scholarly journals Flow Allocation in Meshed AC-DC Electricity Grids

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1233 ◽  
Author(s):  
Fabian Hofmann ◽  
Markus Schlott ◽  
Alexander Kies ◽  
Horst Stöcker
Keyword(s):  
Power Systems ◽  
Power Flow ◽  
Low Carbon ◽  
Computationally Efficient ◽  
Shift Parameter ◽  
Transmission Grid ◽  
High Voltage Direct Current ◽  
Total Transmission ◽  
Transmission Expansion ◽  
Electricity Grids

In power systems, flow allocation (FA) methods enable to allocate the usage and costs of the transmission grid to each single market participant. Based on predefined assumptions, the power flow is split into isolated generator-specific or producer-specific sub-flows. Two prominent FA methods, Marginal Participation (MP) and Equivalent Bilateral Exchanges (EBEs), build upon the linearized power flow and thus on the Power Transfer Distribution Factors (PTDFs). Despite their intuitive and computationally efficient concepts, they are restricted to networks with passive transmission elements only. As soon as a significant number of controllable transmission elements, such as high-voltage direct current (HVDC) lines, operate in the system, they lose their applicability. This work reformulates the two methods in terms of Virtual Injection Patterns (VIPs), which allows one to efficiently introduce a shift parameter q to tune contributions of net sources and net sinks in the network. In this work, major properties and differences in the methods are pointed out, and it is shown how the MP and EBE algorithms can be applied to generic meshed AC-DC electricity grids: by introducing a pseudo-impedance ω ¯ , which reflects the operational state of controllable elements and allows one to extend the PTDF matrix under the assumption of knowing the current flow in the system. Basic properties from graph theory are used to solve for the pseudo-impedance in dependence of the position within the network. This directly enables, e.g., HVDC lines to be considered in the MP and EBE algorithms. The extended methods are applied to a low-carbon European network model (PyPSA-EUR) with a spatial resolution of 181 nodes and an 18% transmission expansion compared to today’s total transmission capacity volume. The allocations of MP and EBE show that countries with high wind potentials profit most from the transmission grid expansion. Based on the average usage of transmission system expansion, a method of distributing operational and capital expenditures is proposed. In addition, it is shown how injections from renewable resources strongly drive country-to-country allocations and thus cross-border electricity flows.

scholarly journals Flow Allocation in Meshed AC-DC Electricity Grids

2020 ◽  
Author(s):  
Fabian Hofmann ◽  
Markus Schlott ◽  
Alexander Kies ◽  
Horst Stöcker
Keyword(s):  
Power Systems ◽  
Power Flow ◽  
Low Carbon ◽  
Computationally Efficient ◽  
Shift Parameter ◽  
Transmission Grid ◽  
High Voltage Direct Current ◽  
Transmission Expansion ◽  
Electricity Grids ◽  
Power Transfer Distribution Factors

In power systems, flow allocation (FA) methods allow to allocate usage and costs of the transmission grid to each single market participant. Based on predefined assumptions, the power flow is split into isolated generator specific or producer specific sub-flows. Two prominent FA methods, Marginal Participation (MP) and Equivalent Bilateral Exchanges (EBE), build upon the linearized power flow and thus on the Power Transfer Distribution Factors (PTDF). Despite their intuitive and computationally efficient concept, they are restricted to networks with \emph{passive} transmission elements only. As soon as a significant number of \emph{controllable} transmission elements, such as High-voltage direct current (HVDC) lines, operate in the system, they loose their applicability. This work reformulates the two methods in terms of Virtual Injection Patters (VIP) which allows to efficiently introduce a shift parameter $q$, tuning contributions of net sources and net sinks in the network. Major properties and differences of the methods are pointed out. Finally, it is shown how the MA and EBE algorithm can be applied to generic meshed AC-DC electricity grids: Introducing a \emph{pseudo-impedance} which reflects the operational state of controllable elements, allows to extend the PTDF matrix under the assumption of knowing the current system's flow. Basic properties from graph theory are used for solving the pseudo-impedance dependent on the position in the network. This directly enables \emph{e.g.} HVDC lines to be considered in the MP and EBE algorithm. The extended methods are applied to a low-carbon European network model (PyPSA-EUR) with a spatial resolution of N=181 and an 18\% transmission expansion. The allocations of VIP and MP, show that countries with high wind potentials profit most from the transmission grid expansion. Based on the average usage of transmission system expansion a method of distributing operational and capital expenditures is proposed. Further it is shown, how injections from renewable resources strongly drive country-to-country allocations and thus cross-border electricity flows.

scholarly journals Optimal Sizing and Spatial Allocation of Storage Units in a High-Resolution Power System Model

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3365 ◽  
Author(s):  
Lukas Wienholt ◽  
Ulf Müller ◽  
Julian Bartels
Keyword(s):  
Renewable Energy ◽  
Power Systems ◽  
Power System ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Power Transmission ◽  
Renewable Generation ◽  
Large Power ◽  
Transmission Grid ◽  
Storage Units

The paradigm shift of large power systems to renewable and decentralized generation raises the question of future transmission and flexibility requirements. In this work, the German power system is brought to focus through a power transmission grid model in a high spatial resolution considering the high voltage (110 kV) level. The fundamental questions of location, type, and size of future storage units are addressed through a linear optimal power flow using today’s power grid capacities and a generation portfolio allowing a 66% generation share of renewable energy. The results of the optimization indicate that for reaching a renewable energy generation share of 53% with this set-up, a few central storage units with a relatively low overall additional storage capacity of around 1.6 GW are required. By adding a constraint of achieving a renewable generation share of at least 66%, storage capacities increase to almost eight times the original capacity. A comparison with the German grid development plan, which provided the basis for the power generation data, showed that despite the non-consideration of transmission grid extension, moderate additional storage capacities lead to a feasible power system. However, the achievement of a comparable renewable generation share provokes a significant investment in additional storage capacities.

scholarly journals A Multi-Criteria Decision Framework for Optimal Augmentation of Transmission Grid - Addressing a Tool for Sensitive Zone Detection in Electricity Market

2008 ◽  
Vol 9 (4) ◽  
Author(s):  
Mohammad R. Hesamzadeh ◽  
Nasser Hosseinzadeh ◽  
Peter J Wolfs
Keyword(s):  
Sensitivity Analysis ◽  
Power Systems ◽  
Electricity Market ◽  
Large Scale ◽  
Test System ◽  
Transmission System ◽  
System Structure ◽  
Transmission Grid ◽  
Expansion Planning ◽  
Transmission Expansion

Transmission system structure has an essential effect on the reliability of the power system and electricity market performance, especially when producers bid strategically. As part of on-going research on the design of a robust algorithm for expansion planning of the transmission grid in the Australian electricity market, this paper presents a framework which addresses: (1) the security of power delivery to the load points of the transmission system in case of single line outages; (2) the minimization of transmission system lost load; (3) an efficient electricity market for market participants; (4) construction and maintenance costs of transmission augmentation options; and (5) operation efficiency of the transmission grid.The suggested algorithm benefits from the dynamic programming and sensitivity analysis approaches along with the aggregation method in its multi-criteria decision-making to locate the optimum configuration of a future transmission system. A set of indices, which account for impacts of the augmentation options of the transmission grid on five aforementioned reliability and market criteria, are proposed and used in the optimum framework for expansion planning of the transmission grid.Although the methodology is promising for expansion planning of the transmission system, considering the sensitivity analysis concept employed, the proposed methodology would be suitable to detect the sensitive areas of the transmission system to be expanded. The tool would be very useful in the case of large scale power systems for a smart reduction of the transmission expansion options.The proposed methodology has been applied to a 6-bus and a modified IEEE 30-bus test system to show the effectiveness of the sensitivity-based algorithm.

A Review of Incentive Based Demand Response Methods in Smart Electricity Grids

2015 ◽  
Vol 3 (4) ◽  
pp. 62-73 ◽  
Author(s):  
Vasiliki Chrysikou ◽  
Miltiadis Alamaniotis ◽  
Lefteri H. Tsoukalas
Keyword(s):  
Power Systems ◽  
Demand Response ◽  
Smart Grids ◽  
Power Flow ◽  
Current Approach ◽  
Electricity Distribution ◽  
Distribution Grid ◽  
Incentive Design ◽  
Electricity Grid ◽  
Electricity Grids

Smart electricity grid is a complex system being the outcome of the marriage of power systems with computing technologies and information networks. The information transmitted in the network is utilized for controlling the power flow in the electricity distribution grid. Thus smart grid facilitates a demand response approach, where grid participants monitor and respond to information signals with their electricity demand. This review paper focuses on a subclass of demand response methods and more particularly in incentive based demand response. It aims at providing a review of the existing and proposed methods while briefly explaining their main points and outcomes. In the current approach, the plethora of methods on incentive based demand response is grouped according to the tools adopted to implement the incentives. The overall goal is to provide a comprehensive list of incentive design tools and be a point of inspiration for researchers in the field of incentive based demand response in smart grids.

scholarly journals Design of A Hvdc-Based Controller for Load Change Compensation and Stabilization of Inter-Area Oscillations

2017 ◽  
Vol 20 (3&4) ◽  
pp. 187-202
Author(s):  
I. Ngamroo
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Flow ◽  
Design Method ◽  
Oscillation Mode ◽  
Power Flow Control ◽  
Interconnected Power System ◽  
High Voltage Direct Current ◽  
Load Change ◽  
Tie Line

As an interconnected power system via a High-Voltage Direct Current (HVDC) link is subjected to a rapid load change with the frequency of inter-area oscillation mode, system frequency and tie line power may be severely disturbed and oscillate.  To compensate for the rapid load change and stabilize both frequency and tie line power oscillations due to the inter-area mode, the dynamic power flow control via a HVDC link can be exploited.  To implement this concept, a new design method of HVDC-based controller is proposed.  To grasp a physical characteristic of the inter-area oscillation frequency, the technique of overlapping decompositions is employed to achieve the subsystem embedded with the inter-area mode.  Consequently, the second-order lead/lag controller of HVDC link can be designed in this subsystem.  To acquire the desired overshoot of frequency oscillations, the parameters of the controller are automatically optimized by the Tabu Search (TS) algorithm.  The effectiveness of the designed controller is investigated in a three-area longitudinal interconnected power system which represents the interconnection between the south of Thailand and Malaysia power systems.

scholarly journals Assessment of highly distributed power systems using an integrated simulation approach

2008 ◽  
Vol 222 (7) ◽  
pp. 657-668 ◽  
Author(s):  
G M Burt ◽  
I M Elders ◽  
S J Galloway ◽  
N J Kelly ◽  
R M Tumilty
Keyword(s):  
Power Systems ◽  
Distribution System ◽  
Power Flow ◽  
Flow Simulation ◽  
Load Flow ◽  
Low Carbon ◽  
Distributed Power ◽  
Integrated Simulation ◽  
Security Issues ◽  
Low Carbon Technologies

In a highly distributed power system (HDPS), micro renewable and low carbon technologies would make a significant contribution to the electricity supply. Further, controllable devices such as micro combined heat and power (CHP) could be used to assist in maintaining stability in addition to simply providing heat and power to dwellings. To analyse the behaviour of such a system requires the modelling of both the electrical distribution system and the coupled microgeneration devices in a realistic context. In this paper a pragmatic approach to HDPS modelling is presented: microgeneration devices are simulated using a building simulation tool to generate time-varying power output profiles, which are then replicated and processed statistically so that they can be used as boundary conditions for a load flow simulation; this is used to explore security issues such as under and over voltage, branch thermal overloading, and reverse power flow. Simulations of a section of real network are presented, featuring different penetrations of micro-renewables and micro-CHP within the ranges that are believed to be realistically possible by 2050. This analysis indicates that well-designed suburban networks are likely to be able to accommodate such levels of domestic-scale generation without problems emerging such as overloads or degradation to the quality of supply.

scholarly journals Dynamic grid fault analysis in wind power plant with DFIG by using supervisory control and data acquisition (SCADA) viewer

2020 ◽  
Vol 181 ◽  
pp. 03006
Author(s):  
Nduwamungu Aphrodis ◽  
Ntagwirumugara Etienne ◽  
Utetiwabo Wellars ◽  
Mulolani Francis
Keyword(s):  
Power Systems ◽  
Power Flow ◽  
Control Strategies ◽  
Electrical Power ◽  
Fault Analysis ◽  
Operational Mode ◽  
Electrical Power Systems ◽  
Fault Ride Through ◽  
Before And After ◽  
Clearing Time

Faults in electrical power systems are among the key factors and sources to network disturbances, however control strategies are among key faults clearing techniques for the sake of safe operational mode of the system.Some researchers have shown various limitations of control strategies such as slow dynamic response,inability to switch Off and On network remotely and fault clearing time. For a system with wind energy technologies, if the power flow of a wind turbine is interrupted by a fault, the intermediate-circuit voltage between the machine-side converter and line-side converter will fall in unacceptably high values.To overcome the aforementioned issues, this paper used a Matlab simulations and experiments in order to analyze and validate the results.The results showed that fault ride through (FRT) with SCADA Viewer software are more adaptable to the variations of voltage and wind speed in order to avoid loss of synchronism. Therefore at the speed of 12.5m/s a wind produced a rated power of 750W and remained in synchronization before and after a fault created and cleared but worked as generator meanwhile at speed of 3.4m/s wind disconnected from grid and started working as a motor and consumed active power (P=-25watts) and voltage dip at 100% .For the protection purpose, the DC chopper and crowbar should be integrated towards management of excess energy during faults cases.

scholarly journals A Full-Newton AC-DC Power Flow Methodology for HVDC Multi-Terminal Systems and Generic DC Network Representation

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1658
Author(s):  
Leandro Almeida Vasconcelos ◽  
João Alberto Passos Filho ◽  
André Luis Marques Marcato ◽  
Giovani Santiago Junqueira
Keyword(s):  
Power Systems ◽  
Direct Current ◽  
Power Flow ◽  
Large Scale ◽  
Flow Problem ◽  
Control Strategies ◽  
Problem Formulation ◽  
Expansion Planning ◽  
Dc Power ◽  
Power Flow Problem

The use of Direct Current (DC) transmission links in power systems is increasing continuously. Thus, it is important to develop new techniques to model the inclusion of these devices in network analysis, in order to allow studies of the operation and expansion planning of large-scale electric power systems. In this context, the main objective of this paper is to present a new methodology for a simultaneous AC-DC power flow for a multi-terminal High Voltage Direct Current (HVDC) system with a generic representation of the DC network. The proposed methodology is based on a full Newton formulation for solving the AC-DC power flow problem. Equations representing the converters and steady-state control strategies are included in a power flow problem formulation, resulting in an expanded Jacobian matrix of the Newton method. Some results are presented based on HVDC test systems to confirm the effectiveness of the proposed approach.

scholarly journals Special Issue: “Wind Power Integration into Power Systems: Stability and Control Aspects”

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3680
Author(s):  
Lasantha Meegahapola ◽  
Siqi Bu
Keyword(s):  
Power Systems ◽  
Wind Power ◽  
Renewable Energy Sources ◽  
Power Grids ◽  
Energy Sources ◽  
Low Carbon ◽  
Carbon Neutrality ◽  
Stability And Control ◽  
Wind Power Integration ◽  
And Control

Power network operators are rapidly incorporating wind power generation into their power grids to meet the widely accepted carbon neutrality targets and facilitate the transition from conventional fossil-fuel energy sources to the clean and low-carbon renewable energy sources [...]

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