VSC-HVDC Transmission Research Articles

Comparison Performance Analysis of PI and PI-ANFIS in VSC-HVDC Transmission Systems

Comparison Performance Analysis of PI and PI-ANFIS in VSC-HVDC Transmission Systems

An adaptive control strategy for integration of wind farm using a VSC-HVDC transmission system

This study addresses the issue of integrating renewable energy sources into the power grid by proposing advanced power management strategies based on an adaptive observer. The system comprises a wind turbine farm (WTF) connected to an energy storage system via a Vienna rectifier, which serves as the voltage source converter (VSC), and is linked to the DC grid through a high-voltage direct current (HVDC) transmission line. The main objective of this study is to design a nonlinear controller to improve energy extraction from the wind power frame and enhance the stability of the power grid. The system controller is designed to operate in two modes. The main feature of this controller is its ability to achieve multi-objective control using different references. In this study, we have four references but only two control laws. Furthermore, an adaptive observer is designed to estimate the power grid requirements, allowing us to produce depending on the grid state. Finally, simulation results using MATLAB/Simulink will be displayed to demonstrate the stability and efficiency of the proposed implementation.

VSC-HVDC transmission line fault location based on transient characteristics

VSC-HVDC transmission line fault location based on transient characteristics

Impact of short-duration voltage variations on VSC-HVDC performance

The growing load demand globally necessitates increasing the penetration of renewable energy sources into electrical grids as well as interconnecting grids from different countries and even continents through HVDC transmission systems. Since these applications rely on power electronics devices, several power quality issues arise, namely voltage sags and swells. This paper analyzes the response of a VSC-HVDC transmission system that interconnects two asynchronous AC grids to short-duration voltage variations like sag and swell by adjusting the voltage of the controllable AC source. The system is simulated with the help of MATLAB/Simulink. The study records the effect of the manipulated AC voltage on the active/reactive powers and AC/DC voltages at both converter stations to evaluate the system stability due to these prevalent power quality challenges. The obtained results reveal that the system hardly withstands voltage variation for a short period.

Modeling and Reliability Constraint Analysis of MMC Valve

The VSC-converter valve is the core equipment of the VSC-HVDC transmission system, and its reliability directly affects the availability of the VSC-HVDC system. The reliability model of the existing VSC-converter valve mainly considers the relationship between different redundancy and the reliability of the VSC-converter valve. This paper first analyzes the impact of the failure of key components of the VSC-converter valve. According to the different effects, the arm reliability model of the VSC-converter valve is established, and finally, the comprehensive reliability model of the VSC-converter valve is established. Then, based on the model of the VSC-converter valve, the reliability constraints of the VSC-converter valve that meet the engineering requirements are finally derived. An example is given to verify the correctness of the classification reliability evaluation. Finally, according to the reliability model proposed in this paper, the design recommendations for a highly reliable VSC converter valve are given.

Bilateral Inertia and Damping Emulation Control Scheme of VSC-HVDC Transmission Systems for Asynchronous Grid Interconnections

Bilateral Inertia and Damping Emulation Control Scheme of VSC-HVDC Transmission Systems for Asynchronous Grid Interconnections

A novel MODWT-based fault detection and classification scheme in VSC-HVDC transmission line

A novel MODWT-based fault detection and classification scheme in VSC-HVDC transmission line

A Novel Ensemble Fault Diagnosis Model for Main Circulation Pumps of Converter Valves in VSC-HVDC Transmission Systems.

The intelligent fault diagnosis of main circulation pumps is crucial for ensuring their safe and stable operation. However, limited research has been conducted on this topic, and applying existing fault diagnosis methods designed for other equipment may not yield optimal results when directly used for main circulation pump fault diagnosis. To address this issue, we propose a novel ensemble fault diagnosis model for the main circulation pumps of converter valves in voltage source converter-based high voltage direct current transmission (VSG-HVDC) systems. The proposed model employs a set of base learners already able to achieve satisfying fault diagnosis performance and a weighting model based on deep reinforcement learning that synthesizes the outputs of these base learners and assigns different weights to obtain the final fault diagnosis results. The experimental results demonstrate that the proposed model outperforms alternative approaches, achieving an accuracy of 95.00% and an F1 score of 90.48%. Compared to the widely used long and short-term memory artificial neural network (LSTM), the proposed model exhibits improvements of 4.06% in accuracy and 7.85% in F1 score. Furthermore, it surpasses the latest existing ensemble model based on the improved sparrow algorithm, with enhancements of 1.56% in accuracy and 2.91% in F1 score. This work presents a data-driven tool with high accuracy for the fault diagnosis of main circulation pumps, which plays a critical role in maintaining the operational stability of VSG-HVDC systems and satisfying the unmanned requirements of offshore flexible platform cooling systems.

Pole-to-pole fault characteristics in VSC-HVDC transmission system with a resistance-inductance type superconducting fault current limiter

Pole-to-pole fault characteristics in VSC-HVDC transmission system with a resistance-inductance type superconducting fault current limiter

An adaptive neural fuzzy virtual inertia control method for VSC-HVDC system

Compared to conventional DC transmission, Voltage source converter based high voltage direct current transmission (VSC-HVDC) has the advantages of independently controllable transmission power, no commutation failure, no reactive power compensation and low harmonic levels. However, VSC-HVDC transmission cannot provide effective frequency support and regulation for the system after grid connection. For this reason, an adaptive neural fuzzy virtual inertia control method is proposed to impose a control strategy on the converter at the receiving end of a VSC-HVDC transmission. The method uses the frequency change rate and the amount of change of frequency as constraints to dynamically adjust the virtual inertia and damping coefficients. It provides larger inertial support when the frequency fluctuation is large and smaller inertial support when the frequency fluctuation is small, thus adapting to different operating conditions. Finally, a hardware-in-the-loop simulation platform is built. The superiority and application prospect of the proposed strategy in frequency stability of the system are verified by comparing the proposed strategy with the traditional virtual control strategy.

Performance Improvement for the VSC-HVDC Transmission System under Cascaded A.C. and D.C. Faults

Performance Improvement for the VSC-HVDC Transmission System under Cascaded A.C. and D.C. Faults

Inertial imitation method of MMC with hybrid topology for VSC-HVDC.

A new virtual synchronous generator (VSG) control strategy was researched and proposed for a VSC-HVDC (High Voltage Direct Current Based on Voltage Source Converter) transmission system. It can be applied to half-bridge or full-half-bridge hybrid topology modular multi-level converter (MMC) to improve the stability and reliability of the system. First, it is proposed that the energy stored in the equivalent capacitor of MMC power module was used to imitate the rotor inertial of synchronous generator. It can buffer transient power fluctuations and synchronize autonomously with the grid. Then the impedance characteristics of the proposed control method have been deduced and analyzed. The results show that the VSG control loop mainly improves the low frequency characteristics of the converter. Secondly, the ability to suppress transient fault current is weak. So, a method, that the given values of inner current loop are calculated by grid impedance matrix, was used. A double closed loop control structure composed by a power outer loop based on VSG control and a current inner loop is obtained. The simulation results show that it can effectively improve the current control capability during the transient process for systems with a 1:2 ratio of converter capacity to grid capacity (The grid short-circuit capacity is 60MW and the MMC is 30 MW). Finally, a hybrid MMC simulation model was built based on PSCAD and the steady-state and transient fault ride-through simulations were performed. The power adjustment time of MMC under the proposed VSG control is about 1s, while the adjustment time under the conventional control strategy is greater than 4s.

Simulation and Analysis of a VSC-HVDC Transmission System Based on DC Line-Line Fault

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

A novel time-domain method for fault detection and classification in VSC-HVDC transmission lines

The short circuit fault current is one of the worst contingencies in voltage source converter (VSC)-based high voltage direct current (HVDC) system. Therefore, having a fast, robust, and selective protection scheme is necessary in HVDC systems. In this paper, a non-communication-based protection scheme is presented using Intrinsic Time Decomposition (ITD) technique in a HVDC system. This time domain approach owns some prominent features such as high speed, low sampling rate and computational burden and no need for parameter's setting. The proposed protection scheme relies on the current signal sampled from the single end. The concept is to obtain the proper rotation component (PRC) of input signal and computing an energy index named Teager Kaiser Energy Operator (TKEO) to identify the fault occurrence in a HVDC line. The performance of the proposed scheme has been assessed against various scenarios including external disturbance such as ac faults and abrupt change of active power in two standard sample systems in MATLAB/SIMULINK and PSCAD/EMTDC environments. In addition, a wide range of internal dc faults are studied to evaluate the sensitivity of the scheme. The appropriate performance of the scheme is verified and the fault detection and classification tasks are done in less than 1 ms.

Review on Voltage Control of Multi Terminal Vsc-Hvdc Transmission System for Offshore Wind Power Plant

Review on Voltage Control of Multi Terminal Vsc-Hvdc Transmission System for Offshore Wind Power Plant

Observer and Nonlinear Control Design of Vsc-Hvdc Transmission System

Observer and Nonlinear Control Design of Vsc-Hvdc Transmission System

Single Ended Protection of Four Terminal Vsc-Hvdc Transmission Line Based on Phase Characteristics of Fault Transient Line Mode Voltage

Single Ended Protection of Four Terminal Vsc-Hvdc Transmission Line Based on Phase Characteristics of Fault Transient Line Mode Voltage

Significance of fault-current-limiters and parameters optimization in HVDC circuit breakers for increased capacity of VSC-HVDC transmission networks application

The voltage and current ratings of the voltage source converter (VSC) based high voltage direct current (HVDC) transmission line projects have increased over the years. It testifies the increasing popularity of VSC-HVDC technology. Since the long-distance, VSC-HVDC transmission lines are more exposed to commonly appearing short circuit faults; thus, protection equipment with increased fault-current handling capability is required. The DC circuit breakers (DCCBs), with or without fault current limiters (FCLs), can effectively handle the fault-current. The variations in VSC-HVDC projects’ ratings and their impact for DCCB with FCL and without FCL are thoroughly analysed in this paper. The paper further includes an in-depth discussion on DCCBs with FCL and without FCL. An equivalent circuit modelling approach is used for simulation analysis of three case studies under the influence of these breakers to analyse current behaviour; the case studies include the Zhoushan HVDC Project, Xiamen HVDC Project, and Zhangbei-I HVDC Project. All these projects have different capacities in terms of their power, voltage, and current ratings. For DCCBs, this paper includes a detailed analytical model to understand the fluctuations in the size of fault-current limiting components (in DCCBs) for increased fault-current handling requirements. The simulation results using PSCAD/EMTDC and MATLAB are presented to verify different aspects of this study. A small scale laboratory prototype is also developed to validate the performance of DCCB with and without FCL. Based on theoretical, simulation, and experimental validations, it is substantiated that for increased VSC-HVDC projects’ ratings, DCCB with FCL can perform better compared to conventional DCCB without FCL.

Losses in the Saturated Iron-Core Superconducting Fault Current Limiter For VSC-HVDC System

This paper presents the loss analysis on the saturated iron-core superconducting fault current limiter (SISFCL) for a VSC-HVDC transmission system. The numerical model of SISFCL as well as its loss calculation on superconducting parts were carried out by the finite-element method (FEM) using the H-formulation merged into the commercial package COMSOL. The SISFCL model was established for a practical ±10 kV VSC-HVDC system, and the fault current situation was simulated using the PSCAD with a SISFCL. The capability of fault current limiting was verified using the analysis of electromagnetic characteristics, and the corresponding patterns of magnetic field in the iron-core were studied. During the process of fault current limiting, the instantaneous power losses in the superconducting components were studied with the increasing DC bias current. Even in a DC grid system, results proved there were considerable amounts of losses occurred in the superconducting parts, when the SISFCL encountered the fault currents.

HVAC Transmission System for Offshore Wind Power Plants Including Mid-Cable Reactive Power Compensation: Optimal Design and Comparison to VSC-HVDC Transmission

The design distance of offshore wind power plants connected through HVAC transmission systems might be extended due to the introduction of mid-cable reactors for reactive power compensation purposes and the latest developments of AC cables for higher voltages. Therefore, the applicability limits between HVAC and HVDC systems must be revised. This paper analyzes the contribution that mid-cable reactive power compensation has on increasing the distance limits of HVAC transmission systems. A methodology is developed to determine an optimal design of such transmission systems. In this methodology, cost of power losses and reactors are minimized for multiple wind speed conditions. As a result, the optimal HVAC voltage level and the optimal number of reactors and their location are determined for different OWPP rated powers and distances. Also, the final transmission system is selected between HVAC and HVDC equivalent configurations based on total costs.