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In order to improve the power quality of wind power generation system, a direct power control (DPC) strategy of open-winding brushless doubly-fed generator (BDFG) system based on dual converters is presented in this paper. The control method is divided into two parts: the grid side converter control and the machine side converter control. In terms of the grid side converter, a model predictive-based...
This paper deals with a voltage disturbance generator output characteristics. Usually a microgrid is connected to utility grid through STS to disconnect in case of fault occurrence. The STS should be opened in case of outage, however, it may be connected in case of voltage sag occurrence. The magnitude of surge or over current through the STS is determined by the dip of the sag. The voltage disturbance...
This paper presents a new method for operating microgrid. Basic control methodology is to de-couple PQ control for grid-forming distributed generator (DG) whose new extra role is to act as reactive power sensor besides generating real power into the microgrid. Reactive power from the grid-forming DG is transferred to and from the instantaneous var compensator when there is a switch-in or switch-off...
This paper concentrates on the control of power flow in single stage photovoltaic energy conversion system. The conversion structure has a twofold requirement that consists in ensuring that the current injected to both load and grid obeys to the grid connection standards and sets the DC bus voltage similar to the reference voltage given by the MPPT algorithm. The advanced functions that can be added...
From the viewpoint of the emerging concept of smart grid, distribution network will require fast power flow solution that must be resolved as efficiently as possible. Presence of distributed generators and power electronic based compensating devices, in modern medium and low voltage distribution networks, additionaly expands requirements for performances of algorithms for power flow calculations which...
Modular multilevel topologies are possible candidates for medium-voltage wind turbines because of their scalability and possible redundancy. This paper concentrates on their design and investigates the influence of generator-to-grid voltage ratio, generator nominal frequency, module-capacitance minimising control approaches, third harmonic injection and fault ride-through capability requirement on...
Wind energy conversion systems (WECSs) have become increasingly popular in the recent years for clean power generation. For all forms of electricity generation, it is important that these sources are reliable and resilient with the ability to sustain abnormal contingency conditions such as electrical faults. Effective electrical protection systems play an important role in enhancing this resilience...
The installed power capacity of grid-connected wind energy conversion systems (WECSs) has increased exponentially around the world. The size of each unit is also increasing as they are becoming more affordable. The grid is a highly non-linear system due to wide spread use of power electronically switched loads and devices. Hence, the grid disturbances affect the output of the WECSs. This paper presents...
The application of STATCOM or STATCON is common in transmission systems—the device has a capability of P-Q control in 4 quadrants. DSTATCOM (for distribution systems) and DVR (Dynamic Voltage Regulator) are somewhat synonymous. The paper describes a unique distribution system with three in-plant generators and an interconnection to weak utility system at 44 kV; the three-phase short-circuit level...
With huge penetration of distributed generators (DGs), distribution systems become more and more active and flexible. To accommodate DGs in a much more optimal way, cooperation between transmission networks and distribution networks, even distribution networks and distribution networks, should be further strengthened. A cooperative sequential reconfiguration method is proposed in this paper, which...
The main objective of this work is to investigate an indirect current control scheme based on slide mode approach to regulate the currents of a three-phase Active Power Filter (APF) in such a way to improve the quality of the power supplied by a diesel generator set. The indirect current control scheme provides the signal reference to active power filter controller without the need of measurement...
This study proposes a sliding-mode direct power control (SMDPC) strategy for a grid-connected bidirectional power converters feeding a doubly-fed induction generator (DFIG) with slip power recovery. The control design, based on the second-order sliding modes (SOSM) is adopted to control both converters rotor side converter (RSC) and the grid side converter (GSC). Simulations performed under Matlab/Simulink...
This paper introduces a simple and fast heuristic approach for solving the distribution feeder reconfiguration problem with an objective of loss reduction and voltage profile improvement. In this paper, a single power flow solution is executed to specify all bus voltages and branch currents. The branch currents are utilized as switching indices to determine the open and closed status of sectionalized...
This paper outlines the optimization problem of unit commitment (UC) and economic dispatch (ED) in microgrids (MG). An improved real coded genetic algorithm (GA) has been developed to schedule the active and reactive powers of integrated controllable generators, battery storage systems (BSS) and shiftable loads in the system. In the proposed GA method, both network restrictions (voltages and loadings)...
A new scheme for incorporating generator Q limit adjustments automatically in Newton Raphson (NR) load flow method is proposed. The current practice for handling this feature is to adopt bus type switching method after the solution (without these limits) converges to a reasonable extent. However, the precise details of this scheme are not well documented and they vary across implementations. A modified...
Multiphase generators starts to compete three-phase counterparts. An obvious application for multiphase generators is electrical power generation from wind turbines. Moreover, they can find a slot in conventional generation stations market due to its advantages. The output power from these generators should be processed using power converters but power quality of the line side converter is a requirement...
The paper presents a Mixed Integer Linear Programming (MILP) model for the solution of the three-phase volt/var optimization (WO) of medium voltage unbalanced distribution feeders. The WO of a distribution feeder is aimed at calculating the most efficient operating conditions by means of the scheduling of transformers equipped with an on-load tap changer and distributed reactive power resources (such...
This paper focuses on reducing generators dispatch cost by means of transmission line switching. The problem is formulated as a mixed-integer nonlinear program (MINLP) optimal power flow (OPF). A scalable heuristic algorithm is proposed to break-down the complexity of the problem due to the huge combinatorial space. The algorithm aims at providing the sequence of lines to be removed from service,...
This paper proposes a low-voltage ride-through (LVRT) protection scheme without fault current limiter (FCL) on the grid-side inverter (GSI), based on energy balance characteristics of permanent magnet synchronous generator (PMSG) wind power systems during the grid voltage drop. The scheme utilizes a series dynamic braking resistor (SDBR) to consume the excess active power from the PMSG transmitting...
This paper presents a method of reactive power optimization based on partitioning of the power system daily load curve. The underlining problem that is being solved is the optimization of elements with defined maximum allowable daily operating times (MADOT). The daily load curve of the power system was partitioned into 24 stationary states which were used as a solution space for determining when to...
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