This paper presents a novel 'mix-mode' energy management strategy (MM-EMS) and its appropriate ba... more This paper presents a novel 'mix-mode' energy management strategy (MM-EMS) and its appropriate battery sizing method for operating the microgrid at the lowest possible operating cost. The MM-EMS is developed by combining three proposed operating strategies, namely "continuous run mode", "power sharing mode" and "ON/OFF mode" for a 24h time period. The objective functions for the proposed strategies are solved using linear programming (LP) and mixed integer linear programming (MILP) optimization methods. A sizing method using the particle swarm optimization (PSO) technique to determine the optimal energy capacity of battery energy storage (BES) in kWh is also presented. Since the size of the BES influences the microgrid's operating cost, the energy management strategy (EMS) and BES capacity are simultaneously optimized. The proposed MM-EMS and battery sizing method were first validated. Then, the variation of optimal battery capacity for different battery state of charge (SOC) levels is analyzed. The variation of microgrid's associated costs for different battery's initial state of charge (SOC) levels is analyzed as well. Finally, a recommendation on the choice of initial SOC level during the start of the day for the economic operation of microgrid is also suggested.
In power system networks, automatic fault diagnosis techniques of switchgears with high accuracy ... more In power system networks, automatic fault diagnosis techniques of switchgears with high accuracy and less time consuming are important. In this work, classification of abnormal location in switchgears is proposed using hybrid gravitational search algorithm (GSA)-artificial intelligence (AI) techniques. The measurement data were obtained from ultrasound, transient earth voltage, temperature and sound sensors. The AI classifiers used include artificial neural network (ANN) and support vector machine (SVM). The performance of both classifiers was optimized by an optimization technique, GSA. The advantages of GSA classification on AI in classifying the abnormal location in switchgears are easy implementation, fast convergence and low computational cost. For performance comparison, several well-known metaheuristic techniques were also applied on the AI classifiers. From the comparison between ANN and SVM without optimization by GSA, SVM yields 2% higher accuracy than ANN. However, ANN yi...
Indonesian Journal of Electrical Engineering and Computer Science, 2017
In this paper, impedance based method and matching approaches were used separately to detect thre... more In this paper, impedance based method and matching approaches were used separately to detect three phase to ground fault (LLLGF). In order to observe the accuracy of each method, Non-homogeneous distribution network was used as a tested network. Actual data from TNB (Tenaga National Berhad) Malaysia was adopted to model the network by using PSCAD/EMTDC simulation program. Both methods were tested to observe the accuracy of fault distance estimation. The comparison result shows different accuracy for each section which simulated in the middle of section. Based on the complexity of the distribution network, it possible to contribute difficulty to obtain the maximum accuracy. The result was obtained through the complete process which involves the database formation acquired through the PSCAD/EMTDC software simulator and the fault location distance calculation carried out by the MATLAB software.
This research introduces four different tools designed for fault type classifications at distribu... more This research introduces four different tools designed for fault type classifications at distribution network. The proposed designs are using Artificial Neural Network, Fuzzy Logic, conventional method and Support Vector Machine as the research techniques with input data obtained from PSCAD simulation. The circuit configuration for fault disturbance at the distribution network was simulated by PSCAD simulation program. The research techniques were applied with multiples input values of voltage and current that extracted from the PSCAD simulation. This research testifies the output result by using different fault resistance values; 0.01Ω, 10Ω, 30Ω, 50Ω and 70Ω. Voltage sag and current swell of phase a, b and c that were obtained from the PSCAD simulation have been used as the input variables for the four different research tools design. The acquired results that represented in average accuracy (%) shows that voltage sag and current swell can draw a satisfying accuracy in classifying ...
International Journal of Electrical Power & Energy Systems, 2012
Differential protection scheme is based on comparison of measured variables such as current and v... more Differential protection scheme is based on comparison of measured variables such as current and voltage at the two ends of a line via a communication channel such as pilot wire. This scheme is preferred and extensively used in distribution feeder protection system in Malaysia due to its fast operation. However pilot-wire differential scheme has its own drawbacks especially on the maintenance of the pilot-wire. Once the plot-wire is out of service, the feeder protection is jeopardised. One of the options to overcome such maintenance issue is to adopt directional relay as the feeder protection. This paper investigates a suitable relay connection and the maximum torque angle for the directional relay for 33 kV underground network. In this study, a section of 33 kV underground network in Kuala Lumpur (KL) city has been analysed. All faults types have been simulated at all possible location in the network. The obtained voltage and current were then used to determine the operation of directional overcurrent and earth-fault relay. The simulation results indicate that 30°relay connection with 0°maximum torque angle (30°/0°) is the most suitable setting to be applied for 33 kV underground network in KL, as against the best general and most versatile setting, 45°/90°Ó
This paper presents an approach to solve the unit commitment problem using a newly developed Mult... more This paper presents an approach to solve the unit commitment problem using a newly developed Multiagent Evolutionary Programming incorporating Priority List optimisation technique (MAEP-PL). The objective of this study is to search for generation scheduling such that the total operating cost can be minimised when subjected to a variety of constraints, while at the same time reducing its computational time. The proposed technique assimilates the concepts of Priority Listing (PL), Multi-agent System (MAS) and Evolutionary Programming (EP) as its basis. In the proposed technique, deterministic PL technique is applied to produce a population of initial solutions. The search process is refined using heuristic EP-based algorithm with multi-agent approach to produce the final solution. The developed technique is tested on ten generating units test system for a 24-h scheduling period, and the results are compared with the standard Evolutionary Programming (EP), Evolutionary Programming with Priority Listing (EP-PL) and Multi-agent Evolutionary Programming (MAEP) optimisation techniques. From the obtained results and the comparative studies, it was found that the proposed MAEP-PL optimisation technique is able to solve the unit commitment problem where the total daily generation cost is effectively B H. Mokhlis
Increasing of the power demand and fuel cost in power generation required an advanced algorithm f... more Increasing of the power demand and fuel cost in power generation required an advanced algorithm for scheduling the output of generating unit in economical manner. The economic load dispatch problem (ELD) problem consists several operational and system constraints such as prohibited operating zones (POZs) and ramp-rate limit that need to handle wisely by optimization algorithm. Previously, the penalty function is widely used to satisfy the power balance and other constraints by augmenting the objective function with the penalized function. However, it required a proper penalty factor tuning and depends on the size of problem. This paper proposes an efficient constraint handling based on the repairing or adjusting infeasible solution into feasible solution in every iterative process. The simulation results show that the proposed constraints handling approach is better than penalty function approach in term of convergence characteristic and robustness.
2013 IEEE 7th International Power Engineering and Optimization Conference (PEOCO), 2013
This paper presents an approach to sigma multiobjective optimization particle swarm (σ-MOPSO) tec... more This paper presents an approach to sigma multiobjective optimization particle swarm (σ-MOPSO) technique for optimal allocation of Flexible AC Transmission System (FACTS) devices. For this study, Static Var Compensator (SVC) is selected as a compensation device. Proposal σ-MOPSO technique has been implemented to minimize the transmission losses and the cost of investment in the system. Simulations performed on standard IEEE RTS 30-bus and IEEE 118-bus RTS. Results are compared with those obtained from the programming of multiobjective evolutionary technique (MOEP) in order to highlight its advantages.
This paper presents a novel 'mix-mode' energy management strategy (MM-EMS) and its appropriate ba... more This paper presents a novel 'mix-mode' energy management strategy (MM-EMS) and its appropriate battery sizing method for operating the microgrid at the lowest possible operating cost. The MM-EMS is developed by combining three proposed operating strategies, namely "continuous run mode", "power sharing mode" and "ON/OFF mode" for a 24h time period. The objective functions for the proposed strategies are solved using linear programming (LP) and mixed integer linear programming (MILP) optimization methods. A sizing method using the particle swarm optimization (PSO) technique to determine the optimal energy capacity of battery energy storage (BES) in kWh is also presented. Since the size of the BES influences the microgrid's operating cost, the energy management strategy (EMS) and BES capacity are simultaneously optimized. The proposed MM-EMS and battery sizing method were first validated. Then, the variation of optimal battery capacity for different battery state of charge (SOC) levels is analyzed. The variation of microgrid's associated costs for different battery's initial state of charge (SOC) levels is analyzed as well. Finally, a recommendation on the choice of initial SOC level during the start of the day for the economic operation of microgrid is also suggested.
In power system networks, automatic fault diagnosis techniques of switchgears with high accuracy ... more In power system networks, automatic fault diagnosis techniques of switchgears with high accuracy and less time consuming are important. In this work, classification of abnormal location in switchgears is proposed using hybrid gravitational search algorithm (GSA)-artificial intelligence (AI) techniques. The measurement data were obtained from ultrasound, transient earth voltage, temperature and sound sensors. The AI classifiers used include artificial neural network (ANN) and support vector machine (SVM). The performance of both classifiers was optimized by an optimization technique, GSA. The advantages of GSA classification on AI in classifying the abnormal location in switchgears are easy implementation, fast convergence and low computational cost. For performance comparison, several well-known metaheuristic techniques were also applied on the AI classifiers. From the comparison between ANN and SVM without optimization by GSA, SVM yields 2% higher accuracy than ANN. However, ANN yi...
Indonesian Journal of Electrical Engineering and Computer Science, 2017
In this paper, impedance based method and matching approaches were used separately to detect thre... more In this paper, impedance based method and matching approaches were used separately to detect three phase to ground fault (LLLGF). In order to observe the accuracy of each method, Non-homogeneous distribution network was used as a tested network. Actual data from TNB (Tenaga National Berhad) Malaysia was adopted to model the network by using PSCAD/EMTDC simulation program. Both methods were tested to observe the accuracy of fault distance estimation. The comparison result shows different accuracy for each section which simulated in the middle of section. Based on the complexity of the distribution network, it possible to contribute difficulty to obtain the maximum accuracy. The result was obtained through the complete process which involves the database formation acquired through the PSCAD/EMTDC software simulator and the fault location distance calculation carried out by the MATLAB software.
This research introduces four different tools designed for fault type classifications at distribu... more This research introduces four different tools designed for fault type classifications at distribution network. The proposed designs are using Artificial Neural Network, Fuzzy Logic, conventional method and Support Vector Machine as the research techniques with input data obtained from PSCAD simulation. The circuit configuration for fault disturbance at the distribution network was simulated by PSCAD simulation program. The research techniques were applied with multiples input values of voltage and current that extracted from the PSCAD simulation. This research testifies the output result by using different fault resistance values; 0.01Ω, 10Ω, 30Ω, 50Ω and 70Ω. Voltage sag and current swell of phase a, b and c that were obtained from the PSCAD simulation have been used as the input variables for the four different research tools design. The acquired results that represented in average accuracy (%) shows that voltage sag and current swell can draw a satisfying accuracy in classifying ...
International Journal of Electrical Power & Energy Systems, 2012
Differential protection scheme is based on comparison of measured variables such as current and v... more Differential protection scheme is based on comparison of measured variables such as current and voltage at the two ends of a line via a communication channel such as pilot wire. This scheme is preferred and extensively used in distribution feeder protection system in Malaysia due to its fast operation. However pilot-wire differential scheme has its own drawbacks especially on the maintenance of the pilot-wire. Once the plot-wire is out of service, the feeder protection is jeopardised. One of the options to overcome such maintenance issue is to adopt directional relay as the feeder protection. This paper investigates a suitable relay connection and the maximum torque angle for the directional relay for 33 kV underground network. In this study, a section of 33 kV underground network in Kuala Lumpur (KL) city has been analysed. All faults types have been simulated at all possible location in the network. The obtained voltage and current were then used to determine the operation of directional overcurrent and earth-fault relay. The simulation results indicate that 30°relay connection with 0°maximum torque angle (30°/0°) is the most suitable setting to be applied for 33 kV underground network in KL, as against the best general and most versatile setting, 45°/90°Ó
This paper presents an approach to solve the unit commitment problem using a newly developed Mult... more This paper presents an approach to solve the unit commitment problem using a newly developed Multiagent Evolutionary Programming incorporating Priority List optimisation technique (MAEP-PL). The objective of this study is to search for generation scheduling such that the total operating cost can be minimised when subjected to a variety of constraints, while at the same time reducing its computational time. The proposed technique assimilates the concepts of Priority Listing (PL), Multi-agent System (MAS) and Evolutionary Programming (EP) as its basis. In the proposed technique, deterministic PL technique is applied to produce a population of initial solutions. The search process is refined using heuristic EP-based algorithm with multi-agent approach to produce the final solution. The developed technique is tested on ten generating units test system for a 24-h scheduling period, and the results are compared with the standard Evolutionary Programming (EP), Evolutionary Programming with Priority Listing (EP-PL) and Multi-agent Evolutionary Programming (MAEP) optimisation techniques. From the obtained results and the comparative studies, it was found that the proposed MAEP-PL optimisation technique is able to solve the unit commitment problem where the total daily generation cost is effectively B H. Mokhlis
Increasing of the power demand and fuel cost in power generation required an advanced algorithm f... more Increasing of the power demand and fuel cost in power generation required an advanced algorithm for scheduling the output of generating unit in economical manner. The economic load dispatch problem (ELD) problem consists several operational and system constraints such as prohibited operating zones (POZs) and ramp-rate limit that need to handle wisely by optimization algorithm. Previously, the penalty function is widely used to satisfy the power balance and other constraints by augmenting the objective function with the penalized function. However, it required a proper penalty factor tuning and depends on the size of problem. This paper proposes an efficient constraint handling based on the repairing or adjusting infeasible solution into feasible solution in every iterative process. The simulation results show that the proposed constraints handling approach is better than penalty function approach in term of convergence characteristic and robustness.
2013 IEEE 7th International Power Engineering and Optimization Conference (PEOCO), 2013
This paper presents an approach to sigma multiobjective optimization particle swarm (σ-MOPSO) tec... more This paper presents an approach to sigma multiobjective optimization particle swarm (σ-MOPSO) technique for optimal allocation of Flexible AC Transmission System (FACTS) devices. For this study, Static Var Compensator (SVC) is selected as a compensation device. Proposal σ-MOPSO technique has been implemented to minimize the transmission losses and the cost of investment in the system. Simulations performed on standard IEEE RTS 30-bus and IEEE 118-bus RTS. Results are compared with those obtained from the programming of multiobjective evolutionary technique (MOEP) in order to highlight its advantages.
Technology advancement for renewable energy resources and its integration to the distribution net... more Technology advancement for renewable energy resources and its integration to the distribution network (DN) has garnered substantial interest in the last few decades. Integrating such resources has proven to reduce power losses and improve the reliability of DN. However, the growing number of these resources in DN has imposed additional operational and control issues in voltage regulation, system stability, and protection coordination. Incorporation of various types of distributed generators (DG) into DN causes significant changes in the system. These including new fault current sources, new fault levels, a blinding effect in the protection scheme, reduction in the reach of relays, and decrement in the detection of lowlevel fault currents for existing relays. Such changes will jeopardize the effectiveness of the entire protection scheme in the DN. This research aims to propose a robust protection scheme in which the relay coordination settings are optimized based on the network layout. The potential impacts of DGs on the DN are mitigated by utilizing a user-defined overcurrent-based relay characteristic to obtain the minimum operating time while satisfying protection coordination constraints. A hybrid optimization algorithm based on Metaheuristic and Linear Programming that has the capability to attain the optimal solution and reduces computational time is proposed in this work. The performance of the proposed technique is tested on radial DN integrated with microgrid (MG). The results obtained show the proposed technique has successfully reduced the relay operating time while meeting the protection coordination requirements for dynamic operating modes of a network.
Technology advancement in the last few decades allows large penetration of renewable energy resou... more Technology advancement in the last few decades allows large penetration of renewable energy resources in the distribution network (DN). The integration of such resources has shown a substantial impact on DN through power loss reduction and improved network reliability. Besides this, the existing protection system has encountered coordination challenges due to the bidirectional power flow, different types and capacity of generation sources, and changes in fault levels due to network operating modes (grid-connected or islanded). Such conditions may cause the relays to malfunction and imperil the effectiveness of the existing protection scheme. Therefore, an efficient and robust protection coordination scheme is imperative to avoid network reliability and stability issues to the grid. This review paper presents a comparative analysis of various protection techniques implemented to alleviate the impact of integrated resources into DN. Moreover, a comparison of classical and modified protection approaches in terms of advantages, shortcomings, and implementation costs is presented. The prime objective of this study is to highlight the prominence of utilizing user-defined programmable relays for modern DNs. Moreover, recommendations are presented by considering the application of user-defined relay characteristics that can be proved as a robust protection scheme to cope with the protection challenges in existing and future power systems developments. INDEX TERMS Distribution networks (DN), microgrids (MG), protection coordination scheme, renewable energy resources (RES), user-defined characteristics (UDC).
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Papers by Hazlie Mokhlis