This study aims at: (1) developing an index to measure CEO risk tolerance using publicly available data, and (2) examining the association between this index and investment in risky projects. Using ...relative pay‐at‐risk as a proxy for risk preference (tolerance) is a new proposition and is supported by having significant association with CEOs' socio‐demographic variables—the variables often studied in connection with risk aversion. Furthermore, this risk preference indicator has a positive association with risk‐taking behaviour as proxied by R&D expenditures. The in‐sample estimation and out‐of‐sample predictions support (a) using relative pay‐at‐risk as a valid proxy for risk tolerance, and (b) finding statistically significant positive association between this measure and R&D expenditures. The association has different degrees of strength for nine out of 11 industries.
Accounting standards for prepaid commodity swaps did not exist until 2003. This absence of regulation gave Enron the opportunity to have its own homemade accounting. Two actions facilitated this task ...for Enron: (a) The Securities and Exchange Commission granted Enron in January 1992 a unilateral privilege to use mark-to-market valuation for energy contracts. This private communication was made at a time when viable markets did not exist. (b) Big banks colluded with Enron’s top executives to design structured finance contracts that allowed Enron to report at least US$8.7 billion of loans as cash flow from operations. Seventy-one percent of the cash flow from operations reported in the last 5 years of Enron’s existence came from these loans. JPMorgan Chase and Citigroup effectively made it easy for Enron to carry out this fraud. The two banks established their own special purpose entities to give these loans the appearance of legitimate trade transactions using prepaid commodity forwards and swaps. This article outlines some of the schemes that the two banks devised to help Enron appear financially healthy when in reality it was near bankruptcy for years.
Both the International Financial Reporting Standards (IFRS) and the codified accounting standards (ASC) for the US GAAP categorize hedging relationships as falling into several buckets. The two ...buckets of relevance in this paper are (i) hedging the volatility of fair values, and (ii) hedging the volatility of future cash flow. In this paper, I argue that at least three accounting treatments of derivatives and hedging lead to creating serious distortion of reporting actual transactions, to combining hard and plastic valuations, and to violating adherence to the principle of ‘faithful representation’. The three accounting treatments are as follows: (1) creating the fictional Hypothetical Derivatives Method; (2) allowing for the establishment of purely discretionary valuation adjustments for all over‐the‐counter derivative assets (Credit Valuation Adjustment) and liabilities (Debt Valuation Adjustment) without any guides or constraints; (3) requiring subjective metaphysical separation of embedded derivatives with the main guide being the management's own perception of the instrument's embodiment of unrelated value and risk generators. To remedy the resulting distortion in financial reporting, significant revisions of certain accounting standards are sorely needed.
•We studied the performance of single loop control of the Inverter Based Distributed generators at faults, we found it not stable.•We made a Matlab model to study how the different fault current ...generated by the IBDG affect the power system protection.•We proposed with mathematical analysis an additional control loop to solve the problems at faults.•We built the necessary experimental setup using two voltage source inverters connected to the grid.•The results of the proposed method are presented.
Inverter-based distributed generation (IBDG) is characterized by its negligible fault current contribution compared with synchronous generators due to its inherent non-overload capabilities. Thus, IBDG hardly affects the fault current level; this shadows the conventional protection schemes resulting in improper system protection especially with a high penetration of IBDGs at high power levels and/or in island operation mode. This paper presents an experimental investigation of two scenarios for IBDG fault current contribution under different fault conditions. In the first scenario, the inverter is controlled to produce zero output current or is disconnected upon fault occurrence, which is the case for most commercial grid-connected inverters. In the second scenario, the inverter contributes its rated current to the fault. The practical selection may be questionable and is affected by the fault level, employed protection scheme, and the penetration level of IBDGs. The introduction of double-loop proportional-resonant (PR) current controller is investigated using three case studies applying the previously described fault current contribution scenarios. The double-loop PR controller is found favorable when the inverter is designed to contribute its rated current to the fault. This conclusion is verified experimentally in this work.
During the period 1995–2012, U.S. financial institutions had contributed significantly to the growth in financial derivatives. The notional amount of total derivatives held by the 25 largest U.S. ...bank holding companies grew eighteen times from $16.6trillion in 1995 to $308trillion in 2012, while the U.S. GDP merely doubled from $7.7trillion to $16.2trillion over the same period. In this paper, we examine three possible drivers of this growth: (a) the Gramm-Leach-Bliley Act of 1999, (b) the Commodity Futures Modernization Act of 2000, and (c) FAS 133 (now ASC 815), Accounting for Derivative Instruments and Hedging Activities, which became effective in 2000. Using a sample of U.S. bank holding companies, we find a temporal association between the passage of the two Congressional Acts and the abnormal growth in trading/over-the-counter derivatives. We also predict and find that the use of cash flow hedge accounting treatment helps reduce earnings volatility/equity risk, and that firms increase their use of non-trading derivatives when facing high level of earnings volatility/equity risk.
•A steady-state model based on symmetrical components theory is used to estimate machine currents and developed torque under open circuit phase(s).•The performance of the multiphase IM under open ...circuited phase(s) is assessed.•A genetic algorithm is used to generate to achieve the optimum current distribution in the healthy phases.•Derating factor is calculated during faults to avoid increase of DC-link voltage.•Eleven-phase machine is used as a prototype model to achieve these derating factors.
Multiphase machines have become a promising candidate in high-power applications as they offer many advantages over their three-phase counterparts. The main salient feature is the high fault tolerance capability. During faults, two alternatives for machine operation are possible, namely; open loop control and optimal current control. While the former corresponds to higher torque ripple and unbalanced winding currents, the latter option necessitates unbalanced phase voltages and typically an increased DC-link voltage to source the required optimal currents. Consequently, an increase in the employed semiconductor device rating is required, which is a critical design factor especially in medium voltage applications. This paper investigates an eleven-phase induction machine with concentric windings under fault conditions. An unbalanced steady-state machine model based on symmetrical components theory is developed as a mathematical tool to estimate different machine currents and total developed torque under open circuit phase(s). The effect of different sequence planes is also included in the derived model. This model is then experimentally verified. It is shown that the application of optimal current control in multiphase induction machines with open circuited phase(s) optimizes torque production while maintaining minimum stator copper loss and torque ripples. This optimization problem usually incorporates solving complicated nonlinear equations that increase in complexity with higher numbers of phases. Alternatively, a genetic algorithm is used in this paper to provide a simple method to obtain the optimum currents in the remaining healthy phases. Based on the derived optimal currents, the steady-state model is used to estimate the required DC-link voltage reserve that ensures no machine de-rating. Finally, the required derating factors to avoid machine overheating are calculated for different numbers of disconnected phases when DC-link voltage limitation is introduced.
A Four-Switch Three-Phase SEPIC-Based Inverter Diab, Mohamed S.; Elserougi, Ahmed; Massoud, Ahmed M. ...
IEEE transactions on power electronics,
09/2015, Letnik:
30, Številka:
9
Journal Article
Recenzirano
The four-switch three-phase (FSTP) inverter has been proposed as an innovative inverter design to reduce the cost, complexity, size, and switching losses of the dc-ac conversion system. Traditional ...FSTP inverter usually operates at half the dc input voltage; hence, the output line voltage cannot exceed this value. This paper proposes a novel design for the FSTP inverter based on the topology of the single-ended primary-inductance converter (SEPIC). The proposed topology provides pure sinusoidal output voltages with no need for output filter. Compared to traditional FSTP inverter, the proposed FSTP SEPIC inverter improves the voltage utilization factor of the input dc supply, where the proposed topology provides higher output line voltage which can be extended up to the full value of the dc input voltage. The integral sliding-mode control is used with the proposed topology to optimize its dynamics and to ensure robustness of the system during different operating conditions. Derivation of the equations describing the parameters design, components ratings, and the operation of the proposed SEPIC inverter is presented in this paper. Simulation model and experimental setup are used to validate the proposed concept. Simulations and experimental results show the effectiveness of the proposed inverter.
This study aims at: (1) developing an index to measure
CEO
risk tolerance using publicly available data, and (2) examining the association between this index and investment in risky projects. Using ...relative pay‐at‐risk as a proxy for risk preference (tolerance) is a new proposition and is supported by having significant association with
CEO
s' socio‐demographic variables—the variables often studied in connection with risk aversion. Furthermore, this risk preference indicator has a positive association with risk‐taking behaviour as proxied by
R
&
D
expenditures. The in‐sample estimation and out‐of‐sample predictions support (a) using relative pay‐at‐risk as a valid proxy for risk tolerance, and (b) finding statistically significant positive association between this measure and
R
&
D
expenditures. The association has different degrees of strength for nine out of 11 industries.
► This paper presents a power control strategy to charge/discharge a flywheel DFIM storage system. ► The controller is based on conventional vector control system supplemented by an ANN-based current ...decoupling network. ► The controller is designed to avoid overloading both stator and rotor circuits while the flywheel charges/discharges. ► The validity of the developed concept is confirmed by computer simulation for a medium voltage 1000hp FW-DFIM. ► The simulation is carried out for UPS applications and power leveling to electric power delivered by wind generators.
A large-capacity low-speed flywheel energy storage system (FESS) based on a doubly-fed induction machine (DFIM) consists of a wound-rotor induction machine and a back-to-back converter rated at 30–35% of the machine power rating used for rotor excitation. This system has been promoted as a viable mean of energy storage for power system applications as grid frequency support/control, uninterruptible power supply (UPS), power conditioning, and voltage sag mitigation. This paper presents a simple power control strategy based on artificial neural networks (ANN) to charge/discharge a flywheel DFIM (FW-DFIM) storage system while maintaining controllable grid side power. The proposed controller is based on conventional vector control system supplemented by an ANN-based current decoupling network used to develop the required rotor current components based on the required grid power level and flywheel instantaneous speed. The controller is designed to avoid overloading both stator and rotor circuits while the flywheel is charged/discharged. Additionally, it avoids using the required outer power loop or a hysteresis power controller, hence, simplifies the overall control algorithm. The validity of the developed concept along with the effectiveness and viability of the control strategy in power system applications is confirmed by computer simulation using Matlab/Simulink for a medium voltage 1000hp FW-DFIM. The simulation study is carried out for uninterruptible power supply (UPS) applications and power leveling to improve the quality of electric power delivered by wind generators.
► An indirect vector controlled multiphase induction motor drive with harmonic injection to obtain a near rectangular air-gap flux is introduced. ► The proposed controller, avoids multiple ...PI-controllers; only two PI-controllers are used. ► An eleven-phase induction machine is used as a prototype. ► A comparison between the conventional controller, using multiple PI controllers, and the proposed controller is made for third harmonic injection.
Torque enhancement by stator current harmonic injection is one possible use of the additional degrees of freedom offered by multiphase machines yielding a near rectangular air-gap flux. The number of injected harmonics depends on the phase order and the corresponding sequence planes. As the number of machine phases increases, the injected harmonic order can be increased where each plane requires two PI controllers, to control its current components, resulting in a complicated tuning process. Moreover, the deployment of conventional indirect vector control with multiple PI controller fails to maintain a near rectangular air-gap flux with different loading conditions due to synchronization problem between different planes. In this paper, the conventional indirect vector control based on multiple PI-controllers is replaced by only two PI-controllers to develop the fundamental dq voltage components from which the dq voltage components for other planes are determined using offline optimized constant gains. The proposed controller makes the tuning process is easier and achieve near rectangular air-gap flux during loading conditions. The proposed controller tested using a prototype eleven-phase induction machine where injection up to the ninth harmonic can be engaged. A comparison between the conventional controller, using multiple PI controllers, and the proposed controller is made for third harmonic injection. Practical results are introduced as a conformance to simulation results.
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