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In order to solve a series of problems caused by photovoltaic (PV) off-grid, PV must have the low voltage ride through (LVRT) capability ensuring grid-connected operation and outputting reactive power to power grid within a certain time range. At present, the control strategies of PV grid-connected inverter under balance fault have been used effectively. However, the strategy of keeping the inverter...
Grid connection of distributed generation would have a certain impact on safe and stable operation of receiving-end network, so systematic analysis on it would be significant. The method for comprehensive assessment on effects caused by grid connection of distributed generation on power grid is presented. The assessment system is divided into steady-state operation assessment, reliability assessment,...
This paper proposes a full-order terminal sliding-mode based energy saving control for the grid-connected converter of induction motor systems. DC-link voltage and currents controllers of the converter are designed respectively using the full-order terminal sliding manifold and the related control strategies. The chattering in the sliding-mode control is attenuated, and continuous control signals...
A novel single-phase five-level active rectifier based on the VIENNA-type rectifier with model predictive current control is presented. The proposed topology operates in unidirectional mode, imposing a sinusoidal grid-side current with unitary power factor. A unidirectional electric vehicle battery charger is the target application in which the proposed rectifier is used; however, it can also be used...
For a unified power flow controller (UPFC) operated in constant power-flow control mode, a novel control scheme of bus voltage regulation is presented. The voltage magnitudes of the ac buses are monitored in real-time operation and are controlled within their limits by the adjustment of the reactive power setting of the series converter. Firstly, the sensitivity of the voltage magnitudes of ac buses...
With the rapid development of bulk power grid under extra-high voltage (EHV) AC/DC hybrid power system and extensive access of distributed energy resources (DER), operation characteristics of power grid have become increasingly complicated. To cope with new severe challenges faced by safe operation of interconnected bulk power grids, an in-depth analysis of bulk power grid security defense system...
The aim of this paper is the design and implementation of the control algorithm of a PWM boost rectifier capable to handle bidirectional energy flow. For this goal, the boost rectifier control loops must be tuned for the proper operation of absorbing active power from the power grid and transfer it to the dc load at constant output voltage, and also to give the rectifier the ability to generate back...
This paper presents a single-phase shunt active power filter (SAPF) with bidirectional dc-dc converter for uninterruptible power supply (UPS) operation. The proposed system comprises two power converters, namely a dc-ac converter to interface the power grid and a bidirectional isolated dc-dc converter connected to a battery pack, with both converters sharing the same dc-link. The arrangement of the...
High power ultra-fast charging station for public transport systems becomes integral part of an urban power grid. In some cases the station has to be supplied by existing power grid 3×400VAC. This paper describes charging station based on a cost-effective topology with an output power over 300kW intended for charging electrical busses. Main part is focused on control algorithm proposal. Performance...
This paper presents a comprehensive study about a Simplified Rail Power Conditioner (SRPC) based on a half-bridge indirect AC/DC/AC Modular Multilevel Converter (MMC) and a V/V traction power transformer. The proposed system with a half-bridge MMC can decrease the costs, reduce the control complexity, and require less hardware devices in comparison with the rail power conditioner based on a full-bridge...
A novel control strategy for solving unbalanced three-phase load in low voltage power grid is proposed in this paper. The compensating current determined by a new method based on instantaneous voltage vector orientation, which overcomes the shortcomings of phase-locked loops (PLL) in the traditional detection methods. A static var generator (SVG) is employed to compensate the unbalanced current obtained...
The situation of automatic generation control(AGC) in ultra-high voltage(UHV) receiving-end grid has changed greatly, and it is necessary to develop on-line monitoring and remote diagnosis technology to solve new AGC control problems. Through the construction of generation-grid integrated data platform of Shandong power system, online running data of sixteen typical thermal power units are accessed...
Voltage dip has become the most user complaint problems about power quality, in order to ease voltage dip to guide the operation, planning and transformation of power grid. In this paper, based on the voltage dip caused by four kinds of busbar fault, the voltage dip matrix of each type fault is established, the grid structure evaluation indexes based on voltage dip is proposed. Based on the column...
Distributed Generation (DG) has gained relevance In Medium Voltage (MV) / Low Voltage (LV) power grids worldwide. One of the main drawbacks related to high penetration of DG plants is represented by abrupt voltage raises. Such an issue typically occurs in the presence of either low demand conditions or high power production from renewable sources. This work is focused on the online management of distributed...
This paper presents results of a heuristic optimization method for parameterization of decentral reactive power control, which can be used to improve static voltage quality in distribution grids. With an optimized Q(V)-curve it is possible to significantly reduce the additional reactive energy and accomplish lower losses in the grid while keeping the voltage within the specified limits. In this paper...
Rising energy costs, growing public concern about environmental impacts of fossil fuel energy generating resources and energy constraints of utilities across the globe have increased the relevance and need for alternative renewable energy resources at the customers point of use. In South Africa, there is a strong interest from electricity suppliers and customers in rooftop photovoltaic systems connection...
In the power grid lacking conventional power sources for black start, adopting wind farm as a power source for black start is a beneficial attempt. With Jangsu local power grid as research object in China, and combining with the special geographical and demand of the local power grid, a black start scheme using permanent-magnet synchronous generator(PMSG)-based wind farm as black start power is proposed...
Currently, major technical challenges linked to the implementation strategy of Distributed Generation (DG) are associated with new studies and researches regarding the impact of renewable energy sources on the parameters of power transmission and distribution networks. To increase the energy efficiency and to reduce the power losses in power distribution networks, specific measures are proposed: increasing...
The aim of this paper is the implementation of the control algorithm of an active DC traction substation using the dSpace DS1103 DSP control board. The adopted current control method is the indirect current control, which assumes that the current regulator controls the power grid current instead of the active filter output current. The active character of the traction substation is given, on one hand,...
The objective of this paper is to provide a method for steady-state short-circuit analysis in power networks with distributed energy resources (DERs). For this purpose, we suggest an approach that takes into account the impact of current controlled DERs in the fault analysis. The current controlled DER has some characteristics that we should consider–1) DER's large filter inductance and 2) the limit...
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