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In the era of smart grid, the demand for power system security is further urgent. Two-terminal electromagnetic loop networks (two-terminal EMLNs) are pervasive in power networks. Their potential hazard threatens the safety of both power network and users. Due to the influence of the power flow on the high voltage side of the EMLN, the power flow on the low voltage side tends to operate at a critical...
In this paper, a load flow initialisation method is proposed to calculate the steady-state initial conditions required for small signal stability analysis of a converter-dominated microgrid. The proposed load flow simulation eliminates the need to run a flat start time-domain analysis in order to arrive at the initial values and therefore allows for the rapid small signal analysis of different network...
Energy router is an emerging conceptual device based on advanced power electronic technique. It is able to realize the flexible and dynamic electric power distribution in power systems as information router in the Internet. It is of great interest to investigate how the energy router can be used to improve the power system operation. This paper proposes a generalized configuration of the energy router...
This paper discusses the impact of several operating conditions and design considerations on power balancing in a MTDC system. A five terminal MTDC system is analyzed for instantaneous power balancing and variations in DC bus voltages by considering one of the terminals in constant power mode while others in DC voltage droop control mode. The study explores how the deviations in power/voltage are...
The concept of Voltage Source Converter based MultiTerminal High Voltage Direct Current (VSC-MTDC) grids, represents both challenges and opportunities for the future of large power transfer and integration of renewable energy sources. For this kind of grids, the control aspect is of great importance, with voltage-droop based methods considered as one of the most attractive solutions. All existing...
DC System Operator (DCSO) is a radical concept. This single entity is designed to coordinate, to control and monitor the operation of the DC transmission system. DCSO is accountable for safeguarding the reliability and security of the DC meshed grid in real-time and co-ordinate the supply of and demand for electricity, in a manner that avoids violations of technical and economic standards. This paper...
Steady state voltage problems in power systems are those associated with undervoltages resulting from increasing loads. Steady overvoltages can also arise when loads served by networks are reduced, and the problem can be exacerbated if lines supplying load centres are long. This paper reports on a study that was conducted to assess the impact of derating voltage of lines, by using step down transformers...
The voltage droop control concept is the most appropriate strategy to provide primary control in multiterminal VSC-HVDC (MTDC) transmission systems. However, due to voltage drops in the dc lines/cables, the primary power balancing is influenced by the dc grid topology and line resistances. This phenomenon is also evident when determining the secondary control strategy in MTDC systems. In this paper,...
Steady state analysis of power grids is typically performed using power flow analysis, where nonlinear balance equations of real and reactive power are solved to calculate the voltage magnitude, phase, and power at every bus. Transient analysis of the same power grids are performed using circuit simulation methods. We propose a novel approach to modeling the nonlinear steady state behavior of power...
Grid-connected photovoltaic (PV) systems with relatively high capacity effectively reduce peak load, but because of their reverse power flow, they can cause overvoltage along a feeder that can exceed five percent of the rated voltage. Modern PV systems with the capability of Volt/Var control can mitigate overvoltage by either injecting or absorbing reactive power. Thus, the objectives of this study...
The main objective of this paper is to study the influence of dispersed generation upon the steady state of distribution networks, especially upon the voltage level, active power losses and branch currents flow. Power flow calculation of electrical distribution networks with and without distributed generation was realized in MATLAB environment, based on backward-forward sweep. The tests were performed...
In this paper, the operation of Voltage Source Converter (VSC) based multi-terminal DC (MTDC) transmission system is evaluated under loss of converter station. From the control point of view, i) Master/Slave control method, and ii) droop control method are explored to control the multi-terminal DC grid. This paper compares different control methods for MTDC control under normal and loss of any terminal...
This paper deals with the droop control of load sharing among multiple sources in DC microgrid. The DC Electrical Power Distribution System (EPDS) with parallel sources are under study in this paper. The voltage-fed and the current-fed paradigms are investigated including the cases when the cable impedances cannot be neglected. Global voltage feedback and local voltage feedback are discussed in terms...
Low power factor and high harmonic content are the major drawbacks of conventional front-end rectifiers. Front-end converter is reported in this paper for three-phase system. A systematic design approach is presented for front-end converter and the modelling of the same is also described in detail in presented work. The control strategy for three phase front-end converter consists of inner current-loop...
This paper will present the modeling and the design of multi-parallel-connected SSSC (MSSSC) with daisy-chained transformers. The advantages of the proposed MSSSC structure include its modularity, scalability, controllability, and flexibility in power transfer, autonomous behavior, and well current-sharing performance. The principle of operation, the steady-state and transient current-sharing characteristics...
A time sequence load-flow method for steady-state analysis in large scale heavy meshed distribution system with Distributed Generations (DG) is proposed in this paper. Since DG is the intermittent type source, and distribution system has time delay based protection device, traditional single snapshot load-flow methods has limitations in the case with DG. Proposed time sequence load-flow method is...
A unified power flow controller (UPFC) is an advanced member of the group of flexible AC transmission systems (FACTS). In this paper, the performance of UPFC is investigated to minimize the power loss in the transmission line using load flow analysis. Loss allocation is an important aspect in determining the cost of power transmission. This paper focuses on the steady-state modeling of UPFC for the...
Photovoltaic Distributed Generation (PV) is experiencing a growing proliferation prompted by a mixture of favorable legislation, incentives, technology developments and cost reduction. PV installed capacities can vary from a few kW (small-scale) to several MW (large-scale). Due to its intermittent nature, increasing penetration of large-scale PV may lead to potential impacts on planning and operations...
This paper introduces the mathematics models of power flow and continuation power flow including the actions of CSVC(coordinated secondary voltage control). In order to meet the demand of on-line calculation of steady state voltage stability margin quickly in large scale power grid, several schemes of improving the robustness and velocity in continuation power flow computation including the actions...
The power leveling (PL) unit is required to maintain a balance of power flow for photovoltaic (PV) system. It is important for it to respond quickly against fluctuation of power generation. A new control scheme based on discrete time system for the PL unit in the distributed generator (DG) is proposed to improve the response. In the proposed method, the deadbeat control is performed using state equations...
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