The SmartValve™ leverages proven Guardian™ technology and builds upon the success of its predecessors. The SmartValve can increase or decrease the reactance of a line, thereby pushing power away from or pulling more power towards the circuit on which it is installed.

A modular, Static Synchronous Series Compensator (SSSC), the SmartValve injects a leading or lagging voltage in quadrature with the line current, providing the functionality of a series capacitor or series reactor respectively. The SmartValve does not have the negative characteristics of these passive devices, such as the risk of sub‐synchronous resonance (SSR) with series capacitors and the constant VAR consumption of series reactors.

SmartValve solutions are connected in series with a utility facility, operate at line potential and have no connection to ground. This technology is particularly effective in highly meshed electric grids where spare system capacity can be utilized to resolve overload situations. SmartValve devices are typically installed on dedicated transmission towers (SmartTowers™) or in banks (SmartBanks™) within or near the transmission right-of-way. Due to their modularity and high kVAr output in compact and lightweight enclosures, they are particularly well-suited for Mobile applications. SmartValve technology is applied to all three phases, with the number of devices per phase determined by the amount of compensation required.

Explore the tabs below for product-specific information and details on how this technology is deployed, controlled and operated.

Note: The SmartValve was formerly known as the Power Router.

Deployment Options

Click to enlarge image


This tower can replace an existing structure within a circuit or serve as a new dedicated tower in the middle of a span. Existing towers can also be modified to accommodate units. Utilities needing to replace old poles or towers can use this method to upgrade their infrastructure and simultaneously add power flow control capabilities to their system.

Click to enlarge image


This method consists of multiple metal structures, each carrying multiple SmartValves. This extremely high-density deployment can be constructed on a small footprint within an existing right-of-way, a substation or a dedicated parcel of land adjacent to the ROW or a substation.

The SmartBank pictured here has two rows of towers, with each tower supporting six SmartValves. An empty row of towers is also pictured, allowing the utility to quickly add more units as needed. Smart Wires works directly with the utility to determine the SmartBank design that is best suited for a particular application.

Click to enlarge image


The mobile deployment method is a containerized solution that can be fully installed and commissioned in a matter of weeks. Installation requires a very limited outage ranging from a couple of hours to a couple of days, depending on site conditions. This method is ideal for short-term and near-term needs such as construction & maintenance support, short-term congestion, transmission emergencies and bridge solutions.

The equipment and methods used for installing the mobile solution are dictated by the particular deployment site conditions and each utility’s requirements and standards. Smart Wires will work with each utility to determine the connection option best-suited for a particular application.

Operating Principles

This figure illustrates the basic electrical configuration of the SmartValve. The SmartValve acts as a solid state synchronous voltage source, consisting of a voltage-sourced inverter as shown by the single-phase H-Bridge the figure. The H-Bridge employs the use of Insulated Gate Bipolar Transistors (IGBTs). The H-Bridge is controlled to inject a voltage directly into the transmission line to maintain a desired reactance. It does this by sensing the line current thru CT1 (Current Sensing) to determine the correct injection voltage magnitude to maintain the desired reactance.

The SmartValve works in conjunction with the SmartBypass™ for protection and control of insertion of the reactance into the transmission line, as shown in the figure.  The SmartBypass is essentially a switch connected in parallel with the SmartValve and is either opened (SmartValve can inject reactance) or closed (SmartValve is bypassed).

The SmartBypass provides rapid bypass of the SmartValve during fault conditions in 1 msec or less.  Under normal operation, it enables operators to switch a SmartValve in series with the transmission line. This enables a SmartValve to inject its controllable reactance for power flow control.  The SmartBypass directly carries the transmission line current when the SmartValve is bypassed.

Operating Range

Unlike conventional series capacitors or reactors, the SmartValve can inject the voltage independently of the line current, thus increasing the effective reactance injection when operated below the rated value, as shown in the graph in the figure.

The figure shows the effective reactance injection as a function of line current.  The orange boundary of the operating range reflects the maximum reactance available of an individual SmartValve 2000-3600 with a maximum output voltage of ±566 V RMS of the fundamental. The grey area inside reflects the range available if the output voltage is varied lower than ±566 V RMS of the fundamental. The collective fleet of SmartValve units can be controlled to maintain a fixed reactance since the injected voltage can be controlled as a function of line current.  Other SmartValve models follow a similar operating range curve; the maximum current and maximum reactance values will differ.

Operating Modes

The SmartValve has two distinct modes of operation. The modes during normal operation are determined by the state of the SmartBypass as follows:

  1. Injection Mode – The SmartBypass uses proprietary technology including a normally-closed mechanical contactor and fast-acting semi-conductor Silicon Controlled Rectifiers (SCRs), enabling the SmartValve to inject a voltage into the transmission line. The maximum magnitude of the voltage is determined by the respective SmartValve voltage rating.
  2. Monitoring Mode – No voltage is injected as the normally-closed mechanical contactor is closed and the SmartValve is bypassed.
Control Methods

The SmartValve uses a wireless communication link to connect to the End-to-End Communication and Control System.  The operator does not need to control individual devices, but can program a desired value for the fleet as follows:

  1. Injection at a fixed voltage – The SmartValve fleet outputs a fixed voltage injection level that is either capacitive or inductive. In this control method, the injected reactance will vary as the line current changes.
  2. Injection at a fixed reactance – The SmartValve fleet outputs a fixed reactance that is either capacitive or inductive. In this control method, the injected voltage will vary as the line current changes to keep the reactance at a set value.

More advanced control methods are possible depending upon each utility’s needs and the way the equipment is integrated into the system. For example, it is possible to automatically change the injected reactance or voltage injection as a function of the line current to limit current below a specified level or maintain flow through the line at a specified level.

Communication & Control

Click to enlarge image

The End to End (E2E) Communication and Control System (referred to as the E2E system) seamlessly interfaces with utility Energy Management Systems (EMS) and manages the operation of Smart Wires Field Devices (SWFDs).

Utilities operators control of the amount of reactance provided by the fleet of SWFDs at the EMS level. EMS commands are transmitted to the PowerLine Gateway over a secure communication channel. The PowerLine Gateway is an IT/SCADA device, located at the substation, which provides configuration, observation, control and asset management services for the SWFDs. The PowerLine Gateway supports multiple communication protocols – including DNP3, IEC 61850, 60870-5-104 and others – and transmits the utility’s EMS commands to the PowerLine Coordinator. The PowerLine Coordinator, an IT/SCADA device located either in the substation or in the field, manages the secure wireless network that is used for communication with the SWFDs.

Optional PowerLine Manager software runs on a server located in the utility data center. This software includes features such as remote access to all the diagnostic data from the SWFDs and the ability to perform remote software updates.

Once the SWFDs are programmed initially, each unit largely controls its individual reactance injection on the transmission circuit. The SWFDs detect faults and automatically bypass when the current is at fault condition levels.

The Smart Wires Difference

Smart Wires solutions offer key advantages compared to traditional approaches to infrastructure investments. All of Smart Wires products are modular in-nature, meaning that deployments can be fine-tuned to meet system needs. Should utilities require a different amount of power flow control at some point in the future, Smart Wires’ installations can be easily scaled up or down. Smart Wires solutions are quick to deploy, providing utilities with an installed solution capable of addressing emergency needs. Also, all products are designed to be easy to re-deploy. This means that if grid conditions change and power flow control is no longer needed on a specific circuit, the Smart Wires solution can be moved to a different location on the grid. This reusable investment is perfectly suited for addressing problems that are known to be short-term or temporary in nature.