International Journal of Applied Power Engineering (IJAPE)
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A Fault Detection Technique for Series-compensated Lines by TCSC during Power Swing
Get PDFThe performance of a distance relay is very susceptible to power swing. In order to avoid generating unwanted trip in such condition, a power swing block function (PSB) is used in distance relays. However, if a fault occurs in power swing condition, the relay should distinguish the fault from power swing and generate trip rapidly. Detection a fault in a series-compensated line by Series Capacitor (SC) during the power swing is more complicated than in an uncompensated line due to complex transients generated by series capacitor and the Metal–Oxide Varistor (MOV) operation. In a series-compensated line by TCSC, it is further complicated due to nonlinear variation of compensation level during power swing and fault, moreover, non-unique application mode of TCSC for different faults which is dependent on fault current. This paper examines a method based on negative sequence current to detecting all types of fault during power swing in a series-compensated line by TCSC. The method is tested for different TCSC-compensated power systems include SMIB and 9-bus 3-machine systems. Different types of faults, i.e., symmetrical, asymmetrical and high resistance faults occurring during a power swing are simulated by MATLAB/SIMULINK to examine the algorithm
Netload-constrained Unit Commitment Considering Increasing Renewable Energy Penetration Levels: Impact of Generation Schedules and Operational Cost
Get PDFIn the context of low carbon power systems, the penetration levels of Renewable Energy Sources (RES) are expected to increase dramatically. In this regard, this paper investigates the maximum RES penetration level constrained by net load while considering an inflexible Unit Commitment (UC) model. To solve the UC problem, an enhanced priority list (EPL) based method is developed. In the proposed method, the plants were activated sequentially based on the operational price. The system constraint violations were repeatedly corrected until all system constraints (such as net load and spinning reserves) were satisfied. The proposed EPL method was efficient to achieve a near optimal solution under high shares of RES. Furthermore, the research work investigates three different scenarios representing penetration levels of 10% solar-only, 14.5% wind-only and 27.5% mixture of both solar and wind. The impact of each penetration level on the system scheduling and operational cost were analyzed in detail. The analysis presented shows that a potential operational cost savings of 21.6 /MW and 11.1 $/MW is feasible under each of the represented scenarios, respectively
Vector Control of VSC HVDC System under Single Line to Ground Fault Condition
Get PDFThis paper proposes a model of a VSC (voltage source converter) based Back to Back HVDC system and its control technique under fault condition. From the mathematical model of the system relationship between the controlling and the controlled variables is determined to control the system parameters. An appropriate vector control technique is used to control active and reactive power and to maintain DC link voltage. The proposed controlling unit consists of outer control loop and inner control loop which effectively damped out the system oscillation and maintains the system stability. The validity of the model and the feasibility of the control method have been proved by the simulation results. In this paper the system performance is studied under fault condition is studied
Three Area Power System Load Frequency Control Using Fuzzy Logic Controller
Get PDFSystem frequency is one of the most important parameters of a power system. Du to generation-load mismatches, the system frequency can vary over a small range. When the power consumed by loads and overall losses is greater than the generated power, the operating frequency of the system will decrease, resulting in a situation known as the under frequency condition. In some other case, if some of the loads in a system are disconnected from the system suddenly, or lost, it leads to a condition called as the over frequency condition. This condition is char acterized by greater input power than the consumed power by the loads. The rest of the loads in the system will absorb the extra power and the generator inertia, leading to an increase in the system frequency. In both the cases, the system frequency fluctuates from the power system’s limited frequency range, further leading to tripping off of the substation and further collapsing of the entire system. The paper describes a new method employing a smart meter to monitor and control the power system frequency which changes according to the loading conditions in the system, whether under load condition or overload condition.
Analysis of Various Carriers Overlapping PWM Strategies for a Single Phase Ternary Multilevel Inverter
Get PDFMultilevel inverters are used in power conversion system due to improved voltage and current waveforms. This paper presents the comparison of various Carrier Overlapping Pulse Width Modulation (COPWM) Strategies for the three phase Cascaded Multi Level Inverter (CMLI). Various new schemes adopting the constant switching frequency and also variable switching frequency multicarrier control freedom degree combination concepts are developed and simulated for the chosen three phase CMLI. A single phase CMLI is controlled in this paper with Sinusoidal PWM (SPWM) reference along with Carrier Overlapping (CO) techniques and simulation is performed using MATLAB-SIMULINK. The variation of fundamental RMS output voltage and total harmonic distortion is observed for various carrier overlapping techniques. Among the various equal amplitude and unequal amplitude carriers carrier overlapping techniques such as COPWM-A, COPWM-B and COPWM-C, It is observed from Table 4 that all PWM method provides output with relative low distortion for equal amplitude carriers. If equal voltage sources are chosen then the THD will be less in the case of unequal amplitude carriers. But for the unequal voltage sources the THD is more in the case of unequal amplitude carriers. It is observed from simulation results that (Table-5) almost in all the strategies unequal amplitude carriers gives more fundamental RMS values compared to equal amplitude carriers. It is seen from table 6 that peak voltage is more in the case of unequal amplitude carriers compared to equal amplitude carriers. It is observed from the table 7 that dc components are less in both equal and unequal amplitude carriers
Meleagris Gallopavo Algorithm for Solving Optimal Reactive Power Problem
Get PDFIn this paper, Meleagris Gallopavo Algorithm (MGA) is proposed for solving optimal reactive power problem.As a group-mate Meleagris gallopavo follow their poultry to explore food, at the same time it prevent the same ones to eat their own food. Always the overriding individuals have the lead to grab more food and Meleagris gallopavo would arbitrarily pinch the high-quality food which has been already found by other Meleagris gallopavo. In the region of the mother Meleagris gallopavo, Poults always search for food. In the Projected Meleagris Gallopavo Algorithm (MGA) additional parameters are eliminated, in order to upsurge the search towards global optimization solution.Proposed Meleagris Gallopavo Algorithm (MGA) has been tested on two modes a. with the voltage stability Evaluation in standard IEEE 30 bus test system, b. Without voltage stability Evaluation in standard IEEE 30, 57,118 bus test systems & practical 191 test system. Simulation results show clearly the better performance of the proposed Meleagris Gallopavo Algorithm (MGA) in reducing the real power loss, enhancement of static voltage stability Index and particularly voltage profiles within the specified limits
Micro Hydropower System Design for Gua Kelam Electricity Supply
Get PDFSufficient and uninterrupted electricity supply is one of the main factors to develop the country. Today, electricity can be generated using a variety of sources, whether from non-renewable sources as well as renewable resources. To generate electrical power, Malaysia can't rely entirely on non-renewable resources such as petroleum and coal as these are finite resources which are experiencing depletion around the world. Electricity generated from renewable sources such as water, particularly from micro hydropower systems is considered the cheapest and most environmentally friendly source of electrical energy. Based on the reconnaissance study conducted, the streams of flowing water in Gua Kelam have the potential to yield about 34.29 kW of electricity power, based on the head height of 27 m and flow rate 0.216 m3/s. In this paper, a model for an ordinary micro hydropower facility has been proposed. It links various electromechanical equipment consisting of a hydraulic turbine governor, and a synchronous generator. The modeling was executed to design a micro hydropower system as an alternative source of supply of electricity to Gua Kelam, Perlis. The proposed model was tested by placing a three-phase fault to earth for the purpose of testing the reliability of the system. With the selection of an appropriate control system, the proposed model is very suitable for the development of micro hydropower system at a potential site such as Gua Kelam
Seven Level Inverter Fault Mitigation Using Redundant Cell for Induction Motor Drive
Get PDFFaults that might occur in inverter driven induction motor drives. In this paper, seven-level multi level inverter was taken up for testing of mitigation using redundant cell and the results were compared with five-level inverter to exhibit the performance of mitigation policy. This paper presents analysis of inverter feeding an induction motor drive when switch open and short fault occurs. When the fault occurs, the redundant cell activates and thus the drive system operates. In this paper, the function for redundant cell was explained with the results of drive system simulated in Matlab/Simulink
Robust Speed-Sensorless Vector Control of Doubly Fed Induction Motor Drive Using Sliding Mode Rotor Flux Observer
Get PDFThis paper presents a robust observer for sensorless speed control of doubly fed induction motor (DFIM), based on the slidin mode. In the first step, a model of the doubly fed induction motor fed by two PWM inverters with separate DC bus link is developed. In the second step and in order to provide a robust separate control between flux and motor speed a vector control by field oriented strategy applying a sliding mode regulator was implemented. Finally, speed estimation of a doubly fed induction motor based on sliding mode observer is presented. The simulation tests schow the effectiveness of the proposed method especially in the load disturbances, the change of the refrence speed and low speed. Also the influence of parameter variations will be studied by simulatio
Analysis of Six-Phase Interior Permanent Magnet Synchronous Machines for Optimal Parameter Considerations
Get PDFUnderstanding the merits of six-phase interior permanent magnet synchronous machines (IP-MSMs) over their three-phase counterparts, this paper analyses the six-phase machine for optimal parameter and performance considerations. Initially, a mathematical model of the six-phase IPMSM is developed employing the dq-axis theory and performance predicted by the model is verified under identical operating conditions with those using a machine designed and tested through finite element analysis (FEA). The developed and verified machine model is then employed to exclusively derive the relation between various machine parameters in order to obtain optimum flux weakening region in the six-phase IPMSM. Thereafter, the equations derived on the basis of maximum torque per ampere (MTPA) control theory are analyzed to understand the effect of various parameters and variables in influencing the machine’s performance in the ‘constant torque’ region and ‘constant power’ region, power output capability, a ratio of reluctance torque to magnet-assisted torque with changes in the stator current vector etc. This is the contribution of this paper