Ardyono Priyadi

A New Method for Obtaining Critical Clearing Time for Transient Stability

This paper proposes a new formulation for transient stability analysis for electric power systems. Different from existing methods, a minimization problem is formulated for obtaining critical clearing time (CCT) for transient stability. The method is based on the computation of a trajectory on the stability boundary, which is referred to as critical trajectory in this paper. The critical trajectory is defined as the trajectory that starts from a point on a fault-on trajectory at CCT and reaches a critical point of losing synchronism. The new proposal includes a modified trapezoidal formulation for numerical integration, the critical conditions for synchronism, and the unified minimization formulation. It will be demonstrated that the solution of the minimization problem successfully provides the exact CCT that agrees with the conventional numerical simulation method.

Transient stability assessment as boundary value problem

This paper proposes a method for transient stability analysis for multimachine electric power systems. Different from existing methods, a minimization problem with boundary values is formulated for obtaining critical conditions for transient stability, where a new numerical integration method is developed by modifying the trapezoidal formula to solve effectively the boundary value problem. The proposed method is to compute directly a trajectory on the stability boundary, which is referred to as critical trajectory in this paper. The critical trajectory to be obtained is the trajectory that starts from a point on a fault-on trajectory and reaches a critical point such as an unstable equilibrium point (UEP), or more exactly, controlling UEP (CUEP). The solution of the minimization problem provides the critical trajectory and the exact critical clearing time (CCT) without major approximation.

Digital overcurrent relay with conventional curve modeling using Levenberg-Marquardt backpropagation

Overcurrent relays (OCRs) play an important role in the protection component that requires high reliability to maintain high security for power systems. Modeling of the OCRcurve using methods like the direct data storage and curve fitting gave only approximate models. Therefore, in this paper proposes modeling of OCRs using Levenberg-Marquardt backpropagation (LMBP). An implementation of OCR in the digital OCR used ARM microcontroller STM32F407VGT6 is to improve performance of the relay significantly. LMBP is developed using different numbers of neurons. The current and opening time of the circuit breaker are used as input and output in the LMBP training. LMBP developed in the OCR curve model using sample data from protection coordination is implemented as real time in Hess Indonesia Corporation. The weights obtained by the LMBP are used to run the LMBP program in the digital OCR. The well known digital OCR product is used for comparison. The results show that this proposed method is accurate and encouraging with percentage error is 0.24% and very promising to be applied in the digital OCR.

Overcurrent relay curve modeling and its application in the real industrial power systems using adaptive neuro fuzzy inference system

Create an accurate model with over-current relays (OCRs) play an important role in the coordination of power system protection. Modeling of the OCR using methods like the direct data storage and software models gave only approximate models. Moreover, modeling based on mathematical models is not appropriate to deal with ill-defined and uncertain systems. Therefore, in this paper proposes modeling of OCRs using adaptive neuro fuzzy inference system (ANFIS). ANFIS is developed using different numbers and types of membership functions (MFs). Each MF is implemented using training and checking data. The load current and time of opening of the circuit breaker are used as input and output in the ANFIS training. ANFIS, which is developed in the OCR curve model using sample data from protection coordination, is implemented in Hess Indonesia Corporation. Different types of MFs are to obtain the optimal design of OCR curves. The result of ANFIS in the OCR curve modeling is accurate and encouraging; thus, the ANFIS model can be used in digital relays and applied successfully in the real systems. In all cases, ANFIS models using 30 Gbell-type MFs yields a very minimum average percentage error of 0.028419 %.

Photovoltaic module and maximum power point tracking modelling using Adaptive Neuro-Fuzzy Inference System

This paper proposes an intelligent control method using Adaptive Neuro-Fuzzy Inference System (ANFIS) for maximum power point tracking (MPPT) of PV module. The method is verified under several irradiance and temperature conditions. DC - DC boost converter is connected between the PV module and the load. Duty cycle of DC - DC boost converter is controlled by ANFIS in order to obtain the MPPT. The ANFIS directly takes operating power and voltage level as input. The proposed system is developed under Simulink-Matlab and the system of PV is simulated in PSIM to verify the effectiveness of method. The results show the proposed method can obtain the highest output power than Fuzzy Logic (FL) and Perturbation and Observation (P&O) method i.e., 30.893 and 42.973 for irradiance is 750W/m2 and 1000W/m2, respectively.

Overcurrent relay curve modeling using adaptive neuro fuzzy inference system

In this paper, modeling of overcurrent relay (OCR) curves using adaptive neuro fuzzy inference system (ANFIS) are proposed. The accurate models of OCR curve with inverse time relay characteristics have an important role for protection coordination of power system. Models of OCR curve are appropriate with IEC standard. This model implements of microcontroller AT mega 128 as digital relay and personal computer as facility to design of OCR curve. ANFIS is developed to OCR curve modeling with different types of membership function and each membership function is trained for 10 iterations. Input for training to OCR curve using the load current and current setting or IL/IS. Time to opening the circuit breaker or TCB is used as output for training of OCR curve. ANFIS is developed using visual basic. The simulation results are compared with different types of membership function to obtain the optimal design of OCR curve. Moreover, the testing results are compared with OCR curve modeling to check validation and accuracy of the proposed model.

Critical Trajectory Method for Transient Stability Analysis

This paper proposes a method for transient stability analysis for multi-machine electric power systems. Different from existing methods, a minimization problem with boundary values is formulated for obtaining critical conditions for transient stability, where a new numerical integration method is developed by modifying the trapezoidal formula to solve effectively the boundary value problem. The proposed method is to compute directly a trajectory on the stability boundary, which is referred to as critical trajectory in this paper. The critical trajectory to be obtained is the trajectory that starts from a point on a fault-on trajectory and reaches a critical point such as an Unstable Equilibrium Point (UEP), or more exactly, Controlling UEP (CUEP). The solution of the minimization problem provides the critical trajectory and the exact Critical Clearing Time (CCT) without major approximation.

Maximum power point tracking algorithm for photovoltaic system under partial shaded condition by means updating β firefly technique

This paper proposes new Simplified Firefly Algorithm (SFA) with an updated β coefficient to maximum power point tracking (MPPT) of photovoltaic system under partial shading condition. The different from standard firefly algorithm is neglected a and y coefficients to simplify an algorithm. The other new feature is updated β coefficient for each iteration step in order to achieve faster convergence. This proposed algorithm is to obtain the optimal solution for MPPT of PV system under three shaded conditions. The simulation results are compared with traditional Perturbation and Observation (P&O) and standard Firefly Algorithm (FA) to verify the proposed method performance. Highest maximum powers and efficiencies are produced by the proposed algorithm. The ripple in steady state condition is also better than P&O and standard FA. The main advantage of proposed algorithm is simpler and faster convergence yet still accurate compared to standard firefly.

Modeling and simulation of MPPT-bidirectional using adaptive neuro fuzzy inference system (ANFIS) in distributed energy generation system

Photovoltaic system (PV) is widely used in various renewable energy application. The main problem of PV system is how to get the maximum output power. Furthermore, the redundancy output power generated by on a distribution system should also be considered. This study utilizes the excess power for energy storage using bidirectional converter. Since the DC voltage which generated by PV and the energy storage will be converted into AC voltage using inverter toward load. This paper proposes ANFIS as search optimization method using SEPIC converter with a maximum efficiency of 99.95%.

Designing angle bowl of turbine for Micro-hydro at tropical area

Tropical area has two seasons, which are rainy and dry seasons. In the rainy season. In the rainy season, the river flows a large amount of water, usually causing flood, conversely, the river shrinks in the dry season. The Excess water can be used to turn turbines. Turbine which is used to turn the generator will produce electric energy. To generate electrical energy in a long time with the condition of the changing seasons, an efficient turbine is required beside the water level, pressure and diameter of the turbine should be considered. In this paper we discus the turbine bowl angle settings to get the maximum volume of water to produce maximum torque of the turbine. With level of water 17 meter, the transmission pulley 4 step, produce rotation of turbine 23-25 rpm, rotation rate of the the generator is 1500 rpm. By using the Matlab simulation, volume turbine bowl will maximum at 5.574 cm3 calculated by angle theta 11 degrees and alpha 9 degrees. Thus, these conditions produce the greatest torque. The Micro hydro in Dusun Gambuk Pupuan Tabanan Bali [19], [20] now only produces power of 700 watts, then by adjustments angel bowl of turbine generated electricity double before now about 1400 Watt.