Optimal Placement of Phasor Measurement Units for Power Systems Using Genetic Algorithm

Power grids require monitoring to operate with high efficiency while minimizing the chances of having a failure. However, current monitoring scheme which consists of SCADA (Supervisory Control and Data Acquisition), accompanied with conventional meters distributed throughout the grid, is no longer sufficient to maintain an acceptable operation of the grid. This is evident from the multiple failures and blackouts that happened and are still happening in grids worldwide. This issue became more severe due to systems being operated near their limits (to reduce costs and due to the increase in electricity demands), as well as, the addition of renewable energy sources, which usually have abrupt changes. Smart grids were introduced as a solution to this issue by the inclusion of Wide Area Monitoring System (WAMS), which is mainly based on Phasor Measurement Units (PMU), which are measurement devices that provides synchronized time stamped measurements with high sending rate which significantly improves the monitoring of the grid. However, PMUs are relatively expensive (considering both direct and indirect costs incurred). Thus, it is desired to know the minimum number of PMUs required for achieving certain monitoring criteria. Thus, Optimal PMU Placement (OPP) formulates an optimization problem to solve this issue. In the literature of OPP, multiple objectives and constraints are considered, based on desired criteria. In this thesis, a review of OPP is made, followed by the application of selected algorithms (Integer Linear Programming and Genetic Algorithm) on various test systems as a verification and then applying it to Qatar Grid, to compare between different considerations as well as gain insight about the possible PMU placements for Qatar Grid. The contribution of this thesis is introducing a modified fitness function for the Genetic Algorithm that provides more diverse results than previous papers, while incorporating for various considerations like Zero Injection Buses, Conventional Measurements and current branch limit. It also analyzes the results of current branch limit and provides new plots describing their effects

PHASOR MEASUREMENT UNIT DEPLOYMENT APPROACH FOR MAXIMUM OBSERVABILITY CONSIDERING VULNERABILITY ANALYSIS

In recent years, there has been growing interest of synchrophasor measurements like Phasor Measurement Units (PMUs) Power systems are now being gradually populated by PMU since they provide significant phasor information for the protection and control of power systems during normal and abnormal situations. There are several applications of PMUs, out of which state estimation is a widely used. To improve the robustness of state estimation, different approaches for placement of PMUs have been studied. This thesis introduces an approach for deployment the PMUs considering its vulnerability. Two different analysis have been considered to solve the problem of locating PMUs in the systems. The first analysis shows that using a very limited number of PMUs, maximum bus observability can be obtained when considering the potential loss of PMUs. This analysis have been done considering with and without conventional measurements like zero injections and branch flow measurements. The second analysis is based on selection of critical buses with PMUs. The algorithm in latter is specifically used for the system which has existing PMUs and the scenario where new locations for new PMUs has to be planned. The need for implementing this study is highlighted based on attack threads on PMUs to minimize the system observability. Both the analysis are carried out using Binary Integer Programming (BIP). Detail procedure has been explained using flow charts and effectiveness of the proposed method is testified on several IEEE test systems

Heuristic Method for Optimal Placement of Phasor Measurement Units (PMUs)

The phasor measurement units (PMUs) are very important tool for monitoring and control the power system. PMUs give real time, synchronized measurements of voltages at the buses and also current phasors which are incident to those buses where these PMUs are located. It is unnecessary and impossible to place PMU at each bus to estimate the states because high cost of PMUs and also the cost of communication facilities. It is necessary to find out the minimum number of PMUs to entire power system observable. The optimal placement of PMUs (OPP) problem solved by various techniques such as mathematical programming, metaheuristic techniques. The recently some heuristic optimization technique proposed to determine the minimum number of PMUs for various systems should be completely observable. This optimal PMUs placement (OPP) problem is pure binary optimization problem. A topological observability based three stages optimal PMU placement technique is proposed for solving this problem. For topological observability a set of minimum PMUs is required to make the system completely observable. It is assumed that there are strategic buses in every system using that the PMU placement becomes an easy task. The proposed method tested on standard IEEE bus systems and compared the results of the proposed method to the previously methods

Optimal PMU Placement and Signal Selection for Monitoring Critical Power System Oscillations

In this thesis, a strategy for phasor measurement unit (PMU) optimal placement and signal selection is proposed for monitoring critical oscillations in electric power systems. A robust indicator, mode in output proportion factor (MOPF), is introduced for identify critical PMU locations and signal channels, in order to better monitor power system oscillations with specific oscillation modes. Based on the proposed MOPF, a two-layer algorithm is presented. This algorithm could benefit system operators and planners in the following two ways: 1) it identifies existing PMU devices and signal channels, which provides the best observability for critical oscillation modes; 2) it suggests optimal locations for further PMU deployments, in order to enhance the observability for critical oscillation modes. The performance of proposed algorithm is illustrated via a modified 16-machine-68-bus system and NPCC-140-bus system. Based on the proposed algorithm, all modes of interest can be observed sufficiently under various disturbances. Therefore, the proposed algorithm can be applied to prioritize or deploy PMUs to observe critical oscillation modes in power systems

Roles of dynamic state estimation in power system modeling, monitoring and operation

Power system dynamic state estimation (DSE) remains an active research area. This is driven by the absence of accurate models, the increasing availability of fast-sampled, time-synchronized measurements, and the advances in the capability, scalability, and affordability of computing and communications. This paper discusses the advantages of DSE as compared to static state estimation, and the implementation differences between the two, including the measurement configuration, modeling framework and support software features. The important roles of DSE are discussed from modeling, monitoring and operation aspects for today's synchronous machine dominated systems and the future power electronics-interfaced generation systems. Several examples are presented to demonstrate the benefits of DSE on enhancing the operational robustness and resilience of 21st century power system through time critical applications. Future research directions are identified and discussed, paving the way for developing the next generation of energy management systems and novel system monitoring, control and protection tools to achieve better reliability and resiliency.Departamento de Energía de EE. UU TPWRS-00771-202

Optimal allocation of phasor measurement units using practical constraints in power systems

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London.The purpose of the research is to find a strategic placement of phasor measurement units (PMUs) that can maintain the observability of the power system using a binary variant of particle swarm optimisation method (BPSO). In recent years, integer linear programming (ILP) is the common optimisation method used to solve this problem. However, recent studies have shown that deterministic methods such as ILP are still unable to find the most optimal placement of PMUs. Therefore, there is still room for further investigation using heuristic algorithm due to its search-based nature. It is important to determine the most strategic placement of PMUs to ensure that the PMUs are fully utilised due to their expensive price tag. The challenge in using heuristic algorithm lies in its weakness when involving large-sized problem since it is prone to stuck in local optima as shown in earlier studies where most of them applied their proposed approach to small bus systems. To prevent the BPSO method from being stuck in local optima, a mutation strategy is proposed in addition to the V-shaped sigmoid function replacing the S-shaped sigmoid function. The proposed method is designed to intensify the local search of the algorithm around the current best solution to help instigate the particles from being stuck in local optima and consequently finding a better solution. This is shown to be a crucial factor based on the numerical results obtained where it outperforms all methods for all bus systems tested including the IEEE 300-bus system in terms of measurement redundancy and the number of PMUs. This study also considers other problem constraints such as zero-injection bus, single PMU loss and also PMU’s channels limit. Most of the existing studies considered PMU to have an unlimited number of channels whereas in practical, PMU does have a finite number of channels that it can use.Majlis Amanah Rakyat (MARA) and University Kuala Lumpur (UniKL

Benzetilmiş Tavlama Algoritması İle Fazör Ölçüm Birimlerinin Optimal Yerleşimi

Gelişen teknoloji ve artan nüfus ile birlikte elektrik enerjisine olan ihtiyaç ve talep her geçen gün artmaktadır. Enerji talebindeki artış güç sistemlerini kararlılık sınırlarına yakın bölgelerde çalışmaya zorlamaktadır. Bu durum güç sistemlerinde gerilim kararsızlığı ve gerilim çökmesi gibi sonuçlar doğurmaktadır. Güç sistemlerinin kararlılık durumunun gerçek zamanlı olarak takip edilmesi kritik önem taşımaktadır. Bu sebeple güç sistemlerinin izlenebilirliği ve kontrolünü sağlayan sistemlere duyulan ihtiyaç da artmıştır. Fazör Ölçüm Birimi (FÖB) bu sistemlerden birisidir. FÖB’ler Global Positioning System (GPS) yardımıyla gerilim, akım ve faz açısının anlık olarak takip edilmesine imkan sağlamaktadır. Ancak maliyet kısıtı nedeniyle FÖB’ler iletim hatlarında tüm baralara yerleştirilememektedirler. Bu yüzden FÖB’leri şebekeye maksimum gözlenebilirliği sağlayacak optimal bir şekilde yerleştirmek önem arz etmektedir. Optimal yerleşim için literatürde pek çok yöntem kullanılmaktadır. Bu çalışmada Benzetilmiş Tavlama Algoritması kullanılarak Enterkonnekte güç sisteminin bir kısmı olan Trakya Güç Sistemi’ne optimal FÖB yerleşimi yapılmıştır. Benzetilmiş Tavlama Algoritması ile elde edilen sonuçlar, Power System Analysis Toolbox (PSAT) programı ile FÖB yerleşim algoritmalarından çıkan sonuçlarla karşılaştırılmıştır. Bu çalışma ile sistemin tamamını anlık olarak takip edebilmek için kullanılan FÖB’lerinin, Trakya Güç Sistemi’nde hangi baralara yerleştirilmesi gerektiği tespit edilmiş ve optimal yerleşim gerçekleştirilmiştir