SSVG- High-voltage static Reactive power Generator
SSVG- High-voltage Stationary Reactive Generator
Product overview
Static var generator (SVG), also known as static synchronous compensator (STATCOM), is a dynamic reactive power compensation device based on high-power inverter. The output voltage of SVG is connected to the system by connecting reactance to keep the same frequency and phase with the system side voltage. The output voltage is determined by adjusting the relationship between the output voltage amplitude and the system voltage amplitude When its amplitude is greater than the system side voltage amplitude, it will output capacitive reactive power and less than it will output inductive reactive power. The device is the third generation voltage stability and reactive power compensation controller, which represents the latest development direction of flexible AC transmission technology.
In recent years, dynamic reactive power compensation and harmonic control devices are more and more widely used in the power grid and power users, to improve the voltage stability of the grid, improve the power quality of users and achieve the purpose of energy saving. When SVG is used in transmission network, it can improve the stability of power system, increase system damping and restrain system oscillation, thus greatly improving the voltage transmission capacity. With the rapid development of China's inter regional power grid construction, the problems of reactive power and dynamic voltage stability in power system become increasingly prominent. Installing high voltage and large capacity SVG is a more effective means.
SVG is used in distribution network (also known as DSTATCOM), which can compensate voltage fluctuation and flicker, load imbalance, power factor and harmonics quickly and effectively. It can effectively improve power quality and achieve obvious energy saving and consumption reduction benefits. For example, when SVG is used to compensate electric arc furnace, calcium carbide furnace and other loads, the average power consumption is In the past, it can be reduced by 4% - 15%, and the economic benefit is very significant.
The products can be used in the following industries:
Electric power industry refers to the major power grid companies, provincial power companies and power supply companies in various regions
In the power grid substation, the method of switching capacitor banks by stages is generally used to compensate the reactive power of the system, stabilize the grid voltage and improve the power factor. This method can only provide capacitive reactive power to the system, and can not achieve rapid and accurate adjustment with the change of the power grid. It is easy to cause reactive power back to the system, raise the bus voltage, and endanger the stability of electrical equipment and system
The SVG system can quickly and accurately carry out capacitive and inductive reactive power compensation, stabilize the bus voltage and improve the power factor, completely and conveniently solve the problem of reactive power switching. Moreover, after installing the new SVG system, the original fixed capacitor bank and thyristor phase controlled reactor can be used to achieve the best effect with less investment.
Electrified railway and urban rail transit industry
The locomotive adopts a three-phase inverter to reduce the negative power factor of the traction grid, which can reduce the negative power of the traction power supply system.
Wind farm
The uncertainty of wind resources and the operation characteristics of wind turbine itself make the output power of wind turbine fluctuate, which leads to the problems of unqualified power factor, voltage deviation, voltage fluctuation and flicker. When large capacity wind farms are connected to the system, there are also stability problems, which need dynamic reactive power compensation system. In addition, the short-circuit capacity of wind farms is generally small, and the fluctuation of wind turbine output power or load may cause frequent voltage fluctuation of the access bus, which not only affects the power quality of the grid, but also affects the normal power generation operation of wind turbines.
SVG is a better choice for wind farm compensation. It can not only meet the requirements of power factor, voltage fluctuation and flicker of wind power access system, but also reduce the impact of system disturbance on wind turbine. It can be integrated with low-cost capacitor banks to realize seamless connection with low-cost solutions. Svg has excellent dynamic performance and short-term high overload capacity, which can provide constant voltage regulation, power factor regulation and low voltage ride through for the whole wind farm.
Rolling mill, hoist and other large industrial load
Rolling mill, hoist and other large-scale industrial electrical load system is composed of high-power AC and DC motors and various rectifiers, inverters, frequency converters and other high-power power electronic equipment. The reactive power impact produced in the work will cause the voltage drop and voltage fluctuation of the power grid. In serious cases, the electrical equipment can not work normally, the production efficiency is reduced, and the power factor is low. At the same time, the transmission device of the load will produce harmful high-order harmonics, mainly the odd harmonics represented by the 5th, 7th, 11th and 13th times, which will cause serious distortion of the power grid and change the loss of the industrial distribution network At the same time, it will cause harmonic peak voltage and damage the cable insulation.
SVG can stabilize the system voltage and meet the needs of production by controlling the power quality of rolling mill, hoist and other loads or its distribution network; meanwhile, it can greatly improve the power factor, reduce the reactive power penalty and reduce the power loss of the system, bringing huge economic benefits to large enterprises such as metallurgy, mining, petrochemical, port transportation, etc.
Arc Furnace
AC and DC electric arc furnace, as nonlinear and irregular load, will lead to serious three-phase unbalance, negative sequence current, low power factor, serious voltage fluctuation and flicker, and high-order harmonics. The coexistence of odd harmonics such as 2nd and 4th harmonics and odd harmonics of 3rd, 5th and 7th order are common, which makes voltage distortion more complex.
The only way to solve the above problems is to install SVG with fast response speed. The system response time is less than 5ms. It can make comprehensive compensation for dynamic reactive power, harmonic and unbalanced load current of the electric arc furnace power supply system. It can completely eliminate the three-phase imbalance caused by the electric arc furnace, eliminate all kinds of harmful harmonics, suppress voltage fluctuation, improve smelting efficiency, and bring remarkable benefits Economic benefits.
Working method
The basic principle of ssvg is a chain type voltage source converter composed of high-power fully controlled power electronic devices (IGBT). It is connected in parallel with the power grid through the connecting reactor. The amplitude and phase of the output voltage of the converter are properly adjusted, or the AC side current of the converter is directly controlled, so that the converter can absorb or emit the required current and realize dynamic reactive power compensation and treatment The purpose of harmonic management.
The circuit schematic diagram of ssvg is shown in Fig. 1 and Fig. 2. It is mainly composed of chain voltage source converter, connecting reactor, controller and other auxiliary equipment (such as grid connection switch, cooling device, etc.) of man-machine interface.
Performance characteristics
Main functions:
Fast dynamic reactive power compensation can improve power factor, restrain voltage fluctuation and flicker, correct three-phase voltage unbalance (compensate unbalanced load current), and reduce harmonic current and voltage.
Main features:
Various compensation functions: ssvg can not only compensate reactive power, but also control harmonic current and negative sequence current. Wide compensation range: ssvg can continuously output reactive power from rated inductive condition to rated capacitive condition, and multiple sets in parallel can form continuous compensation in any range. Fast dynamic response speed: ssvg has fast reactive power output within 5ms, so it has better compensation effect for fast impact load and better suppression effect for voltage flicker; while the response time of traditional SVC is generally 40 ms-60 Ms.
Super reactive power compensation and overload capacity: ssvg presents current source characteristics, and its output reactive current is not affected by bus voltage. When the system voltage drops to 20%, it can still output rated reactive current or even several times of the rated current for a short time (can be customized according to user requirements), so that it has strong reactive power support capacity and overload capacity; while the traditional SVC is impedance type, output reactive power The current decreases linearly with the decrease of bus voltage.
Excellent harmonic output characteristics: ssvg can not only output nearly sine wave reactive current (without harmonics, for reactive power compensation), but also can completely output specific times of harmonic current (for load harmonic control), that is, SVG output current is fully active and controllable, fully meeting the needs of application; while SVC generates a large number of uncontrollable harmonic current, a large number of uncontrollable passive filters are required Wave branch to eliminate the harmonic current generated by itself.
Small floor area: ssvg is based on the converter composed of fully controlled power devices, without bulky filter branch in SVC, and its installation size is generally only 1 / 5-1 / 3 of SVC, which is especially suitable for occasions with high requirements on floor space.
High efficiency: ssvg adopts a new type of low loss fully controlled power device, the direct output voltage range is 3kv-35kv, the connection transformer is omitted, and the device efficiency can reach more than 98%; its operation loss is generally only 30% - 50% of SVC, and the equivalent operation power consumption is much lower than SVC.
High reliability: ssvg adopts n + 1 or N + 2 redundancy design and modular design, and can continue to run with full load after one (or two) link units are damaged.
Perfect protection function: ssvg has over-current, overheating, over-voltage protection; at the same time, it can fully cooperate with the connected power system and its protection equipment, which can reliably avoid misoperation or refuse to operate.
Friendly man-machine interface and event monitoring and recording function: the relevant functions of the control system ensure that users can easily know the system operation status and query the operation history records.
Product code:
Technical index
Rated working voltage: 3kv-35kv;
Power factor: the system power factor after compensation is greater than or equal to 0.95;
Response time: up to 5ms;
Current overload capacity: 1.1 times overload can operate continuously;
1.2-1.4 times overload operation time: 60 seconds / hour;
Over operation time of more than 1.5 times shall not exceed 2 seconds;
Working voltage: ≤ 1.2 times of rated voltage;
Allowable voltage unbalance: no more than 6%;
Protection functions: over current, short circuit, grounding, over-voltage, under voltage, input phase loss, over temperature, control power failure, communication failure, etc.
Usage environment
Ambient temperature: - 10 ℃～ + 40 ℃
Relative humidity: no more than 85%, no condensation
Altitude: no more than 1000m (> 1000m, reduced capacity operation or special customization)
Installation location: the vertical inclination shall not exceed 50, without fire, explosion, conductive dust, corrosive gas and severe vibration.
Executive Standards
Power quality voltage fluctuation and flicker (GB / t12326-2008)
Power quality harmonics in public power grid (GB / T14549-93)
"High voltage static var compensator Part 1 system design" (DL / t1010.1-2006)
Reactor (GB / t10229)
Matching instructions：
System diagram and parameters: rated voltage, rated current, operating voltage, etc;
Total active power and average power factor, target power factor or reactive power compensation capacity required in normal operation of load equipment;
In line mode, environmental conditions, order quantity, delivery time, delivery mode, transportation mode, etc;
Users can order according to the model, capacity, specification and quantity provided by our company, and also can provide parameters and requirements to be designed and determined by our company;
Installation site: indoor or outdoor, size;
Other special requirements
