Storinka 102 of 130

14.2. Good luck, that dzherela reactive pressure

Let's take a look at the report on the balance of the reactive tension of the UES. Equal to the balance up to the pressure of the generators in the power plants, the reactive pressure of the compensating attachments in the SQ CU is to be blamed, as well as the reactive pressure that is generated by the high-voltage power lines SQ C

Calming reactive tension. The skin slowing down electricity is characterized by a slow active pressure P, which is converted by mechanisms and accessories into other types of energy (mechanical, thermal, light and other). The reduction of reactive tension Q is determined by the tension coefficient tg j = Q/P. The main relievers of reactive tension are asynchronous motors (tg j = 0.75-1.3), induction ovens(tg j \u003d 1-2.7), valve converting (tg j \u003d 0.75-1.2), brewing units (tg j \u003d 1.5-2.7) thin. Industries of business - the main ones to reduce reactive tension, a part of asynchronous tension in the reactive tension relieved by them is 60-70%. In some electric chains, the reduction of reactive tension is less. It is reactive to deposit apartments due to the availability of electric butt equipment and the type of stoves for cooking hedgehogs. The year of the evening has a maximum of interest for apartments gas stoves tg j = 0.5, for apartments with electric stoves tg j = 0.35. The power of the power supply of the headroom electric devices (lifts, pumps, ventilation, etc.) is greater than the reactive tension on the introduction into the booths, to the fact that asynchronous electric motors are used to drive these electric devices.

Use reactive tension. The main part of the reactive pressure losses is spent at transformers and repeating lines (PL) electric lines. So, spend reactive pressure in the transformer to become 10-12%. again. When transferring electricity from a power plant to an electrical receiver, no less than a few transformations are carried out, and therefore, the cost can reach approximately 50% of the total tension of electrical receivers. Lose the reactive tension of the PL to lie down in the long line and struma, which flows through it. Transmitted along the line, tension can be assessed for the throughput of the line, yak, in your line, can be characterized by natural tension R nat. When transmitting natural tension through the PL, use the reactive tension equal to the reactive tension Q C generated by the line. The value of P nat is weakly deposited at the intersection of wires, it is determined by the weak support of the line and in the middle road: for 110 kV submarines - 30 MW, 220 kV - 135 MW, 500 kV - 900 MW.

Charging tightness of the lines. The electrical conductivity of the submarine is guaranteed at voltages of 110 kV and more. Charging pressure of the line Q C lie in rated voltage that її dozhini. For example, the generation of reactive tension in a line with a length of 100 km to become: at a pressure of 110 kV - 3.5 Mvar, 220 kV - 14 Mvar, 500 kV - 90 Mvar. For the middle lengths of the line, pritamanny dermal nominal tension, the charging tension should be set from 6 to 30% of the natural tension of the line, moving from the increase in the tension of the PL.

Generators of power plants are the main source of reactive pressure. The nominal pressure coefficient of the generators, which increases the intensity of the active pressure of the generator P g to the 1st full pressure S g (cos j g = P g / S g), becomes 0.85-0.9, and, therefore, the generation of reactive pressure generators cannot to change 0.5-0.6 of the active tension generated by them. This means that the generators of the power plants cannot supply all the needs of the jet exhaust. That is why in the EEC there will be widespread outbuildings to compensate. Before them one can see:

• Capacitor batteries (KB), which are mainly operated at a voltage of 0.22-10 kV. Being installed at the tension nodes, the stench allows the frequent separation of electric lines in the form of reactive tension transmission over them;
• synchronous compensators (SC) - synchronous machines, yakі pratsyut navantazhennya on the shaft, tobto. at idle mode. Synchronous compensators are released in equal amounts of high pressure (50-320 MB A) and are installed, as a rule, at regional substations, the schedule of pressure changes in wide ranges, and the balance of reactive tension changes significantly. As a rule, substations with a voltage of 330-500 kV and more, de SC are installed on tires lower voltage(10-20 kV). A synchronous compensator can be provided with an attachment for automatic regulation of the voltage, and with a decrease in the voltage of the valves, it automatically reduces the vibration of the reactive strain, thereby stabilizing the voltage itself;
• static thyristor compensators (STK) are built up in parallel with core reactors and KB, which are connected to the high voltage through a transformer. To regulate the reactive tension, thyristors are installed. Thus, the replacement of reactors and design bureaus allows you to win the STK for generation (when overwhelmed єmnіsny element), so for the reduction of reactive tension (when the inductive element is overextended). Static thyristor compensators are used for high nominal tension and are installed at intermediate and terminal substations of high voltage power transmission lines, as well as at large voltage nodes for stabilization of the grid mode with a sharp change in the nature of the voltage. Vykoristannya STK in the living space allows: stabilizing the voltage in the area of ​​connection of the STK; change the active strain in the power transmission; increase the capacity of the line and reduce the need to arrange a new line; improve your mind and regulate the voltage; dampening of tightness and tension;
• shunt reactors (ShR) are switched to reduce the load of reactive pressure in the EEC and the introduced voltage in the permissible area. The reactors are absolutely necessary for the presence in the EEC of extended lines of superhigh voltage, as it was intended more, to generate reactive tension, after which it is possible to increase the voltage on the EEC elements over the allowable value. Reactors are installed at the end and intermediate substations of long-term power transmission lines, and their switching on and off is carried out by the staff at the order of the EEC dispatcher. Vykoristannya regulovanih ShR allows zdіysniti stabilіzatsiyu naruga at the point of connection of the reactor.

The pressure that is vibrated by the generator includes active and reactive storage:

The total pressure module can be found through the active pressure and generator pressure coefficient:

Changes in reactive tension appear when the struma of arousal changes. In the nominal mode, at the nominal pressure coefficient, the generator vibrates the nominal value of the active R nom and reactive Q number of pressures. The generator can increase the vibration of reactive pressure over the nominal value, and even if the vibration of the active pressure decreases according to nominal value to the nominal value. Such an increase is allowed in the boundaries, which are separated by the nominal values ​​of the stator and rotor streams.

Wash the exchange of vibration of reactive tension can be determined by vector diagrams. The replacement circuit of the generator for stimulating the vector diagrams is shown in fig. 16.3. Her generator has a synchronous inductive support x d that EPC E q.

The value of the complex EPC is worth the sum of the vectors U and that drop in the voltage in the support x d:

E q = U r+ j.

We will wake up the VD (Fig. 16.4).

Really axes and put a load U m. Take away a point but. Under the hood φ nom vіdkladaєmo strum I nom. Let's put yoga on the active I noma ta reactive I warehouse number. 3 points but x d type of jet warehouse par strumu . V_n U m. Take away a point h. 3 points h we add the vector of the voltage drop at the support x d in the active warehouse nominal amount . Tsey vector of perpendiculars to the strain. U m. Take away a point b. Vector - the vector of the total voltage drop in the nominal struma in the support x d: . Z'єdnuєmo cob of coordinates іz point b. EPC proportional vector E q and struma zbudzhennya.

From the cob of coordinates with a radius of equal E q let's draw an arc. It determines the allowable value of the shock wave or the EPC E q behind the minds heating the generator rotor. 3 points but radius let's draw an arc. It determines the admissible parameters of the generator for the mind heating of the stator.

Sides of tricot abc proportional to the coming values:

.

Let's take a look at the work of the generator when vugill, then when (With reduced cosine). Pobudov vector diagrams are drawn in a similar way. Trikutnik is taken off Acceptable mode for the generator to confirm the EPC value E q1. In what direction can I:

(vіdrіzok ace 1 >ace); (vіdrіzok ab 1 <ab).

In this rank, the generator can see reactive pressure greater than nominal.

ale with a decrease in active tension according to delivery to nominal

Generator pid hour of work with moving cosine (i ) viroblyayet active pressure greater, lower nominal. With which reactive tension becomes less than nominal:

P 2 > P nom i Q 2 < Q nom.

EPC value E q2 intermedium heating the stator.

The operation of the generator for more, lower nominal, active pressure due to turbine overdrive and any other is permissible.

The possibility of an increase in reactive tension due to a change in active tension can be tolerated in times of excessive active tension, then in the regime of minimal pressure. In this case, part of the generator can be transferred to work with a decrease in the coefficient of tension.

The reserve of reactive tension and the possibility of changeover by reactive tension are important in case of an emergency voltage drop. All generators can be attached to the ATS, which, when the voltage is reduced on the generator clamps, will automatically increase the surge and vibration of the reactive pressure.

Lecture №15

Reactive tension in the energy system. Reactive reactive

Tension. Vibration of reactive pressure by EC generators

1. Zagalni position.

2. Regulatory effect of vanishing.

3. Relaxing reactive tension.

4. Generation of reactive pressure by EC generators.

burning position

From the balance of reactive tension in the energy system, it is evident that, in different cases, the generation of reactive tension outweighs the decrease, the voltage increases in the measure. With a deficiency of reactive tension, the voltage changes. Tsei visnovok was already taken off, if they looked vector diagram power transmission lines with a voltage of 110 kV. Єmnіsny strum LEP, which works on an unfriendly move, or, in other words, the tension that is generated by the LEP, pushing the voltage in the end of the LEP.

On the basis of the balance of active tension, the balance of reactive tension cannot be completely changed to the core of reactive tension. If the active tension vibrates only generators and power plants, then the reactive tension can be removed from the supplementary vents, which can be installed near the stations. Qi dodatkovі dzherel are called installations that compensate.

When designing an electric truss, it is necessary to change the balance of reactive tension both in the whole of the energy system and in the other parts. In case of any follow-up, it is necessary to protect the reserve of reactive tension.

The balance of reactive tension should be transferred to the skin for the mode of measure. The characteristic modes of the system are:

Highest mode active quest. The regime is characterized by the greatest reduction in reactive tension and the greatest tension of compensating attachments;

· The mode of the most active pursuit. Mode of dressing with the greatest involvement of generators in active tension with the least vibration of reactive tension;

· The mode of the least active targeting. In this mode, part of the generators is turned on. Vibration of reactive pressure by generators of power plants changes;

· post-emergency and repair modes. These modes have the greatest exchange of reactive tension.

As in the energy system, there is a deficiency of active tension, and it is blamed for excess active tension in other systems. To cover the insufficiency of reactive pressure, it is more economical to generate with compensating attachments, which are installed in the given power system, and not to be transmitted from land systems.

Regulatory effect of vanishing

Changes in active and reactive voltages are dependent on static characteristics (Fig. 16.1). Let's look at it, as a rank of reaction to the vanity to change the regime the simplest system(Figure 16.2).

http://pandia.ru/text/78/046/images/image002_147.gif" width="132" height="25">

http://pandia.ru/text/78/046/images/image005_53.gif" width="79" height="29"> and the loss of voltage, and the voltage in the end of the LEP http://pandia.ru/text/ 78/046/images/image008_51.gif" width="64" height="28">.

Critical voltage to become (0.7 - 0.8) U nom.

In this manner, with stresses greater than critical, the pressure, changing its tension, should increase the constant stress on its tires. It's up to you to talk about the positive regulatory effect of vanity.

At voltages smaller, lower critical, a negative regulatory effect of the bias appears. Active tension slows down to static characteristics change. The reactivity of reactive tightness begins to increase. Moreover, the value of reactive tension increases in the larger world, lower decrease in active. Tse Vede to zbіlshennya spozhivannya reactive sweating. and a further decrease in voltage, etc. A vindictive phenomenon, as it is called an avalanche of voltage. For such an accident, asynchronous motors are shaking. The reactive strain of asynchronous motors grows, the balance of reactive strain is broken, and the reduction of reactive strain significantly shifts the vibration:

.

Tse own line to bring to a decrease in voltage. The reduction in voltage in case of this accident can only be turned on by turning on the tension.

So that the voltage does not drop below the critical level on generators and tight synchronous motors, automatic wake-up regulators (ARV) are installed. Under the generator and synchronous motors, the vibration of reactive pressure is increased.

Calming reactive tension

The robot, which is gentle in nature, is in the presence of an electric field, the energy of which in an unpaired quarter (first, third) period is given to the dzherel, and for a pair of a quarter (other, fourth) period is taken from the dzherel. For the support of the inductive nature of the robot, it is placed in a magnetic field. In this unpaired quarter (first, third) period, energy is taken from the dzherel, and for the partner, the quarter (friend, fourth) period is taken from the dzherel.

Energy cogeneration in magnetic and electric fields other outbuildings zminnogo struma obumovlyu spozhivannja by them _inductive reactive or reactive єmnіsnoї natuzhnostі. In engineering practice reactive sweating push on inductive the strain, which is generated by the inductive elements of the electrical system, is generated in the removable elements.

The main dampers of reactive pressure in electrical systems are transformers, repeat lines power transmission, asynchronous motors, valve conversions, induction electric furnaces, charging units.

On the industrial undertakings, the main dampers of jet tension are asynchronous motors. 65-70% of reactive tension falls on a part, which is relieved by admission. 20-25% reduction in reactive pressure falls on the transformers of the subsidiaries and close to 10% - on other receivers and power lines.

The total amount of reactive tension in the hem becomes close to 50% of the tension that comes to the hem. Tse richer more, less active strain. For equalization, the average statistical loss of active strain at power transmission lines is 3%, and at transformers - 2%. Approximately 70-75% of all reactive power losses are in transformers. For example, for a tri-winding transformer with a voltage of 40 MVA and a voltage of 220 kV (TDTN-40000/220), with a coefficient of engagement that is 0.8, the loss of reactive voltage becomes close to 12% of the nominal voltage of the transformer.

The total losses of reactive pressure in the system are summed up in the losses in the supports of power transmission lines and the losses in transformers:

Lose the reactive tension at the supports of the power transmission line to be covered by the formula

and become approximately 5% of the tension required to undergo LEP.

The generation of reactive tension in the conduction of the LEP is characterized as follows:

The average value of reactive pressure, which is generated in the LEP with a length of 100 km, becomes:

U nom, kV
Δ Q s, Mwar

For repeated power transmission lines with a voltage of 110 - 150 kV, the reactive power at the supports and the generation at the conductors are approximately the same:

And here natural tightness is transmitted along the LEP.

Spend the reactive pressure in the supports of the transformers by using the following formula:

and become approximately 10% of the tension that is transmitted.

Generation of reactive pressure by EC generators

The pressure that is vibrated by the generator includes active and reactive storage:

The total pressure module can be found through the active pressure and generator pressure coefficient:

Change of reactive tension occurs when the jet is changed, the generator vibrates the nominal value of the active R nom and reactive Q number of pressures. The generator can increase the vibration of reactive pressure over the nominal value, and even if the vibration of the active pressure decreases according to nominal value to the nominal value. Such an increase is allowed in the boundaries, which are separated by the nominal values ​​of the stator and rotor streams.

http://pandia.ru/text/78/046/images/image027_13.gif" width="103" height="29">.

We will wake up the VD (Fig. 16.4).

Really axes and put a load U m. Take away a point but. Under the hood φ nom vіdkladaєmo strum I nom. Let's put yoga on the active I noma ta reactive I warehouse number. 3 points but we add the vector of the voltage drop at the support xd in reactive warehouse nominal stream http://pandia.ru/text/78/046/images/image029_13.gif" width="104" height="29 src=">. U m. Take away a point b. Vector - the vector of the total voltage drop in the nominal struma in the support xd: http://pandia.ru/text/78/046/images/image032_12.gif" width="24" height="24 src="> proportional EPC E q i strumu zbudzhennya (vіdrіzok) butb 1<butb).

In this rank, the generator can see reactive pressure greater than nominal.

ale with a decrease in active tension according to delivery to nominal

Generator when working with moving cosine ( ) viroblyayet active pressure greater, lower nominal. With which reactive tension becomes less than nominal:

P 2 > P nom i Q 2 < Q nom.

EPC value E q2 intermedium heating the stator.

The operation of the generator for more, lower nominal, active pressure due to turbine overdrive and any other is permissible.

The possibility of an increase in reactive tension due to a change in active tension can be tolerated in times of excessive active tension, then in the regime of minimal pressure. In this case, part of the generator can be transferred to work with a decrease in the coefficient of tension.

The reserve of reactive tension and the possibility of changeover by reactive tension are important in case of an emergency voltage drop. All generators can be attached to the ATS, which, when the voltage is reduced on the generator clamps, will automatically increase the surge and vibration of the reactive pressure.

For the heads of the modern electric power industry - cost reduction electrical pressure that electricity. Reactive pressure compensation- found cheaper effective zasib raising the power of electrical systems

The presence of reactive exhaustion reduces the electric power level, leads to additional losses and overheating of wires, rewiring of substations, the need to protect the transformer exhaustion and cable cuts, and the voltage in the electric circuit.
In addition, reactive exhaustion at the same time with active exhaustion is paid by electricity suppliers, and as a result, they pay for the current tariffs and start earning money in the accounts for electric energy.

Compensation for reactive pressure on the underside allows:

Zmenshiti navantazhennya the transformer, i yak naslіdok - zbіlshiti termіn їh Service (Pіdvischennya koefіtsієnta potuzhnostі navantazhennya scho zhivitsya od transformer generally produces up zmenshennya Strum through Demba scho dozvolyaє Add your navantazhennya (pіdklyuchiti dodatkovі spozhivachі elektroenergії) Practical pіdvischennya cosφ (koefіtsієnta potuzhnostі) Mauger. it will be cheaper, less costly to replace the transformer with a smaller one;
- twisted cables and darts of lesser cut;
- connect additional savings of electricity for the distribution of cables to be supplied;
- change the preference for commuting equipment for the change in the air flow at the preference lances;
- change the heating of the electric power and, as a last resort, change the term of the yogo service;
- change the possibility of a deep supply of voltage on the power lines of distant cities;
- remove fines for lowering the capacity of electricity through lowering the intensity coefficient;
- Change your bills for electricity.

Calming reactive tension.

Spozhivachami reaktivnoї potuzhnostі, yak neobhіdna for stvorennya elektromagnіtnih polіv, Je yak okremі Lanka elektroperedachі (transformers, lіnії, reactor), so i elektropriymachі scho peretvoryuyut elektroenergіyu on Inshyj view energії, SSMSC for svoєї robot vikoristovuyut magnіtne field (asinhronnі dvigun, іnduktsіynі pechі toscho ). P.). Up to 80% of all reactive pressure, due to magnetic fields, is supported by asynchronous motors and transformers. There is a small part of the sleeping part of the reactive tension, and other coolants: induction furnaces, heating transformers, conversion installations, luminescent lighting.

Transformer - the transformer is one of the main elements of the transmission of electricity from power plants to the spigot. Fallow in the middle of a power plant and a slower number of steps of transformation can reach six. Therefore, the intensity of the connected transformers at the kilka once outweighs the total intensity of the generators. Leather transformer to reduce reactive pressure. Reactive potency is necessary to create a changeable magnetic flux, from which energy from one winding of the transformer is transferred to another.

Asynchronous motor - asynchronous motors at once from the active pressure reduce up to 60-70% of the reactive pressure load of the energy system. Following the principle of diy asynchronous motor similar to the transformer. As a transformer, the energy of the primary winding of the motor - the stator is transferred to the secondary - the rotor behind the auxiliary magnetic field.

Induction furnaces - up to electropriymachiv, which demonstrate their great reactive pressure, are introduced induction furnaces of industrial frequency for melting metals. In fact, the ovens and stoves are exhausted, and the transformers are perfected at a glance secondary winding some of them are metal, which are melted by induction in a new stream.

Converting installations - converting installations that are being converted change strum in the elderly, for help, they can be seen to the great relief of reactive tension. The stench knew zastosuvannya in industry and transport. So, installations of greater pressure with mercury conversion vicorists are used for the life of electrically insulating baths, for example, for the production of aluminum. Railway transport in our country may have more electrification, before that there is a significant part zaliznit vicorist constant strum conversion installations.

To change the reactive tension, vicorous adjustments are made reactive pressure compensation units are used for maintaining a constant setpoint value of the pressure coefficient (cosφ) in electric sockets three-phase meshes industrial enterprises and other objects with voltage up to 400V, frequency 50 Hz.
The settings ensure cosφ tasks in the periods of maximum and minimum pressures, and also turn on the mode of generation of reactive pressure in the life span.
Units comply with TU 3414-001-52734000-04 and comply with the standards for capacitor units and components (GOST 12.2.007.0-75, GOST 27389-87 and GOST 1282-88)
The units are completed with Epcos components:
capacitors, rozrakhovanі 200-fold wattage on the stream and 30% overvoltage.
condenser contactors, which do not create a discharge.
microprocessor controller with multi-row display. Russian instruction. Can be modified from RS-485.

Designation butt: AKU-0.4-250-12.5-UHLZ IP31 (Automatic capacitor unit, voltage 0.4 kV, intensity 250 kvar, krok 12.5 kvar, climate change UHL3-peace-cold, 3-category of placement, IP31 protection. ).