Alireza Fereidouni

The Impact of Solid State Fault Current Limiter on Power Network With Wind-Turbine Power Generation

In this paper, it is aimed to investigate the impact of the various solid-state fault current limiters (SSFCLs) on several electric power networks with the wind-turbine power generation (WTPG). Distributed generations (DGs) are predicted to perform an increasing role in the future electrical power system. Expose of the DG, can change the fault current during a grid disturbance and disturb the existing distribution system protection. Fault current limiters (FCLs) can be sorted into L-types (inductive) and R-types (resistive) by the fault current limiting impedance. In this paper, a new SSFCL has been proposed. SSFCLs can provide the fast system protection during a rigorous fault. The act of dynamic damping enhancement via the SSFCL is appraised in the presence of the wind-turbine power generation. Hence, its efficiency as a protective device for the wind-turbine system is confirmed via some case studies by time-domain simulation based on the PSCAD/EMTDC.

A new adaptive configuration of PID type fuzzy logic controller

In this paper, an adaptive configuration for PID type fuzzy logic controller (FLC) is proposed to improve the performances of both conventional PID (C-PID) controller and conventional PID type FLC (C-PID-FLC). The proposed configuration is called adaptive because its output scaling factors (SFs) are dynamically tuned while the controller is functioning. The initial values of SFs are calculated based on its well-tuned counterpart while the proceeding values are generated using a proposed stochastic hybrid bacterial foraging particle swarm optimization (h-BF-PSO) algorithm. The performance of the proposed configuration is evaluated through extensive simulations for different operating conditions (changes in reference, load disturbance and noise signals). The results reveal that the proposed scheme performs significantly better over the C-PID controller and the C-PID-FLC in terms of several performance indices (integral absolute error (IAE), integral-of-time-multiplied absolute error (ITAE) and integral-of-time-multiplied squared error (ITSE)), overshoot and settling time for plants with and without dead time.

A Novel Hybrid Islanding Detection Technique Using Rate of Voltage Change and Capacitor Tap Switching

Abstract Distributed generators are acquiring more attention in power systems because they can avoid distribution and transmission upgrade requirements and improve power quality issues. Islanding is one of the problems that arise with integrating these resources into the distribution system. In this article, a novel hybrid islanding detection technique is proposed which uses average rate of voltage change and capacitor bank tap switching. The proposed method is tested on a real system and different load characteristics with different dependence coefficients to voltage and frequency are studied. The power system is perturbed only when the method suspects that islanding has occurred. The proposed method could detect islanding conditions with very small power mismatches in them.

Supervisory Nearly Constant Frequency Hysteresis Current Control for Active Power Filter Applications in Stationary Reference Frame

This paper proposes a new constant frequency space-vector hysteresis-band current control (CF-SVHCC) in the stationary reference frame (SRF) for three-level active power filter applications when applied to isolated neutral point (INP) systems. CF-SVHCC is designed based on two recognized modulation methods: 1) space-vector modulation and 2) adaptive hysteresis current control. The proposed technique consists of a simple circular hysteresis strategy around the current-error vector in SRF with the purpose of employing the zero- and nonzero-voltage vectors of the three-level voltage source inverter. CF-SVHCC continuously estimates an adaptive outer hysteresis-band in the SRF using the inverter switching signals by a simple and fast artificial neural network method called the adaptive linear neuron algorithm. The main part of CF-SVHCC is a supervisory control unit that operates in the SRF to avoid interphase dependency and systematically uses the voltage vectors associated with the estimated outer hysteresis-band to prevent a high switching frequency and, in turn, maintain the switching frequency constant. CF-SVHCC retains most benefits of the conventional HCC and also introduces additional advantages, including a constant switching frequency and the interphases independency in three-phase INP systems.

Enhancement of Power System Transient Stability and Power Quality Using a Novel Solid-state Fault Current Limiter

Solid-state fault current limiters (SSFCL) in power systems are alternative devices to limit prospective short circuit currents from reaching lower levels. Fault current limiters (FCL) can be classified into two categories: R-type (resistive) FCLs and L-type (inductive) FCLs. L-type FCL uses an inductor to limit fault level and is more efficient in suppressing voltage drop during a fault. In contrast, R-type FCL is constructed with a resistance and is more effective in consuming the acceleration energy of generators during a fault. Both functions enhance the transient stability of the power system. In the present paper, a novel SSFCL is proposed to enhance power system transient stability and power quality. The proposed SSFCL uses both functions of an L-type and R-type FCL. SSFCL consists of four diodes, one self-turn-off IGCT, a current-limiting by-pass inductor (L), and a variable resistance parallel with an inductor for improvement of power system stability and prevention of over-voltage across SSFCL. The main advantages of the proposed SSFCL are the simplicity of its structure and control, low steady-state impedance, fast response, and the existence of R-type and Ltype impedances during the fault, all of which improve power system stability and power quality. Simulations are accomplished in PSCAD/EMTDC.

Optimal Sizing, Siting and Operation of Custom Power Devices with STATCOM and APLC Functions for Real-Time Reactive Power and Network Voltage Quality Control of Smart Grid

A new custom power device (CPD) is introduced for real-time control of reactive power and improving the overall network voltage quality of smart grid (SG) at fundamental and harmonic frequencies, respectively. The idea is to take advantage of the online smart meter data transmitted from each bus to the SG central control to concurrently perform the static synchronous compensator and the active power line conditioner operations by optimal compensations of fundamental reactive power and harmonic currents at selected optimal buses. The proposed strategy involves two particle swarm optimization algorithms. The first algorithm is implemented for the worse operating condition to determine the optimal locations and sizes of CPDs while the second algorithm relies on smart meter information to continuously compute fundamental and harmonic reference currents for real-time operation and control of the allocated CPDs. The objective functions are cost minimizations associated with bus voltage regulations, network total harmonic distortions voltage and custom device sizing while the constraints include upper limits for CPD sizes, fundamental, and harmonic bus voltages. Detailed simulations are performed in MATLAB/Simulink to evaluate the performances of allocated CPDs in controlling the reactive power and voltage quality of a distorted 15-bus SG with six nonlinear loads according to the IEEE-519 standard.

Space-vector hysteresis modulation for neutral-diode-clamped inverter in active power filter applications

A space-vector hysteresis modulation (SVHM) technique is presented in this paper for three-level neutral-point-clamped (TL-NPC) multilevel inverter for active power filter (APF) applications. The main responsibility of this modulation technique is to force the actual current to reach the reference current and, simultaneously, balance the capacitor voltages. This scheme is implemented in the stationary reference frame (SRF) to avoid interphase dependency in three-phase floated neutral point (TP-FNP) systems. The space-vector-based method permits for the efficient application of zero-voltage vectors and avoids high switching frequencies triggered by phase interaction in TPFNP systems. The approach comprises of performing two alternative hysteresis strategies around the error vector in SRF. Then, based on the present location of it, the next voltage vector is selected to minimize the next error vector and also balance the capacitor voltages. The performance of the proposed technique is investigated and verified through detailed simulation studies for both steady-state and transient conditions.

Shunt Active Power Filter Enhancement by Means of Frequency-locking Complex Adaptive Linear Combiner

Abstract This article aims to improve the dynamic performance of shunt active power filters that implements their control systems in the synchronous reference frame in order to compensate non-linear loads. In synchronous-based control systems, two parts play an important role for perfect compensation: the phase-locked loop system and the harmonic extraction algorithm. Hence, this article proposes a sophisticated phase-locked loop system based on a new frequency locking complex adaptive linear combiner and an advanced harmonic extractor algorithm based on a new combined particle swarm optimization adaptive linear combiner. The objective of the first algorithm is to simultaneously and shortly estimate the fundamental of amplitude, phase angle, and frequency of the point of common coupling voltage for providing undistorted feedbacks for the control system and keep it synchronized with the power network, while the purpose of the second one is to predict the load current harmonics for the synchronous reference frame control, quickly, precisely, and dynamically. As a result, it can be claimed that shunt active power filters equipped with the proposed control system would be able to fully compensate harmonic current distortions injected by non-linear loads, even though there are frequency deviations, voltage harmonics, and sudden load changes in the system.

A new space-vector Hysteresis current-control modulation for active power filter applications

The Hysteresis current control (HCC) is a popular modulation technique used in active power filter (APF) applications owing to its simplicity of implementation, fast current response and peak current limiting capability. Despite these advantages, it has a major disadvantage when applied to three-phase isolated neutral point (INP) systems: interphases dependency causes very high-switching frequencies. To overcome this problem, this paper presents a new space-vector hysteresis current control (SVHCC) modulation for APFs when applied to three-phase INP systems. The space-vector-based method allows for the efficient use of zero-voltage vectors and prevents high switching frequencies caused by phase interference. The approach comprises of initially performing two hysteresis bands around the error vector in the αβ stationary reference frame (SRF) and then selecting the next voltage vector based on the present location of the error vector to reduce the next error vector. The proposed approach is verified through detailed simulations using MATLAB software.

Enhancing performance of active power filter with fuzzy logic controller using adaptive hysteresis direct current control

Active power filters (APFs) are widely accepted power electronic devices for compensating harmonic currents produced by nonlinear loads. The conventional technology used for APFs is a proportional-plus-integral (PI) controller. However, both the conventional approaches for determining the PI coefficients and also its structure may not provide satisfactory results under transient operating conditions such as a sudden change of load. Therefore, this paper proposes a proportional-integral-derivative fuzzy logic controller (PID-FLC) to improve the steady-state and transient performances of the conventional APF controllers. First, particle swarm optimization (PSO) is utilized to determine the optimal coefficients of the proposed PID-FLC. Then, the direct current control approach is used to generate the reference harmonic signals from the non-sinusoidal load current while an adaptive hysteresis-based current control is selected to control the compensating currents. Simulation results for a power system connected to a nonlinear load are generated to investigate the dynamic performance of APF equipped with the conventional-PI (C-PI), optimized-PI (OPT-PI), optimized-PID (OPT-PID) and optimized-PID-FLC (OPT-PID-FLC) controllers using MATLAB/SIMULINK software.