Research on Illed-Conditioned Equations in Tracking Thevenin Equivalent Parameters with Local Measurements

An, Tianyu; Zhou, Shiqi; Yu, Jie; Lu, W. J.; Zhang, Yanjun

doi:10.1109/icpst.2006.321574

Cited by 8 publications

(6 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In particular, the error of PSO increases beyond the acceptable margins when both loads are time varying and the "Ratio of change margins of the loads" grows up to unity or higher. The SFLA has the lowest error when both loads are constant, while the estimation methods in the previous references are unable to deal with such a condition [15][16][17][18][19][20]. Figure 7 shows the convergence profiles of the SFLA and PSO during estimation processes under the three mentioned conditions.…”

Section: Sample Estimation Resultsmentioning

confidence: 99%

“…However, under constant load, the two equations will be the same and the TE parameters cannot be determined uniquely. Reference [16] tries to give a solution for this problem; however, this is a rigid mathematical problem and cannot be resolved as long as the load is constant.…”

Section: Online Estimation Of Thevenin Equivalent Parametersmentioning

confidence: 99%

“…This equivalent circuit has half the parameters to be estimated compared with that used in [14] and makes evaluation of the short-circuit currents under existing condition of the grid very easier. Many references have dealt with the online estimation of parameters of such TE circuit [15][16][17][18][19][20]. The continuous variation of load current flowing out of the related bus is a key requirement in all of these references, so, with a rather constant load current, estimation of the TE parameters is impossible.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Local online adaptive technique for optimal coordination of overcurrent relays within high voltage substations

Ojaghi

Sudi

Azari

2016

Int. Trans. Electr. Energ. Syst.

View full text Add to dashboard Cite

SUMMARYThe optimal coordination of overcurrent relays is an important task in the field of power system protection. Traditionally, this problem is solved with the assumption of the grid being in maximum or minimum loading and dominant topology, that is, the topology in which the grid operates most of the time. However, the grid condition changes during the time because of many reasons. In this paper, by sampling voltage and load current phasors at the high-voltage (HV) bus of a substation, an online method, based on an evolutionary algorithm, is introduced to estimate the grid's Thevenin equivalent viewed from the HV bus. Then, the Thevenin equivalent together with the connection status and short-circuit model of local power transformers and local distributed generations are used to estimate three-phase short-circuit currents in the existing condition of the grid. Finally, these fault currents are used for adaptive optimal coordination of overcurrent relays of the HV substation, such that the optimal coordination of the relays is preserved in all the grid conditions. Case studies, performed on the overcurrent protection of a typical 230/20 kV substation connected to a 9-bus grid, prove desired performance of the proposed online adaptive setting method. Furthermore, this method needs no telecommunications and represents a step toward self-adjusting overcurrent relays.

show abstract

Section: Sample Estimation Resultsmentioning

confidence: 99%

Section: Online Estimation Of Thevenin Equivalent Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Local online adaptive technique for optimal coordination of overcurrent relays within high voltage substations

Ojaghi

Sudi

Azari

2016

Int. Trans. Electr. Energ. Syst.

View full text Add to dashboard Cite

show abstract

“…The high level procedure is summarised in Fig. 3, where the adaptive technique is based on [60], the recursive least squares (RLS) solver is derived from [61]- [64], and the algebraic technique is derived from [24], [65].…”

Section: ) Local Pmu Derived Observersmentioning

confidence: 99%

Review of Local Network Impedance Estimation Techniques

et al. 2020

View full text Add to dashboard Cite

“…However, their performances cannot solve the problem of algorithm divergence caused by the ill-conditioned matrix inverse and lack the robustness and adaptive tracking ability when the system changes. According to the analysis of the ill-conditioned Thevenin equivalent parameters equations, a method based on Schmidt's orthogonalization transformation is presented in [30] to obtain precise solutions. A dynamic state estimation methodology was proposed in [31], which combined a new regularization-based method with a Markov model representation to improve estimation accuracy over classic methodologies based on static load pseudo measurements.…”

Section: Introductionmentioning

confidence: 99%

Thévenin Equivalent Parameter Adaptive Robust Estimation Considering the Erroneous Measurements of PMU

et al. 2020

View full text Add to dashboard Cite

Parameter estimation based on the measurement data of the phasor measurement unit (PMU) is an important approach for identifying the Thévenin equivalent parameters (TEPs) of power systems. However, in the process of acquiring or transmitting data in PMU, measurement errors due to external interference or internal system faults will affect the accuracy of parameter estimation. In this paper, a TEP estimation algorithm based on local PMU measurement is proposed. The algorithm considers the errors of the PMU and introduces Huber function and projection statistics (PS) to eliminate the effects of outliers and leverage measurements, respectively. Additionally, a variable forgetting factor (VFF) is used to quickly eliminate the historical data with measurement deviation and track the changes of the system. The regularization technique is used to solve the divergence problem in the inverse process of the ill-conditioned matrix, thereby improving the stability and generalization performance of the algorithm. Finally, by minimizing the cost function of this algorithm, a recursive formula for the equivalent parameter estimation is derived. The effectiveness of the algorithm is verified on the IEEE 118-bus and IEEE 30-bus systems, and compared with recursive least squares (RLS) and Huber’s M-Estimation; the mean relative errors decreased by 94.75% and 84.77%, respectively.

show abstract

Research on Illed-Conditioned Equations in Tracking Thevenin Equivalent Parameters with Local Measurements

Cited by 8 publications

References 5 publications

Local online adaptive technique for optimal coordination of overcurrent relays within high voltage substations

Local online adaptive technique for optimal coordination of overcurrent relays within high voltage substations

Review of Local Network Impedance Estimation Techniques

Thévenin Equivalent Parameter Adaptive Robust Estimation Considering the Erroneous Measurements of PMU

Contact Info

Product

Resources

About