Enhancement of performance and response time of cascaded vsc statcom in the presence of voltage variation and low power factor

The power system is an extremely non-linear system with several interconnected loads. When several loads are suddenly connected at distribution ends or when the power system is subjected to the fault, the stability of the system will be disturbed. The major problems here are the voltage sag, voltage swell and low power factor (PF). A static synchronous compensator (STATCOM) is one of the most effective flexible alternating current transmission systems (FACTS) device that can inject or absorb proper reactive power to retrieve the reliability of the grid-connected systems in presence of mentioned disturbances. STATCOM circuit comprises a control circuit, voltage source converter (VSC), and PWM technique. The STATCOM performance is mainly relying on how accurately and quickly the error signal (input of control unit) is compensated. Various controllers for STATCOM control circuit have been proposed to regulate its performance, artificial neural network (ANN)- based STATCOM control circuit is the dominant and liberal solution for enhancing STATCOM performance during the period of different disturbances. The recent researches are training ANN-based STATCOM upon tackling one or two case of disturbances, which leads to creating a weak and unreliable STATCOM during the period of other disturbances that could happen through normal daily operations, whereby the STATCOM will work in reliability if ANN trains on a different range of operating states. Also, although space vector PWM (SVPWM) that uses with STATCOM is an advanced PWM method and possibly the best among all the PWM techniques, the currently used SVPWM circuit is considered complexity since it requires the calculation of switching time and sector identification. Moreover, even-though the PWM technique and VSC are parts of the STATCOM circuit, there is a lack of investigation on the effect of VSC level and switching frequency on enhancement of performance and response time while tackling disturbances. In this thesis, a developed approach for the STATCOM circuit has been introduced. The proposed STATCOM circuit includes a modified circuit of SVPWM to reduce the implementation complexity in conventional technique, hence minimizing volumetric size, and a reliable ANN control unit able to enhance performance and response time in terms of improving voltage magnitude, power factor (PF) amplitude, and STATCOM current's total harmonic distortion (THD) in the presence of five various types of disturbances, which are voltage sag ( SLG and LL fault case), voltage swell, lagging PF load, and leading PF load. Also, this thesis presented the characteristic responses of affecting factors (VSC level and switching frequency) that enhances STATCOM performance and its response time while tackling aforementioned disturbances. The simulation outcomes showed that the developed STATCOM circuit was able to enhance voltage and PF rapidly in 0.02 sec with THD less than 5% during all disturbances. Moreover, the results of changing the factors from the point of VSC level and switching frequency have proven the possibility of enhancing response time and performance of STATCOM, whereby the response time and improvement in bus voltage increase when the STATCOM based on 5-level VSC rather than 3-level VSC. In contrast, response time decreases without enhancement in voltage when the switching frequency is raising, whereas the PF amplitude and THD value are enhanced once the VSC level and switching frequency increases

The impact of partial discharge on the dielectric properties of refined bleached and deodorized palm oil (RBDPO)

Several years ago, insulation oil played an important role in electrical power equipment. Mineral oil extracted from petroleum resources (a non-renewable source) has been widely used as an insulating material in the transformers. Therefore, there is a need to find renewable alternatives to the petroleum-based mineral oil. Refined bleached and deodorized palm oil (RBDPO) is a palm-based oil which has undergone several modifications. In this paper, the dielectric properties of RBDPO and the conventional transformer oil were investigated, followed by an investigation of its partial discharge (PD) impact on the dielectric properties. The breakdown voltage was measured according to the international electrotechnical commission (IEC 6056) standard and the viscosity test was done according to BS EN ISO 3104:1996. The experiments have proved that RBDPO can be used as an insulating oil due to the closeness of its dielectric properties compared to the conventional oil

Shunt Hybrid Active Power Filter Based on Two Compensation Strategies with PI and Fuzzy Logic Controllers

Industrial designs have tremendously changed within the last decade, with its time and nonlinear variation loads in power frameworks spectrum expanding widely. This revolution has resulted in increased quality control problems such as current unbalance, current and voltage harmonics, flicker and poor power factor in control frameworks. The aim of this paper is to address this problem through the development of Synchronous Reference Frame and Reactive Power (SRF and P-Q) control methods. The DC voltage was regulated to its set reference for providing the current reference using proportional-Integral (PI) and fuzzy logic controllers. From the results, Fuzzy logic control was shown to achieve an adequate DC capacitor energy storage optimization, the sinusoidal type of the current and the change of the power factor. A low Total Harmonic Distortion (THD) that met the suggestions of IEEE- 519 standard on symphonious levels was achieved with the proposed method

Enhancement of cascaded multi-level VSC STATCOM performance using ANN in the presence of faults

A system can be disturbed in terms of stability when connected to a number of loads at the distribution ends or when subjected to faults. To reverse such systems to a stable state, FACTS devices such as static synchronous compensator (STATCOM) are used. In this paper, a cascaded multi-level voltage source converter (VSC) STATCOM was designed and implemented with a novel space vector pulse width modulation (SVPWM) scheme. Artificial neural network (ANN) controller was used instead of instead of Proportional-Integral (PI) controller in the proposed scheme to improve the response time (RT) and performance of STATCOM in terms of power factor (PF) and voltage amplitude during periods of voltage sag. During the implementation, two fault sources (single-line-to-ground (SLG) and line-to- line (LL) faults) were used to create voltage sag. STATCOM was subjected to performance evaluation in the presence of these disturbances via MATLAB simulation in IEEE 3-bus system. The outcome of the simulation studies showed the ANN controller to perform better than PI as it was able to rapidly recover voltage value (<1 cycle) with unity PF

Comparisons of PI and ANN controllers for shunt HPF based on STF-PQ Algorithm under distorted grid voltage

This paper proposes a shunt hybrid power filter (HPF) for harmonic currents and reactive power compensation under a distorted voltage and in a pollutedenvironment. For this purpose, the reference current of the shunt HPF is computed based on the instantaneous reactive power (p-q) theory with self tuning filter (STF). In order to adjust the dc voltage as a reference value, PI and ANN controllers have been utilized. Moreover, the system has been implemented and simulated in a MATLAB-SIMULINK platform, and selected results are presented. Therefore, the results verified the good dynamic performance, transient stability and strong robustness of the ANN controller. Furthermore, the shunt HAPF with ANN controller has been found to be in agreement with the IEEE 519-1992 standard recommendations on harmonic levels

Enhancing the performance of cascaded three-level VSC STATCOM by ANN controller with SVPWM integegration

This article presents a cascaded three-level voltage source converter (VSC) based STATCOM employing an artificial neuron network (ANN) controller with a new simple circuit of space vector pulse width modulation (SVPWM) technique. The main aim of utilizing ANN controller and SVPWM technique is to minimize response time (RT) of STATCOM and improve its performance regard to PF amplitude, and total harmonic distortion (THD) of VSC output current during the period of lagging/leading PF loads (inductive/capacitive loads). The performance of STATCOM is tested using MATLAB/SIMULINK in IEEE 3-bus system. The simulation results clearly proved that the STATCOM with intelligent controller is more efficient compared to a conventional controller (PI controller), where ANN enables the voltage and current to be in the same phase rapidly (during 1.5 cycles) with THD less than 5%

The impact of partial discharge on the dielectric properties of refined bleached and deodorized palm pil (RBDPO)

Several years ago, electric power equipment, insulation oil played the roles of the electrical insulation. Mineral oil has been widely used in oil impregnated electric equipment for many years. It is extracted from petroleum that is a non-renewable energy source, so its flash/fire point is low and might run out in the future. Therefore, this petroleum based oil needs to be replaced with a new type of oil that is friendly to the environment. Refined bleached and deodorized palm oil (RBDPO) is a palm based oil that has been modified in order to overcome the environment and oxidation problems. This paper deals with the experimental testing to investigate the impact of partial discharge (PD) on the dielectric properties of RBDPO. The performances of oil samples were evaluated using the test results of breakdown voltage where the Breakdown voltage was measured According to the international electrotechnical commission (IEC 6056) using standard test cell. The experiments were found that the RBDPO results were in good agreement and have high biodegradability

Shunt hybrid active power filter based on two compensation strategies with PI and fuzzy logic controllers

Industrial designs have tremendously changed within the last decade, with its time and nonlinear variation loads in power frameworks spectrum expanding widely. This revolution has resulted in increased quality control problems such as current unbalance, current and voltage harmonics, flicker and poor power factor in control frameworks. The aim of this paper is to address this problem through the development of Synchronous Reference Frame and Reactive Power (SRF and P-Q) control methods. The DC voltage was regulated to its set reference for providing the current reference using proportional-Integral (PI) and fuzzy logic controllers. From the results, Fuzzy logic control was shown to achieve an adequate DC capacitor energy storage optimization, the sinusoidal type of the current and the change of the power factor. A low Total Harmonic Distortion (THD) that met the suggestions of IEEE- 519 standard on symphonious levels was achieved with the proposed method