Fast-decoupled rectangular co-ordinate state estimation with efficient data structure management
01 Sep 1991-Vol. 138, Iss: 5, pp 462-468
TL;DR: Two different state estimation decoupling techniques using node voltages in rectangular co-ordinates are presented: the exact-decoupled technique and the modified fast-decouple technique, which decouple the Jacobian matrix into real- and reactive-power submatrices.
Abstract: The paper presents two different state estimation decoupling techniques using node voltages in rectangular co-ordinates: the exact-decoupled technique and the modified fast-decoupled technique. The proposed techniques decouple the Jacobian matrix into real- and reactive-power submatrices, which are evaluated only once at the beginning of the process. The paper also presents efficient data structure management algorithms to improve the computational process required in calculating the nonzero elements of the Jacobian matrix, and the elements of the mismatching vector, which are essential to any state estimation problem. The performance of these techniques and algorithms are evaluated using several power system networks.
Citations
More filters
12 Apr 1994
TL;DR: The authors present an algorithm for power system state estimation based on the square root filtering technique and the estimator proposed is decoupled in nature due to modifications made in the measurement equations resulting in a new observation model.
Abstract: The proper analysis and successful operation of a power system implies a reliable estimate of its state. As a result state estimation (SE) is nowadays considered as the heart of modern control centers. Several dynamic state estimation algorithms based on the extended Kalman filtering theory (EKF) have been proposed in the literature but, as has been reported, numerical problems may arise in its implementation in practice. To circumvent the problems inherent to the Kalman filter algorithm the authors present in this paper an algorithm for power system state estimation based on the square root filtering technique. The estimator proposed is decoupled in nature due to modifications made in the measurement equations resulting in a new observation model. >
19 citations
Dissertation•
01 Dec 2013
TL;DR: In this paper, the authors proposed two distributed algorithms to cope with the computational efficiency problem and developed a transient state estimation algorithm based on synchronised measurements from PMUs. But, the integration of synchronized measurements with state estimation can introduce efficiency problems due to the substantial burden of data.
Abstract: The world-wide application of Phasor Measurement Units (PMUs) brings great benefit to power system state estimation. The synchronised measurements from PMUs can increase estimation accuracy, synchronise states among different systems, and provide greater applicability of state estimation in the transient condition. However, the integration of synchronised measurements with state estimation can introduce efficiency problems due to the substantial burden of data.
The research is divided into two parts: finding a solution to cope with the computational efficiency problem and developing a transient state estimation algorithm based on synchronised measurements from PMUs.
The computational efficiency problems constitute important considerations in the operation of state estimation. To improve the low computational efficiency, two distributed algorithms are proposed in Chapters 4 and 5. In these two algorithms, the modelling, structure, and solution are described, and the corresponding procedures of bad data processing are presented. Numerical results on the IEEE 30-bus, 118-bus and 300-bus systems can verify the effectiveness of the two proposed algorithms.
A novel transient state estimation algorithm based on synchronised measurements is proposed in Chapter 6. Considering the scanning cycle and sampling rate of PMU measurements, the proposed algorithm can estimate transient states in a practical way. The performance of the proposed algorithm is demonstrated in a transient simulation on the IEEE 14-bus system.
7 citations
Cites background from "Fast-decoupled rectangular co-ordin..."
...Other important developments of the fast decoupled state estimation can be referred to in [97, 133-136]....
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TL;DR: The above two problems have been addressed by transforming all measurements so that they can be classified as quasi-real power measurements and quasi-reactive power measurements, leading to a generalised FDSE (GFDSE) with a solid theoretical foundation.
Abstract: Nowadays the fast-decoupled state estimation (FDSE) is widely used in almost every power system control centre. FDSE is effective and efficient for most transmission systems but it may not converge for systems with a large ratio of branch resistance to reactance (R/X); meanwhile the branch current magnitude measurements (BCMMs) cannot be reliably used in FDSE, thereby limiting its applications especially for the distribution systems where BCMMs abound. In this study, the above two problems have been addressed by transforming all measurements so that they can be classified as quasi-real power measurements and quasi-reactive power measurements, leading to a generalised FDSE (GFDSE) with a solid theoretical foundation. The formulation of GFDSE is based on only the assumption, rather than three assumptions used in FDSE. As a result, GFDSE has good adaptability to transmission systems as well as distribution systems; additionally, BCMMs can be reliably used in GFDSE. Case studies based on IEEE benchmark systems and a real grid of China demonstrate that the proposed GFDSE has very good convergence properties for transmission systems and distribution systems; and at the same time, the proposed GFDSE is also superior to FDSE in terms of computational efficiency under almost all cases.
4 citations
Cites methods from "Fast-decoupled rectangular co-ordin..."
...In [24], two different decoupling techniques using node voltages in rectangular co-ordinates are proposed: the exact decoupled technique (EDT) and the modified fast-decoupled technique (MFDT)....
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TL;DR: This paper presents efficient data structure management algorithms to reduce the amount of CPU time required during the recomputational process of updating the Jacobian matrix and mismatching vector for power system state estimation.
3 citations
TL;DR: In this paper, the authors proposed a method to improve the convergence characteristics of fast-decoupled state estimator (in rectangular coordinates) using the optimal multiplier μ, followed by a reliable technique to detect bad data.
Abstract: From power system on-line operation and security control view point, state estimation, a methodology used to obtain reliable estimate of power system state, has become one of the important issues. Among some state estimation methods, the fast-decoupled state estimator is commonly used as a prevailed method and has been implemented by many utilities. However, it has been recognized that its convergence characteristics may become deteriorated when it encounters bad system conditions. Therefore, in this paper, first of all, we present the fast-decoupled state estimator which is used in present power systems. Next, we propose a method to improve the convergence characteristics of fast-decoupled state estimator (in rectangular coordinates) using the optimal multiplier μ, followed by a reliable technique to detect bad data. The proposed method has been tested on several types of load flow test systems and successful results have been obtained.
References
More filters
TL;DR: This paper presents fast-decoupled state estimators, using also decoupled detection and identification of bad data, using the sparse inverse matrix method.
Abstract: This paper presents fast-decoupled state estimators, using also decoupled detection and identification of bad data. Bad data is eliminated by pseudo-measurement generation. This procedure avoids gain-matrix retriangulations or the use of modification techniques like Woodbury formula. In the identification process, the diagonal of the covariance matrix of the measurement residuals is calculated using the sparse inverse matrix method. Two main types of fast-decoupled estimators were tested : algorithm- decoupled and model-decoupled. The methods have been tested on IEEE 30-bus load-flow test system, and the FURNAS and CPFL systems that form part of the 835-bus interconnected 15 GW power system of the S.E. Brazil.
225 citations
01 Jan 1979
TL;DR: In this paper, fast decoupled state estimators are used for detection and identification of bad data using pseudo-measurement generation, which avoids gain-matrix retriangulations or the use of modifica- tiontechniques like Woodbury formula.
Abstract: This paperpresentsfast-decoupled stateestimators, using also decoupled detection and identification of baddata.Baddatais eliminated by pseudo-measurement generation. This procedureavoids gain-matrix retriangulations or the use ofmodifica- tiontechniques likeWoodburyformula.Inthe identi- ficationprocess,the diagonalof the covariance matrixof the measurementresidualsis calculated usingthesparseinversematrixmethod.Twomaintypes of fast-decoupled estimators weretested: algorithm- decoupled andmodel-decoupled. Themethodshave been testedon IEEE30-busload-flow testsystem,andthe FURNASandCPFLsystemsthatformpartof the835-bus interconnected 15GWpowersystemof theS.E.Brazil.
218 citations
TL;DR: In this paper, a new algorithm is described to solve the static, time-invariant weighted least-square state estimation problem for large-scale electric power systems, which is obtained through P-θ and Q-V decoupling and alternately iterating the active and reactive equations using fixed, simplified submatrices of the information matrix.
Abstract: A new algorithm is described to solve the static, time-invariant weighted least-square state-estimation problem for large-scale electric power systems. The solution is obtained through P-θ and Q-V decoupling and alternately iterating the active and reactive equations using fixed, simplified submatrices of the information matrix. Thus, a much faster algorithm is obtained yielding the exact solution and requiring little computer storage. The new method is compared with the basic "Weighted-least-square" and the "Line-Only" algorithms on a practical HV network.
104 citations
TL;DR: This paper presents a fast, reliable and storage -saving algorithm for Power System State Estimation (PSSE) that employs a Single sub-Matrix of a Decoupled Jacobian matrix (SMDJ) to solve a PSSE weighted least-squares problem.
Abstract: This paper presents a fast, reliable and storage -saving algorithm for Power System State Estimation (PSSE). Instead of using a Single sub-Matrix of a Decoupled Gain matrix (SMDG), the new algorithm employs a Single sub-Matrix of a Decoupled Jacobian matrix (SMDJ); the Givens transformations is then used to solve a PSSE weighted least-squares problem. Thus, the algorithm has the advantages of both decoupling and orthogonal transformations. It will be shown in theory and practice that the new algorithm performs better than the algorithm using the SMDG. The new algorithm has been tested on two power systems, including an IEEE 30-bus test power system. From the numerical results we conclude that the proposed algorithm is considerably superior to the conventional normal equation algorithm and other decoupling algorithms.
37 citations
TL;DR: In this article, three improved methods to solve the static state estimation problem of power systems are presented: a modified fast decoupled state estimator, a new constant matrix model and a second order load flow model.
Abstract: This paper presents three improved methods to solve the static state estimation problem of power systems. The first method presents a modified fast decoupled state estimator which is faster than the fast decoupled state estimator available in the literature. The second method is based on a new constant matrix model which is more reliable than the fast decoupled state estimator. The third method is based on a second order load flow model. The proposed methods are tested on different IEEE test systems and relevant results are presented to illustrate the same.
9 citations