System Loss Minimization Research Articles

A novel approach for system loss minimization in a peer-to-peer energy sharing community DC microgrid

The conventional electric power system is undergoing a transition from high fossil fuel dependence to significant renewable energy share primarily due to decreasing costs of renewable technologies, increasing environmental pollution, and favorable energy policies. The introduction of distributed energy resources with minimal power losses has also recently promoted the DC power systems deployment at small scale such as community-based DC microgrids. These systems allow the possibility of trading surplus energy from distributed energy resources with peer-to-peer (P2P) energy sharing. As power losses in a sharing scheme are non-linear concerning the distance between trading prosumers and power trade level, therefore, P2P energy sharing cannot be optimally managed with conventional factory-warehouse transportation techniques. In this work, we modeled a DC microgrid system with P2P sharing using a non-linear programming technique which allows the users to share their surplus energy from distributed energy resources with minimal system losses including distribution losses as well as conversion losses in comparison to conventionally employed factory-warehouse transportation technique. The proposed model is applied to a community microgrid having independent photovoltaic (PV) and battery systems installed at each house. Results show that the total system losses are reduced by up to 25% with the proposed optimization framework as compared to conventional factory-warehouse transportation sharing mechanism.

Loss Minimization Control of Dual Three‐Phase Linear Induction Motor with System‐Level Loss Model

Traditional loss model of linear induction motors usually only considers iron loss and copper loss. However, the neglect of power electronic losses will reduce the accuracy of model calculations. Moreover, in multi‐phase motor drive systems, power electronics losses are relatively higher and cannot be omitted. Considering the above problems, loss models of six‐phase inverter under various PWM modulation methods were derived. And combined with an improved dynamic end effect loss model of dual three‐phase linear induction motor, a system‐level loss model is obtained. Furthermore, optimal excitation current can be calculated based on the model using Newton–Raphson method to minimize system loss. Simulation results showed that this strategy can always bring efficiency improvement under all working conditions, especially under certain light load working conditions (0.2 pu, 5 m/s), the loss reductions of both the inverter and the overall system can achieve by 50% approximately. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

A Risk-Based Dynamic Decision-Making Approach for Cybersecurity Protection in Industrial Control Systems

Decision-making is a key component of industrial control system (ICS) security. However, due to the stability and real-time requirements of ICSs, current decision-making approaches typically designed for IT systems are not entirely suitable for ICSs. In this paper, with consideration of the characteristics of ICSs, a risk-based multistep dynamic decision-making approach for protecting ICSs is proposed. Following this proposal, multiple models, including multilayer Bayesian network, process model, and attack-defense strategy model are built first. On this basis, a state controller is designed to ensure the safe degradation/upgradation of ICSs. Finally, a game theory-based optimal defense strategy generation approach is presented. To verify the effectiveness of the proposed approach, a simulation on a simplified chemical reactor control system is conducted in MATLAB. The simulation results clearly demonstrate that the proposed dynamic decision-making approach has the ability to generate the optimal defense strategy to minimize system loss.

Optimized Two-Time Scale Robust Dispatching Method for the Multi-Terminal Soft Open Point in Unbalanced Active Distribution Networks

To alleviate the impact of output uncertainty of renewable energy sources (RESs) in unbalanced active distribution networks (ADNs), this paper proposed a two-time scale robust optimization method for the multi-terminal soft open point (SOP). In the long-term scale, the operation points of the SOP were optimized by semidefinite programming (SDP) model to minimize system loss and mitigate voltage unbalance. An improved iterative cutting plane (ICP) method was proposed to strengthen the exactness of the SDP rank-one relaxation. In the short-term scale, V 2- P and V 2- Q droop control mode was implemented in the SOP to better respond to the output uncertainty of RESs. Then a slope robust optimization model was established based on long-term operation points and short-term forecast data to improve system robust security. To coordinate these two time scales, a co-optimization re-dispatch strategy was proposed in the short-term model so that the robust safety margin could be further expanded in extreme conditions. Case studies show that the proposed method can fully utilize the flexible power flow regulation ability of the multi-terminal SOP to reduce system loss, mitigate voltage unbalance and guarantee system robust security in the presence of RES output uncertainty.

ART(Angle Reference Transposition) 손실감도를 이용한 전력계통 연산 사례

The angle reference, the reference for the angles of all bus voltages in a power system, has been specified conventionally on the slack bus in power flow computation(e.g., θ₁=0), however, it can be specified on any bus in the system without affecting the power flow solution. In this paper, loss sensitivities, ∂P<SUB>loss</SUB>/∂P<SUB>G</SUB>, ∂P<SUB>loss</SUB>/∂Q<SUB>G</SUB>, Q<SUB>loss</SUB>/∂P<SUB>G</SUB> and ∂Q<SUB>loss</SUB>/∂Q<SUB>G</SUB>, of all generators including the slack bus are derived by specifying the angle reference on a load bus that has no generation using the nature of the Jacobian matrix which is re-constructed by transposition of the angle reference bus.<BR>With these loss sensitivities, this paper shows the following four example applications to power system computation:<BR>New calculation of penalty factors for classical ELD computation<BR>Optimal P-Q generation for cost minimization<BR>Optimal P generation for system loss minimization<BR>Optimal P-Q generation for system loss minimization<BR>Derived loss sensitivities and application algorithms are tested and verified on a sample system.

Optimal Allocation of Static Var Compensators in Electric Power Systems

In the current age, power systems contain many modern elements, one example being Flexible AC Transmission System (FACTS) devices, which play an important role in enhancing the static and dynamic performance of the systems. However, due to the high costs of FACTS devices, the location, type, and value of the reactive power of these devices must be optimized to maximize their resulting benefits. In this paper, the problem of optimal power flow for the minimization of power losses is considered for a power system with or without a FACTS controller, such as a Static Var Compensator (SVC) device The impact of location and SVC reactive power values on power system losses are considered in power systems with and without the presence of wind power. Furthermore, constant and variable load are considered. The mentioned investigation is realized on both IEEE 9 and IEEE 30 test bus systems. Optimal SVC allocation are performed in program GAMS using CONOPT solver. For constant load data, the obtained results of an optimal SVC allocation and the minimal value of power losses are compared with known solutions from the literature. It is shown that the CONOPT solver is useful for finding the optimal location of SVC devices in a power system with or without the presence of wind energy. The comparison of results obtained using CONOPT solver and four metaheuristic method for minimization of power system losses are also investigated and presented.

Primal-Dual Interior-Point Technique for Optimisation of 330kV Power System on One Variable

The work deal on a method for optimisation of 330KV power system load flow which excels other existing methods.This method is called, PRIMAL-DUAL INTERIOR-POINT TECHNIQUE for solving optimal load flow problem. As problems of load-shedding, power outages and system losses have been cause for worries, especially among the developing nations such as Nigeria, hence need for a load flow solution technique, which, this work addresses. Optimisation is achieving maximum of required and minimum of un-required and it is obtained mathematically by differentiating the objective function with respect to the control variable(s) and equating the resulting expression(s) to zero. In 330KV Power System, optimization is maximisation of real power injection, voltage magnitude and cost effectiveness, while minimization of reactive power injection, power loss, critical clearing time of fault conditions and time of load flow simulation.. This work developed a mathematical model that solves load flow problems by engaging non-negative PRIMAL variables, “S” and “z” into the inequality constraint of the load flow problems in other to transform it to equality constraint(s). Another non-negative DUAL variables “” and “v” are incorporated together with Lagrangian multiplier “?” to solve optimisation. While solving optimisation Barrier Parameter “” which ensures feasible point(s) exist(s) within the feasible region (INTERIOR POINT). Damping factor or step length parameter “?”, in conjunction with Safety factor “” (which improves convergence and keeps the non-negative variables strictly positive) are employed to achieve result. The key-words which are capitalized joined to give this work its name, the PRIMAL-DUAL INTERIOR-POINT. The initial feasible point(s) is/are tested for convergence and where it/they fail(s), iteration starts. Variables are updated by using the computed step size and the step length parameter “?”, which thereafter, undergo another convergence test. This technique usually converges after first iteration. Primarily, this technique excels the existing methods as; it solves load flow problems with equality and inequality constraints simultaneously, it often converges after first iteration as against six or more iterations of the existing methods, its solution provides higher power generations from available capacity and minimum system loss. Example, Geregu Power Station on Bus 12 generates 0.1786p.u power from the available 0.2000p.u through the PD-IP tech. as against 0.1200p.u of the existing methods. Also it supplies 0.1750p.u with loss of 0.0036p.u as against 0.0236p.u with loss of 0.0964p.u of the existing methods. This results in 90% generation as against 60% of existing methods. Generation loss is 1.8% as against 80.3% of existing methods and availability loss of 12.5% as against 88.2% of existing. Therefore this method ensures very high system stability.

Primal-Dual Interior-Point Technique for Optimisation of 330kV Power System on One Variable

The work deal on a method for optimisation of 330KV power system load flow which excels other existing methods.This method is called, PRIMAL-DUAL INTERIOR-POINT TECHNIQUE for solving optimal load flow problem. As problems of load-shedding, power outages and system losses have been cause for worries, especially among the developing nations such as Nigeria, hence need for a load flow solution technique, which, this work addresses. Optimisation is achieving maximum of required and minimum of un-required and it is obtained mathematically by differentiating the objective function with respect to the control variable(s) and equating the resulting expression(s) to zero. In 330KV Power System, optimization is maximisation of real power injection, voltage magnitude and cost effectiveness, while minimization of reactive power injection, power loss, critical clearing time of fault conditions and time of load flow simulation.. This work developed a mathematical model that solves load flow problems by engaging non-negative PRIMAL variables, “S” and “z” into the inequality constraint of the load flow problems in other to transform it to equality constraint(s). Another non-negative DUAL variables “” and “v” are incorporated together with Lagrangian multiplier “λ” to solve optimisation. While solving optimisation Barrier Parameter “” which ensures feasible point(s) exist(s) within the feasible region (INTERIOR POINT). Damping factor or step length parameter “α”, in conjunction with Safety factor “” (which improves convergence and keeps the non-negative variables strictly positive) are employed to achieve result. The key-words which are capitalized joined to give this work its name, the PRIMAL-DUAL INTERIOR-POINT. The initial feasible point(s) is/are tested for convergence and where it/they fail(s), iteration starts. Variables are updated by using the computed step size and the step length parameter “α”, which thereafter, undergo another convergence test. This technique usually converges after first iteration. Primarily, this technique excels the existing methods as; it solves load flow problems with equality and inequality constraints simultaneously, it often converges after first iteration as against six or more iterations of the existing methods, its solution provides higher power generations from available capacity and minimum system loss. Example, Geregu Power Station on Bus 12 generates 0.1786p.u power from the available 0.2000p.u through the PD-IP tech. as against 0.1200p.u of the existing methods. Also it supplies 0.1750p.u with loss of 0.0036p.u as against 0.0236p.u with loss of 0.0964p.u of the existing methods. This results in 90% generation as against 60% of existing methods. Generation loss is 1.8% as against 80.3% of existing methods and availability loss of 12.5% as against 88.2% of existing. Therefore this method ensures very high system stability.

Hybrid Optimization for Optimal Distributed Generation Unit Placement in Radial Distribution System

In recent years, the demand for electric power is growing at a faster rate. This makes present time power system into a more composite one in structure and in terms of placing utility elements, operation, maintenance and control of power system to deliver the electric power to customers. To satisfy the demand for electricity is necessitate more generating units nearer to customer points and need of proper operational planning. The power loss is a major concern towards distribution system performance. Hence, minimization of losses in the system is a major consideration. The distributed generation plays significant role in satisfying the need for electricity demand and also helps in minimization of system losses by adopting intelligent algorithm technique. Among all its advantages, power losses, voltage enhancement and cost benefits are the prime areas of study in distributed generation units. So, placing and allocation of distributed generation acquire more attention towards distribution system. In this paper, an intelligent hybrid optimization technique is proposed for optimal distributed generating unit for minimizing the losses in radial distribution system. The proposed optimization technique is implemented for IEEE 33-bus system radial distribution system. The obtained simulated results provide the good applicability and enhancement in execution of the proposed hybrid method.

Input-Throughput-Output Analysis of Water Resources in Sorsogon City, Philippines

Water is vital in sustaining life and will become increasingly critical in the long run, considering theconstant population growth and economic development of a city. The study aimed to measure the input,throughput, and output of Sorsogon City along water and sanitation. Water and sanitation data wereobtained from Sorsogon City Mayor’s office and Sorsogon City Water District (SCWD) office. Data werealso gathered through key informant interviews with SCWD personnel, city health officer, public healthnurse, sanitary inspector, community environmental and natural resources officers, and wastewatertreatment facility staff, and focus group discussions with eight barangay captains of barangays not servedby SCWD and nine members of Barangay Water and Sanitation Associations. An input-throughputoutput analysis on water resources was done. SCWD and non-SCWD have annual production volumeof 3,292,566 m3/annum and 2,017,920 m3/annum, respectively. SCWD’s billed volume was 2,370,648m3/annum: (domestic: 1,927,573; commercial/industrial: 301,879; institutional: 141,196) while nonSCWD domestic was 597,547.63 m3/annum. Wastewater from household, commercial/industrial, andinstitutional plumbing were 2,525,120.63, 1,227.203, and 141,196 m3/annum, respectively. The wetmarket and slaughterhouse wastewater treatment facilities treated 32,850 and 4,136.05 m3/annum ofwastewater respectively. Total input was 5,310,486 m3/annum while the combined utilization and outputwas 6,861,715.26 m3/annum. Their difference was 1,551,229.26 m3/annum, which can be attributed torun-offs and leakages from pipes and connections. The input is not equal to the sum of the throughputand output of water and sanitation in Sorsogon City; hence, the city has not efficiently managed itswater and sanitation resources as evidenced by partial coverage of SCWD, high system losses, absence ofcentralized sewerage system, and inadequate waste water treatment facility. It is therefore recommendedthat the city’s water management system must be periodically upgraded to minimize system losses.

Determining the Hosting Capacity of Solar Photovoltaic in a Radial Distribution Network Using an Analytical Approach

Integrating high photovoltaic (PV) on distribution grid system has a positive impact by significantly reducing the losses and improving the voltage profile at the same time reducing the pollution of the environment However, integrating high proportions of PV in the distribution grid can bring the grid to its operational limits and result in power quality issues. The maximum PV capacity that can be integrated without incurring any grid impacts is referred to as the PV hosting capacity of the grid. This paper intends to evaluate the hosting capacity of solar PV in Dodhara-Chandani (DoC) distribution feeder as one of the feeder of Integrated Nepal Power System (INPS), considering grid parameters and operating condition in Nepal. Three main criteria were investigated for determining the hosting capacity of PV; reverse power flow, maximum voltage deviation of feeder and current carrying limit of conductor. The analysis has been performed by means of static load-flow simulation in Electrical Transient &amp; Analysis Program (ETAP) and coding in MATLAB R2017a. The study shows that PV of rated capacity 687kWp can be installed at a point of interconnection (POI) whereas an optimal placement of solar PV is found to be at 18th node (in between starting and end of the feeder) considering minimum system losses. The minimum voltage profile at end of the feeder has improved by 8 % while the active power loss reduction of network has reduced by 83.6 % after the integration of solar PV. The results indicate voltage at different buses and the ampacity of most of the conductors have been improved after the integration of PV system into DoC feeder.

Loss Minimization With Optimal Power Dispatch in Multi-Frequency HVac Power Systems

Low-frequency high-voltage ac transmission scheme has recently been proposed as an alternative approach for bulk power transmission. This paper proposes a multi-period optimal power flow (OPF) for a multi-frequency HVac transmission system that interconnects both conventional 50/60-Hz and low-frequency grids using back-to-back converters with a centralized control scheme. The OPF objective is to minimize system losses by determining the optimal dispatch for generators, shunt capacitors, and converters. The OPF constraints include the operational constraints of all HVac grid and converter stations. The resulting mixed-integer nonlinear programing problem is solved using a proposed framework based on the predictor-corrector primal-dual interior-point method. The proposed OPF formulation and solution approach are verified using a multi-frequency HVac transmission system that is modified from the IEEE 57-bus system. The results with the optimal dispatch from the proposed method during a simulated day show a significant loss reduction and an improved voltage regulation compared to those when an arbitrary dispatch is chosen.

Hybrid Salp Swarm Algorithm for integrating renewable distributed energy resources in distribution systems considering annual load growth

Load growth in electrical distribution networks became naturally occurring due to industrial development and human population demand growth. Consequently, system losses are continually raised while the voltage profile is reduced. This paper presents a novel hybrid method to determine the best locations and sizes of single and multiple of different renewable distributed energy resources (DER). The presented hybrid method is based on Salp Swarm Algorithm (SSA) and combined power loss sensitivity (CPLS). Integration of photovoltaics (PV) and wind turbines (WT) in distribution network is used to enhance the system voltage, minimize system losses and increase the system capacity. The effect of annual load growth in system load and system operating constraints are taken in consideration. IEEE 33-bus and 69-bus radial distribution systems (RDS) are used to validate the presented algorithm for integrating the DERS in distribution system. In addition, the presented algorithm is compared with different recent optimization algorithms in order to prove its effectiveness and superiority.

Power system loss minimization using optimal placement of UPFC given by Bat algorithm

Power system loss minimization using optimal placement of UPFC given by Bat algorithm

Power System loss minimization by using UPFC placed at optimal location given by Artificial Bee Colony Algorithm

Power System loss minimization by using UPFC placed at optimal location given by Artificial Bee Colony Algorithm

A Game-Theoretic Approach to Cross-Layer Security Decision-Making in Industrial Cyber-Physical Systems

Current security measures in industrial cyber-physical systems (ICPS) lack the active decision capability to defend against highly-organized cyber-attacks. In this paper, a security decision-making approach based on stochastic game model is proposed to characterize the interaction between attackers and defenders in ICPSs and generate optimal defense strategies to minimize system losses. The major distinction of this approach is that it presents a practical way to build a cross-layer security game model for ICPSs by means of quantitative vulnerability analysis and time-based unified payoff quantification. A case study on a hardware-in-the-loop simulation testbed is carried out to demonstrate the feasibility of the proposed approach.

Optimal Allocation of Transformer and Its Effects on Distribution System Loss Minimization

The periodic growth in megacities has incremented the power consumption in the name of modernized techniques and hustle-free lifestyles. In the state of Tamil Nadu, the voltage and power regulation has created a drastic decrements in the efficiency for the tail end consumers. Thus, resulting in shortage of voltage and vehemently opposing the performance factors of home appliances, micro-industries and minute gadgets used on a day-to-day basis. In this paper, a solution is provided to magnificently ameliorate by catering a high voltage distribution system, simulating its results for serving, good to the Tamil Nadu Electricity Board having fed by the Electrical Transient Analysis Program Software. Therefore, in reference to the contingent PSO algorithm enabling to convert Low Voltage Distribution System to High Voltage Distribution Systems, sufficiently acquiring a redemption for utmost performance usage of the transformer. The relational composition of the supply in the LVDS and HDVS magnitudes demonstrate the necessary output demands. The line losses vividly broadcast the allocated transformer and the HDVS holds good in showcasing power loss in advanced tail and voltage prescriptions.

Optimal placement of unified power flow controller using differential search algorithm

Optimal power flow (OPF) problem plays a crucial role to run an economically efficient and well-planned power system. It is a challenging task for the power system researchers to cope with the ever-increasing load-demand while getting the minimum system loss. The development of flexible ac transmission system (FACTS) has added a new dimension both to the system operation and research. Unified power flow controller (UPFC) is the most reliable FACTS controller, which can provide both series and shunt compensation. As a matter of fact, UPFC can reliably control the different power system parameters. In this article, UPFC is incorporated into the modified IEEE 5-bus and modified IEEE 30-bus test system. Differential search algorithm (DSA) is proposed and implemented to run the OPF with and without UPFC and the results are listed, analysed and compared with the same that is obtained by genetic algorithm (GA) and BAT search algorithm.

A PSO based search for optimal tuning and fixing of UPFC to improve usefulness of distribution system

With socio-economical development, power distribution systems are forced to work with both heavy as well as light loads, which causes voltage instability and power loss. This paper develops a Particle Swarm Optimization (PSO) based algorithm to find an optimal place and parameter of Unified Power F low Controller (UPFC) to improve voltage profile with minimum system loss. UPFC is a most versatile Flexible Alternating Current Transmission System (FACTS) controller, which can control bus voltage; flow of active as well as reactive power through lines. The novelty of this work is to fix the location of UPFC at base load to make power distribution system more secure and efficient, by tuning its parameters at all possible load conditions. The developed methodology is employed in IEEE 30-bus system with different intensities of the load. Results prove the success of developed technique and verify the potential of UPFC for improvement of system stability with mitigation of losses.

Multiobjective Optimal DERs Placement and Sizing Considering Generator Shaft Fatigue

Optimal placement and sizing of distributed energy resources (DERs) can be performed from various points of view. In this paper, a multiobjective function is employed to determine optimal place and size of DERs including combination of photovoltaic resources and a small-scale synchronous generator (SSSG) with an internal combustion engine as its prime mover. As the objective function, not only minimization of investment costs, operation costs, and system losses are used, but also the voltage of microgrid (μG) busses and current of lines are considered as constraints. In addition, this paper shows mechanical stresses can be imposed on the SSSG caused by generator swings after short circuit fault clearing. Furthermore, it may lead to mechanical fatigue in its associated shaft and prime mover. Meanwhile, it is revealed that the mechanical stresses depend on the DERs placement and size. Thus, a novel index representing the stresses on the SSSG shaft is applied in the multiobjective goal function. This decreases SSSG loss of life in a μG with overhead lines which has high rate of short circuit faults. Optimization studies are performed in a six-bus and four-DER μG using time-based simulations.