Modeling of Grid-Connected Single-Phase LCL Converter Considering Line Impedance Effect and Its Improvement on System Stability and Current Distortion with DDC

2021 ◽  
Author(s):  
Tsai-Fu Wu ◽  
Yun-Hsiang Chang ◽  
Chin-Fen Pai
Keyword(s):  
Single Phase ◽  
System Stability

scholarly journals Multi-machine transient stability by using static synchronous series compensator

2020 ◽  
Vol 11 (3) ◽  
pp. 1249
Author(s):  
Nur Ashida Salim ◽  
Nur Diyana Shahirah Mohd Zain ◽  
Hasmaini Mohamad ◽  
Zuhaila Mat Yasin ◽  
Nur Fadilah Ab Aziz
Keyword(s):  
Power System ◽  
Transient Stability ◽  
Single Phase ◽  
Power Transmission ◽  
System Stability ◽  
Phase System ◽  
Proportional Integral ◽  
Before And After ◽  
In Series ◽  
Static Synchronous Series Compensator

<span lang="EN-US">Transient stability in power system is vital to be addressed due to large disturbances that could damage the system such as load changes and voltage increases. This paper presents a multi-machine transient stability using the Static Synchronous Series Compensator (SSSC). SSSC is a device that is connected in series with the power transmission line and produces controllable voltage which contribute to a better performance in the power system stability. As a result, this research has observed a comparison of the synchronization of a three-phase system during single-phase faults before and after installing the SSSC device. In addition, this research investigates the ability of three different types of controllers i.e. Proportional Integral (PI), Proportional Integral Derivation (PID), and Generic controllers to be added to the SSSC improve the transient stability as it cannot operate by itself. This is because the improvement is too small and not able to achieve the desired output. The task presented is to improve the synchronization of the system and time taken for the voltage to stabilize due to the fault. The simulation result shows that the SSSC with an additional controller can improve the stability of a multi-machine power system in a single phase fault.</span>

BIFURCATION IN WIND ENERGY GENERATION SYSTEMS

2010 ◽  
Vol 20 (11) ◽  
pp. 3795-3800 ◽  
Author(s):  
ZHEN LI ◽  
SIU-CHUNG WONG ◽  
CHI K. TSE ◽  
GRACE CHU
Keyword(s):  
Wind Energy ◽  
Bifurcation Analysis ◽  
Single Phase ◽  
Energy Generation ◽  
System Stability ◽  
Generation System ◽  
Constant Power ◽  
Wind Energy Generation ◽  
Constant Power Loads ◽  
Phase Constant

This letter reveals the possibility of Hopf bifurcation in a grid-connected wind energy generation system which handles an unbalanced loading. The wind energy generation system consists of a typical doubly fed induction generator (DFIG) which allows variable speed operation by using partially rated back-to-back quadruple active and reactive power PWM converters. Many control schemes reported in the literature are designed to solve some specific control problems associated with DFIG and have rarely been tested for general stability. Specifically, bifurcation analysis of the system has not been reported so far. We study the system stability in terms of the magnitude of some unwanted oscillation of the voltage link capacitor under a practical scenario where the system interacts indirectly with unbalanced single-phase constant power loads through the power grid. In this letter, the rotor speed of the DFIG is used as a variation parameter for bifurcation analysis. Bifurcation diagram of the voltage link capacitor indicates a Hopf-like bifurcation of the system in super-synchronous operation. This clearly explains the instability phenomenon of the practical DFIG system when unbalanced single-phase constant power loads are connected to the connecting grid.

Design-Oriented Analysis of Slow-Scale Bifurcations in Single Phase DC–AC Inverters via Autonomous Transformation Approach

2017 ◽  
Vol 27 (06) ◽  
pp. 1750086 ◽  
Author(s):  
Hao Zhang ◽  
Honghui Ding ◽  
Chuanzhi Yi
Keyword(s):  
Theoretical Analysis ◽  
Circuit Design ◽  
Single Phase ◽  
Underlying Mechanism ◽  
System Stability ◽  
Equivalent Model ◽  
Eigenvalue Sensitivity ◽  
Physical Experiments ◽  
Averaged Model ◽  
Theoretical Results

This paper deals with the design-oriented analysis of slow-scale bifurcations in single phase DC–AC inverters. Since DC–AC inverter belongs to a class of nonautonomous piecewise systems with periodic equilibrium orbits, the original averaged model has to be translated into an equivalent autonomous one via a virtual rotating coordinate transformation in order to simplify the theoretical analysis. Based on the virtual equivalent model, eigenvalue sensitivity is used to estimate the effect of the important parameters on the system stability. Furthermore, theoretical analysis is performed to identify slow-scale bifurcation behaviors by judging in what way the eigenvalue loci of the Jacobian matrix move under the variation of some important parameters. In particular, the underlying mechanism of the slow-scale unstable phenomenon is uncovered and discussed thoroughly. In addition, some behavior boundaries are given in the parameter space, which are suitable for optimizing the circuit design. Finally, physical experiments are performed to verify the above theoretical results.

The Effect of Digital Process of Single-Phase Photovoltaic Grid Connected Inverter

2014 ◽  
Vol 1070-1072 ◽  
pp. 60-63
Author(s):  
Hong Tao Shan ◽  
Bin Zhou
Keyword(s):  
Digital Control ◽  
Single Phase ◽  
Zero Order ◽  
System Stability ◽  
Stability Range ◽  
Delay Control ◽  
One Step ◽  
Grid Connected Inverter ◽  
The Stability ◽  
Sample Time

Digital control possesses evident advantages and has become a mainstream control of photovoltaic grid connected inverter.The mathematical model and parameter setting of the single phase photovoltaic grid connected inverter with L filter was introduced in the paper.It was analysed on the effect on system stability of digital process from the two aspects which were the zero-order-hold and one-step-delay control. The bode diagram was verified the theoretical analysis on system stability.The conclusions were made that the introduction of digital control reduces the critical stable gain of photovoltaic grid connected inverter system,system stability is varied with sample time, the parameters of L can affect the system stability range,zero-order-hold reduces the stability range and limits the performance improved of digital control system,one-step-delay control on photovoltaic grid connected inverter reduces again the stability range on the basis of the zero-order-hold control.

scholarly journals Potency of PR controller for multiple harmonic compensation for a single-phase grid connected system

2020 ◽  
Vol 11 (3) ◽  
pp. 1491
Author(s):  
D Sattianadan ◽  
Soumen Gorai ◽  
G. R. Prudhvi Kumar ◽  
S. Vidyasagar ◽  
V. Shanmugasundaram
Keyword(s):  
Single Phase ◽  
Harmonic Distortion ◽  
System Stability ◽  
Phase System ◽  
Pv System ◽  
Lcl Filter ◽  
Grid Synchronization ◽  
Harmonic Content ◽  
Wide Range ◽  
Pr Controller

<p><span lang="EN-US">Harmonics and grid synchronization are one of the major problems faced when dealing with a single-phase system. The development of technology in the PV system makes the consumer to use it in a wide range. The power transferred from PV to grid needs DC to AC conversion process which is done by static devices operating with the higher frequencies that causes the harmonics in the grid connected system. The main aim of the paper is to implement grid synchronization and reduce total harmonic distortion in a single-phase grid connected system. The design of LCL filter is addressed in this paper which depends on current ripple, filter size and switching ripple attenuation.  In order to account the harmonic content, the FFT analysis is made both in analysis and Matlab Simulink. The Proportional Resonant (PR) controller is developed and work along with LCL filter for reducing the harmonic content. The stability of the system with PR is analyzed using root locus and bode plots and results are compared with PI controls. The result shows that PR controller performs better compared to the PI controller for reducing the harmonic content present in the single-phase system and for improving the system stability.</span></p>

Microtransformers for Teaching and System Stability Research

1986 ◽  
Vol 23 (2) ◽  
pp. 121-125
Author(s):  
P. H. G. Allen ◽  
K. J. D'Souza
Keyword(s):  
Single Phase ◽  
Second Order ◽  
System Stability ◽  
Rotating Machines ◽  
Linear Features ◽  
Three Phase ◽  
Non Linear ◽  
Design And Manufacture

Large transformers, like highly rated rotating machines, can be modelled in ‘micro’ form to demonstrate significant second order, non-linear, features. The design and manufacture of 3 kVA (nominal) rating three-phase and three single-phase transformer bank units, all with three-limb cores and 0.17 per unit leakage reactance are described.

scholarly journals A review of single phase adaptive auto-reclosing schemes for EHV transmission lines

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Waqar Ahmad Khan ◽  
Tianshu Bi ◽  
Ke Jia
Keyword(s):  
Transmission Lines ◽  
Single Phase ◽  
Circuit Breaker ◽  
System Stability ◽  
Critical Survey ◽  
Severe Damage ◽  
Overhead Lines ◽  
Permanent Faults ◽  
External Objects ◽  
The Subject

Abstract Statistics shows that transients produced by lightning or momentary links with external objects, have produced more than 80% of faults in overhead lines. Reclosing of circuit breaker (CB) after a pre-defined dead time is very common however reclosing onto permanent faults may damage the power system stability and aggravate severe damage to the system. Thus, adaptive single-phase auto-reclosing (ASPAR) based on investigating existing electrical signals has fascinated engineers and researchers. An ASPAR blocks CB reclosing onto permanent faults and allows reclosing permission once secondary arc is quenched. To address the subject, there have been many ASPARs techniques proposed based on the features trapped in a faulty phase. This paper presents a critical survey of adaptive auto-reclosing schemes that have hitherto been applied to EHV transmission lines.

scholarly journals A Power Calculation Algorithm for Single-Phase Droop-Operated-Inverters Considering Linear and Nonlinear Loads HIL-Assessed

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1366 ◽  
Author(s):  
Jorge El Mariachet ◽  
Jose Matas ◽  
Helena Martín ◽  
Mingshen Li ◽  
Yajuan Guan ◽  
...  
Keyword(s):  
Single Phase ◽  
System Stability ◽  
Power Calculation ◽  
Parallel Operation ◽  
Calculation Algorithm ◽  
Nonlinear Loads ◽  
Nonlinear Load ◽  
Low Pass ◽  
Dynamic Velocity ◽  
The Stability

The active and reactive powers, P and Q, are crucial variables in the parallel operation of single-phase inverters using the droop method, introducing proportional droops in the inverter output frequency and voltage amplitude references. P and Q, or P-Q, are calculated as the product of the inverter output voltage and its orthogonal version with the output current, respectively. However, when sharing nonlinear loads these powers, Pav and Qav, should be averaged by low-pass filters (LPFs) with a very low cut-off frequency to avoid the high distortion induced by these loads. This forces the droop method to operate at a very low dynamic velocity and degrades the system stability. Then, different solutions have been proposed in literature to increase the system velocity, but only considering linear loads. Therefore, this work presents a method to calculate Pav and Qav using second-order generalized integrators (SOGI) to face this problem with nonlinear loads. A double SOGI (DSOGI) approach is applied to filter the nonlinear load current and provide its fundamental component to the inverter, leading to a faster dynamic velocity of the droop-based load sharing capability and improving the stability. The proposed method is shown to be faster than others in the literature when considering nonlinear loads, while smoothly driving the system with low distortion levels. Simulations, hardware-in-loop (HIL) and experimental results are provided to validate this proposal.

scholarly journals VOLT-SECOND BALANCE METHOD FOR MITIGATION OF INRUSH CURRENT IN SINGLE PHASE TRANSFORMERS

2013 ◽  
pp. 63-67
Author(s):  
D P BALACHANDRAN ◽  
R SREERAMA KUMAR ◽  
B JAYANAND
Keyword(s):  
Single Phase ◽  
Simple Technique ◽  
Power System Stability ◽  
System Stability ◽  
Inrush Current ◽  
Flux Linkage ◽  
The Core ◽  
Transient Period ◽  
Inrush Currents ◽  
Sequential Phase

During the transient period at the start of transformer energization, it experiences a flux linkage that is up to twice its nominal steady state value and saturates the core. This causes a large inrush current to flow which affects the power system stability and power quality especially when the source is weak. Sequential phase energization technique and addition of neutral resistor are the major methods for minimization of inrush current. This paper proposes a simple technique to limit the flux linkage during the time of transformer energization and prevents the flux saturation there by reducing the inrush current. This is based on a volt-second balance which injects a transient voltage to the primary of the transformer during inrush currents. The effectiveness of the proposed scheme is verified by simulation.

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