtained from the P–V and Q–f droop characteristics curves, where P and Q are the active and reactive power supplied to the load, respectively. Proportional–Integral (PI) controllers process the voltage and frequency errors and set the reference currents (in the dq frame) to be imposed by each VSC. Simulation results considering high-power solar and wind generation systems are presented to validate the proposed control strategy.

scholarly journals A STUDY ON POWER OUTPUT OF HORIZONTAL-AXIS WIND TURBINES UNDER RAIN

2019 ◽  
Vol 57 (3) ◽  
pp. 356
Author(s):  
Nguyen Tuan Anh ◽  
Nguyen Huu Duc
Keyword(s):  
Wind Turbines ◽  
Control Strategies ◽  
Horizontal Axis ◽  
Operating Environment ◽  
Physical Processes ◽  
Horizontal Axis Wind Turbines ◽  
Widespread Phenomenon ◽  
Rain Drops ◽  
And Performance ◽  
And Control

The power of the wind turbine are significantly affected by the air conditions of the operating environment. Rain is a widespread phenomenon in many parts of the world especially in Vietnam, so exploring its effect on the power of wind turbines will provide valuable insights into the design of a new wind tower. In this paper, a method and a model is developed to estimate the effect of precipitation by simulating the actual physical processes of the rain drops forming on the surface of the blades of horizontal-axis wind turbines (HAWT), thereby determining optimal wetness, then power and performance respectively. Consequently, it makes a contribution to operation and control strategies for horizontal-axis wind turbines.

scholarly journals Control of DFIG Wind Turbines Based on Indirect Matrix Converters in Short Circuit Mode to Improve the LVRT Capability

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Ahmad Khajeh ◽  
Reza Ghazi
Keyword(s):  
Control System ◽  
Wind Turbines ◽  
Reactive Power ◽  
Low Voltage ◽  
Short Circuit ◽  
Electrolytic Capacitor ◽  
Dominant Type ◽  
Matrix Converters ◽  
Induction Generators ◽  
Doubly Fed

Nowadays, the doubly-fed induction generators (DFIGs) based wind turbines (WTs) are the dominant type of WTs. Traditionally, the back-to-back converters are used to excite the rotor circuit of DFIG. In this paper, an indirect matrix converter (IMC) is proposed to control the generator. Compared with back-to-back converters, IMCs have numerous advantages such as higher level of robustness, reliability, and reduced size and weight due to the absence of bulky electrolytic capacitor. According to the recent grid codes wind turbines must have low voltage ride-through (LVRT) capability. In this paper a new crowbar system is proposed so that along with the control system it protects the IMC from large fault currents and supports the grid voltage dips during grid faults. This crowbar system is provided using the existing converter switches to establish a short circuit mode without any extra circuitry. Even in severe fault conditions, the duration of short circuit mode is quite small so the control system will be activated shortly after the fault to inject reactive power as required by new LVRT standards. Therefore, the new LVRT standards are well satisfied without any extra costs. PSIM simulation results confirm the efficiency of the proposed method.

scholarly journals PENERAPAN DOUBLY-FED INDUCTION GENERATOR (DFIG) UNTUK PEMBANGKIT LISTRIK TENAGA ANGIN

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Radita Arindya
Keyword(s):  
Power Generation ◽  
Wind Energy ◽  
Wind Turbines ◽  
Reactive Power ◽  
Low Voltage ◽  
Short Circuit ◽  
Induction Generator ◽  
Doubly Fed Induction Generator ◽  
Variable Speed ◽  
Doubly Fed

Wind energy has become one of the most important and promising sources of renewable energy, which demands additional transmission capacity and better means of maintaining system reliability. The evolution of technology related to wind systems industry leaded to the development of a generation of variable speed wind turbines that present many advantages compared to the fixed speed wind turbines. These wind energy conversion systems are connected to the grid through Voltage Source Converters (VSC) to make variable speed operation possible. The studied system here is a variable speed wind generation system based on Doubly Fed Induction Generator (DFIG). The rotor side converter (RSC) usually provides active and reactive power control of the machine while the grid-side converter (GSC) keeps the voltage of the DC-link constant. The additional freedom of reactive power generation by the GSC is usually not used due to the fact that it is more preferable to do so using the RSC. However, within the available current capacity the GSC can be controlled to participate in reactive power generation in steady state as well as during low voltage periods. The GSC can supply the required reactive current very quickly while the RSC passes the current through the machine resulting in a delay. Both converters can be temporarily overloaded, so the DFIG is able to provide a considerable contribution to grid voltage support during short circuit periods. This report deals with the introduction of DFIG, AC/DC/AC converter control and finally the SIMULINK/MATLAB simulation for isolated Induction generator as well as for grid connected Doubly Fed Induction Generator and corresponding results and waveforms are displayed.

Optimization and performance of an optically asymmetrical heliostat field

1999 ◽  
Vol 09 (PR3) ◽  
pp. Pr3-71-Pr3-76 ◽  
Author(s):  
M. Romero ◽  
V. Fernández ◽  
M. Sánchez
Keyword(s):  
And Performance ◽  
Optimization And Performance
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