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Power Distribution Fundamentals
Published in Dale R. Patrick, Stephen W. Fardo, Brian W. Fardo, Electrical Power Systems Technology, 2021
Dale R. Patrick, Stephen W. Fardo, Brian W. Fardo
An alternative to transmitting AC voltages for long distances is HVDC power transmission. HVDC is suitable for long-distance overhead power lines or for underground power lines. DC power lines are capable of delivering more power per conductor than equivalent AC power lines. Because of its fewer power losses, HVDC is even more desirable for underground distribution. The primary disadvantage of HVDC is the cost of the necessary AC-to-DC conversion equipment. There are, however, some HVDC systems in operation. At present, HVDC systems have been designed for transmitting voltages in the range of 600 kV. The key to the future development of HVDC systems may be the production of solid state power conversion systems with higher voltage and current rating. With a continued developmental effort, HVDC should eventually play a more significant role in future electrical power transmission systems.
Power Distribution Fundamentals
Published in Stephen W. Fardo, Dale R. Patrick, Electrical Power Systems Technology, 2020
Stephen W. Fardo, Dale R. Patrick
An alternative to transmitting AC voltages for long distances is high-voltage direct current (HVDC) power transmission. HVDC is suitable for long-distance overhead power lines, or for underground power lines. DC power lines are capable of delivering more power per conductor than equivalent AC power lines. Because of its fewer power losses, HVDC is even more desirable for underground distribution. The primary disadvantage of HVDC is the cost of the necessary AC-to-DC conversion equipment. There are, however, some HVDC systems in operation in the United States. At present, HVDC systems have been designed for transmitting voltages in the range of 600 kV. The key to the future development of HVDC systems may be the production of solid state power conversion systems with higher voltage and current rating. With a continued developmental effort, HVDC should eventually playa more significant role in future electrical power transmission systems.
FACTS and HVDC
Published in Stuart Borlase, Smart Grids, 2018
Neil Kirby, Johan Enslin, Stuart Borlase, Neil Kirby, Paul Marken, Jiuping Pan, Dietmar Retzmann
FACTS and HVDC applications will play an important role in the future development of smart power systems. This will result in efficient, low-loss AC/DC hybrid grids, which will ensure better controllability of the power flow and, in doing so, do their part in preventing “domino effects” in case of disturbances and blackouts. By means of these DC and AC, ultrahigh-power transmission technologies, the “smart grid,” consisting of a number of highly flexible “microgrids,” will turn into a “super grid” with bulk power energy highways, fully suitable for a secure and sustainable access to huge renewable energy resources such as hydro, solar, and wind. The state-of-the-art AC and DC technologies and solutions for smart and super grids are explained in the following sections.
Fault Detection Using Backward Propagating Traveling Waves for Bipolar LCC-HVDC Lines
Published in Electric Power Components and Systems, 2022
Ravi Shankar Tiwari, Om Hari Gupta, Vijay K. Sood
Figure 1 shows a bipolar LCC-HVDC transmission system—a modified version of the monopole HVDC transmission system of [28]. The HVDC system is rated at 500 kV, 1000 MW per pole consisting of 12-pulse converter on both inverter and rectifier ends. The considered LCC-HVDC system is connected between the two asynchronously operated AC grids via DC overhead line of 900 km length. The parameters of the HVDC system, transmission line parameters, and tower structure are included in the Appendix. The modeling of the DC transmission line is based on a distributed parameter constant-frequency model; this model provides acceptable accuracy for the high-frequency TW components. The error in fault length calculation is more crucial for VSC-HVDC due to the use of cables and smaller line lengths compared to the overhead line in LCC-HVDC. Thus frequency-dependent transmission line model is necessary for the VSC-HVDC to reduce the error in calculating the fault length while for LCC-HVDC either can be used. The frequency-dependent transmission line models use curve fitting to duplicate the frequency response of a line and offer accurate results. However, the method requires further developments [8].
A PSO Optimal Power Flow (OPF) Method for Autonomous Power Systems Interconnected with HVDC Technology
Published in Electric Power Components and Systems, 2021
John E. Syllignakis, Fotios D. Kanellos
Keeping the power losses low for the electrical power transmission over long distances is a big challenge in modern power systems. In some cases, the strong rising share of renewable sources increased the distances between power generation and consumption. Submarine power transmission lines are being used more and more for interconnections between autonomous systems. Large scale off-shore wind production is an example, where often power has to be transmitted in cables over long distances to the mainland power grid [1]. High-voltage direct current (HVDC) power transmission is a commonly used technology for long distance power transmission. Its higher investment cost compared to AC transmission system is compensated by lower power losses and increased stability margins for long distances [2]. The break-even transmission line length where the total construction and operation costs of overhead HVDC and AC lines become equal is typically 500–800 km [3]. However, the break-even point is typically less than 50 km for cables [4]. The increased use of HVDC transmission shows that future HVDC transmission systems are expected to comprise multiple terminals of several HVDC transmission lines [5]. Such systems are referred as multi-terminal HVDC (MTDC) systems in the literature. One of the major technical obstacles in the deployment of system of this type, is the development of DC breakers [6]. In this direction, there are a few advanced ideas to realize this device in near future [7, 8].
Active and reactive power control of hybrid offshore AC and DC grids
Published in Automatika, 2019
An efficient, economical, and reliable offshore wind power plant transmission system has utmost importance for the development of the future “SuperGrid” [1]. The selection between high voltage alternating current (HVAC) or HVDC transmission for the offshore wind power plant connection predominantly depends on its distance from the shore and the installed capacity [2]. For the long distances, HVDC transmission system has preference over HVAC cables since the latter has higher losses and requires additional reactive power compensation. The offshore wind power plants located within the distance of 60 km from the shore are individually connected with the HVAC cables [3]. Longer connection also possible using HVAC cables by having multiple intermediate AC compensating stations [4,5]. The offshore wind power plant integration with the offshore AC hub is economically suitable if it has distance less than 20 km. This benefit reduces as the distance increase, and it provides no economical advantage beyond 40 km [6]. The received power at the offshore AC hub can be transferred to shore via VSC–HVDC transmission system either using point-to-point or multi-terminal (MT) configuration [7].