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This paper presents improved indices to evaluate the contribution of reactive power compensators at HVdc converter terminals. The presence of such compensators impacts converter performance, such as the maximum available power (MAP) limit, susceptance to commutation failure, fault recovery time and temporary over voltage. Traditionally, the Effective Short Circuit Ratio (ESCR) has been used to indicate system strength. However, this index cannot be directly applied when power-electronics based converters are used to provide the reactive power support. The approach of this paper is to use an improved form of the ‘Apparent increase in Short Circuit Ratio’ (AISCR) index to quantify the impact of the compensator on the HVdc system. This index is evaluated by comparing the performance with the reactive power device with a system without the device, but having the same performance. The paper shows that a single AISCR index cannot quantify all behaviors and suggest modifications to AISCR for each of several HVdc phenomena. In this paper two types of compensators are considered – the Synchronous Compensator and the Static Synchronous Compensator (STATCOM). [ABSTRACT FROM AUTHOR]

This letter proposes an extended SVC model with thyristor firing angle law to improve transient performances of frequency and voltage of multi-machine power systems. A firing angle control synthesis framework for imposing any desired SVC susceptance value without linearization around a fixed operation point is proposed. In light of this method, the designed firing angle controller only requires local bus measures and parameters. The performance of the extended firing angle-controlled SVC model is evaluated on a 150-bus 27-machine power system and compared with conventional SVC model. [ABSTRACT FROM AUTHOR]

DC ice melting is an effective technical method against ice disaster on transmission lines. To satisfy the demand for simultaneous de-icing and reactive power compensation for substations, this paper proposed a large-capacity low-cost DC deicer with reactive power compensation, which is mainly composed of rectifier transformer, Static Var Generator (SVG) and diode rectifier. In the proposed topology, SVG and diode rectifier share the rectifier transformer, but rectifier transformer capacity is not increased compared with a single deicer. This paper firstly presents the proposed topology and analyzes its advantages. Then, the rectifier transformer design is introduced, and the SVG control strategy is presented. Simulation results for the proposed device are presented, and an engineering devices with a capacity of 21.8 MVA developed for the 220 kV Fuchong substation is described. The simulation and application results indicate that the proposed devices work well. [ABSTRACT FROM AUTHOR]

This paper presents application guidelines for a new generic plant controller model that can be used for renewable plant dynamic system analysis that may include the control of static compensators (STATCOMs), static var compensators (SVCs), and/or energy storage devices. The authors originally presented the need for such a model to the Western Electricity Coordinating Council (WECC) and contributed to various stages of the new model development led by WECC. As Independent System Operators (ISOs)/Regional Reliability Organizations (RTOs)/Transmission Service Providers (TSPs) are moving toward acceptance and use of generic models only the authors have for the first time applied this new model for an operating renewable plant. The new model was configured, parameterized, and tuned to control two STATCOMs and multiple switched capacitors/reactors to represent a master/auxiliary control strategy as implemented in the plant. Dynamic simulations show that the configured and parameterized model is performing properly as expected. This tuned model was submitted to the system operator for compliance with the interconnection requirements of the plant. This is the first submission of the new generic model for this type of control for a renewable project. The submitted model is appropriate for dynamic simulations, which are routinely performed by ISOs/RTOs/TSPs in system impact studies or transmission planning studies. This paper provides useful guidelines in applying this new model for similar projects. [ABSTRACT FROM AUTHOR]

An improved switching scheme for static VAr compensators (SVCs) that have fixed capacitor-thyristor-controlled reactors (FC-TCRs) for load balancing and power factor improvement has been addressed in this paper. The proposed control scheme can eliminate negative-sequence current caused by unbalanced load while improving the source power factor simultaneously. Thus total current supplied by the source can be minimized along with improvement of the load voltage profile. As the switching of TCR can introduce additional harmonics in the line, an optimized switching function is adopted in the proposed scheme for minimum injected harmonics without using an external filter. The gravitational search algorithm has been used for obtaining the optimized switching angle. The proposed scheme has been verified through proper simulations backed by suitable experimental results on a practical system. [ABSTRACT FROM PUBLISHER]

This paper presents a fault detection and classification scheme for a shunt [static var compensator (SVC)] compensated line. The proposed relaying scheme is based on the concept of superimposed sequence components-based integrated impedance (SSCII). For an internal fault, the magnitude of SSCII is small and for an external fault, it is very large. In the SVC compensated line, a fault forces SVC to vary its impedance. Superimposed components are injected due to this impedance variation, along with the fault components. These SVC-injected components are treated as fault-injected components and, therefore, even the sound phases are detected as faulty phases. To avoid such failure, fault-injected superimposed components have been extracted by using the modified prefault data, which is estimated according to SVC impedance variations. The superimposed components measured using the modified prefault data consist of fault-injected superimposed components only. The proposed scheme has been tested for all types of faults, different values of fault resistances, and several fault locations and SVC locations. The results demonstrate that the proposed scheme successfully detects and classifies the faults. Also, the proposed scheme is robust against variations in fault resistance, source impedance, and SVC location. [ABSTRACT FROM AUTHOR]

To solve problems of catenary icing, this paper presents an online antiicing technique using the Joule effect on the catenary of the high-speed electric railway. According to its scheme, a couple of static var generators (SVGs) are, respectively, placed at the traction power substation and sectioning post to automatically generate an adjusted current, varying with the change of temperature, wind speed, and traction load, which will be obtained by online monitoring. The online antiicing current is not only determined by the developed heat balance equation for the contact wire, but also the developed relationship of the distributed current on catenary and the voltage of the traction network. The simulation and experimental results on an autotransformer (AT) traction power-supply system illustrate that the temperature of the contact wire can be maintained above 0 ^\circC with the antiicing current and the voltage of traction network also in the normal range. [ABSTRACT FROM AUTHOR]

In electrical arc furnaces (EAFs), an unstable arc leads to unfavorable operation of the EAF, which can be rectified by using series reactors. Installation of the series inductor affects some electrical parameters of the EAF, such as arc stability, power factor, arc length, and the EAF efficiency. Furthermore, it reduces the effective transferred power to the EAF. To achieve desired transferred power after installation of the series reactors, the secondary voltage of the EAF transformer should be increased. However, after any tap changing of the EAF transformer, arc stability and other relevant parameters are affected. So the impact on the EAF electrical magnitudes caused by changes in the series reactor and in the EAF transformer tap should be simultaneously studied. This research deals with a new method for optimal setting of the series reactor and EAF transformer tap to achieve the EAF best performance. Using a nonlinear model for the EAF, its electrical characteristics, at nominal transformer current and for all of the possible transformer and reactor taps, are calculated and the results are tabulated. Using these tables, the optimal setpoint for transformer and series reactor taps is determined in different conditions. Finally, the method is investigated from an economic point of view. [ABSTRACT FROM AUTHOR]