Controlled shunt reactors
Controlled shunt reactor (CSR) is a new type of FACTS devices (controlled equipment for AC transmission networks)
Controlled shunt reactor is a shunt-type static device with stepless regulation of inductive reactance. Controlled shunt reactors manufactured by ZTR PJSC are purposed for automatic control over reactive power flows and stabilization of voltage levels that ensure the following:
- Elimination of daily and seasonal voltage oscillations in the electric network;
- Improvement of electric energy quality;
- Optimization and automation of the power network operating modes;
- Decrease losses of electric energy during power transmission and distribution;
- Ten times improvement of operational conditions of electric equipment owing to rapid step-down of switchings of non-regulated devices of reactive power compensation and restrain of usage of lesser serviceable in operation transformer and autotransformer OLTC devices;
- Increase of transfer capability of HV lines and ensuring of reliable automatic voltage control over voltage levels at power flows, closed the limits as for static stability;
- Elimination of voltage collapses in case of emergency conditions in the electric network (e.g., load rejections, shutdown of generator, line outages, etc.);
- Assurance of operation conditions for power plant generators in such reactive power generation range which facilitates the most favorable operational duties.
Tasks to be solved by means of CSRs
- Increase of transfer capability of interconnecting mains;
- Automatic stabilization of voltage levels;
- Assurance of permissible voltage levels within performance of switching-over programs;
- Optimization of electric network operational modes and reduction of electric energy losses;
- Maintenance of voltage reserve at modes with high-level active power flows;
- Improvement of electric energy quality;
- Assurance of required loading of power plant generators as related to reactive power;
- Decrease of the breaker switching-over;
- Decrease of switching number of the transformer and autotransformer OLTC devices;
- Pay-back period is from 2 up to 5 years;
- Price is 2,5 times lower if compared with similar compensation systemsalternative projects.
Principle of operation
Controlled shunt reactor is a variable inductance, smoothly regulated by magnetic biasing of ferromagnetic elements of magnetic circuit.
Magnetic system of CSR single phase consists of two cores. Each core is equipped with control and power windings.
In case of regulated DC current source connection to the control windings, biasing flow is increasing and directed to different sides in the adjacent cores. This resulted in saturation of CSR cores at relevant half-period of the voltage.
Core saturation is resulted in increase of the current in the power winding due to reducing of reactor inductance. Due to this a stepless variation of voltage levels in CSR connection point as well as the value of reactive power consumed by the reactor is ensured.
CSR main parameters
- Reactive power regulation range – 100%;
- Control power – 1–3% of CSR rated power;
- Guaranteed rate of obtaining the full power – 0.15–3 s.;
- Time of obtaining the full power with pre-magnetization – not more than 0.02 s.;
- Specific total gravity 1.5–3 kg/kVAr;
- No-load 0,5–1,0 W/kVAr;
- Nominal 4–8 W/kVAr.
- Permissible overload as related to current – 120 % (30 minutes max);
- Fully automatic operating mode;
- Reliability level, operating conditions and current maintenance corresponds with the ordinary shunt reactors.
CSR advantages against similar equipment
- Regulation range is 100% of CSR rated power;
- Stepless (smooth) regulation with unlimited resource of possible variation;
- Non-use of OLTC devices;
- Capability of normalized CSR overload up to 130% and short-term overload up to 200%;
- Regulation of voltage and reactive power directly in the connection point;
- Use of low-power valve devices with decreased losses and lack of necessity to employ water cooling;
- Traditional requirements as for qualification of the maintenance staff at the substation;
- Much more lower level of the losses: by 1.5–3 times;
- Outdoor installation;
- Significantly lower price.