Medium voltage STATCOM
May 20,2020


STATCOM (Static Synchronous Compensator)continuously provides variable reactive power in response to voltage variations, supporting the stability of the grid. STATCOM operates according to voltage source converter (VSC) principles, combining unique PWM (pulse width modulation) with millisecond switching. STATCOM functions with a very limited need for harmonic filters, contributing to a small physical footprint. If required, switched or fixed air core reactors and capacitors can be used with the VSC as additional reactive power elements to achieve any desired range.

zddq 33kv statom applied in wind farm

Problems of Power Networks

In order to descript the quality of power grid voltage, several indicators are used, such as stability, symmetry and sine. With the development of power electronics, more and more non-linear loads are connected to the grid, which seriously affect power quality. The main interference sources are power electronic switching devices and load fluctuations, which bring the following affects.

  1. Reducing the stability of power transmission system for lack of regulate reactive power timely.
  2. Causing low voltage or voltage collapse for lack of regulate reactive power immediately
  3. Increasing grid loss and production cost, decreasing productivity and with low power factor.
  4. Causing voltage reduces, voltage fluctuation, flicker for reactive power impact.
  5. Producing a large amount of harmonic currents, resulting in grid voltage distortion, it’s the invisible killer of grid.
  6. Causing grid three-phase unbalance, and producing negative sequence currents to make the vibration of motor rotor

STATCOM the best solution for power quality improvement

Currently, the best solution is using STATCOM, which can improve grid stability, increase transmission capacity, eliminate reactive power impact and balance the three-phase grid.

  1. Improve the stability of transmission line
    STATCOM not only compensate the reactive power losses, raise the line voltage and improve the grid capacity when the system is working, but also regulate the reactive power, improve grid stability when the system fail.
  2. Maintain the terminal voltage and enhance the voltage stability
    Due to large load capacity and without reactive power devices, the voltage may be lower and even voltage collapse. The STATCOM can maintain the load voltage and improve the stability, because of fast ability of reactive power correction.
  3. Compensate reactive power, improve power factor, reducing line losses and saving energy.
    Lower power factor will increase the line losses and reduce voltage quality. The efficiency of power generation, transmission and power supply equipment will be reduced. And it will increase electricity costs.STATCOM is the best answer for lower PF.
  4. Suppress voltage fluctuation and flicker
    When the loads(such as Arc furnace, rolling mill and electric locomotive.) change dramatically, it will lead to the dramatic change of load current. As a result, the voltage flicker and fluctuation occur. STATCOM can change the reactive power current quickly to compensate the voltage fluctuation and flicker.
  5. Balancing three phase unload
    There are lots of 3 phase unbalanced loads(such as electric locomotives and Arc furnace. SVG can quickly compensate the unbalance, which ensure the three-phase currents on the grid side be balance and improve the power quality.ZDDQ Indoor 10kv statcom


ZD-FGSVG series STATCOM, using IGBT (2-Level) as the core power device which can quickly and continuously generate capacitive or inductive reactive power, achieve constant reactive power, constant voltage and constant PF control through the assessment point, and ensure network stable, high efficiency and high quality. In networks, the small capacity FGSVG can significantly improve the power quality (improve PF, balance 3 phase load, eliminate voltage flicker and fluctuation, mitigate harmonics).

Air cooling system and water cooling system are optional.

STATCOM Features

FGSVG series STATCOM with high performance, high reliability is designed to meet users’ demands of improving PF of power transmission, compensating harmonic and the negative sequence of current. It is easy to operate. Its features are as follows,

The structure of power cell is using one molding abrasive structure with strong versatility. The same serialized products can share spare parts. The unified of primary terminals and secondary signal interfaces, make it is easy to maintain.

Auto SMT imported from Germany

      • Using power connectors to install power cells, which is easy to install, repair and maintain.
      • Output current harmonics(THDi) ≤3%
      • Multi operation modes: such as constant reactive power device, constant assessment point of reactive power, constant assessment point of power factor, constant assessment point of voltage, load compensation.
      • Real-time track load changes, compensate reactive power dynamically and smoothly, improve PF, real-time compensate harmonics, compensate the negative sequence of current, improve power quality.
      • Suppress voltage flicker, improve voltage quality, stable the system voltage.
      • High-tech design of circuit parameters, small heat value, high efficiency, low operating cost.
        Assembly production and welding workshop
      • Compact structure, small footprint.
      • The dust filter is easy to maintain, which can be cleaned when the STATCOM is running.
      • The power cell is consist of H-bridge IGBT, each phase is composed of multiple identical power cell, the output PWM waveform is formed by step wave which is approximate to sine.
      • Redundant design to meet the needs of high reliability system.
      • Modular design of power circuit, easy maintenance and good interchangeability
      • Lots of protections. It can record fault waveform instantly, easy to find the fault point and maintain with high reliability.
        35Kv experimental station and full test equipment
      • Provide a variety of interfaces, such as Ethernet,RS485.Support MODBUS_RTU, CDT, IEC104.
      • Friendly HMI, real-time digital and analog display, operation record, historical curve records query, power cell status monitoring, system information query, historical fault query, system self-test after power on, one key to startup-shutdown,  time-sharing control, oscilloscope (AD channel mandatory record), instant voltage/current fault record.
      • Provide FC interface, combine with FC effectively, more economical and more flexible compensation programs for users.
      • No transient impact, no inrush phenomenon, no arc reignition, switch directly without discharge.
      • Easy connection, without regard to the phase sequence when connecting to the system
      • Be installed in parallel, easy to expand capacity. Use the fiber optic communication, which has a fast communication speed and can well meet the requirement of real-time compensation.
      • CE Certificate, routine test, Environment and EMC Test, Type Test.
      • Many years of manufacturing experiences, and rich application experiences in coal, metallurgy, photovoltaic and wind.

Advanced aging and testing system


Adopt comprehensive protection strategy, include 3 level(component protection, device protection and system protection) Protection Type: (DC) Over voltage, under voltage, over current, lost pulse, abnormal  triggering, over heat, over load, short circuit, abnormal frequency, single phase grounding, external fault , input interface, output interface, abnormal power

3 LEVEL Protection Strategy

Protection Response Time

Typical Protection Type

Component Protection


Over current, over voltage, signal abnormal

Device Protection


Over Load, DC over voltage

System Protection


Loss voltage, over voltage, cooling system fault


Indoor Type and outdoor type, with air cooling system and water cooling system

Indoor 6kv 6Mvar STATCOM

Indoor 6kv 6Mvar STATCOM

Outdoor container type 10KV 6Mvar STATCOM

Outdoor container type 10KV 6Mvar STATCOM

ZDDQ STATCOM Applications
  • Power substation
  • Long distance power transmission
  • Wind Farm
  • Solar Plant
  • Metallurgy Arc Furnace
  • Rolling mill
  • Mine
    zddq 35kv indoor statcom assemble
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