Definition of reactive power

For three-phase circuit, without considering voltage distortion. Set the sine wave voltage effective value is U, distortion current effective value is I, the fundamental value of current and voltage phase angle difference respectively is 11 and the effective value of n times harmonic is In. Consider to different frequency between voltage and current generate active power, as per definition can be obtained:

In this case, both Qf and D have definite physical meaning. Qf is reactive power generated by fundamental current, and D is reactive power generated by harmonic current. At this time power factor is

Reactive power is very important foroperation ofpower supply system andload as below:
■Increase the power supply capacity and investment increased;
■Increase equipment and line loss, reduce system security;
■Increase voltage drop of line and transformer, causing voltage fluctuation and flicker of grid.

National standards for power quality
GB/T 12325-2008   Power quality   Supply voltage deviation
GB/T 12326-2008   Power quality   Voltage fluctuation and flicker
GB/T 15543-2008   Power quality   Three phase voltage unbalance
GB/T 15945-2008   Power quality   Power system frequency deviation
GB/T 14549-1993   Power quality   Public power grid harmoni

Necessity of ;reactive power compensation
In view of high and low power factor of customer take full advantage of equipment of generate electricity, power supply and power utilization or save electric energy and improve voltage quality have important influence, and the state promulgated measures for Administration of Power Factor Adjustment. Its core content is to adjust electric charge according to user's power factor.

Power factor with 0.90 as standard value to adjust electric charge

Reduce the tariff	Practical power factor	0.90	0.91	0.92	0.93	0.94	0.95 〜1.00
	Tariff reduction per month %	0.0	0.15	0.30	0.45	0.60	0.75
Increase in electricity	Practical power factor	0.89	0.88	0.87	0.86	0.85	0.84	0.83	0.82	0.81	0.80	0.79	0.78	0.77
	Tariff reduction per month %	0.5	1.0	1.5	2.0	2.5	3.0	3.5	4.0	4.5	5.0	5.5	6.0	6.5
	Practical power factor	0.76	0.75	0.74	0.73	0.72	0.71	0.70	0.69	0.68	0.67	0.66	0.65
	Tariff reduction per month %	7.0	7.5	8.0	8.5	9.0	9.5	10.0	11.0	12.0	13.0 | 14.0		15.0
Power factor is under 0.64, every 0.01 reduce to increase 2% in electric charge

Power factor with 0.85 as standard value to adjust electric charge

Reduce the tariff	Practical power factor	0.85	0.86	0.87	0.88	0.89	0.90	0.91	0.92	0.93	0.94 〜1.00
	Tanff reduction per month %	0.0	0.1	0.2	0.3	0.4	0.5	0.65	0.80	0.95	0.75
Increase in electricity	Practical power factor	0.84	0.83	0.82	0.81	0.80	0.79	0.78	0.77	0.76	0.75	0.74	0.73	0.72
	Tariff reduction per month %	0.5	1.0	1.5	2.0	2.5	3.0	3.5	4.0	4.5	5.0	5.5	6.0	6.5
	Practical power factor	0.71	0.70	0.69	0.68	0.67	0.66	0.65	0.64	0.63	0.62	0.61	0.60
	Tariff reduction per month %	7.0	7.5	8.0	8.5	9.0	9.5	10.0	11.0	12.0	13.0	14.0	15.0
Power factor is under 0.59, every 0.01 reduce to increase 2% in electric charge

In power system, reactive power is fast dynamic compensation, it can achieve the following functions;
■Power factor correction for dynamic reactive power load;
■Improve voltage adjustment;
■Improve static and dynamic stability of power system;
■Reduced over voltage;
■Reduce voltage flicker;
■Damped oscillation;
■Reduce voltage and current imbalance.

To compensate reactive power of network, not only can reduce power supply capacity and reduce investment, but also can reduce the line loss, and most important is to improve system power factor, to avoid reactive power, therefore, the reactive power compensation is an important measure of enterprise "energy saving and reducing consumption".

1、Principle

Fundamental of SVGiStatic Var Generator basic principle is to self commutated phase bridge circuit unconventional reactors are directly connected in parallel on grid, appropriate regulating phase and amplitude of bridge circuit of AC side output voltage or direct control of its AC side current, can make current sending out to satisfy requirements of reactive current, realization of dynamic reactive power compensation.

2、Design production reference standard

3、Demonstration of the type
Model：AN—SVG-500/0.4

4、Technical features
The traditional reactive power compensation device has wide range of applications, such as resonance，slow response time and so on.
SVG is the most advanced reactive power compensation device, it is no longer to adopt a large capacity capacitor and inductance device, but high frequency switching power electronic devices to achieve reactive energy conversion, so that reactive power compensation technology has produced qualitative leap;

(1)Faster response
SVG response time: ≤5ms
SVG complete from rated capacitive reactive power to rated emotional power conversion within a very short period, unparalleled in response speed can be competent on impact load compensation.

(2)Higher security
SVG is controlled as current source, without possibility of harmonic of system impedance and security is higher.

(3)Diversification of compensation function
Using same set of SVG devices, different kinds of compensation functions can be realized;
Reactive power compensation; Compensated load harmonics; Unbalanced compensation; At the same time compensation of reactive power, harmonics and imbalance.

(4)Low harmonic content
SVG uses PWM technology and multiple technologies, compared with TCR type SVC, harmonic content is very low, and power grid will not produce two pollution.

(5)Smaller area
SVG uses direct PWM current control technology, its output current waveform and phase is completely controllable, SVG can run in rated sensitivity to rated capacity of range. Due to no large capacity capacitor and reactor to do energy storage components, the largest area of SVG is only the same capacity 50%.

5、Form

(1 )World leader in power components Using the world's leading IGBT component, main circuit is bridge full control PWM converter, with the characteristics of high power density and high reliability. (2 )Digital control system DSP high speed detection and operation, to ensure that reactive power detection and compensation control is accurate and effective; use of word control system, all control process using software, making whole control system is simpler and more reliable. (3 )Monitoring and display system Intelligent monitoring and display system makes device operation flexible, operating parameters, operating status at glance, fault self diagnosis, with remote communication interface, can communicate with host computer.

6、Technical parameters

1、Application domain analysis

	Lifting machine, rolling mill and other heavy industrial occasions Lifting machine and typical impact load of rolling mill term, mainly exists in various mining production occasions and metallurgical industry, power grid has following effects: *Reactive power impact is larger, resulting in power grid voltage fluctuations, serious interference with other equipment operation and reduce production efficiency; *Power factor is low, a large number of reactive fines need to pay per month; *Part of device generates harmonics and maintains network security.
	Drilling power supply system The main load of power supply system of oil and gas drilling platform includes winch, rotary table and mud pump, etc., due to particularity of drilling operation, the system term typical impact load. The impact on grid is as follows: *Reactive power impact is big and power factor is low; *Current harmonics is big; *Voltage fluctuations, high voltage distortion rate, impact of control system, PLC, logging equipment and other equipment.
	Electrified railway and rail transit High speed railway and rail transit power supply system uses a large number of cables for power transmission, power grid has the following threats: *Produce a large number of reactive power and low power factor; *Raising line terminal voltage; *It is possible to exist in system.

SVG ANKLAM® can be used to solve problems of reactive power and harmonic wave.

2、Application scheme
SVG
In case of reactive power compensation capacity is small and current distortion is small.

SVG+APF
In view of large capacity of reactive power compensation, the current distortion is serious.
SVG reactive power compensation system; APF suppress harmonic current of power system, improve power grid voltage, both of their duties.


SVG+PF
In view of large capacity in reactive power compensation, the cost is strictly required.
SVG and PF (passive filter) with reactive power, SVG can be configured as system capacity of half or smaller, effectively reduce the cost; PF can be configured as single tuned filter, effectively suppress harmonic current.

SVG+APF+PF
In view of large reactive power compensation capacity, the current distortion is serious and cost control is strict.
SVG and PF (passive filter) with reactive power, SVG can be configured as system capacity of half or smaller, effectively reduce the cost; PF can be configured as single tuned filter, effectively suppress the harmonic current; APF used to suppress harmonic current.

3、 Selection Guide (calculation of compensation capacity)
The capacity of reactive power compensation is determined by following formula:

In this formula that PC-Maximum active load of power supply by substation in that month (kW):

For example:
The maximum active load of substation is 2000kW, the average load rate is 0.75, the power factor is 0.6 and target power factor is 0.92, reactive power needed to compensate for change point is:

Consider certain margin, can choose compensation capacity of 1500kvar compensation device.

4、 Application of SVG in truth system
The main load of power supply system in oil drilling platform includes winch, rotary table, mud pump and top drive etc., following damage to power grid caused by equipment: ?
■ Reactive current is big , power factor is low;
■ High current harmonic and high voltage distortion rate.

Through test, due to work of DC speed control system for power supply voltage of drilling platform is very large (THD>30%)I power grid harmonic current (THD>30%) and system power factor is very low (0.3-0.5) caused by South West drilling company, and pay a large number of reactive fines in every month. Our company through field test and program demonstrates that use of SVG+APF dynamic reactive power compensation device for reactive power compensation and harmonic control, total capacity is 1.6Mvar, in which capacity of SVG is 1.2Mvar, capacity of APF is 400kVA.

SVG and APF are advanced power electronic equipment which adopts high speed switching device, and compensation device of passive device is compared with the device, it has the following advantages:
(1)It will not occur parallel resonance with grid;
(2)It is not sensitive to power grid;
(3)Device automatic limiting value of output current will not be burned down;
(4)Stepless regulation will not appear to compensate;
(5)Fast response speed.
According to running situation of running field, the device has good effect on fast fluctuation of load. The grid side current compensation device for removal of reactive power, and power factor curve. By compensation device can be seen, after stopping operation, the current effective value increased from 1100A to 1900A, reactive power increased from 150kvar to 530kvar, and power factor from 0.93 to 0.55.