Voltage Performance Index Research Articles

Analisis Pengaruh Penambahan Gardu Induk Terhadap Aliran Daya dan Profil Tegangan

Addition of the Guluk-Guluk Substation, it will affect the flow of power and voltage in the electric power system. Based on the analysis of normal conditions before and after the Guluk-Guluk Substation in terms of the voltage value on each connected bus, it is still within the permitted limits, while the contingency ranking calculation using the Voltage Performance Index (PIv) method can determine contingency conditions N-1 to N -3 before and after the Guluk-Guluk Substation. In this case, it was found that during the contingency conditions N-1 to N-3 before the Guluk-Guluk Substation there was a decrease in the value of the voltage which was still within the permissible limits, but in the N-3 contingency there was also an overload on the line due to the release of two generator units and one channel. After the existence of the Guluk-Guluk Substation, during the N-1 to N-2 contingency conditions the voltage value was still within the permissible limits, but the voltage drop that occurred was bigger than the condition before the Guluk-Guluk Substation. For the N-3 contingency condition the voltage value does not meet the standard due to overload on the Ujung Substation - Bangkalan Substation line and the lack of power flow.

Application Contingency Analysis of An IEEE 30 Bus System Using Matpower

Contingency analysis is significant for power system protection. Internal component failures or external causes such as lightning and equipment overloading can cause power system contingencies. Multiple outage scenarios are crucial in today’s deregulated environment for how the transmission network is utilized. The transmission network is highly pressured due to rising load demand and the need to operate economically. Contingency analysis of an IEEE 30 bus system is provided in this article utilizing Matpower software, which includes the source code. Matlab and Matpower are suggested as platforms for developing a screening process that examines the severity of each non-islanding branch failure, generator outage, MVA, and voltage violation. The generator terminal voltages will be permitted to fluctuate between 0.95 per unit and 1.05 per unit, as specified in the case30 input data files, to provide a broader practical zone. The performance index (PI) value is generated by adding the apparent performance index and the voltage performance index to rank the severity of the line outages. For the extreme contingency situation, a load flow study was performed. The four most severe scenarios, generator 22, generator 13, generator outage 23, and branch outage 28, should be constantly monitored to keep the electrical system safe.

Analisis Pengaruh Penambahan Gardu Induk Terhadap Aliran Daya dan Profil Tegangan

Addition of the Guluk-Guluk Substation, it will affect the flow of power and voltage in the electric power system. Based on the analysis of normal conditions before and after the Guluk-Guluk Substation in terms of the voltage value on each connected bus, it is still within the permitted limits, while the contingency ranking calculation using the Voltage Performance Index (PIv) method can determine contingency conditions N-1 to N -3 before and after the Guluk-Guluk Substation. In this case, it was found that during the contingency conditions N-1 to N-3 before the Guluk-Guluk Substation there was a decrease in the value of the voltage which was still within the permissible limits, but in the N-3 contingency there was also an overload on the line due to the release of two generator units and one channel. After the existence of the Guluk-Guluk Substation, during the N-1 to N-2 contingency conditions the voltage value was still within the permissible limits, but the voltage drop that occurred was bigger than the condition before the Guluk-Guluk Substation. For the N-3 contingency condition the voltage value does not meet the standard due to overload on the Ujung Substation - Bangkalan Substation line and the lack of power flow.

Development and Application of Probabilistic Performance Index for Ranking N-1 Contingencies

Contingency analysis and ranking are important tasks in modern electrical power systems which aim at keeping the power system secure, reliable, and stable. N-1 contingency is the loss of any one component of power system and is obviously the most frequent contingency in power system. Contingency ranking has most often been done using deterministic indices which can be either active power performance index (PIP), voltage performance index (PIV) or the overall performance index (PI). Power system contingencies are ranked based on the calculated Performance index for each contingency. Ranking is from the contingency with the highest performance index first and proceeds in a descending manner which corresponds to the most severe to the least severe contingency. Due to the fact that Contingencies are unpredictable events, researchers of recent have suggested the inclusion of the probability of the occurrence of a contingency in its ranking index. This makes the index probabilistic. In this work, the development and application of probabilistic performance index for ranking N-1 contingencies is considered. It is illustrated with a case study.

Development and Application of Probabilistic Performance Index for Ranking N-1 Contingencies

Contingency analysis and ranking are important tasks in modern electrical power systems which aim at keeping the power system secure, reliable, and stable. N-1 contingency is the loss of any one component of power system and is obviously the most frequent contingency in power system. Contingency ranking has most often been done using deterministic indices which can be either active power performance index (PIP), voltage performance index (PIV) or the overall performance index (PI). Power system contingencies are ranked based on the calculated Performance index for each contingency. Ranking is from the contingency with the highest performance index first and proceeds in a descending manner which corresponds to the most severe to the least severe contingency. Due to the fact that Contingencies are unpredictable events, researchers of recent have suggested the inclusion of the probability of the occurrence of a contingency in its ranking index. This makes the index probabilistic. In this work, the development and application of probabilistic performance index for ranking N-1 contingencies is considered. It is illustrated with a case study.

Nodal Sensitivity-Based Smart Inverter Control for Voltage Regulation in Distribution Feeder

Overvoltage is one of the issues in distribution grids with high penetration of photovoltaics (PVs). Centralized or droop-based methods of active power curtailment (APC) and/or reactive power control of PVs are viable solutions to prevent overvoltage. This article proposes two distributed methods to control PV inverters, which are based on nodal sensitivities. Then, the performance of the proposed methods is compared with two commonly used control methods, i.e., a distributed method that follows IEEE-1547 but uses arbitrarily chosen droops and a centralized optimal power flow (OPF) based method. Performance is evaluated using a 730-node feeder with up to 100% penetration of inverters. Based on the case studies, the key findings are: first, local droop setting as per IEEE-1547, whether the droops are arbitrarily chosen or systematically calculated using sensitivities, can eliminate overvoltage if reactive power control and APC are coordinated, second, the proposed sensitivity-based approach yields the best voltage performance index computed based on voltage profile compared to the maximum allowed upper bound, and third, OPF-based method is desirable if communication infrastructure exists and minimum energy curtailment is sought.

Contingency Analysis and Ranking of Kurdistan Region Power System Using Voltage Performance Index

In this paper, analysis and ranking of single contingency due to the outage of transmission lines for a large scale power system of the Kurdistan Region (KR) are presented. Power System Simulator software (PSS®E33) is used to simulate the Kurdistan Region power system network and perform the contingency analysis for single line outage. This analysis is essential in order to predict and evaluate the voltage stability in case of contingency occurrence to know the most severe case and plan for managing it. All possible transmission line outages of the network are tested individually. After each branch disconnects, load flow analysis are applied by using Newton Raphson method then all bus voltages are recorded, and compared with them before the contingency. Voltage performance index is calculated for all possible contingencies to rank them according to their severity and determine the most severe contingency which is corresponding to the highest value of performance index. Also, the contingencies which cause load loss and amount of this load are observed.

Security Analysis of Hybrid Multi-Carrier Energy Systems

Multi-carrier energy systems (MCESs) provide collaboration between various kinds of energy carriers to supply the electricity, heating, and cooling demands. With the widespread use of MCESs in recent years, the security assessment of energy systems has attracted the attention of many contemporary researchers. However, the complexity of an MCES, including electrical, natural gas, and district heating networks, and different uncertainties imposes vast challenges to keep a safe operation energy supply. In this paper, a systematic methodology for the security analysis of MCESs is presented. For this purpose, considering electrical, natural gas, and district heating networks, an integrated model of energy systems is introduced. The security analysis of this framework is evaluated using some indices. In this approach, two well-known performance indices, including power performance index (PIP) and voltage performance index (PIV), are used to analyze the electrical networks’ security. Besides, the concept of Energy not supplied (ENS) is used for natural gas and district heating networks. In this regard, security analysis of a typical MCES including the IEEE 14-bus electrical network, the IEEE 30-bus electrical network, 20-node Belgian natural gas network, and 14-node district heating network is examined. The applicability of the proposed technique will be proven using comprehensive simulation analysis.

Power System Contingency Analysis by using Voltage and Active Power Performance Index

Power System Contingency Analysis by using Voltage and Active Power Performance Index

Identification of system vulnerabilities in the Ethiopian electric power system

The Ethiopian Electric Power (EEP) has been operating and managing the national interconnected power system with dispersed and geographically isolated generators, a complex transmission system and loads. In recent years, with an increasing load demand due to rural electrification and industrialization, the Ethiopian power system has faced more frequent, widely spread and long lasting blackouts. To slash the occurrence of such incidents, identifying the system vulnerabilities is the first step in this direction. In this paper, the vulnerability assessment is performed using indices called active power performance index (PIp) and voltage performance index (PIv). These indices provide a direct means of comparing the relative severity of the different line outages on the system loads and voltage profiles. Accordingly, it is found that the most severe line outages are those lines that interconnect the high load centered (Addis Ababa and Central regions) with the rest of the regional power systems. In addition, the most vulnerable buses of the network in respect of voltage limit violations are mainly found at the high load centers.

A parallel computing approach for integrated security assessment of power system

Abstract Fast and accurate assessment of integrated security of present day complex and highly interconnected power system within time frame is a challenging task. The traditional methods used for integrated security assessment are fast but approximate. On the other hand, full simulation methods provide more accurate security assessment, but require large computation time. This paper proposes the use of parallel computing for fast and accurate assessment of integrated security of power system by running full Newton Raphson (NR) load flow program with sparsity technique to compute real power flow or MW performance index ( MWPI ), and voltage performance index ( VPI ), and continuation power flow program with sparsity technique to compute voltage stability index ( VSI ) for all possible single line outage contingencies. The proposed work has been carried out using the Matlab Parallel Computing Toolbox Software (PCTS). To implement parallel computing, the job scheduler, a part of PCTS, divides a computationally intensive job into various tasks and distributes these tasks to its assigned workers for evaluation. Effectiveness of the proposed approach has been demonstrated on IEEE 30-bus system and a practical NREB 246-bus Indian power system. As the proposed method utilizes NR load flow and continuation load flow programs, the accurate post contingency operating status of a power system is also available, which can be used for appropriate corrective actions planning to bring the power system back into secure state. The proposed approach is quite accurate and fast and hence can be implemented for integrated security assessment of practical power systems in smart grid environment also.

An online power system static security assessment module using multi-layer perceptron and radial basis function network

Abstract Efficient contingency screening and ranking method has gained importance in modern power systems for its secure operation. This paper proposes two artificial neural networks namely multi-layer feed forward neural network (MFNN) and radial basis function network (RBFN) to realize the online power system static security assessment (PSSSA) module. To assess the severity of the system, two indices have been used, namely active power performance index and voltage performance index, which are computed using Newton–Raphson load flow (NRLF) analysis for variable loading conditions under N − 1 line outage contingencies. The proposed MFNN and RBFN models based PSSSA module, are fed with power system operating states, load conditions and N − 1 line outage contingencies as input features to train the neural network models, to predict the performance indices for unseen network conditions and rank them in descending order based on performance indices for security assessment. The proposed approaches are tested on standard IEEE 30-bus test system, where the simulation results prove its performance and robustness for power system static security assessment. The comparison of severity obtained by the neural network models and the NRLF analysis in terms of time and accuracy, signifies that the proposed model is quick, accurate and robust for power system static security evaluation for unseen network conditions. Thus, the proposed PSSSA module implemented using MFNN and RBFN models are found to be feasible for online implementation.

English

In the area of power system planning and operation, contingency analysis plays an important role. In the present days, on-line security assessment is done by contingency ranking, with the help of various computer software, incorporating iterative method like Newton Raphson power flow for obtaining the magnitudes of different parameters. The motive of contingency ranking is to create a short list of potential contingencies quickly and rank them according to their severity in an accurate manner. In this paper sensitivity based wide performance index with respect to outage have been presented. The Newton-Raphson power flow results were used to construct two kinds of performance indices, namely the real power performance index and voltage performance index, which reflect the degree of severity of contingencies. Then full AC load flow was performed for each contingency case, to study the contingency effect. The effectiveness of the proposed method has been demonstrated by contingency screening and ranking on a standard 6-bus and IEEE 14-bus system.

Allocation of distributed generation using proposed DMSP approach based on utility and customers aspects under deregulated environment

Abstract Many methods were proposed in the literature for finding best allocations for DG placement considering various objectives. Sometimes, it becomes cumbersome task for system planners to select the objective for DG allocation based on utility and customer point of view. For this purpose, a set of optimization functions and sensitivity factors have been developed for allocation of DGs in the system. The optimization method consists of maximizing loadability, minimizing losses and cost while satisfying power system constraints. The sensitivity factor comprises voltage performance index and loss sensitivity factor for DG allocation. A decision made by system planner (DMSP) approach has been proposed to decide the allocation of DGs in the system based on utilities and customer demand. For this purpose, first DG locations have been planned in the system based on various objectives. Then, suitable objective has been decided from utility and customer necessities by DMSP. Having these in order, DMSP and analytic hierarchy process (AHP) has been used to make a decision over getting the appropriate locations for DGs placement in the system. A combined suitable option for DG allocations with equal weightage to the various objectives has also been studied in this work.

Optimal Location of SVC Considering Critical Contingency and Varying Load

The flexible Alternating Current transmission system (FACTS) may play a vital role in solving various problems of modern restructured power system networks, which have to operate under highly stressed conditions because of ever increasing demand of electric power. However, due to huge capital investment, an intensive investigation is required at planning stage to select optimal location and size of these devices to acquire maximum benefit of it. In this paper, Continuous Genetic Algorithm (CGA) based method is proposed for placement of Static Var Compensator (SVC) for minimizing real power loss, load bus voltage deviations and size of SVC. As a first step, contingency ranking is performed to determine the most severe line outages by evaluating voltage performance index (VPI) for both cases i.e. for base load condition and when load is varied randomly. Thereafter, Continuous Genetic Algorithm (CGA) has been applied to solve mixed continuous-discrete optimization problem. The optimization is carried out to find optimal location and size of SVC to minimize real power loss, load voltage deviation and rating SVC. The effectiveness of the proposed methodology is demonstrated on a standard IEEE 30-bus system.

An implementation of AC model to transmission expansion planning considering reliability constraints

In this paper, a hybrid heuristic methodology that employs fuzzy logic for solving the AC transmission network expansion planning (AC-TEP) problem is presented. An enhanced constructive heuristic algorithm aimed at obtaining a significant quality solution for such complicated problems considering contingency is proposed. In order to indicate the severity of the contingency, 2 performance indices, namely the line flow performance index and voltage performance index, are calculated. An interior point method is applied as a nonlinear programming solver to handle such nonconvex optimization problems, while the objective function includes the costs of the new transmission lines as well as the real power losses. The performance of the proposed method is examined by applying it to the well-known Garver system for different cases. The simulation studies and result analysis demonstrate that the proposed method provides a promising way to find an optimal plan. Obtaining the best quality solution shows the capability and the viability of the proposed algorithm in AC-TEP.

Fast voltage contingency analysis of power systems using model trees

This paper presents a model tree (MT) based approach for fast voltage contingency ranking, of most severe contingencies for online applications in energy management systems. To measure the severity of contingencies, a bus voltage violation based scalar performance index is used. Model trees are developed to estimate the real value of voltage performance index (VPI) and rank the single line outage contingencies, according to their severity. Full AC power flow is performed, to generate the training and testing patterns for the proposed MT under each contingency. The effectiveness of the proposed approach is tested on IEEE test systems. Once trained, the MT method gives fast and accurate ranking of contingencies for unknown load patterns, hence it is suitable for online applications in energy management systems.

Neural network approach to contingency screening and ranking in power systems

An artificial neural network (ANN) approach to power system contingency analysis is proposed. Using fast voltage and line-flow contingency screening. Full AC load flow is performed for each contingency case. The off-line results of full AC load flow calculations are used to construct two kinds of performance indices, namely the real power performance index ( PI MW) and voltage performance index ( PI V), which reflect the degree of severity of contingencies. The results from off-line load flow calculations are used to train the “ screening module”, which is a multi-layered perceptron (MLP) network, for estimating the performance indices ( PI MW, PI V PI V). The MLP is trained to classify the contingencies either as critical or non-critical cases using back-propagation (BP) algorithm. The screened critical contingencies are passed on to the “ ranking module” for ranking of the contingencies. The effectiveness of the proposed method is demonstrated by contingency screening and ranking on a standard 6-bus and IEEE 14-bus systems. The performance of the proposed method is compared with a traditional Newton Raphson (NR) method and the results discussed. The proposed methodology was implemented using the MATLAB Neural Network Toolbox. The generalization capability of the trained neural network was able to identify unknown contingencies with large range of operating conditions and changes in network topology. The proposed approach to contingency analysis was found to be suitable for fast voltage and line-flow contingency screening and ranking.

An efficient multi-objective fuzzy logic based successive LP method for optimal reactive power planning

Abstract This paper presents a new and efficient method to solve the Optimal Reactive Power Planning (ORPP) problem, simultaneously minimising transmission losses and improving voltage profile using Multi-objective Fuzzy logic based LP (MFLP) model in Successive Linear Programming (SLP) framework. The ORPP problem is concerned with optimally siting and sizing new capacitors at prospective sites in a planned grid with projected load demands such that, minimum number and quantum of new capacitors are allocated, the transmission losses are minimised and a satisfactory voltage profile is obtained. In this paper, all the prospective capacitor locations are ranked using Voltage Performance Index (VPI) based on sensitivity factors. From the top of the ranked list, a minimum number of locations are chosen for siting new capacitors. Reactive powers at these selected capacitor sites along with generator voltage magnitudes, reactive powers of existing switchable VAR sources and on-load tap changer (OLTC) settings of transformers are used as control variables in this method. In the MFLP framework, each of the objectives and each of the constraints are assigned a satisfaction parameter. The satisfaction parameter corresponding to any objective quantifies the degree of closeness of the current state of the objective to the optimum. The satisfaction parameter corresponding to a constraint describes the degree of enforcement of that constraint. By maximising the minimum of these satisfaction parameters, the objectives are optimised and the constraint enforcements are maximised. The MFLP based SLP method is found to be very effective while planning for systems which have severe under-voltage violations due to insufficient reactive powers, as the method is capable of selectively relaxing certain load voltage constraints, while simultaneously enforcing all other constraints strictly. The MFLP technique optimises all the objectives, i.e. minimises number and quantum of new capacitors, minimises transmission losses and maximises constraint enforcement of all violated constraints, while simultaneously imposing all other problem constraints strictly. This method uses compactly stored, factorised constant matrices in all MFLP steps, both for construction of the MFLP model as well as for the power flow solution. The method was tested on IEEE test systems and on a practical 191 bus electric utility system. The merits of the method, compared with SLP method using non-fuzzy approach, are brought out.

Voltage contingency ranking using fuzzified multilayer perceptron

Abstract A fuzzified multi-layer perceptron (FMLP) trained by back-propagation algorithm is proposed for on line voltage contingency analysis and ranking. The input vector consists of fuzzy membership values of loads to different linguistic categories, while the output vector is defined in terms of fuzzy membership values of a voltage performance index in different severity classes. Fuzzifying the loads into linguistic categories using non-linear membership functions enables efficient modeling of uncertainty associated with loads. Angular distance based clustering has been used to determine significant inputs to the fuzzified neural network. Due to the incorporation of fuzzy logic, the method is capable of handling even those contingencies that belong to more than one class. The effectiveness of the method has been shown on IEEE 30-bus test system and 75-bus Indian system and it is found to classify and rank the contingencies quite accurately for unknown load patterns.