Modeling and Simulation of Modular Multilevel Converter Based-HVDC Connecting to Offshore Wind Farms

2014 ◽  
Vol 905 ◽  
pp. 421-426 ◽  
Author(s):  
Seung Hyun Kim ◽  
Woo Cheol Jeong ◽  
Eel Hwan Kim
Keyword(s):  
Wind Farm ◽  
Reactive Power ◽  
Control Method ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Offshore Wind Farms ◽  
Hvdc System

Modular multilevel Converter (MMC) is a new type of voltage source converter (VSC) topology. The use of this converter in a high-voltage direct current (HVDC) system is called by a MMC-HVDC system. The MMC-HVDC has the advantage in terms of scalability, performance, and efficiency over two-and three-level VSC-HVDC. In this paper, the MMC-HVDC system is used to connect between main grid in Jeju Island and virtual offshore wind farms. The aim is to transfer the power from offshore wind farm to the main grid and to compensate reactive power for the main grid. The simulation is carried out by using PSCAD/EMTDC program, and the results will confirm the effectiveness of the proposed control method.

Technology of Offshore Wind Turbines and Farms and Novel Multilevel Converter-Based HVDC Systems for Their Grid Connections

2002 ◽  
Vol 26 (6) ◽  
pp. 383-395 ◽  
Author(s):  
Vassilios G. Agelidis ◽  
Christos Mademlis
Keyword(s):  
Wind Turbines ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Offshore Wind Farms ◽  
Offshore Wind Turbines ◽  
Hvdc System

The technology associated with offshore wind farms is discussed in detail. First, the various offshore wind turbines are reviewed and the factors influencing their characteristics are outlined in comparison with their onshore counterparts. This overview serves as a basis for the discussion that follows regarding the possible electrical connection within the farm, and between the farm and the grid. Voltage-source converter-based HV DC connection is compared with HVAC connection. Finally, a novel multilevel converter-based HVDC system, based on flying capacitor multilevel converters is proposed, as a possible interface between the farm and the grid.

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 Novel Adaptive Control Approach Based on Available Headroom of the VSC-HVDC for Enhancement of the AC Voltage Stability

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3222
Author(s):  
Duc Nguyen Huu
Keyword(s):  
Adaptive Control ◽  
Voltage Stability ◽  
Reactive Power ◽  
Control Method ◽  
Offshore Wind ◽  
Voltage Source ◽  
Long Distance ◽  
Control Approach ◽  
Hvdc System ◽  
Voltage Support

Increasing offshore wind farms are rapidly installed and planned. However, this will pose a bottle neck challenge for long-distance transmission as well as inherent variation of their generating power outputs to the existing AC grid. VSC-HVDC links could be an effective and flexible method for this issue. With the growing use of voltage source converter high-voltage direct current (VSC-HVDC) technology, the hybrid VSC-HVDC and AC system will be a next-generation transmission network. This paper analyzes the contribution of the multi VSC-HVDC system on the AC voltage stability of the hybrid system. A key contribution of this research is proposing a novel adaptive control approach of the VSC-HVDC as a so-called dynamic reactive power booster to enhance the voltage stability of the AC system. The core idea is that the novel control system is automatically providing a reactive current based on dynamic frequency of the AC system to maximal AC voltage support. Based on the analysis, an adaptive control method applied to the multi VSC-HVDC system is proposed to realize maximum capacity of VSC for reactive power according to the change of the system frequency during severe faults of the AC grid. A representative hybrid AC-DC network based on Germany is developed. Detailed modeling of the hybrid AC-DC network and its proposed control is derived in PSCAD software. PSCAD simulation results and analysis verify the effective performance of this novel adaptive control of VSC-HVDC for voltage support. Thanks to this control scheme, the hybrid AC-DC network can avoid circumstances that lead to voltage instability.

scholarly journals Real Time Simulation of Wind Farm Connected MMC-HVDC System

2020 ◽  
Vol 8 (6S) ◽  
pp. 46-52
Keyword(s):  
Real Time ◽  
Wind Farm ◽  
Computing Time ◽  
Offshore Wind ◽  
Modular Multilevel Converter ◽  
Offshore Wind Farm ◽  
Multilevel Converter ◽  
Real Time Simulation ◽  
Hvdc System ◽  
Time Simulation

Real time simulators play a major role in R&D of Offshore wind farm connected modular multilevel converter (MMC)-HVDC system. These simulators are used for testing the actual prototype of controllers or protection equipment required for the system under study. Modular multilevel converter comprises of number of sub modules (SMs) like Half/ full bridge cells. While computing time domain Electromagnetic transients (EMTs) with the system having large number of SMs pose a great challenge. This computational burden will be more when simulated in real time. To overcome this, several authors proposed equivalent mathematical model of MMC. This paper proposes the real time simulation start-up of offshore wind farm connected modular multilevel converter (MMC)-HVDC system. This paper also describes about how the above said systems is simulated in OPAL-RT based Hypersim software.

scholarly journals A Multi-Terminal HVdc Grid Topology Proposal for Offshore Wind Farms

2020 ◽  
Vol 10 (5) ◽  
pp. 1833
Author(s):  
Ali Raza ◽  
Muhammad Younis ◽  
Yuchao Liu ◽  
Ali Altalbe ◽  
Kumars Rouzbehi ◽  
...  
Keyword(s):  
High Voltage ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Offshore Platforms ◽  
Offshore Wind Farms ◽  
Dc Fault ◽  
Grid Side

Although various topologies of multi-terminal high voltage direct current (MT-HVdc) transmission systems are available in the literature, most of them are prone to loss of flexibility, reliability, stability, and redundancy in the events of grid contingencies. In this research, two new wind farms and substation ring topology (2WF-SSRT) are designed and proposed to address the aforementioned shortcomings. The objective of this paper is to investigate MT-HVdc grid topologies for integrating large offshore wind farms with an emphasis on power loss in the event of a dc grid fault or mainland alternating current (ac)grid abnormality. Standards and control of voltage source converter (VSC) based MT-HVdc grids are defined and discussed. High voltage dc switch-gear and dc circuit topologies are appraised based on the necessity of dc cables, HVdc circuit breakers, and extra offshore platforms. In this paper, the proposed topology is analyzed and compared with the formers for number and ratings of offshore substations, dc breakers, ultra-fast mechanical actuators, dc circuits, cost, flexibility, utilization, and redundancy of HVdc links. Coordinated operation of various topologies is assessed and compared with respect to the designed control scheme via a developed EMTDC/PSCAD simulation platform considering three fault scenarios: dc fault on transmission link connecting the wind farm to mainland power converters, dc fault within substation ring of VSC-HVdc stations, and ultimate disconnection of grid side VSC station. Results show that 2WF-SSRT is a promising topology for future MT-HVdc grids.

scholarly journals Power Oscillation Damping from OffshoreWind Farms Connected to HVDC via Diode Rectifiers

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3387 ◽  
Author(s):  
Saborío-Romano ◽  
Bidadfar ◽  
Göksu ◽  
Zeni ◽  
Cutululis
Keyword(s):  
Reactive Power ◽  
Wind Farms ◽  
Open Loop ◽  
Active Power ◽  
Offshore Wind ◽  
Voltage Source ◽  
Offshore Wind Farms ◽  
Power Oscillation ◽  
Power Oscillation Damping ◽  
Oscillation Damping

Diode rectifiers (DRs) have elicited increasing interest from both industry and academiaas a feasible alternative for connecting offshore wind farms (OWFs) to HVDC networks. However,before such technology is deployed, more studies are needed to assess the actual capabilities ofDR-connected OWFs to contribute to the secure operation of the networks linked to them. This studyassessed the capability of such an OWF to provide support to an onshore AC network by means of(active) power oscillation damping (POD). A semi-aggregated OWF representation was considered inorder to examine the dynamics of each grid-forming wind turbine (WT) within a string whenproviding POD, while achieving reasonable simulation times. Simulation results corroboratethat such an OWF can provide POD by means of OWF active power controls similar to thosedeveloped for OWFs connected to HVDC via voltage source converters, while its grid-forming WTsshare the reactive power consumption/production and keep the offshore voltage frequency andmagnitude within their normal operating ranges. Open-loop test results show that such capabilitycan, however, be restricted at operating points corresponding to the lowest and highest values ofactive power output.

scholarly journals Investigating the Converter-Driven Stability of an Offshore HVDC System

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2341
Author(s):  
Matthias Quester ◽  
Fisnik Loku ◽  
Otmane El Azzati ◽  
Leonel Noris ◽  
Yongtao Yang ◽  
...  
Keyword(s):  
Wind Farm ◽  
Short Circuit ◽  
Impedance Measurement ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Response Analysis ◽  
Offshore Wind Farms ◽  
The North ◽  
Ac Transmission

Offshore wind farms are increasingly built in the North Sea and the number of HVDC systems transmitting the wind power to shore increases as well. To connect offshore wind farms to adjacent AC transmission systems, onshore and offshore modular multilevel converters transform the transmitted power from AC to DC and vice versa. Additionally, modern wind farms mainly use wind turbines connected to the offshore point of common coupling via voltage source converters. However, converters and their control systems can cause unwanted interactions, referred to as converter-driven stability problems. The resulting instabilities can be predicted by applying an impedance-based analysis in the frequency domain. Considering that the converter models and system data are often confidential and cannot be exchanged in real systems, this paper proposes an enhanced impedance measurement method suitable for black-box applications to investigate the interactions. A frequency response analysis identifies coupling currents depending on the control system. The currents are subsequently added to the impedance models to achieve higher accuracy. The proposed method is applied to assess an offshore HVDC system’s converter-driven stability, using impedance measurements of laboratory converters and a wind turbine converter controller replica. The results show that the onshore modular multilevel converter interacts with AC grids of moderate short-circuit ratios. However, no interactions are identified between the offshore converter and the connected wind farm.

scholarly journals Resource aware wind farm and D-STATCOM optimal sizing and placement in a distribution power system

2021 ◽  
Vol 11 (6) ◽  
pp. 4641
Author(s):  
Anzum Ansari ◽  
Shankarlingappa C. Byalihal
Keyword(s):  
Power System ◽  
Distribution System ◽  
Wind Farm ◽  
Reactive Power ◽  
Wind Farms ◽  
Offshore Wind ◽  
Optimal Placement ◽  
Offshore Wind Farms ◽  
Optimal Sizing ◽  
Multi Objective

<span lang="EN-US">Doubly fed induction generators (DFIG) based wind farms are capable of providing reactive power compensation. Compensation capability enhancement using reactors such as distributed static synchronous compensator (D-STATCOM) while connecting distribution generation (DG) systems to grid is imperative. This paper presents an optimal placement and sizing of offshore wind farms in a coastal distribution system that is emulated on an IEEE 33 bus system. A multi-objective formulation for optimal placement and sizing of the offshore wind farms with both the location and size constraints is developed. Teaching learning algorithm is used to optimize the multi-objective function constraining on the capacity and location of the offshore wind farms. The proposed formulation is a multi-objective problem for placement of the wind generator in the power system with dynamic wind supply to the power system. The random wind speed is generated as the input and the wind farm output generated to perform the optimal sizing and placement in the distributed system. MATLAB based simulation developed is found to be efficient and robust.</span>

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