scholarly journals Optimization to Limit the Effects of Underloaded Generator Sets in Stand-Alone Hybrid Ship Grids

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 708 ◽  
Author(s):  
Sergey German-Galkin ◽  
Dariusz Tarnapowicz ◽  
Zbigniew Matuszak ◽  
Marek Jaskiewicz
Keyword(s):  
Power Systems ◽  
Power Distribution ◽  
Reactive Power ◽  
Negative Impact ◽  
Combustion Engine ◽  
Synchronous Generator ◽  
Parallel Operation ◽  
Variable Speed ◽  
Diesel Generator ◽  
Power Load

For the safety of the supply, diesel generator (DG) sets are used in various stand-alone power systems using variable-speed generators. The stand-alone hybrid grid system presented in this article, with a wind generator and a diesel generator, but also the system of a ship’s network, serves as an example. To ensure the safety of the ship’s exploitation, the parallel operation of two stand-alone power supplies is required. In parallel operation with the required symmetrical active power load (regardless of the load size), the internal combustion engine of the DG set is often underloaded. This leads to deterioration of its technical properties and, consequently, to a negative impact on the environment. This article presents an analysis of the stand-alone hybrid power system of a ship’s grid consisting of a DG with a speed and voltage regulator and a shaft generator of variable speed—a permanent magnet synchronous generator (PMSG). The possibility of controlling the active and reactive power distribution between the DG and shaft generator (SG) was also studied. Control over the mechatronic SG–DG system limits the harmful influence of the DG on the environment and, most of all, improves the technical qualities of the engine of the DG system, which is often underloaded. Analytic studies of the system were performed, and simulation results of the mechatronic model are presented.

scholarly journals Determination of reliability of power supply of ship's responsible power receivers

2020 ◽  
pp. 22-26
Author(s):  
С.Е. Кузнецов ◽  
Н.А. Алексеев ◽  
А.А. Виноградов
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Supply ◽  
Electric Power System ◽  
Time To Failure ◽  
Parallel Operation ◽  
Diesel Generator ◽  
Operating Modes ◽  
Reliability Indicators ◽  
Supply Reliability

Изложена методика расчета показателей безотказности электроснабжения (вероятности безотказного электроснабжения и средней наработки до отказа) ответственных приемников морского судна, подключаемых к аварийному электрораспределительному щиту. Методика реализована применительно к судовой электроэнергетической системе с тремя источниками электроэнергии – двумя основными дизель-генераторными агрегатами, подключенными к главному электрораспределительному щиту, и одним аварийным дизель-генераторным агрегатом, подключенным к аварийному электрораспределительному щиту. Рассмотрены различные режимы работы судовой электроэнергетической системы: при работе до первого отказа одного основного дизель-генератора, при параллельной работе двух основных дизель-генераторов, при работе одного аварийного дизель-генератора; а также после обесточивания с учетом возможности последующего включения резервного или (и) аварийного дизель генератора. Методика, с соответствующими корректировками, может быть использована для расчета показателей безотказного электроснабжения в судовых электроэнергетических системах другой комплектации. Расчет показателей безотказности электроснабжения необходим при проектировании для обеспечения требуемого уровня надежности электроснабжения судовых приемников электроэнергии, а при эксплуатации – для предупреждения отказов и планирования технического обслуживания и ремонта элементов судовых электроэнергетических систем. The methodology for calculating the indicators of the reliability of power supply (the probability of failure-free power supply and the mean time to failure) of critical receivers of a sea vessel connected to the emergency electrical switchboard is presented. The technique is implemented in relation to a ship power system with three sources of electricity - two main diesel generator sets connected to the main electrical switchboard, and one emergency diesel generator set connected to an emergency electrical switchboard. Various operating modes of the ship's electric power system are considered: during operation until the first failure of one main diesel generator, during parallel operation of two main diesel generators, during operation of one emergency diesel generator; as well as after de-energizing, taking into account the possibility of subsequent switching on of the backup and / or emergency diesel generator. The technique, with appropriate adjustments, can be used to calculate indicators of reliable power supply in ship power systems of a different configuration. Calculation of power supply reliability indicators is necessary during design to ensure the required level of power supply reliability for ship power receivers, and during operation - to prevent failures and plan maintenance and repair of elements of ship power systems.

Voltage stability enhancement using an adaptive hysteresis controlled variable speed wind turbine driven EESG with MPPT

2014 ◽  
Vol 25 (2) ◽  
pp. 48-60
Author(s):  
R. Jeevajothi ◽  
D. Devaraj
Keyword(s):  
Wind Turbine ◽  
Voltage Stability ◽  
Reactive Power ◽  
Synchronous Generator ◽  
Maximum Power ◽  
Induction Generator ◽  
Variable Speed ◽  
Maximum Power Point ◽  
Variable Speed Wind Turbine ◽  
Power Point

This paper investigates the enhancement in voltage stability achieved while connecting a variable speed wind turbine (VSWT) driven electrically excited synchronous generator (EESG) into power systems. The wind energy conversion system (WECS) uses an AC-DC-AC converter system with an uncontrolled rectifier, maximum power point tracking (MPPT) controlled dc-dc boost converter and adaptive hysteresis controlled voltage source converter (VSC). The MPPT controller senses the rectified voltage (VDC) and traces the maximum power point to effectively maximize the output power. With MPPT and adaptive hysteresis band current control in VSC, the DC link voltage is maintained constant under variable wind speeds and transient grid currents.The effectiveness of the proposed WECS in enhancing voltage stability is analysed on a standard IEEE 5 bus system, which includes examining the voltage magnitude, voltage collapse and reactive power injected by the systems. Simulation results show that the proposed WECS has the potential to improve the long-term voltage stability of the grid by injecting reactive power. The performance of this scheme is compared with a fixed speed squirrel cage induction generator (SCIG), a variable speed doubly-fed induction generator (DFIG) and a variable speed permanent magnet synchronous generator (PMSG).

scholarly journals Grid-connected Response Verification of AC Microgrid under Single Line-to-ground Short Circuit

2019 ◽  
pp. 1-10
Author(s):  
Maruf A. Aminu
Keyword(s):  
Power Systems ◽  
Reactive Power ◽  
Short Circuit ◽  
Synchronous Generator ◽  
Dynamic Responses ◽  
Single Line ◽  
Physical Systems ◽  
Short Circuits ◽  
Power System Performance ◽  
Grid Interconnection

In design of power systems, assumptions are made to model the physical systems. The assumptions may not sufficiently reflect the behavior of the system under normal and faulted conditions. Under short circuit conditions, system parameters vary significantly, particularly in microgrids with grid interconnection capabilities. This paper presents the result of validating the response of a microgrid which is capable of grid interconnection and islanding under voltage and reactive power control regimes. The microgrid is modeled to incorporate two wind turbines, each rated 5.5 kW, 400 V. The utility has synchronous generator rated 100 MW, 13.8 kV. Both the utility and microgrid are capable of exchanging active power and reactive power. Single line-to-ground short circuits are introduced and withdrawn at 30.00 s and 32.00 s, respectively. The dynamic responses of the testbed are captured pre-, during- and post-short circuit in grid-connected mode under both control regimes. The response of the testbed is verified to be consistent with established short circuit theory, verifying the validity of the system for short circuit detection and analysis. The testbed can therefore be used for short circuit and related studies, design optimization and power system performance prediction.

Contribution of Variable-Speed Wind Turbines to Voltage Control

2002 ◽  
Vol 26 (6) ◽  
pp. 347-358 ◽  
Author(s):  
Pablo Ledesma ◽  
Julio Usaola
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Reactive Power ◽  
Voltage Control ◽  
Synchronous Generator ◽  
Induction Generator ◽  
Base Case ◽  
Variable Speed ◽  
Control Techniques ◽  
Control Schemes

Variable speed, grid connected, wind turbines open new possibilities for voltage control, because they use electronic converters, which may regulate the reactive power interchange with the grid. This paper proposes two voltage control schemes for variable speed wind turbines with double-fed induction generator. The first scheme acts on the wind-turbine power factor, while the latter acts directly on the converter current. Advantages and drawbacks of both techniques are discussed. Both control techniques have been tested by simulations of a base case, which represent a synchronous generator, a wind farm and a local load, and several disturbances such as the loss of compensator capacitors.

Simulation and Analysis of Synchronous Diesel Generation System Based on PSCAD

2012 ◽  
Vol 614-615 ◽  
pp. 870-874 ◽  
Author(s):  
Shu Li Wen ◽  
Hai Lan ◽  
Jie Meng ◽  
Li Jun Zhang ◽  
Xin Zhao
Keyword(s):  
Transient Response ◽  
Combustion Engine ◽  
Synchronous Generator ◽  
Droop Control ◽  
Diesel Generator ◽  
Generation System ◽  
Current Frequency ◽  
Pi Regulator ◽  
Operation Conditions ◽  
Islanded Mode

In view of the challenging issues in microgrid diesel modeling and connecting to the power grid, this paper presents the design and simulation of a diesel generation system which contains an internal combustion engine and a synchronous generator. Furthermore, droop control with PI regulator applies to the diesel generator model and the performance of the generation system has been tested under various operation conditions using the PSCAD/EMTDC simulation platform, the simulation demonstrates that synchronous diesel generation system can operate smoothly either in islanded mode or in the grid-connected mode. The transient response is analyzed and all the variables voltage/current/frequency are under IEEE 1547 standard.

scholarly journals Precise Reactive Power-Voltage Droop Control of Parallel Virtual Synchronous Generators that Considers Line Impedance

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1344
Author(s):  
Xiangwu Yan ◽  
Hongbin Ma ◽  
Jiaoxin Jia ◽  
Waseem Aslam ◽  
Chenguang Wang ◽  
...  
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Integrated Control ◽  
Synchronous Generator ◽  
Control Voltage ◽  
Droop Control ◽  
Parallel Operation ◽  
Distributed Generators ◽  
Power Decoupling ◽  
Virtual Synchronous Generator

Problems such as high power coupling, low distribution accuracy, and insufficient reactive power-voltage droop accuracy occur when distributed generators are operated in parallel due to the influence of line impedance. The precise control of output reactive power and voltage is difficult to achieve using traditional virtual synchronous generator (VSG) control. Taking this into consideration, this study proposes a virtual synchronous generator reactive power-voltage integrated control strategy that considers line parameters to solve this problem. First, the impedance voltage drop of the line is compensated for in accordance with local information control to ensure the consistency of the control voltage in parallel operation of distributed generators and to realize the precise droop control of reactive power and the voltage of the point of common coupling (UPCC). Second, virtual negative impedance control is added to change the equivalent output impedance characteristics of the system and achieve power decoupling. On this basis, the active frequency and reactive voltage decoupling control effect of the improved control strategy is quantified and analyzed using the relative gain matrix. The accuracy of reactive power distribution and droop control is theoretically derived and analyzed by establishing a small-signal model of a two-machine parallel system. Finally, the accuracy and effectiveness of the proposed integrated control strategy are verified via a simulation model and an experimental platform for parallel operation. Results show that the proposed integrated control strategy can effectively solve the problems of power decoupling and accurate distribution, reduce system loop current, and realize accurate reactive power-voltage droop. Compared with the traditional VSG control strategy, the dynamic deviation of UPCC is reduced by at least 40% when a large-scale load disturbance occurs.

scholarly journals Power station based on variable speed diesel generator and buffer storage device

2020 ◽  
Vol 2020 (3) ◽  
pp. 71-81
Author(s):  
Oleg Stanislavovich Khvatov ◽  
Dmitry Sergeevich Kobyakov ◽  
Mikhail Evgenievich Yurlov
Keyword(s):  
Power Plant ◽  
Block Diagram ◽  
Experimental Studies ◽  
Transient Processes ◽  
Storage Device ◽  
Parallel Operation ◽  
Variable Speed ◽  
Diesel Generator ◽  
Buffer Storage ◽  
Charge Discharge

The article describes the diesel generator complex which consists of two diesel generators. In order to save fuel, it is advisable to choose one diesel generator of inverter type, i.e. to switch it to a variable speed mode. The buffer storage device is used as a part of the power plant in order to ensure the required parameters of the generated electricity under peak loads, as well as when the generator is operating at the limit of rated power. There has been given the control algorithm and transient processes of the charge / discharge of the buffer storage device in a diesel generator power plant. The power plant that consists of a classic diesel generator and a variable speed diesel generator unit (valved generator) has been chosen as an object research. A block diagram of the power plant conducting is proposed, as well as a power transformer topology of a variable-speed diesel generator based on a step-down pulse-width converter. There has been presented an algorithm for controlling the connection of a buffer storage device depending on its charge and the load power value both in stand-alone mode and in parallel operation of generator sets. In the MatLab Simulink computer environment a simulation model of a power plant was developed and transient processes of load switching, as well as charge / discharge of a buffer energy storage device were studied. An electrical circuit diagram of an experimental bench of a variable-speed diesel generator set is illustrated. The results of experimental studies of dynamic modes of operation on a prototype variable speed diesel generator with a power of 3.2 kW are also presented.

Power Analysis Using Various Types of Wind Turbines

2022 ◽  
pp. 271-286
Author(s):  
Bibhu Prasad Ganthia ◽  
Monalisa Mohanty ◽  
Jai Kumar Maherchandani
Keyword(s):  
Power Systems ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Synchronous Generator ◽  
Type I ◽  
Variable Speed ◽  
Type Iv ◽  
Wind Turbine System ◽  
Simulation Based ◽  
Wind Power Systems

This chapter highlights on the design, operation, and comparative analysis of different types of wind turbine systems with respect to steady state and transient phenomenal activities under rapid wind speed variations. Here, Type I, which is fixed speed induction generator based, and Type II, which is DFIG based, variable speed operated systems are initially compared. In the next part, Type III wind turbine system is presented, which uses DFIG; later, it is compared with the Type IV WT system, which uses permanent magnet synchronous generator. This chapter provides a comparative overview on existing wind power systems including an analytic discussion of key principles and innovations for wind turbines. In this energy conversion system, various designs of wind turbines, pitch angle controlled based variable speed wind turbines governed by help of electronic power converters, were preferred. This scope of dynamic simulation-based study is implemented using MATLAB Simulink to convey the feasibility of the proposed wind turbine models.

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