Tracking of Thevenin Equivalent Parameters on Weak Voltage Load Bus Groups

An, Tianyu; Zhou, Shiqi; Yu, Jie; Zhang, Yanjun

doi:10.1109/psce.2006.296147

Cited by 19 publications

(13 citation statements)

References 3 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%

“…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 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

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: Introductionmentioning

confidence: 99%

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

“…Great variability of Thevenin equivalent impedance (TEI) (grid impedance) at PCCs [25] unavoidably leads to different voltage regulation requirements [31]. So far, an accurate TEC has been used for the calculation of the short-circuit current [32] (at a connection point of interest) and for control purposes in an attempt to ensure the stability of the power system [33]. Additionally, in integration studies, the TEC is chosen randomly according to the needs of the investigation or on an empirical basis (taken from survey data [34]) giving useful but general results which may differ from real case scenarios.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Up to now, different regulation methods have been used depending on the case and cost. Among them, power curtailment, installation of storage means and regulation of reactive power [10, 33] are the main methods available to help in maintaining the voltage of distribution grids to desirable levels. The choice of voltage regulation method should be preferably done based on the characteristics of the PV system installation.…”

Section: Theorymentioning

confidence: 99%

Simplified distribution grid model for power quality studies in the presence of photovoltaic generators

Patsalides

Efthymiou

Stavrou

et al. 2015

IET Renewable Power Generation

View full text Add to dashboard Cite

Renewable energy sources are expected to have a considerable share in the global energy mix over the next years and consequently further research is required to enhance the planning strategies, modify prudently the existing standards and set quality levels on delivered power in order to accommodate the penetration of these technologies. Depending on the distribution grid dynamics and the load demand, the amplitude of voltage may vary significantly, and therefore proper simulation models are required for performing dedicated studies. In this study, a simplified and accurate model representing the distribution grid dynamics is introduced for power quality studies in the presence of distributed photovoltaic (PV) generators. The proposed simplified distribution grid model (SDGM) is validated using measurements and it is then used along with a verified PV system model to estimate the voltage variation and PV capacity of the distribution grid under investigation. Moreover, a sensitivity analysis is performed by varying the parameters of the SDGM to assess how the PV capacity is altered. As a last step, common voltage regulation schemes are analysed through the use of the proposed model, validating operational modes that can accommodate high distributed PV capacities.

show abstract

“…One of the challenges in the operational reliability assessment of the interconnected power system is to select a reasonably accurate static equivalent model to simplify the external network. The commonly used static equivalence models of external networks include Thevenin equivalence [17][18][19], Ward equivalence and its extended methods [20][21][22], and radial equivalent independent (REI) equivalence and its extended methods [23,24]. These equivalence methods only consider the consistency of power flow before and after equivalence, but ignore the consistency of sensitivity between variables before and after equivalence.…”

Section: Introductionmentioning

confidence: 99%

Operational Reliability Assessment of an Interconnected Power System Based on an Online Updating External Network Equivalent Model with Boundary PMU

et al. 2019

View full text Add to dashboard Cite

Information between interconnected power systems is difficult to share in real time, due to trade secrets and technical limitations. The regional power grid cannot timely detect the impact of changes in the operation mode of the external power grid on the regional reliability, due to faults, load fluctuations, power generation plan adjustments, and other reasons. How to evaluate the reliability of a regional power system under the conditions of information isolation is a difficult problem for the security of interconnected power systems. Aiming at this problem, an operational reliability evaluation method for an interconnected power system is proposed herein, which does not depend on external network information directly, but only uses boundary phasor measurement unit (PMU) measurement data and internal network information. A static equivalent model with sensitivity consistency was used to simplify the external network to ensure the accuracy of the reliability calculation of interconnected power systems. The boundary PMU measurement data were used to update the external network equivalent model online. The algorithm flow of the operation reliability assessment for the interconnected power grid is given. The results of an example based on the IEEE-RTS-96 test system show that the proposed method can track the equivalent parameters of the external network without depending on the actual topological information, and calculate the reliability index of the internal network accurately.

show abstract

Tracking of Thevenin Equivalent Parameters on Weak Voltage Load Bus Groups

Cited by 19 publications

References 3 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

Simplified distribution grid model for power quality studies in the presence of photovoltaic generators

Operational Reliability Assessment of an Interconnected Power System Based on an Online Updating External Network Equivalent Model with Boundary PMU

Contact Info

Product

Resources

About