scholarly journals Modelling and fault ride-through control of grid supporting inverter-based microgrid

2021 ◽  
Author(s):  
◽  
Elutunji Buraimoh ◽  
Keyword(s):  
Reactive Power ◽  
Voltage Source ◽  
Voltage Sag ◽  
Primary Control ◽  
Secondary Control ◽  
Supporting System ◽  
Fault Ride Through ◽  
Power Injection ◽  
Control Schemes ◽  
Signal Cancellation

This thesis is focused on modeling and fault ride-through control, local load power delivery, and grid power exchange of power electronic interfaced Distributed Energy Resources (DERs) for grid supporting microgrids. Active and reactive power regulations are the requirements for a grid-supporting system operating as a current source, while frequency and voltage magnitude regulation in the grid-supporting system acting as a voltage source. Consequently, these are put into consideration as the primary control requirements for the inverter-based microgrid. To that end, two discrete-time models of a grid-feeding system and grid-forming system were developed to serve as controls for a single DER operating in grid-connected mode and islanded mode, respectively. Consequently, for the first set of mathematical models: grid feeding and grid forming were interfaced with a droop control to allow for parallel operation of additional DERs for power coordination within the microgrid for grid-connected and islanded operation. However, virtual impedance was incorporated into the grid-supporting system's droop control operating as a voltage source to emulate the link feeder's physical impedance to the main grid. Based on the developed grid supporting models, the microgrid primary control schemes effectively delivered power to the host grid and simultaneously contributed to the grid's frequency and voltage regulation. Furthermore, to ensure grid code compliance and ensure the microgrid provides ancillary services to the host grid, such as fault ride-through and reactive power compensation for voltage recovery, a novel technique is proposed in the microgrid's secondary control. The secondary control realizes the fault ride-through for the grid supporting system using a delay signal cancellation algorithm for negative sequence detection. The proposed control scheme actualizes grid code requirements by providing a secondary voltage control, which is active and more prominent in the transient period of faults without mode switching. The strategy's performance is further enhanced with an IGBT-Diodes switched AC reactor to improve the voltage and prevent the transient overcurrent in the microgrid during the grid fault. This ensures a continued supply of the microgrid's local sensitive load while meeting the grid code requirement. Similarly, the active power injection into the main grid is limited to maximize reactive power injection into the main network to support the grid voltage sag. The detection algorithm using the delayed signal cancellation algorithm is implemented to detect the instance of fault in 1.6% of the half-cycle under grid disturbance/fault to activate the proposed secondary control. This effectiveness and fault ride-through compliance of the developed control models were tested on an inverter-based microgrid system with an ideal voltage source DERs. Finally, to accommodate for the grid dynamics introduced to the DC link parameters of an ideal voltage source DER such as PV, the models were also implemented and assimilated for a solar PV sourced DER used with a grid supporting inverter-based microgrid. The injection of active power into the main grid is constrained by systematically shifting the MPPT operating point based on voltage sag depth to maximize reactive power injection to support the grid voltage sag. The strategy developed in the PV sourced system also ensured that the DC-link voltage and AC grid current raises are suppressed while meeting microgrid load requirements. The models' implementation, DER primary control, and proposed secondary control schemes are established through detailed time-domain simulation studies using MATLAB Simscape Electrical™ and Control System

scholarly journals Fault Ride-Through Enhancement of Grid Supporting Inverter-Based Microgrid Using Delayed Signal Cancellation Algorithm Secondary Control

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3994 ◽  
Author(s):  
Elutunji Buraimoh ◽  
Innocent E. Davidson ◽  
Fernando Martinez-Rodrigo
Keyword(s):  
Reactive Power ◽  
Renewable Energy Sources ◽  
System Stability ◽  
Positive Sequence ◽  
Voltage Source ◽  
Stable Operation ◽  
Droop Control ◽  
Secondary Control ◽  
Fault Ride Through ◽  
Signal Cancellation

The growing level of grid-connected renewable energy sources in the form of microgrids has made it highly imperative for grid-connected microgrids to contribute to the overall system stability. Consequently, secondary services which include the fault ride-through (FRT) capability are expected to be possessed characteristics by inverter-based microgrids. This enhances the stable operation of the main grid and sustained microgrid grid interconnection during grid faults in conformity with the emerging national grid codes. This paper proposes an effective FRT secondary control strategy to coordinate power injection during balanced and unbalanced fault conditions. This complements the primary control to form a two-layer hierarchical control structure in the microgrids. The primary level is comprised of voltage/power and current inner loops fed by a droop control. The droop control coordinates grid power-sharing amongst the voltage source inverters. When a fault occurs, the participating inverters operate to support the grid voltage, by injecting supplementary reactive power based on their droop gains. Similarly, under unbalanced voltage condition due to asymmetrical faults in the grid, the proposed secondary control ensures the positive sequence component compensation and negative and zero sequence components clearance using a delayed signal cancellation (DSC) algorithm and power electronic switched series impedance placed in-between the point of common coupling (PCC) and the main grid. While ensuring that FRT ancillary service is rendered to the main utility, the strategy proposed ensures relatively interrupted quality power is supplied to the microgrid load. Consequently, this strategy ensures the microgrid ride-through the voltage sag and supports the grid utility voltage during the period of the main utility grid fault. Results of the study are presented and discussed.

scholarly journals Fault Ride through Capability Augmentation of a DFIG-Based Wind Integrated VSC-HVDC System with Non-Superconducting Fault Current Limiter

2019 ◽  
Vol 11 (5) ◽  
pp. 1232 ◽  
Author(s):  
Md Alam ◽  
Mohammad Abido ◽  
Alaa Hussein ◽  
Ibrahim El-Amin
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Current Control ◽  
Control Mode ◽  
Voltage Source ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Hvdc System ◽  
Fault Ride Through ◽  
Current Limiter

This paper proposes a non-superconducting bridge-type fault current limiter (BFCL) as a potential solution to the fault problems of doubly fed induction generator (DFIG) integrated voltage source converter high-voltage DC (VSC-HVDC) transmission systems. As the VSC-HVDC and DFIG systems are vulnerable to AC/DC faults, a BFCL controller is developed to insert sizeable impedance during the inception of system disturbances. In the proposed control scheme, constant capacitor voltage is maintained by the stator VSC (SVSC) controller, while current extraction or injection is achieved by rotor VSC (RVSC) controller. Current control mode-based active and reactive power controllers for an HVDC system are developed. Balanced and different unbalanced faults are applied in the system to show the effectiveness of the proposed BFCL solution. A DFIG wind-based VSC-HVDC system, BFCL, and their controllers are implemented in a real time digital simulator (RTDS). The performance of the proposed BFCL control strategy in DFIG-based VSC-HVDC system is compared with a series dynamic braking resistor (SDBR). Comparative RTDS implementation results show that the proposed BFCL control strategy is very efficient in improving system fault ride through (FRT) capability and outperforms SDBR in all cases considered.

Study on Direct Current Controlled Distribution Static Synchronous Compensator with Mechanical Properties Used for Improvement of Voltage Quality

2013 ◽  
Vol 387 ◽  
pp. 254-257
Author(s):  
Qun Feng Zhu ◽  
Lei Huang ◽  
Deng Xiang Yang ◽  
Guang Yao Zhu
Keyword(s):  
Direct Current ◽  
Reactive Power ◽  
Current Control ◽  
Control Mode ◽  
Voltage Source ◽  
Voltage Sag ◽  
Static Synchronous Compensator ◽  
Synchronous Reference Frame ◽  
Voltage Quality ◽  
Voltage Control Mode

A type of direct current controlled static reactive power compensator (DSTATCOM) used for improvement of voltage quality in low-medium distribution network is introduced. The main circuit of DSTATCOM consists of VSI-SPWM voltage source inverter. The extraction of reference current and the tracking control of compensator current are realized in synchronous reference frame. The function of DSTATCOM to mitigate voltage sag and flicker is presented in this paper and the control mode of DSTATCOM is discussed in detail. The function of DSTATCOM to mitigate voltage sag and flicker under different control mode is simulated with MATLAB. The simulation results shows that the current control mode is suitable for mitigating voltage flicker and the voltage control mode is suitable for mitigating voltage sag.

scholarly journals D-STATCON model for voltage sag mitigation

2019 ◽  
Vol 10 (4) ◽  
pp. 2214
Author(s):  
Hendri Masdi ◽  
Rini Nur Hasanah ◽  
Hadi Suyono ◽  
Ismail Bin Musirin ◽  
Taufik Taufik
Keyword(s):  
Reactive Power ◽  
Asynchronous Motor ◽  
High Capacity ◽  
Distribution Networks ◽  
Fast Response ◽  
Voltage Source ◽  
Voltage Sag ◽  
Synchronous Condenser ◽  
Study Results ◽  
And Performance

<span>Development of a FACTS device model for mitigating voltage sag is presented. It deals with a static synchronous condenser (STATCON) to be used in the AC distribution networks. Simulation with the help of a commercial software Matlab/Simulink was explored to investigate its characteristics and performance during the voltage sag occurrence. The considered main cause of voltage sag was the starting of high capacity asynchronous motor. A voltage source inverter based on the phase-controlled thyristor components was implemented in this application to compensate the change in reactive power of the system. The concerns have been put on the influence of initial operation point and DC capacitance. The study results show the capability of D-STATCON model to reduce the consequence of voltage sag following the starting of high-power asynchronous motor in the distribution network. A fast response of the condenser work confirmed the desired performance.</span>

scholarly journals Compensation of voltage Sag using STATCOM

2018 ◽  
Vol 7 (2.8) ◽  
pp. 673
Author(s):  
Savitha Venkatesan ◽  
Booma Nagarajan
Keyword(s):  
Transmission Line ◽  
Reactive Power ◽  
Sudden Change ◽  
Transmission System ◽  
Voltage Source ◽  
Voltage Sag ◽  
Voltage Source Converter ◽  
Linear Load ◽  
Non Linear ◽  
Non Linear Load

Due to unpredicted non-linear loads, power quality problems, a raise in the transmission system. One such problem is voltage sag. Voltage sag is caused by the non-linear load which demands reactive power, but the balanced 3F source provides required reactive power of the load with reduced voltage at the receiving end. In this paper, simulation study has been performed to reducethe voltage sag issue. A transmission system with generation source with different loading conditions is considered and study has been done. A 3F medium P model transmission line is designed with a power source of 11kV.  A shunt connected compensation unit called Static Synchronous Compensator (STATCOM) reduces the voltage sag in the transmission line. STATCOM provides the required reactive power demanded by the non-linear load along with the source for compensation of voltage sag. The STATCOM circuit comprises of Voltage source converter(VSC) unit and a DC source. Reactive power compensation is done by VSC unit firing angle control. The source of the STATCOM can also be from renewable energy system. This AC source is converted by a AC-DC-AC converter unit.The firing angle is controlled by the control unit which ensures the continuous and balanced power flow even under sudden change in load conditions. The simulation results depict the characteristics of the developed STATCOM.

Simulated Onshore-Fault Ride through of Offshore Wind Farms Connected through VSC HVDC

2008 ◽  
Vol 32 (2) ◽  
pp. 103-113 ◽  
Author(s):  
A. Arulampalam ◽  
G. Ramtharan ◽  
N. Caliao ◽  
J.B. Ekanayake ◽  
N. Jenkins
Keyword(s):  
Wind Farm ◽  
Reactive Power ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Offshore Wind Farm ◽  
Offshore Wind Farms ◽  
Grid Connection ◽  
Fault Ride Through

Effective Onshore-Fault Ride Through was demonstrated by simulation for a Fixed Speed Induction Generator (FSIG) offshore wind farm connected through a Voltage Source Converter HVDC link. When a terrestrial grid fault occurs, power through the onshore converter reduces and the DC link voltage increases. A control system was then used to block the offshore converter. The offshore AC network voltage was reduced to achieve rapid power rejection. Reactive power at the onshore converter was controlled to support the AC network voltage according to the GB Grid Code requirements. Two cases, a 200 ms terrestrial fault and a 50% retained voltage fault of duration 710 ms, at the grid connection point were studied. The simulation results show that power blocking at the offshore converter was effective and the DC link voltage was controlled.

scholarly journals A Bidirectional Electrical Vehicle Charger and Grid Interface for Grid Voltage Dip Mitigation

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3784
Author(s):  
Osama Saadeh ◽  
Anwar Al Nawasrah ◽  
Zakariya Dalala
Keyword(s):  
Power Quality ◽  
Reactive Power ◽  
Voltage Sag ◽  
Load Variations ◽  
Load Demand ◽  
Voltage Dip ◽  
Fault Ride Through ◽  
Voltage Quality ◽  
Electrical Vehicle ◽  
Grid Connected Converters

Power quality issues have recently become a source of major concern due to the large increase in load demand and the addition of various sources of disturbance at the distribution level. Power quality mainly refers to voltage quality. Sudden load variations can lead to a fall in the line voltage magnitude, creating what is called a voltage sag. Many solutions have been proposed and implemented for voltage sag compensation. Power electronics-based solutions such as grid-connected converters and AC/DC schemes are considered basic units for transient voltage fault ride-through capability. This paper describes a multifunctional intelligent bidirectional electrical vehicle (EV) charger that is able to charge the EV battery at different power ratings in addition to voltage sag compensation. The performance of the proposed system is verified and validated through MATLAB/Simulink simulations (R2020A). The proposed solution can effectively meet three main requirements: charging the EV battery at different power ratings, detecting the voltage sag event, and providing the required active and reactive power compensation for voltage sag compensation.

Direct Current-Controlled Distribution Static Synchronous Compensator for Voltage Quality Improvement

2013 ◽  
Vol 648 ◽  
pp. 361-364
Author(s):  
Lei Huang ◽  
Deng Xiang Yang ◽  
Jie Tang ◽  
Qun Feng Zhu
Keyword(s):  
Quality Improvement ◽  
Direct Current ◽  
Reactive Power ◽  
Voltage Control ◽  
Current Control ◽  
Control Mode ◽  
Voltage Source ◽  
Voltage Sag ◽  
Voltage Quality ◽  
Voltage Control Mode

This paper presents a direct current-controlled static reactive power compensator (DSTATCOM) for voltage quality improvement of low-medium distribution network. The main circuit of the DSTATCOM uses VSI-SPWM structure-based voltage source inverter (VSI), and both operation of reference current and control of compensation current are realized in synchronous reference frames. The function of DSTATCOM to mitigate voltage sag and flicker, two common voltage quality problems, is discussed in detail in this paper. According to the forming way of reactive reference current, operation mode of DSTACOM are classified into current control mode and voltage control mode. And under the two operation modes the function of DSTATCOM to mitigate voltage sag and flicker under different control modes is simulated with MATLAB. The simulation results show that the current control mode is suitable for mitigating voltage flicker, while the voltage control mode for voltage sag.

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