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Droop control is widely used in distributed generators for relating their terminal parameters to power generation. These generators are usually assumed to have enough capacities for supplying the required power. This is however not always true, especially with renewable sources with no or insufficient storage. To deal with this issue, an improved droop-based control is proposed for single-phase two-stage...
Droop control is a widely used technique for load sharing in DC microgrids (MGs). However, it has its limitations due to the MG voltage deviating from its rated level and, more importantly, it suffers from possible poor current sharing accuracy. Voltage drops across coupling line impedances is the main factor that causes these limitations, which is further deteriorated by the virtual impedance introduced...
Overcurrent or overvoltage problems caused by DC line faults endanger the security of modular multilevel converter based high voltage direct current (MMC-HVDC) system. To improve the reliability of fault identification for MMC-HVDC transmission lines, a novel pilot protection scheme based on DC power difference is proposed in this paper. Characteristics of the DC power difference between positive...
To address the DC link voltage regeneration issue in parallel Uninterruptible Power Supply (UPS) system, a DC link voltage protection (DCVP) method through online virtual resistance regulation is proposed. The proposed control strategy is able to protect the DC link from overvoltage that may trigger the protection mechanism of the UPS system. Moreover, a current sharing control strategy by regulating...
A low-dropout regulator (LDO) with 800 mA load current with wide range input voltage is designed and proposed in this paper. The designed LDO includes two cascaded LDOs. The first one uses a p-type of DMOS power transistor to convert a wide input voltage (3.9 to 20 V) to a stable output voltage of 3 V, which provides a supply voltage for other circuits. The second LDO is designed to achieve a large...
This paper addresses the problem of voltage regulation by multiple DC/DC converters and without communication amongst the converters. In DC systems where multiple different energy storage devices need to regulate a common DC bus while executing their individual battery management algorithms, it is necessary to find an automatic mechanism to coordinate how the different converters share the responsibility...
Various configurations can be considered for a dc Microgrid (MG) comprising distributed generation (DGs) units and loads. Renewable energy sources and energy storage systems of plug-and-play nature can change the configuration of the MG at any time. Each configuration has a distinct and unique mathematical representation that influences the operation of the MG. However, the voltage throughout the...
Modular Multi-level Converters (MMCs) are considered as one of the promising multilevel converter topologies specially in high voltage applications such as HVDC transmission systems. The idea behmd MMC is to use floating capacitors as a voltage sources along with a switchmg circuit (chopper cell) to form what is called “submodules”. These submodules are inserted or bypassed according to the required...
In this paper, a maximum power point tracking (MPPT) control system for thermoelectric generation is proposed. The MPPT algorithm is based on the open-circuit voltage method. Model equations of the thermoelectric generation circuit including a thermoelectric generation module (TEM), a DC-DC converter and an electric load are explained. The MPPT control system based on operator theory is designed for...
This paper describes the concept of the dynamic duty-cycle limiter of the boost dc-dc converter. Duty-cycle limitation in boost converters is usually used to protect the bottom switch against an excessive current, and also to avoid instability occurring at high duty-cycle operations. Compared to fixed limitation, dynamic limiter enables to detect and maintain maximal possible output voltage VMAX,...
For battery and ultracapacitor hybrid energy storage systems, the design and control of the DC-DC converter is an important stage of the system design process. The design approach for a model-based controller for a half-bridge DC-DC converter is presented with experimental results from a scaled test configuration. The contribution of this paper lies in presenting a well-behaved discrete-time system...
Droop control is broadly used in source paralleling and distributed dc systems. While the dc droop resistance guarantees static load sharing, the output impedance determines the dynamic performance and is important in stability analysis. In this paper, a general small signal model is established to derive the output impedance of a droop-controlled power source. Using buck converter as an example,...
The paper refers to modelling characteristics of a simple photovoltaic system with thermal phenomena taken into account. This system consists of a photovoltaic panel, battery and two switched-mode voltage regulators. The electrothermal models of all the components of such systems are presented. These models are dedicated to electrothermal dc and transient analyses. The correctness of the models of...
This paper presents an energy harvesting system for adaptation with thermoelectric generators (TEG). The TEG system is a dc power source based on Seebeck effect, which utilizes the temperature gradient between hot and cold sides of the TEG module. The output voltage is highly dependent on temperature difference. A DC-DC converter is needed to regulate the output power of the TEG and to actively track...
This paper presents a load sharing method applied in a distributed micro grid system. The goal of this method is to balance the state-of-charge (SoC) of each parallel connected battery and make it possible to detect the average SoC of the system by measuring bus voltage for all connected modules. In this method the reference voltage for each battery converter is adjusted by adding a proportional SoC...
The microprocessor control device for power generating objects' (PGO) parameters, which is based on the automatic control system (ACS) effecting the controlled object, has been proposed and implemented in this paper. The proposed method for measuring insulation resistance of the PGO representing networks of direct or alternating currents (single or three phase), isolated and usually having large capacitances...
Portable AC generators directly driving isolated AC loads require tight voltage regulation, good voltage waveform quality and high efficiency. This paper compares the performance of a 4-pole, 16 kW, three-phase interior permanent-magnet generator with a single-phase resistive load when operating with both star and delta winding connections. The results of analytical and finite-element simulations...
Matrix converter nonlinear errors due to voltage drop and commutation delay introduce a distortion between voltage reference signals and output phase voltages. In current controlled applications, the current regulators are capable of compensating for such voltage command error. However, where output voltage estimation is required such as in state observers used for sensorless control of ac drives,...
This paper describes the design and performance of a modular wideband high-voltage dc (HVDC) reference divider with a ratio uncertainty of less than 0.005% at 1000 kV. The divider has a maximum nominal voltage of 1000 kV when five 200-kV modules are stacked on top of each other. The divider is used for traceable calibration of HVDC measuring systems in customers’ laboratories. The first priority in...
In this paper project and measured characteristics of the laptop's power supply station with photovoltaic module are presented. This device consists of two switch-mode voltage regulators, photovoltaic module and the lead-acid battery. In the following sections step-down and step-up switch-mode voltage regulators are described and the measured by the author characteristics of voltage regulators and...
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