This paper presents an autotuning technique for the online selection of the cost function weight factors in model predictive control (MPC) The weight factors in the cost function with multiple control objectives directly affect the performance and robustness of the MPC The proposed method in this paper determines the optimum weight factors of the cost function for each sampling time; the optimization of the weight factors is done based on the prediction of the absolute tracking error of the control objectives and the corresponding constraints The proposed method eliminates the need of the trial-and-error approach to determine a fixed weight factor in the cost function The application considered is a capacitor-less static synchronous compensator based on the MPC of a direct matrix converter This technique compensates lagging power factor loads using inductive energy storage elements instead of electrolytic capacitors The result demonstrates that the proposed autotuning approach of cost function weights makes the control algorithm robust to parameter variation and other uncertainties in the system The proposed capacitor-less reactive power compensator based on the autotuned MPC cost function weight factor is verified experimentally

/pdf/autotuning-technique-for-the-cost-function-weight-factors-in-3gho9ep3to.pdf

Autotuning Technique for the Cost Function Weight Factors in Model Predictive Control for Power Electronic Interfaces

This paper presents the concept of a capacitorless static synchronous compensator (STATCOM) that uses a matrix converter (MC) and model predictive control (MPC) to compensate lagging power factor (p.f.) loads using inductors instead of electrolytic capacitors (e-caps) for energy storage. Although ubiquitous in power electronic converters, e-caps have well-known failure modes and wear-out mechanisms. In practice, the bus capacitors in a voltage-sourced inverter reactive power compensator may require monitoring and replacement, which can increase the cost of ownership of a traditional reactive power compensation method. The proposed MPC-MC-STATCOM uses a $3\times3$ direct MC, which when properly controlled using finite-set MPC, creates a phase shift of 180° from the input to output current, and thus supplies reactive power to the utility grid using inductors instead of the e-caps. This paper presents the fundamental concept and model derivation. The theoretical analysis is accompanied by simulation and experimental results that verify the intended operation of the controls and circuity in steady state under ideal grid conditions and dynamically to demonstrate robustness of the MPC control under step changes in grid voltage distortion and load characteristics. The conclusion is that the capacitorless STATCOM can provide the reactive power needed to compensate lagging p.f. load.

Model Predictive Control of a Capacitorless Matrix Converter-Based STATCOM

The urgency for an increased capacity boost bounded by enhanced reliability and sustainability through operating cost reduction has become the major objective of electric utilities worldwide. Power electronics have contributed to this goal for decades by providing additional flexibility and controllability to the power systems. Among power electronic based assets, high-voltage dc (HVdc) transmission systems and flexible ac transmission systems (FACTS) controllers have played a substantial role on sustainable grid infrastructure. Recent advancements in power semiconductor devices, in particular in voltage source converter based technology, have facilitated the widespread application of HVdc systems and FACTS devices in transmission networks. Converters with larger power ratings and higher number of switches have been increasingly deployed for bulk power transfer and large scale renewable integration—increasing the need of managing power converter assets optimally and in an efficient way. To this end, this paper reviews the state-of-the-art of asset management strategies in the power industry and indicates the research challenges associated with the management of high power converter assets. Emphasis is made on the following aspects: condition monitoring, maintenance policies, and ageing and failure mechanisms. Within this context, the use of a physics-of-failure based assessment for the life-cycle management of power converter assets is introduced and discussed.

Asset Management Strategies for Power Electronic Converters in Transmission Networks: Application to Hvdc and FACTS Devices

This paper presents results of an extensive study launched by Hydro One Networks aimed at determining air blast circuit breaker reliability measures from a statistical analysis of outage data. The study examines how the breaker failure rate depends on such factors as equipment age, voltage level, manufacturer, and number of repairs. Planned outage rates due to equipment maintenance were also investigated. Results presented in this paper are based on outage records involving 318 breakers and covering a period of 12 years. The results can form input information for probabilistic risk analysis studies.

A comprehensive study of outage rates of air blast breakers

Extraction of Time-varying Failure Rates on power distribution system equipment considering failure modes and regional effects

This paper describes the study of the reliability of capacitor units installed and operated in a distribution system during the period 1980 through 1990. Failures of capacitor units in distribution substations can be very costly to the supply of reliable power to consumers. To enhance utility reliability, failure analysis and rates, failure origin and physical damage causes were performed for these capacitor units. Two approaches, statistical and physical, were utilized in this study. In the statistical area, failure modes, reliability levels and failure causes are analyzed. The physical study mainly deals with the mechanism of deterioration of the composite dielectric, The results of the study on 2912 capacitor banks including 8736 capacitors installed at 153 distribution substations showed that the failure mode of capacitor units may be represented by a Weibull distribution and each capacitor manufactures has different failure rate. Analysis showed that partial discharge properties are a critical indicator for capacitor failure. Useful conclusions are presented both for power system operators and manufacturers. The methodology used in this study also applies to other equipment in the distribution system such as oil switches, transformers and insulators.

Failure analysis of composite dielectric of power capacitors in distribution systems

Failure analysis of composite dielectric of power capacitors used in distribution systems

This paper describes the study of the reliability of capacitor units installed and operated in distribution system during the period 1980 through 1990. Failures of capacitor units in distribution substations can be very costly to the supply of reliable power to consumers. To enhance utility reliability, failure analysis, and rates, failure origin and physical damage causes were performed for these capacitor units. Two approaches, statistical and physical, were utilized in this study. In the statistical area, failure modes, reliability levels and failure causes are analyzed. The physical study mainly deals with the mechanism of deterioration of the composite dielectric. This paper models capacitor's failure mathematical mode and calculates their failure rate. The results of the study of 2912 capacitor banks including 8736 capacitors installed at 153 distribution substations showed that the failure mode of capacitor units may be represented by Weibull distribution and each capacitor manufacturer has a diffe...

Failure Analysis of Composite Dielectric of Power Capacitors Used in Distribution Systems

This paper describes the study of the reliability of capacitor units installed and operated in a distribution system during the period of 1980 through 1990. Failures of capacitor units in distribution substations can be detrimental to the supply of reliable power to consumers. To enhance utility reliability, failure analysis and rates, failure origin and physical damage causes were studied for these capacitor units. Two approaches, statistical and physical, were utilized in this study. In the statistical area, failure modes, reliability levels and failure causes are analyzed. The physical study mainly deals with the mechanism of deterioration of the composite dielectric. This paper models the capacitor's failure mathematical mode and calculates the capacitor failure rate. The results of the study on 2912 capacitor banks including 8736 capacitors installed at 153 distribution substations showed that the failure mode of capacitor units may be represented by a Weibull distribution and that each capacitor manufacturer has a different failure rate. Analysis showed that partial discharge properties are a critical indicator for capacitor failure mechanisms. Useful conclusions are presented both for power system operators and manufacturers. The methodology used in this study also applies to other equipment in the distribution system such as oil switches, transformers and insulators.

M. Moon

Papers

Failure analysis of composite dielectric of power capacitors in distribution systems

Failure analysis of composite dielectric of power capacitors used in distribution systems

Failure Analysis of Composite Dielectric of Power Capacitors Used in Distribution Systems

Failure analysis of composite dielectric of power capacitors used in distribution systems