The most crucial device used in the control system is the Compensator which is operated for the regulation of other systems. In many of the cases, this is operated by regulating either the output or input to the control system. There are essentially three kinds of compensators which are lead, lag, and lag-lead. In order to enhance the execution, adjusting the control system might pose damage to the performance like feeble stability or unbalanced stability. So, to make the system function as expected, it is more recommended to restructure the system and include a compensator where this tool counteracts the inadequate efficiency of the actual system. This article gives a detailed explanation of one of the most prominent types of compensators Static Var Compensator.
This is a parallelly connected static type of VAR absorber or generator where the output is modified so as to substitute inductive or capacitive current where this regulates or manages corresponding factors of the current mainly the bus voltage factor. A static VAR compensator is dependent on thyristors having no gate switching off ability. The functionality and features of the thyristors understand the SVC adaptable reactive impedance. The crucial equipment which is included in this device is TCR and TSR which are a thyristor-controlled capacitor and thyristor-controlled reactor.
The device also provides quick functional reactive power in the case of extreme voltage electrical transmission systems. SVC’s come under the classification of adaptable AC transmission networks, voltage control, and system stabilization. The basic static VAR compensator circuit diagram is shown as follows:
Static VAR compensator basics can be explained as follows:
The assemblage of thyristor switch in the device regulates the reactor and the firing angle is used for the regulation of the voltage and current values that flow through the inductor. In correspondence to this, the inductor’s reactive power can be regulated.
This device holds the ability to reduce the regulation of reactive power even across extended ranges showing a zero-time delay. It enhances the constancy of the system and the power factor. Few of the schemes followed by SVC devices are:
In the one-line configuration of the SVC, through the PAM type of modulation by the thyristors, the reactor might be shifter internal to the circuit and this shows a constantly variable type of VAR to the electrical system. In this mode, extended levels of voltages are regulated by the capacitors and this is mostly known for providing efficient control. So, the TCR mode provides good control and enhanced reliability. And the thyristors can be regulated in an electronic way.
In the same way as semiconductors, thyristors also deliver heat and for cooling purposes, deionized water is used. Here, when the slicing of reactive load into the circuit takes place, brings in unwanted kind of harmonics, and in order to restrict this, a high range of filters are generally used to smooth out the wave. As there is capacitive functionality in the filters, they also will spread out MVAR to the power circuit. The block diagram is shown as below:
The device has a control system and it is included with:
The static VAR compensator device needs to be operated in a phasor simulation technique which is simulated using a powerful section. It can also be utilized in 3-phase power networks along with the synchronous type of generators, dynamic loads for the execution, and observation of the device on electromechanical variations.
High-end designs of static VAR compensators can also be designed where the exact level of voltage control is necessary. Voltage controlling can be done through a closed-loop controller. This is the static VAR compensator design.
In general, SVC devices cannot be operated at the line voltage levels, some transformers are required to step down the transmission voltage levels. This decreases the equipment and the size of the device necessary for the compensator even though the conductors be required to manage the extended levels of currents related to the minimum voltage.
Whereas in few of the static VAR compensators used in commercial purposes like electric furnaces, where there might be prevailing mid-range of bus bars are present. Here, a static VAR compensator will have a direct connection so as to conserve the transformer price. The other general point for connection in this compensator is for the delta tertiary winding of Y-type autotransformers which are used for the connection of transmission voltages to the other kinds of voltages.
The dynamic behavior of the compensator will be in the format that how thyristors are series-connected. The disc type of SC’s will have a high range of diameters and these are usually placed in the valve houses.
A static VAR compensator can be operated in two approaches:
For the voltage controlling mode, the VI characteristics are shown as below:
As far as the susceptance value stays at constant within the less and high threshold limits levied by the entire reactive power of the capacitors and reactors, then the voltage value is controlled at the equilibrium point which is termed as a reference voltage.
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Though voltage decrease generally takes place and this ranges in between the values of 1 and 4 % when there is extreme reactive power at the output. The VI characteristic and the equations for this condition are shown below:
V = Vref + Xs.I ( When the susceptance lies in between high and low ranges of capacitor and reactor banks)
V = -(I/Bcmax) at the condition (B = Bcmax)
V = (I/Bcmax) at the condition (B = Blmax)
Few of the advantages of static VAR compensator are
The disadvantages of the static VAR compensator are:
Merus® SVC is a cost-effective Static Var Compensator solution with fast reactive power compensation for higher-power-class applications.
Static Var Compensators built with thyristor-based power electronics technology have been in use since the s. They continue being installed in demanding applications, such as Electric Arc Furnaces, mining plants, and transmission and distribution networks. High reliability and availability are required from these installations, as they play an extremely vital role in eliminating flicker, reducing voltage variation and increasing productivity in industrial facilities, and extending transmission and distribution capacity in the electrical networks of utilities.
Keeping an aging SVC up and running can be a challenge for several reasons, including the shorter lifetime of active components versus passive components. The manufacturer’s specific electronic control components may have become obsolete, and the electrical characteristics of new spare thyristors must be closely matched with the other thyristors in the valves. Thus, the reliable long-term operation of an aging SVC system can be compromised leading to operational or safety risks.
We are experts at helping our customers migrate their already existing compensation systems to new technology while fully utilizing their existing CAPEX investment.
At Merus Power, we guide you effortlessly through complexities, ensuring you find the ideal modernization solution that meets your needs. No prior knowledge needed—our expertise is at your service.
The process begins with an on-site inspection of the existing SVC, followed by a detailed analysis of the customer’s objectives, including system operation, performance needs, and future plans. As experts in designing complex compensator systems, we offer insights on how these enhance productivity, such as in EAFs, positioning us uniquely to create solutions with significant ROI.
Our specialists will choose the appropriate technology by comparing various options to match the customer’s performance expectations and budget. Key considerations include process improvements, lifetime and reliability requirements, and technical constraints that affect system design.
After developing preliminary designs and budget estimates, and the customer is ready to move forward with the investment, we finalize the investment case and main design specifications. The result is a custom-built business model that exemplifies true collaboration, developed in partnership with the customer.
Once a project begins, our design team collaborates with the customer’s engineers to integrate our modernization solutions smoothly with existing systems. Procurement and manufacturing are then efficiently executed to ensure timely readiness. The final stages involve installation and commissioning at the customer’s facility, coordinated with the plant’s regular annual maintenance to minimize disruptions.
We prioritize effective training and thorough maintenance to enhance the longevity and efficiency of our systems. Our comprehensive training program equips our customers’ teams with the skills needed for daily operations and system maintenance. Additionally, we offer a tailored multi-year operation and maintenance agreement to ensure long-term reliability and optimal performance of the modernized SVC system. Our proactive maintenance includes our cloud-based IoT service, Merus® MERUSCOPE™, to ensure consistent, high-quality performance.