Firing Angle Research Articles

Generalized voltage estimation of TCSC-compensated transmission lines for adaptive distance protection

The variable performance of the thyristor-controlled series compensator (TCSC) system represents a vital challenge for conventional distance relays. Most existing algorithms are based on the measured data at two ends of the TCSC-compensated lines. However, some of single-end algorithms need to modify the distance relay for the series capacitor (SC) only. This paper introduces a generalized algorithm to estimate the voltage drop across the TCSC. The distance relay uses the estimated TCSC voltage drop for terminal voltage compensation. The second objective of the proposed algorithm is to estimate the conduction angle of the thyristor-controlled reactor (TCR) branch under different modes of operation. This algorithm is effective for different TCSC modes such as the capacitive or the inductive modes, in addition to the method of firing angle of synchronization current or voltage synchronization modes. The main benefit of the proposed algorithm is presenting a parameter-less distance scheme for TCSC-compensated transmission line. A 400-kV overhead transmission line test system is simulated in MATLAB/SIMULINK package® and the numerical modeling is implemented in the MATLAB® script in order to evaluate the proposed algorithm effectiveness. The proposed technique is tested under several stress conditions that may face the conventional distance relay. The results illustrate the effective performance of the proposed algorithm.

A New Adaptive Broadband Thyristor-Controlled Impedance Matching Network

In this article, we present an adaptive broadband thyristor-controlled impedance matching network (TCIMN) for increasing power utilization from a power amplifier to the loads. Different from the conventional passive impedance matching methods, the proposed one can achieve load impedance matching under a wide frequency range of power amplifiers. First, the operation principle of TCIMN is introduced mathematically. Based on that, the parameter design method is proposed based on the required frequency range. Moreover, the operating range and harmonic analyses are provided to give the TCIMN firing angle operating ranges under different frequencies and alleviate the potential harmonic problem caused by thyristors. To control the proposed TCIMN, the dynamic impedance identification is applied to match the load reactive power adaptively. Finally, the simulation and experimental results of a prototype are given to demonstrate the validity of the proposed TCIMN, analysis, and control method. The results clearly show that the proposed TCIMN can adaptively match the load impedance for the different loads and broadband frequency range. More importantly, the power amplifier power utilization factor is significantly improved without causing harmonic pollutions.

Numerical Investigation on the Asymmetric Flow Characteristics of Two Propane Fires of Unequal Heat Release Rate in Open Space

Multiple fires of unequal heat release rate (HRR) is a common fire scenario in real fire accidents. Differing from most previous research assumption of identical fire sources, the unequal HRR for those fire sources is regarded as more reasonable in reality. To explore the asymmetric flow characteristics surrounding multiple fires under such circumstances, simulations of two square propane burners with the same side length but different HRRs were carried out. The HRR combination and burner separation distance were varied. The results showed that the asymmetric flow characteristic was found in both the flame and the smoke plume zone. In the flame region, the flame morphology in terms of the tilt angle is a good parameter indicating the asymmetric flow characteristic. In general, the tilt angle of the small fire is larger than that of the big fire. The tilt angle of the small fire decreases while that of the big fire increases until equaling to each other under the HRR ratio reaching unity. In the smoke plume region, the smoke plumes from the small and the big fire will converge at a certain height with some shifting distance, which is another parameter indicating the asymmetric flow characteristic. Besides, the smoke plume merging process driven by asymmetric air entrainment can be divided into three stages, namely the I) Separate stage, II) Converging stage and III) Complete coalescence stage. Correlations of the converging & coalescence height suggesting the starting point of the II and III stages were proposed.

Design and implementation of model predictive control for microgrid energy system with power quality improvement features

ABSTRACT The harmful outcome of fossil fuel emission and growing concern about the deficiency of power resources has started a new requirement of cleaner, reliable, and sustainable energy resources. Thus, wind power and solar energy based systems are the best emerging energy sources amongst the various renewable energy resources. The proposed system involves a boost converter with an inverter circuit, where first solar and wind energy is regulated, and the inverter is employed for grid integration. In the proposed work, model predictive control is applied to a 3-phase inverter and it uses a model to estimate the predictions of upcoming values of the system voltage for a provided sequence of voltages. Further, the cosine firing angle arrangement is also used for adjusting the output voltage of the boost converter. The three-phase inverter is also employed as a harmonic reduction device, this allows the utility grid to continuously supply or absorb the good quality of power. The proposed approach escapes the use of nonlinear and linear controllers and it does not include the modulator, hence this is a simple method and the control algorithm is easy to implement. The outcomes show that the planned scheme has excellent performance.

A Developed H-Bridge Cascaded Multilevel Inverter with Reduced Switch Count

Multilevel Inverter integrates several Direct Current (DC) sources to produce a single-phase Alternating Current (AC) waveform that can be used to meet the domestic and commercial power demand. This article introduces a novel Multi Source Cascaded Multilevel Inverter with a reduced number of switches for the efficient use of DC voltage sources. The conversion efficiency can be increased by the presented topology which is simple in design to overcome the significant switching losses in the power electronics devices. Optimal Firing Angle and Phase Opposition Disposition Pulse width Modulation Techniques were used to reduce the harmonics at the desired output of the inverter and also to improve the power quality of the presented topology. This article also proposes two Asymmetric Multilevel Inverter Topologies. A comparison has been made, on the number of switches required and the efficiency of the inverters to differentiate the presented Topologies from other topologies of the multilevel inverter. Finally, the performance characteristics of the presented topologies have been designed and investigated using MATLAB Simulation. Simulation results were validated using an experimental setup.

Controllable-Dual Bridge Fault Current Limiter for Interconnection Micro-Grids

Different types of fault current limiters (FCLs) have been developed and designed based on non-superconducting DC reactors (NSDRs). This paper proposes a controllable dual-bridge FCL (CDBFCL) based on the NSDR for use in an AC-type micro-grid. It includes a NSDR and two series and shunt bridge circuits. The series bridge is based on diode semiconductor switches and is coupled in series with the line via a transformer. The shunt bridge is based on thyristor semiconductor switches and is coupled in parallel with the line. The shunt bridge provides a variable voltage source. It compensates for the DC side voltage drop due to NSDR resistance and semiconductor switches during normal operating condition. In addition, by controlling the shunt bridge firing angle, it produces a controllable DC voltage, which can control the fault current amplitude during a fault. The structure, principle operating work, and control system of the proposed CDBFCL are presented. The CDBFCL performance is studied analytically and through simulation by the PSCAD/EMTDC software. In addition, the simulation results are compared with those obtained experimentally from a prototype CDBFCL and show a close correlation.

Effective Controls of Fixed Capacitor-Thyristor Controlled Reactors for Power Quality Improvement in Shipboard Microgrids

Addressing power quality issues in shipboard microgrids (SMs), which are mainly attributable to the increased installation of power converters, has received much attention recently. To this end, static VAR compensators, such as thyristor-switched capacitors and fixed capacitors-thyristor controlled reactors (FCs-TCRs), can be effective solutions. Controlling these compensators, however, is not a trivial task as it involves sophisticated operations, especially estimating the firing angle, which should be carried out based on some nonlinear equations. This article aims to propose the application of some simple yet numerically efficient algorithms based on bisection, Newton-Raphson, false position, and secant methods for estimating the firing angle of the FC-TCR. The effectiveness and robustness of these algorithms are demonstrated via modeling of the FC-TCR with the electrical power system of a practical hybrid ferry under MATLAB/Simulink environment, where the results proved that the enhanced power quality issues respect the IEC standards 61000-4-7/30. Furthermore, an experimental setup consists of a digital signal processor and a programmable source is used to demonstrate that these techniques can be effectively applied in real-time applications.

PWM Inverter with Digital Microcontroller for Speed Control Applications

Inverters are the record significant device to apply renewable energy resourcefully. A planned technique is used to control the output voltage and frequency. This method depends on- offline designs of the width of the signals for only the first quarter cycle and stores. The residual pulses, for comprehensive sequence, are generated by using the values of the first quarter for there are situations of quarter and half–wave symmetry. The chief structures of microcontroller 8951 constructed PWM inverter are simpler strategy, small price, extreme choice of voltage control and compressed in size. This outcome in a large saving of microcontroller time and memory. These groups of firing angles(α) are designed which characterize the expected voltage difference. The microcontroller notices the peak of the output voltage to sense the voltage variation and then implement the suitable table to keep the voltage within the required value. The programmable timer sets the necessary 120° phase shift between the three phases. This paper observes several guidelines to select a technique suitable for application at a specified power level, switching frequency and dynamic response. Simulation outcomes are gotten for success of the test.

Line Commutated Converter Response during Total and Partial De-Blocking of a Bipolar MTDC System

This paper focuses on the fault blocking analysis and operational issues associated with MTDC systems incorporated in an AC network. The dynamic modelling of a line-commutated converter based bipolar multi-terminal direct current (LCC MTDC) system are shown, and the dynamic response of the converter during a DC converter fault is discussed. The converter controller design for both rectifiers and the inverters system was modelled for a realistic active power and extinction angle (γ) control with consideration to the VI characteristics of all the converter stations. An overall power controller was modelled for both converter pole. Two operational scenarios of converter fault were simulated using PSCAD EMTDC. The converter firing angle and extinction angle, as well as the voltage-dependent current order limiter, was monitored and plotted on a graph. Results show that the MTDC link became unstable during the full deblocking stage with a continuous occurrence of commutation failure. Furthermore, the results presented in this paper show that during partial converter de-blocking showed a favourable performance, as the power system remains stable and commutation failure of the MTDC system is prevented.

Total Harmonic Distortion and Power Factor Analysis of Thyristor Firing Angle on Electrostatic Precipitator in PLTU Unit 3 & 4 Pangkalan Susu Capacity 2 X 200 MW

The impact of pollution resulting from exhaust gas in the form of coal ash in the Steam Power Plant makes the Electrostatic Precipitator an equipment that can handle these problems. The equipment has a voltage level regulation system using a thyristor which with a certain value can create an electric field capable of capturing charged ash. The thyristor system has a disturbance known as harmonics. Good handling to overcome harmonics is to measure using a certain index, one of which is the Total Harmonic Distortion (THD) and to know its effect on the power factor. In this research, an analysis of the electrostatic precipitator system at PLTU Pangkalan Susu will be carried out by collecting the necessary data and the firing angle installed in the company. From the test results, it can be said that the THD value in the Electrostatic Precipitator system at PLTU Units 3 & 4 Pangkalan Susu is in the normal range. To find out the range of compatible firing angles on the system, it is also necessary to provide a test variable angle. Based on the test, it is known that the firing angle installed in the company is 46 degree with THDv and THDi of 4.01 percent and 3.61 percent respectively and the Power Factor is 0.84876. Whereas with the test variable angle, it is known that the good or normal THDv and THDi values are in the range 30 degree to 60 degree where the THDv value is in the range of 3.83 percent to 4.91 percent and the THDi value is in the range of 3.50 percent to 4. 21 percent.

Enhancing Distance Protection of Long Transmission Lines Compensated With TCSC and Connected With Wind Power

Thyristor controlled series compensation (TCSC) is widely used in long transmission lines to mainly improve power transfer capability. However, TCSC produces complicated impedance that negatively affects distance protection operation. The wind energy generation system produces additional complexity to the distance protection performance due to the variation of wind speed and fault current level. This paper proposes an integrated scheme to change adaptively the settings of the Mho distance protection by shifting the relay characteristics considering the bad impacts of TCSC, wind power and fault resistance. The proposed scheme achieves its main stages starting from fault detection, until relay tripping decision procedure including online estimation for preliminary fault location, impedance of TCSC and fault resistance using limited communication requirements. By extensive MATLAB simulations, the performance of the proposed scheme is examined compared with the conventional Mho relays under different fault locations, fault inception angle, fault resistance, different wind power penetration, different wind speeds and different TCSC firing angles. The achieved results ensured that the proposed scheme improves significantly Mho distance relay operation and avoids under-reaching and over-reaching problems irrespective of the large shunt capacitance along the transmission line, and also without identifying the parameters of TCSC such as the capacitance, the inductance or the firing angle.

More Efficient AC Filterless Flexible LCC HVDC by Analyzing the Impact of Single-Phase Fault on Commutations

Single-phase fault is the most commonly occurred and severe AC fault that causes most of the Commutation Failures (CF) in LCC HVDC systems. It has long been regarded as having the same level of adverse impact on commutations of both 6-pulse bridges in the 12-pulse LCC HVDC scheme. This has resulted in the same level of investment on both 6-pulse bridges, for CF mitigation/elimination, e.g. firing angle advancement and equipment investment. However, due to different winding configurations of converter transformers, single-phase fault actually affects each 6-pulse bridge to different degrees. Based on the previously proposed AC Filterless Flexible LCC HVDC, this paper shows that, compared with the Y-Y bridge, the Y-Δ bridge has much smaller undesired phase advancement of the actual commutation voltage (commutation voltage at secondary side of converter transformer) under severe single-phase fault. As a result, the required voltage rating of controllable capacitors for Y-Δ bridge can be reduced, leading to considerable savings from reduced equipment costs and lower losses of controllable capacitors without compromising the commutation performance. The detailed theoretical analysis in this paper provides a valuable foundation for the development of more efficient CF mitigation/elimination strategies. Simulation results of 1) CIGRE HVDC benchmark system and 2) the same benchmark system but connected to a 39-bus inverter AC network are presented to validate the correctness of the analysis.

Artificial Neural Network and Newton Raphson (ANN-NR) Algorithm Based Selective Harmonic Elimination in Cascaded Multilevel Inverter for PV Applications

In this article, a hybrid Artificial Neural Network - Newton Raphson (ANN-NR) is introduced to mitigate the undesired lower-order harmonic content in the cascaded H-Bridge multilevel inverter for solar photovoltaic (PV). Harmonics are extracted by the excellent choice of opting switching angles by exploiting the Selective Harmonic Elimination (SHE) PWM technique accompanying a unified algorithm in order to optimize and reduce the Total Harmonic Distortion (THD). ANN is trained with optimum switching angles, and the estimates generated by the ANN are the initial guess for NR. In this study, the CHB-MLI is combined with a traditional boost converter, it boosts the PV voltage to a superior dc-link voltage Perturb and Observe (P&O) based Maximum Power Point Tracking (MPPT) algorithm is used for getting a stable output and efficient operation of solar PV. The proposed system is proved over an eleven-level H-bridge inverter, the work is carried out in MATLAB/Simulink environment, and the respective results are confirmed that the proposed technique is efficient, and offers an actual firing angles with a few iterations results in a better capability of confronting local optima values. The suggested algorithm is justified by the experimental development of eleven-level cascaded H-bridge inverter.

Multi-Type Diesel Engines Operating Condition Recognition Method Based on Stacked Auto-Encoder and Feature Transfer Learning

It is of great significance to diagnose the fault of diesel engine, which is widely used in many important fields as key power equipment. The accuracy of fault diagnosis can be effectively improved by obtaining the complex and changeable operating conditions, which can result in the change of monitoring signals. This study proposes a variable operating conditions recognition method based on stacked auto-encoder (SAE) and feature transfer learning. In this method, the vibration in the firing angle domain collected from multi-sensor signals is reconstructed. Then a feature set sensitive to working conditions is extracted from the recombinant signals by a well-constructed stack auto-encoder. According to the dataset test, the softmax classifier can effectively get a high recognition accuracy. Considering that the fault may affect the condition identification, the misfire fault that has a great influence on firing angle domain signals is used to test the robustness of the proposed method. Besides, to enable a well-trained test rig with a large amount of data to be effectively applied to another unit that lacks data, the BDA transfer learning method is used to map the operating conditions of two different engines to the same feature space. The results of experiments conducted on two large power marine multi-cylinder diesel engines show that BDA is capable of transferring the sensitive features of operating conditions.

System configuration of instrumented half-scaled armoured vehicle to enhance handling performance due to lateral firing impact

Yaw disturbance rejection control (YDRC) is developed to improve the handling performance of armoured vehicle due firing impact. Therefore, a complete system configuration of instrumented half-scaled armoured vehicle is required to interface the YDRC algorithm with integrated measurement and control (IMC) data acquisition system, inertial measurement unit (IMU) and rotary encoder sensors. By using this configuration, the impact of firing test has been evaluated at maximum firing angle of 90° and vehicle speed of 40 km/h. Based on the actual testing, the handling response of the armoured vehicle in terms of yaw rate and angle, lateral displacement and acceleration has been improved compare to passive armoured vehicle up to 45% of reduction.

System configuration of instrumented half-scaled armoured vehicle to enhance handling performance due to lateral firing impact

Yaw disturbance rejection control (YDRC) is developed to improve the handling performance of armoured vehicle due firing impact. Therefore, a complete system configuration of instrumented half-scaled armoured vehicle is required to interface the YDRC algorithm with integrated measurement and control (IMC) data acquisition system, inertial measurement unit (IMU) and rotary encoder sensors. By using this configuration, the impact of firing test has been evaluated at maximum firing angle of 90° and vehicle speed of 40 km/h. Based on the actual testing, the handling response of the armoured vehicle in terms of yaw rate and angle, lateral displacement and acceleration has been improved compare to passive armoured vehicle up to 45% of reduction.

Improved predictive calculation-based extinction angle control for HVDC

In HVDC projects, the predictive calculation-based extinction angle control (PC-EAC) generates the firing angle order by means of open loop. Under the steady-state condition, the result of its calculation is accurate. However, when a fault occurs in AC system, a serious calculation error will exist, which increases the risk of commutation failure. Therefore, an improved control is proposed. In this control, the firing angle order of each converter valve is separately calculated according to its commutation voltage, and considering the influence of the firing pulse control system, a compensation term is added to eliminate the deviation between actual firing angle and its order. In order to ensure the equidistant pulse control of each converter valve, the minimum firing angle order of all valves is taken as the output of the controller. Finally, several simulations are conducted on the CIGRE HVDC Benchmark model and a ±500 kV/3 kA project model to validate the performance of the proposed strategy. The simulation results show that the proposed control can effectively reduce the risk of commutation failure, and make the system recovery more stable.

A Proposed ANN-Based Acceleration Control Scheme for Soft Starting Induction Motor

In this article, a new soft starting control scheme based on an artificial neural network (ANN) is presented for a three-phase induction motor (IM) drive system. The main task of the control scheme is to keep the accelerating torque constant at a level based on the value of reference acceleration. This is accomplished by the proper choice of the firing angles of thyristors in the soft starter. Using the ANN approach, the complexity of the online determination of the thyristors firing angles is resolved. The IM torque-speed characteristic curves are firstly used to train the ANN model. Secondly, the IM- soft starter system is modeled using MATLAB/SIMULINK. To prove the effectiveness of the proposed ANN-based acceleration control scheme, different reference accelerations and loading conditions are applied and investigated. Finally, a laboratory prototype of 3 kW soft starter is implemented. The proposed control scheme is executed in a real-time environment using a digital signal processor (Model: TMS320F28335). The simulation and real-time results significantly confirm that the proposed controller can efficiently reduce the IM starting current and torque pulsations. This in turn ensures a smooth acceleration of the IM during the starting process. Moreover, the proposed control scheme has the superiority over several soft starting control schemes since it has a simple control circuit configuration, less required sensors, and low computational burden of the control algorithm.

Research into the dynamic loading on the carrying structure of a flat wagon with lower center of gravity when transporting firing equipment

The article presents the study results of the dynamic loading of a flat wagon with a lower gravity center.The authors built a mathematical model that takes into account displacements of a flat wagon loaded with an anti-aircraft installation firing in motion. The solution of the differential equations of motion is carried out by using the Runge-Kutta method. The maximum vertical acceleration was about 5 m/sec2 and almost independent of the fire angle. The horizontal acceleration was about 37 m/sec2. The acceleration values obtained did not exceed the normative ones. The study defined the natural oscillation frequencies for the frame of a flat wagon with lower gravity center. It was established that the critical oscillation frequencies were within the admissible values. The results of the work will contribute to the creation of recommendations on the transportation of military equipment on wagons and the possibility of conducting military operations from them.

RETRACTED ARTICLE: A novel design and performance improvement of symmetric multilevel inverter with reduced switches using genetic algorithm

Multilevel inverter (MLI) synthesizes the preferred level of alternating voltage from multiple input sources of lower-level direct voltage. By adopting a suitable harmonic elimination technique, the MLI produces stepped sinusoidal waveforms with reduced total harmonic distortion (THD) without using any filter-based applications. MLI will be an apt choice for industries operating under medium- and high-power alternating current (AC) drives, and this finds application in interfacing non-conventional energy sources with power grid lines. This paper emphasizes a novel design of performance-enhanced cascaded MLI (PEC-MLI) with less quantity of switching devices for renewable energy system. The desired switching of MLI cost function is calculated using Genetic Algorithm (GA), and the appraised firing angle is calculated and the same is given as input to the Pulse Width Modulation (PWM) technique coded with chosen Nearest Voltage Level (NVL) control scheme. The gating signals generated for switching devices with the control strategies of NVL—PWM and hybrid PWM techniques using Genetic Algorithm. The MATLAB/Simulink model successfully evaluates the performance of proposed MLI. The simulated results analyze the system efficiency by comparing it with other similar MLI configuration cited in recent research articles. An effective realization of proposed MLI is experimented successfully and whose results are found be satisfactory with the simulated results.