Eigen-Analysis Considering Time-Delay and Data-Loss of WAMS and ITS Application to WADC Design Based on Damping Torque Analysis
Abstract
:1. Introduction
- A unified mathematical model of WAMS signal is proposed according to the mathematical expectation of sampling data and transformed to the frequency domain based on the Pade rational polynomial approximation.
- By applying the model to the linearized equations, the eigenvalue calculation model containing time-delay and data-loss is derived. This model can analyze the impact of data corruption on system dynamic performance and calculate the system stability time-delay margin.
- On the basis of DTA theory, the damping torque index considering data corruption is obtained. The DTI can reflect the sensitivity of eigenvalues impacted by the WADC transfer function and thus, can be applied to execute wide-area signals selection and parameter tuning.
2. Eigen-Analysis Model Considering Time-Delay and Data-Loss
2.1. Closed-Loop Linearized Model with WAMS
2.2. Unified Mathematical Model of Time-Delay and Data-Loss
2.3. Pade Approximation
2.4. Linearized Model of Controller with Wide-Area Signals
3. Wide-Area Damping Controller Design Based on the Damping Torque Index
3.1. Damping Torque Index Considering Time-Delay and Data-Loss
3.2. Wide-Area Damping Controller Design
4. Case Study
4.1. Simulations of Different Models of Data-Loss
4.2. Impact Mechanism
4.3. Controller Signal Selection and Parameter Tuning
4.4. System Stability Time-Delay Margin Calculation
4.5. WADC Parameter Tuning in ECPG
5. Conclusions
- (1)
- The impact mechanism of the time-delay on small-signal dynamics is complicated. An increase in the time-delay may increase the damping of one oscillation mode when it is relatively small. However, when the time-delay is over the stability margin, system stability will get worse rapidly.
- (2)
- Data-loss can reduce the delay margin and system stability. However, the impact is relatively small as it generates an equivalent time-delay of . Therefore, in practical applications, more attention should be paid to the negative impact brought about by time-delay than data-loss.
- (3)
- The system delay margin can be derived by using the proposed eigenvalue calculation model. It is an important parameter of the power system and is helpful for wide-area device improvement and signal selection. The parameter tuning method of WADC based on DTI can extend the system’s time-delay margin and thus enhance system dynamic performance.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Feedback Signal | Time-Delay/s | Data-Loss Ratio | Time-Delay/s | Data-Loss Ratio | Abs (DTI)/p.u. | Angle (DTI)/° |
---|---|---|---|---|---|---|
0.08 () | 0.1 () | 0.08 () | 0.1 () | 0.0006 | −62.35 | |
0.08 () | 0.1 () | 0.08 () | 0.1 () | 0.0042 | −157.54 | |
0.08 () | 0.1 () | 0.08 () | 0.1 () | 0.1856 | −145.32 | |
0.06 () | 0.1 () | 0.06 () | 0.1 () | 0.1058 | −150.97 |
Model | Real Part/Rad/s | Imaginary Part/Rad/s | Frequency/Hz | Damping Ratio |
---|---|---|---|---|
The conventional model | −0.19421 | 5.9067 | 0.9401 | 0.03278 |
The proposed model | −0.34402 | 2.8285 | 0.4502 | 0.1193 |
Mode | Real Part/Rad/s | Imaginary Part/Rad/s | Frequency/Hz | Damping Ratio |
---|---|---|---|---|
The conventional model | −0.18688 | 4.4643 | 0.7105 | 0.04183 |
The proposed model | −0.25484 | 4.8136 | 0.7661 | 0.05287 |
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Zhou, T.; Chen, Z.; Bu, S.; Tang, H.; Liu, Y. Eigen-Analysis Considering Time-Delay and Data-Loss of WAMS and ITS Application to WADC Design Based on Damping Torque Analysis. Energies 2018, 11, 3186. https://doi.org/10.3390/en11113186
Zhou T, Chen Z, Bu S, Tang H, Liu Y. Eigen-Analysis Considering Time-Delay and Data-Loss of WAMS and ITS Application to WADC Design Based on Damping Torque Analysis. Energies. 2018; 11(11):3186. https://doi.org/10.3390/en11113186
Chicago/Turabian StyleZhou, Tao, Zhong Chen, Siqi Bu, Haoran Tang, and Yi Liu. 2018. "Eigen-Analysis Considering Time-Delay and Data-Loss of WAMS and ITS Application to WADC Design Based on Damping Torque Analysis" Energies 11, no. 11: 3186. https://doi.org/10.3390/en11113186