Phasor Measurement Units Placement Research Articles

Multi-objective evolutionary algorithm in tables for placement of SCADA and PMU considering the concept of Pareto Frontier

The main concern of Metering Systems Planning (MSP) for state estimation is the determination of the number, type and location to install metering devices to attend performance requirements related to observability and measurement redundancy. Due to financial constraints, the MSP is a multi-objective, combinatorial optimization problem, which involves conflicting objectives of investment cost and performance requirements. This paper proposes a multi-objective formulation for the MSP problem and a method for its solution. The method combines a Multi-Objective Evolutionary Algorithm based on subpopulation tables with the properties of the so-called HΔ matrix. The method can solve the MSP problem considering the existence of only measurements from supervisory control and data acquisition system, only from Phasor Measurement Units (PMUs) or both types of measurements. Using the concept of Pareto Frontier the method enables the project of reliable metering systems (those guaranteeing system observability during normal operating conditions and in the presence of contingency situations that cause the loss of one or two measurements or one remote terminal unit or one PMU) and other three types of metering systems with different performance requirements and costs in only one execution. Simulation results with IEEE test systems and a Brazilian system validate the paper propositions.

Optimal substation-based joint allocation of PMUs and measuring channels considering network expansion planning

This paper proposes an integrated framework to design wide area measurement system (WAMS) addressing the challenges of expansion planning and unknown transformer taps. The proposed framework is formulated as a mixed-integer linear programming (MILP) problem. It minimizes the number of substations disrupted for phasor measurement unit (PMU) placement, PMU buses, and PMU measuring channels. Concepts of substations and buses are separately treated. Power system expansion planning is also considered in order to achieve an optimal solution with the least cost of disrupting existing and future substations. Observability constraints are defined to make both present and expanded grids observable since the time span of WAMS planning is usually shorter than network expansion planning. Moreover, special attention is paid to multiple voltage levels inside a substation; transformers with unknown tap settings are exempt from being treated as observability paths and locating vicious measurement channels. Furthermore, novel ideas are proposed to model branch outages using the concept of backup observability and to model PMU failure using a hybrid method which is a modified version of previous ones. Numerical results from testing the proposed framework on standard test systems verify its performance from perspectives of solution optimality and computational burden.

A Genetic Algorithm Approach Considering Zero Injection Bus Constraint Modeling for Optimal Phasor Measurement Unit Placement

A Genetic Algorithm Approach Considering Zero Injection Bus Constraint Modeling for Optimal Phasor Measurement Unit Placement

Permanent Fault Location in Distribution System Using Phasor Measurement Units (PMU) in Phase Domain

This paper proposes a new method for locating high impedance fault in distribution systems using phasor measurement units (PMUs) installed at certain locations of the system. To implement this algorithm, at first a new method is suggested for the placement of PMUs. Taking information from the units, voltage and current of the entire distribution system are calculated. Then, the two buses in which the fault has been occurred is determined, and location and type of the fault are identified. The main characteristics of the proposed method are: the use of distributed parameter line model in phase domain, considering the presence of literals, and high precision in calculating the high impedance fault location. The results obtained from simulations in EMTP-RV and MATLAB software indicate high accuracy and independence of the proposed method from the fault type, fault location and fault resistance compared to previous methods, so that the maximum observed error was less than 0.15%

A novel linear framework for Phasor Measurement Unit placement considering the effect of adjacent zero-injection buses

A novel linear approach for Phasor Measurement Units (PMUs) placement is proposed in this paper to ensure the topological observability taking into consideration the impacts caused by the adjacent zero-injection buses (ZIBs). The observability analysis in the paper is performed utilizing merely the main topological observability rules. Furthermore, the model is developed to include all possible single contingencies both on the lines and PMUs even where adjacent ZIBs are highly interconnected. To this end, the common approach for handling contingencies is enhanced. Moreover, the presented framework incorporates a subsidiary objective, i.e. maximizing the measurement redundancy among the set of solutions with the minimum number of PMUs beside the main objective, i.e. minimizing the number of the required PMUs. In this regard, a unified Integer Linear Programming (ILP) is used to solve the proposed optimisation problem. It is worth noting that the suggested approach is applied to different test systems like IEEE 14-bus, 30-bus, 39-bus, 57-bus as well as 118-bus system to validate the effectiveness and efficiency of the proposed framework and the obtained results are compared to those reported by the prior researches.

Optimal PMU placement for power system observability considering network expansion and N − 1 contingencies

The determination of the appropriate number and location of the phasor measurement units (PMUs) has raised the issue of the system monitoring as the main challenge. In this study, the problem of optimal PMU placement (OPMUP) is carried out in order to achieve a fully observable power system under normal and contingency conditions considering network expansion. For this purpose, network expansion is investigated considering two fixed and flexible PMU placement scenarios. The contingency index is introduced through the modelling process of N - 1 contingency states. This index is inserted as a new term in the objective function by compromising the observability confidence level and the number of PMUs. Other goals including minimising the number of PMUs, measurement channels and redundancy are considered along with the OPMUP process. The IEEE 57-bus standard network in the MATLAB is studied during the expansion time horizon with the proposed algorithms to achieve the above goals.

Cost Effective Wide Area Measurement Systems for Smart Power Network

Due to the large number of applications of wide area monitoring systems (WAMSs), many power utilities are implementing phasor measurement units (PMUs)-based WAMS replacing the conventional supervisory control and data acquisition system. The biggest challenge in implementing the technology is the cost of WAMS. Many researchers are trying to minimize the cost of WAMS by making the system observable with optimal placement of PMU. Along with the cost of PMU, the cost of communication infrastructure (CI) is dominating the cost of WAMS. Hence, it is necessary to optimize the communication path link and also to find out the optimal location of phasor data concentrator (PDC). In this paper, an optimization model to find the optimal placement of PMU, optimal location of PDC, and their CI is developed. For this, both independent and simultaneous optimization carried out by using differential evolution algorithm. The multi-objective differential evolution is used for simultaneous optimization. The presence of conventional flow measurement device and its effect on overall cost of WAMS with and without considering presence of optical fiber is presented. The method is implemented with different ( $N-1$ ) contingency considerations. Also, the results with the presence of pre-existing PMUs and optical fiber paths are provided.

Reliability-Based Phasor Measurement Unit with Outage of Transmission Lines

This paper discussed on the Monte-Carlo simulation technique to determine the optimal placement of Phasor Measurement Unit (PMU) in power system whilst ensuring the observability of the system. In addition, the information on Force Outage Rate (FOR) of the system can be calculated using Markov Chain technique. The FOR represents the level of risk security for the transmission line that happened because of unscheduled and unexpected failure or repair in the system. Subsequently, the reliability model of the transmission line can be developed. Using IEEE 57-bus system, the results obtained from Monte-Carlo simulation technique demonstrate the optimal PMU placement, the desired reliability of the Wide Area Monitoring System (WAMS) as well as the number and location of covered contingencies of the system.

Optimal placement of voltage measurements for wide area fault location observability considering the uncertainty of network parameters

This paper proposes an optimization method based on genetic algorithm (GA) to determine the number and location of phasor measurement units (PMUs) in order to wide area fault location based on voltage measurement. In the practical condition, due to the uncertainty of network parameters including measurement errors and inaccuracy of line parameter values, the estimation of the fault location may be not accurate. Therefore, the proposed method has been developed to determine the number and location of PMUs in order to achieve an acceptable accuracy with required reliability. Since the number and location of PMU depends on the fault location method, a new fault location method has been developed with minimum required number of PMUs. The new method can determine the fault location by measuring from one side of the fault point instead of two sides. Therefore, the number of required PMUs is minimized at comparison to previously presented methods. The weighted least-square (WLS) method is used to solve the fault location problem by minimizing the measurement errors. To consider unsynchronized condition of measurements, the formulation has been modified using only the magnitudes of voltage measurements. Finally, the method has been applied on New England 39-bus test system, and the results show the efficiency of the proposed PMU placement and fault location methods in the network with the uncertainty of parameters.

Hierarchical Clustering based optimal PMU placement for power system fault observability

Optimal number and location of phasor measurement units (PMUs) in the power system networks faces challenges for achieving the full network observability during fault conditions. Achieving fault observability approach requires more constraints than normal system observability and consequently suffers from complex analysis and heavy computational burden for the large-scale networks. A new algorithm for determining the optimal PMU placement considering the network fault observability is introduced. The proposed algorithm is achieved through four stages. The first stage is achieved through the network fault simulation to obtain the post fault change in voltage (ΔV) at each bus. Then, the post fault change in voltage (ΔV) is used to build the network connectivity matrix (CM) and forming a new developed Faulted Connectivity Matrix (FCM) that describes the power system topology during the fault conditions. The correlation between the buses is obtained, in the second stage, by applying Pearson correlation coefficient. Hierarchical Clustering technique is given, in the third stage, to cluster the network into coherent zones to find the most correlated buses. Finally, the optimal location of the PMUs is identified within each zone based on simple proposed placement rules. The proposed algorithm is tested under a variety of fault events applied on different standard test systems. The results show the simplicity and the effectiveness of the proposed algorithm.

Incremental PMU placement considering reliability of power system network using analytical hierarchical process

This study presents a methodology for enhancing the observability of interconnected power network with the incorporation of component reliability for incremental phasor measurement units (PMUs) placement. Initially, multiple optimal solutions for complete observability have been determined with the use of genetic algorithm. An overall system reliability index has been proposed for the selection of the most suitable solution among the determined solutions. Furthermore, the ranking of the buses for PMU placement has been performed using the proposed reliability observability criteria. An index determined by series-parallel combinations of different components of the network has been used for this purpose. To achieve effective multi-phasing of PMU placement analytical hierarchical process has been utilised. This strengthens the observability through most reliable buses during the initial phases. The proposed methodology is illustrated on IEEE 14-bus and eastern region Indian power grid 90-bus real system.

Application of domination integrity of graphs in PMU placement in electric power networks

In this paper, we propose the application of the concept of power domination integrity to an electric power network. A phasor measurement unit (PMU) is used to analyze and control the power system by measuring voltage phase in electrical nodes and transmission lines. Due to the high cost of PMUs, it is necessary to minimize the number of PMUs such that the depth of observability is ensured. Placing PMUs in a network can be formulated as a graph theoretic problem of finding the minimum number of nodes (PMUs) in a graph that has a maximum number of links with other nodes. To achieve this, the concept of domination in graph theory is applied to power networks by redefining ``adjacency'' of a vertex as an ``observed'' vertex. The power domination number identifies the number of PMUs to be placed. The proposed concept of power domination integrity gives not only the minimum number of PMUs but also identifies the optimal locations for PMU placement in an electric power network.

Multi-Stage Optimal Placement of Branch PMU in Active Distribution Network

Abstract The penetration of distributed generation and electric vehicles requires advanced monitoring and control strategies to maintain the reliable operation of active distribution network (ADN). Phasor measurement unit (PMU), as an advanced measuring device, has been applied in the operation of transmission systems for decades. Recently, it is anticipated that PMUs can be adopted in the distribution network. In this paper, the optimal branch PMU (BPMU) placement is studied. First, an optimization model for the multi-stage BPMU placement is established considering the observability of ADN. Moreover, the weights of buses are designed to consider the influence of uncertain renewable energy generation and loads. Then, probabilistic load flow (PLF) is used to solve power flow with uncertainties, and weights of buses are obtained based on probability distributions of voltage magnitude. Finally, binary integer programming (BIP) is adopted to obtain the locations of BPMUs. The proposed method is tested on customized IEEE 33-bus and PG&E 69-bus distribution network, and the results are compared with those considering other methods.

Optimal placement of phasor measurement units using clustered gravitational search algorithm

Optimal placement of phasor measurement units using clustered gravitational search algorithm

Power systems wide-area voltage stability assessment considering dissimilar load variations and credible contingencies

This paper reveals that the existing techniques have some deficiencies in the proper estimation of voltage stability margin (VSM) when applied to a power system with different load change scenarios. The problem gets worse when credible contingencies occur. This paper proposes a real-time wide-area approach to estimate VSM of power systems with different possible load change scenarios under normal and contingency operating conditions. The new method is based on an artificial neural network (ANN) whose inputs are bus voltage phasors captured by phasor measurement units (PMUs) and rates of change of active power loads. A new input feature is also accommodated to overcome the inability of trained ANN in prediction of VSM under N−1 and N−2 contingencies. With a new algorithm, the number of contingencies is reduced for the effective training of ANN. Robustness of the proposed technique is assured through adding a random noise to input variables. To deal with systems with a limited number of PMUs, a search algorithm is accomplished to identify the optimal placement of PMUs. The proposed method is examined on the IEEE 6-bus and the New England 39-bus test system. Results show that the VSM could be predicted with less than 1% error.

Solving the multistage PMU placement problem by integer programming and equivalent network design model

Recently, phasor measurement units (PMUs) are becoming widely used to measure the electrical waves on a power grid to determine the health of the system. Because of high expense for PMUs, it is important to place minimized number of PMUs on power grids without losing the function of maintaining system observability. In practice, with a budget limitation at each time point, the PMUs are placed in a multistage framework spanning in a long-term period, and the proposed multistage PMU placement problem is to find the placement strategies. Within each stage for some time point, the PMUs should be placed to maximize the observability and the complete observability should be ensured in the planned last stage. In this paper, the multistage PMU placement problem is formulated by a mixed integer program (MIP) with consideration of the zero-injection bus property in power systems. To improve the computational efficiency, another MIP, based on the equivalent network flow model for the PMU placement problem, is proposed. Numerical experiments on several test cases are performed to compare the two MIPs.

Binary cuckoo search based optimal PMU placement scheme for united Indian grid - A case study

The Phasor Measurement Unit (PMU) is becoming very effective device for power system as it produces synchronized parameters of power system. This measurement data helps us in monitoring, controlling and protecting the system effectively. To design a wide-area measurement system that could observe the complete system, a Binary Cuckoo Search (BCS) method is suggested in this paper. It also considers the system observability under line/PMU outage conditions. After testing the methodology on some benchmark systems, it has been applied on the Indian power grid. The results are then compared with the methods available in literature. This comparison has proven the proposed method as the best and accurate.Keywords: Optimal PMU placement (OPP); Binary Cuckoo Search (BCS); Power system observability

Dual Enhancement of Power System Monitoring: Improved Probabilistic Multi-Stage PMU Placement with an Increased Search Space & Mathematical Linear Expansion to Consider Zero-Injection Bus

This paper presents a mathematical linear expansion model for the probabilistic Multistage Phasor Measurement Unit (PMU) Placement (MPP) in which zero-injection buses (ZIBs), as well as communication channel limitations, are taken into consideration. From the linearization perspective, presenting a model formulizing the probabilistic concept of observability while modelling the ZIB is of great significance, and has been done in this paper for the first time. More importantly, the proposed probabilistic MPP utilizes a technique disregarding the prevalent subsidiary optimizations for each planning stage. Although this technique, in turn, increases the problem complexity with manifold variables, it guarantees the global optimal solution in a wider and thorough search space; while in the prevalent methods, some parts of the search space might be missed. Furthermore, the proposed model indicates more realistic aspects of the MPP where system operators are allowed to follow their intention about the importance of buses such as strategic ones based on monitoring the priority principles. In addition, the model is capable of considering the network topology changes due to long-term expansions over the planning horizon. Finally, in order to demonstrate the effectiveness of the proposed formulation, the model is conducted on the IEEE 57-bus standard test system and the large scale 2383-bus Polish power system.

ILP-Based Optimal PMU Placement with the Inclusion of the Effect of a Group of Zero-Injection Buses

Zero-injection buses (ZIBs) can reduce the number of phasor measurement units (PMUs) required to be installed for complete observability. It has been demonstrated that a group of neighboring ZIBs can further reduce this required number of PMUs. In contrast to a single ZIB, the effect of a group of ZIBs has not been incorporated into the model of optimal PMU placement (OPP) using mathematical approaches, except for some heuristics methods. In this paper, a novel methodology to incorporate the effect of a group of ZIBs into the OPP model is proposed, using the integer linear programming approach. Two common contingencies—line outage and PMU loss—are also considered. Moreover, two visualization techniques are used for illustrating the locations of PMUs obtained from OPP: (1) using a graph-based force-directed method and (2) on a map using the geographic information system. The proposed method is verified using several small- and large-scale test systems and compared with other related studies.

An Approach for Optimal Placement of Phasor Measurement Unit for Power Network Observability Considering Various Contingencies

Phasor measurement units (PMUs) play an important role in power system operations. They provide synchronized phasor measurement of voltage and current for preservation and control of electrical power networks. In this work, depth-of-one (DOU1) and depth-of-two (DOU2) unobservability has been considered for optimal PMU placement (OPP) problem. Further, cases ignoring and considering zero injection buses are also taken into account for minimizing the PMUs locations. The influence of DOU1 and DOU2 consisting of the single PMUs outage have also been taken into consideration. Furthermore, this article also proposed the effect of single branch outage on OPP problem. Moreover, to show the scalability of the proposed approach, both single PMU outage and branch outage are considered together. Thus, the critical branch based on line stability index utilizing load flow measurement is determined. Then, binary integer linear programming approach has been developed in this paper to determine the strategic locations of PMUs considering various contingencies. The efficacy and robustness of the proposed methodology are confirmed by implementing on standard IEEE test systems and outcomes thereby authorizing the reliability of the proposed approach. Obtained results have been compared with the standard approaches published in the referred journals, and the results achieved by the proposed methodology outperform the other comparative approaches; thus, the proposed methodology, successfully, accomplishes complete observability of the power networks.