Optimal Locations Of Phasor Measurement Units Research Articles

Allocation of Optimal PMUs for Power System Observability Using PROMETHEE Approach

Phasor measurement units (PMUs) are becoming a vital measurement device in wide-area monitoring, operation, and control. The allocation of PMU at each bus will make that bus directly observable. However, considering the high installation costs, it is not feasible to place PMU at each bus. Thus, placing the PMUs at optimal locations is extremely important. In this study, the Preference Ranking Organization Method for Enrichment of Evaluation (PROMETHEE)-based multi-criteria decision-making (MCDM) technique has been applied for the optimal allocation of phasor measurement units (PMUs) with the aim of achieving full system observability. Along with the entire network observability, the proposed approach provides maximum measurement redundancy (MR) too. Unlike some previous popular MCDM techniques, the proposed approach obtains optimal PMU placement (OPP) solution without performing pruning operations. Different criterion has been formulated to construct a decision matrix (DM). This DM helps in calculating the net outranking flow (NOF) of all the buses during the PROMETHEE approach. Based on the maximum NOF value, the PMUs are placed at those buses. The proposed approach also considers the inclusion of zero injection buses (ZIBs). Further, cases such as single PMU outage and existence of conventional measurements have been considered while determining optimal locations of PMUs. The proposed algorithm is demonstrated on IEEE 14-bus, 30-bus, 57-bus, and 118-bus systems, one Indian practical utility, i.e., Northern Regional Power Grid (NRPG) 246-bus system, and larger Polish 2383-bus system. To prove the effectiveness of the proposed algorithm, it has been compared with some of the popular existing techniques.

Optimal PMU allocation for high-sensitivity wide-area backup protection scheme of transmission lines

In spite of the outstanding benefits provided via phasor measurement units (PMUs) to smart grids in the field of wide area protection, they increase the cost of the infrastructure. Based on PMU location and system topology, subsets of buses and lines are formed representing backup protection zones (BPZs). This paper introduces a proposed criterion to overcome the shortage in formulating the BPZs. Also, this paper presents a proposed framework to define the optimal PMU locations regarding wide area BPZs. The framework is expressed as a multi-objective function, which aims to enhance the system observability, increase the number of transmission lines belonging to BPZs and increase the BPZ threshold sensitivity. The genetic algorithm technique (GA) is used to obtain the optimal locations of PMUs for different cases. The effectiveness of the proposed framework is evaluated by investigating the 14-bus IEEE standard system for different cases of fault location, type and resistance. Furthermore, the 39-bus system is considered for some cases as a larger system. The results show the possibility of enhancing the sensitivity of the BPZs of the system regarding optimal PMU locations.

Novel notions of zero injection property of buses in optimal PMU location with efficient observability enhancement focusing on security concepts

In this paper, a new method is proposed for security-oriented, optimal placement of phasor measurement units (PMUs) incorporating efficient observability redundancy. In this way, novel concepts in zero-injection buses (ZIBs) are introduced. The proposed concepts regard aspects of the ZIBs effect that have not yet been studied; thus, by applying this concept, maximum possible capacity of the ZIBs will be available for use. Therefore, the proposed method is capable of producing optimum possible results with tangibly higher ZIBs capacity usage and measurement redundancy levels than those reached in preceding works. In addition, the reliability of fragile areas monitoring from overvoltage viewpoint is enhanced. Considering the fact that complete synchronized network observability is undeniably significant for making control decision in critical conditions to avoid brownouts or blackouts, a novel practical framework is proposed based on backup observability concept in order to model branch outage in addition to PMU loss and channel failure. All proposed security models can be tested by practical, large-scale test systems such as Polish 2383- and 3375-bus. Also, in the case of branch outage, selective security criteria are considered so as to enhance security of network observability against cascading failures in electric power systems.

Optimal phasor measurement units placement for full observability of power system using improved particle swarm optimisation

Penetration of renewable, advanced metering capabilities, and the urge for situational awareness, all calls for power system state estimation (SE). The SE with phasor measurement units (PMUs) is a powerful technique for full system observability. The results of the SE are more accurate, when using PMUs with optimal locations in the complex power systems. In this study, a proposed technique for optimal PMUs placement is discussed and implemented. The optimal PMUs locations will be determined using improved particle swarm optimisation algorithm. This study also presented an optimisation solution technique for the problem of SE using the weighted least square method, improved and based on optimal PMUs placement. A numerical observability analysis is also presented to check the validity of the proposed technique in power system SE based on gain matrix factorisation. The technique applies to the standard IEEE 14-, 30-, and 118-buses systems. The results showed high efficiency and good performance in power system SE when using optimal PMUs locations with full observability.

Optimal PMU location in power systems using MICA

This study presented a modified imperialist competitive algorithm (MICA) for optimal placement of phasor measurement units (PMUs) in normal and contingency conditions of power systems. The optimal PMU placement problem is used for full network observability with the minimum number of PMUs. For this purpose, PMUs are installed in strategic buses. Efficiency of the proposed method is shown by the simulation results of IEEE 14, 30, 57, and 118-bus test systems. Results of the numerical simulation on IEEE-test systems indicated that the proposed technique provided maximum redundancy measurement and minimum request of PMUs so that the whole system could be topologically observable by installing PMUs on the minimum system buses. To verify the proposed method, the results are compared with those of some recently reported methods. When MICA is used for solving optimal PMU placement (OPP), the number of PMUs would be usually equal to or less than those of the other existing methods. Results indicated that MICA is a very fast and accurate algorithm for OPP solution.

Ant colony optimizer for phasor measurement units placement

This paper proposes an approach for optimal placement of phasor measurement units (PMUs) for complete observability at normal and emergency conditions such as any single line outage or any single PMU loss using ant colony optimization (ACO) algorithm. The objective function is to find the optimal locations of PMUs and the minimum number of PMU channels by optimizing the logic decision of control variables, under the observability constraint. The ACO algorithm is applied to the standard IEEE 14-bus, 30-bus and New England 39-bus systems. In addition, an application of the proposed algorithm to a real power system of the west Delta network (WDN) as a part of the Unified Egyptian Network (UEN) is presented. The results obtained are compared with those obtained using other techniques. Simulation results show that the proposed ACO algorithm is more accurate and efficient for obtaining the optimal placement of PMUs with minimum number of PMU channels, especially with increasing the system size.

Optimal redundant placement of PMUs in Indian power grid — northern, eastern and north-eastern regions

Effective utilization of renewable energy sources and efficient management of electric energy are essential for any developing countries like India. This can be envisioned through the implementation of concepts of smart grid (SG). One of the key requisites for SG implementation is that the grid should be completely observable. Renovation of conventional Indian power grid to a SG necessitates incorporation of the phasor measurement units (PMUs) in the present power grid measurement and monitoring system. Since the cost of PMU is high and any bus containing a PMU makes the neighboring connected buses observable, optimal placement of PMUs is very important for complete observability of the grid. This paper proposes optimal redundant geographical locations in the northern, eastern and north-eastern regions of Indian power grid for PMU placement. The PMUs installed in these geographical locations will make the grid completely observable and maintain the observability under the conditions of failure of some PMUs or branch outages. Integer linear programming has been used for finding the optimal PMU locations. The results proposed in this paper can be a stepping stone for revamping the Indian power grid to a SG ensuring complete observability during different contingency conditions.

Optimal PMU placement for power system state estimation with random component outages

Phasor measurement units (PMUs) provide globally synchronized measurements of voltage and current phasors in real-time and at a high sampling rate. Hence, they permit improving the state estimation performance in power systems. In this paper we propose a novel method for optimal PMU placement in a power system suffering from random component outages (RCOs). In the proposed method, for a given RCO model, the optimal PMU locations are chosen to minimize the state estimation error covariance. We consider both static and dynamic state estimation. To reduce the complexity, the search for the optimal PMU locations is constrained to the set of locations guaranteeing topological observability. We present numerical results showing the application and scalability of our method using the IEEE 9-bus, 14-bus, 39-bus and 118-bus systems.

Multi-criteria decision-making approach for multi-stage optimal placement of phasor measurement units

An important step in the development of synchrophasor-based wide area monitoring and control system is to optimally place the phasor measurement units (PMUs) in the network. Optimal number of PMUs, to fully observe the power system network, may be large. Owing to their relatively high cost, utilities may like to install these devices in stages. A technique is proposed here for placing the PMUs in multiple stages over a given time period that ensures complete power system observability even under a branch outage or a PMU failure. The proposed scheme is based on integer linear programming (ILP) and a multi-criteria decision-making (MCDM) approach. The ILP is used to obtain the optimal PMU locations in the system to completely observe the system and, subsequently, the MCDM model is developed to prioritise these PMU locations. Three indices are proposed to develop the MCDM model, viz. bus observability index, voltage control area observability index and tie-line oscillation observability index. Finally, the PMU placement is carried out in stages based on the ranking of these optimal locations. The proposed method is applied on three test systems – IEEE 14-bus system, New England 39-bus system and Northern Regional Power Grid 246-bus Indian system.

A Unified Approach for the Optimal PMU Location for Power System State Estimation

Phasor measurement units (PMUs) are considered as a promising tool for future monitoring, protection and control of power systems. In this paper, a unified approach is proposed in order to determine the optimal number and locations of PMUs to make the system measurement model observable and thereby can be used for power system state estimation. The PMU placement problem is formulated as a binary integer linear programming (BILP), in which the binary decision variables (0, 1) determine whether to install a PMU at each bus, while preserving the system observability and lowest system metering economy. The proposed approach integrates the impacts of both existing conventional power injection/flow measurements (if any) and the possibility of single or multiple PMU loss into the decision strategy of the optimal PMU allocation. Unlike other available techniques, the network topology remains unaltered for the inclusion of conventional measurements, and therefore the network connectivity matrix is built only once based on the original network topology. The mathematical formulation of the problem maintains the original bus ordering of the system under study, and therefore the solution directly points at the optimal PMU locations. Simulations using Matlab are conducted on a simple testing seven-bus system, as well as on different IEEE systems (14-bus, 30-bus, 57-bus, and 118-bus) to prove the validity of the proposed method. The results obtained in this paper are compared with those published before in literature.