The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In a multi-infeed (MI) HVDC system with inverter and rectifier infeeds, the interaction between the inverter and the rectifier influences the inverter's steady-state and transient characteristics. In this paper, the electromagnetic transient (EMT) model of such a multi-infeed system is used to investigate this influence. The simulation results show that a nearby rectifier will help the inverter by...
Series reactors are used in distribution grids to reduce the short-circuit fault level. Some of the disadvantages of the application of these devices are the voltage drop produced across the reactor and the steep front rise of the transient recovery voltage (TRV), which generally exceeds the rating of the associated circuit breaker. Simulations were performed to compare the characteristics of a saturated...
After the analysis of the characteristics of the direct driven wind turbine with permanent magnet synchronous generator (D-PMSG) and VSC-HVDC, the paper proposed a circuit topology based on the series multi-terminal VSC-HVDC for offshore wind farm integration. The topology simplifies the D-PMSG structure by eliminating the inverter side of full power converter for the D-PMSG, and cascades rectifiers...
The Manitoba Hydro major transmission system features a topology consisting of very high HVdc penetration level, tightly coupled rectifiers as well as tightly coupled inverters. The tight coupling at the rectifiers or the sending end results in multi-egress system characteristics, where as the tight coupling at the inverters or the receiving end results in its multi-infeed characteristics. This paper...
Early proposals for multi-terminal HVDC interconnections have been predominantly radial type connections, that is, between any two nodes there is only one branch. However, plans for ‘HVDC Grids’ in the not too distant future are, or include, meshed sections where there are parallel branches between nodes in the HVDC Grid. In such meshed HVDC Grid the DC current will inherently flow from one node to...
It will be important for the operation of future multi-terminal HVDC systems that each converter unit is capable of limiting the influence of nearby AC faults on the DC grid. Thus, the local control systems at each terminal should be able to prevent double frequency active power oscillations caused by unbalanced AC faults from propagating to the DC-side of the converter. A simple approach for achieving...
Real-time simulation of a three-terminal high-voltage direct-current (HVDC) grid connected to a doubly-fed induction generator (DFIG) based wind farm has been presented in this paper. A recently invented control strategy, known as power-synchronization control, is applied for the integration of the wind farm to the HVDC grid. The dynamic performance study of the system under normal wind power fluctuations...
The article introduces a hierarchical control structure for Multiterminal High Voltage Direct Current (M-HVDC) systems. The presented hierarchy is similar to the control structure of the classical AC systems divided in primary, secondary and tertiary control. The design and interaction between the secondary, or power control, and the primary controllers, or voltage control, are discussed. Furthermore,...
The paper investigates power transmission limitations in a VSC-HVDC system imposed by the ac system's impedance characteristics. An important observation from the study is that the operation of the converter is affected, not only by the magnitude of this impedance (quantified by the Short Circuit Ratio or SCR), but also significantly by its angle. An interesting result is that the larger the resistive...
The increased usage of the phase shifting transformers in various fields within power systems has introduced new challenges in performing on-site maintenance testing. These special transformers were used as converter transformers, rectifier transformers, harmonic mitigating transformers, zigzag transformers and quadrature boosters with unconventional vector groups, having an additional phase shift...
This paper illustrates how dedicated droop controls may take advantage of an offshore DC grid topology to implement different power flow policies, without any communication or master control. The issue of DC grid extension is also tackled with a special emphasis on wind spillage: a process to synthesize spatially correlated winds is described and used to assess the value for different extensions and...
New version of IEC 60143 “Series capacitors for power systems — Part 2: Protective equipment for series capacitor banks” [1] will be published shortly. It determines type tests for series capacitor bank spark gap. Test requirements are more specific and demanding than in previous version of the standard. Similar tests are carried out for Jacques-Cartier series capacitor bank spark gap system according...
The purpose of this paper is to present the design approach of a robust damping controller of thyristor-controlled series compensator (TCSC) for systems with multiple operating points. The design objective is to find a common output feedback controller for TCSC which could increase system damping of power system oscillations under different system operating points. The robust damping control problem...
Power systems operate in a more complicated condition than they used to. Changes in the wholesale electricity market alongside the difficulties in upgrading the transmission system have caused transmission systems to face more challenging network wide issues. Therefore, having a Wide Area Measurement System (WAMS) is vital with regard to ensuring secure and reliable operation. Traditionally, Supervisory...
The paper highlights the main drivers for the Western Link HVDC project from the Transmission Owners' point of view, the main project milestones, the challenges as well as the proposed technical solution. On the technical side the focus is on the key operating and design parameters of the HVDC system. The HVDC converters will apply classic line commutated converter technology requiring harmonic filtering...
The South West scheme is an important part of the development of the Swedish national grid and is a key facility to enable the production of renewable energy, in accordance with Swedish and EU energy policy. It will reinforce the AC network, increase operational reliability, and deal with transmission limitations in southern Sweden and between Sweden and Norway. The paper describes the first phase...
The earlier developed control method using a piecewise linear droop curve, with different droop values for the different segments, has now been optimised for dynamic performance. Non-linearities at the junctions of two linear droop sections have been adressed. Also non-linearity of power based DC voltage control has been adressed. Dynamic instability due to high control gains has been treated and...
The turbo-generator units in the vicinity of HVDC transmission system are vulnerable to Sub-Synchronous Torsional Interactions (SSTI). Based on the AC-DC system decoupling transfer function structure of Generator rotation rate to the electric torque, a novel phase correction method of HVDC supplementary subsynchronous multiple models damping controller is proposed, and a SSDC software for adjusting...
There has been much discussion over how HVDC grids incorporating many converters should be controlled and several methodologies have been proposed. An underlying principle of a proposed method, Voltage Droop control, was the minimisation of the inter-dependency of the control of the individual converters, inferring little, or no, reliance on a communication system. Since then further work has shown...
Energy and environmental issues are amongst the greatest challenges facing the world today and in the future. In response to energy needs and environmental concerns, renewable energy technologies are now considered the future technologies of choice. Renewable energy is produced from freely available and non-polluting natural sources; however, its utilization is not without challenge. There is much...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.