The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The active power filter (APF) has already established itself as a prominent means of addressing harmonic pollution and other power quality issues. Current control of an APF is a key in achieving a good compensation performance. Generally, PI control is used owing to its simplicity and ease of implementation. However, using a proportional resonant (PR) controller can give an added advantage in tracking...
The paper presents an overview about operation and control of the inverter-interface generation units (IGUs) when connected to a microgrid either alone or together with other generation units. The following key connection paradigms are considered: i) one IGU and a grid, ii) one IGU and one machine-interface generation unit, iii) a single IGU, and iv) two IGUs. After illustrating how the IGUs operate...
The virtual synchronous generator (VSG) is the interface between distribute generator and power grid, which has the inertia and damping characteristics of the synchronous generator. This strategy can effectively control influence of inverters on power grid. In order to reduce the circulating current and power oscillation, this paper proposed a pre-synchronization control strategy which adds the pre-synchronization...
Induction industrial welding is one of the most straightforward application for the power inverter. Practical industrial welders require at the same time power levels up to 1 MW while frequencies are in the range between 200–500 kHz, depending on the characteristics of the tube to be weld. SiC devices, as per its superior high frequency characteristics, are ideal components for this type of high power,...
This paper investigates the problem of accurate active power sharing in virtual flux droop where flux angle droop control is used for DG controllers instead of traditional frequency droop control. Firstly, the virtual flux droop control method is introduced. Then, the reasons for inaccurate active power sharing in flux angle droop are analysed. Further, to solve this problem, an active power compensation...
This paper presents the small signal model of a multi Photovoltaic (PV) inverter system to study the effect of controller and system parameters on the frequency modes of a microgrid. The paper describes the state space model of a system having two PV inverters connected by a line and working under droop control mode for active power sharing. The PV sources are working under load following mode and...
Distributed generation (DG) is connected through three-phase inverter to the microgrid. The virtual power based droop control can guarantee the pure decoupling between active and reactive power irrespective of low-voltage or high-voltage microgrid application if the line-impedance information is known in advance. However, unbalances are commonly existent in practice so that this conventional control...
In this work is present the comparison of two methods of controllers design and the model of a single phase inverter for island mode operation in a microgrid. These methods are: direct current conventional method based on frequency analysis that allows the design of a proportional-integral controller and a second method based on dc-ac coordinate transformation, that allows the design of a proportional...
The increasing penetration of renewable energy systems force the grid-connected power converters to use advanced active power controls, which needs to add more functionalities to their control strategies. A power reserve control is being required for grid support capabilities on Renewable Energy Sources (RES). Classical algorithms as the Maximum Power Point Tracking (MPPT) cannot withstand power reserve...
The hybrid power system consisting of new energy inverters and diesel generators has become a typical case of independent power systems in remote areas. Aiming at the problem of generator overload caused by sudden load applying in such systems, this paper proposes a novel emergency control strategy which increases the inverter output power according to the changing rate of system frequency. This control...
In order to test the renewable energy grid-connect converters, a grid simulator is in need which is able to simulate grid transition such as voltage sags, unbalanced voltages, flicker and low-order harmonics. The main concern of this paper is on the harmonics generation. A compound control strategy is proposed on the basis of three-phase inverter to generate precise controllable required voltage harmonics...
A microgrid powered by inverters has become a typical approach to efficient use of renewable energy source. However, the behavior of constantcurrent of the inverters will make it difficult to protect the network. To solve this problem, this paper offers the directional interlocking overcurrent protection for the microgrid powered by the inverters injected with characteristic current. When a fault...
This paper presents a decentralized control for grid-connected cascaded PV inverter system. The system is composed of a number of PV units in series and then connected to utility grid. The topology of this type is meaningful for low voltage (LV) devices to integrate into medium voltage (MV) or high voltage (HV) grid. The proposed decentralized control ensures independent control of each PV unit without...
With the increasing application of photovoltaic, the micro-inverter with interleaved flyback module operating in continuous conduction mode (DCM) and discontinuous conduction mode (DCM)is more popular. However, its difficult to control output current of interleaved flyback micro-inverter because the transfer function has right-half-plane (RHP) zero in CCM and low gain in DCM. To solve this problem,...
This paper is introducing a new method of operation for a series resonant converter, with intended application in megawatt high voltage DC wind turbines. Compared to a frequency-controlled series resonant converter operated in sub-resonant mode, the new method (entitled pulse removal technique) allows the transformer design to be determined by peak load and maximum switching frequency, while still...
This paper describes a method of deriving frequency characteristics of PMSM current control system based on Model Predictive Control (MPC). MPC controller predicts the current behavior using the mathematical model of PMSM and directly selects the optimal switch state based on evaluation of these predicted results. So, we have focused the possibility of MPC, which makes it possible to drive machines...
A circulating current is a major problem introduced by directly connecting voltage source inverter (VSI) in parallel. This circulating current occurs as a zero-sequence current between the inverters by specic switch states. Its alternatives were presented by hardware and software methods in many papers. When coupled inductor (CI) are employed for the high frequency circulating current, a circulating...
This paper proposes improved multi-loop control strategies for three-phase four-leg virtual synchronous generator with unbalanced loads. Through the decoupling control of active and reactive power, inverter can simulate the characteristics of synchronous generator, including primary frequency modulation, primary voltage modulation, inertia and excitation characteristics. To improve the dynamic performance...
In wind generator applications, generator speed varies with wind speed. In the case of permanent magnet synchronous generators, this translates into voltage magnitude and frequency variations. For such applications, it is advantageous to employ active rectifiers with buck-boost capability to interface the generator to a DC-bus. A PWM active rectifier cascaded with a Z-source DC-DC converter circuit...
This paper proposes a general seamless control scheme of inverter for the purpose of ship-to-shore connection by means of active islanding detection method. In the proposed system, the Sandia Frequency Shift (SFS) method combined with a frequency protection scheme is used to detect the islanding instant. The SFS parameter selection is performed using a new phase criterion proposed in the literature...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.