RU2335026C1 - Reactive power source - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, particularly to high-voltage controlled electrical hardware and can be incorporated with the high-voltage circuits rated to 110 to 750 kV for reactive power compensation and voltage stabilisation. The reactive power source (RPS) comprises a three-phase magnetisation-controlled reactor with six cores each accommodating a circuit winding connected in the high-voltage circuit and a control winding, a three-phase capacitor bank made up of two sections and connected to the mains, and the 5^th and 7^th harmonics filter connected to the control winding. It also contains a controlled rectifier with its output connected to the control windings and an automatic control system. The invention novelty consists in that the second additional controlled rectifier, the main and additional three-phase transformer supplying the said rectifiers are introduced into the reactive power source. The reactor control winding of every of the six cores is made up of three parts, the said parts being integrated into three open dual triangles and connected to the controlled rectifier output and to the rectifier supply transformer with the aforesaid 5^th and 7^th harmonics filters. The proposed circuit arrangement allows supplying the rectifiers with symmetric three-phase voltage from the control windings and, at the same time, simplifying rectifier design proceeding from the fact that the rectifiers potential is in fact the ground potential not that of the control winding high potential.

EFFECT: expanded performances and higher reliability.

4 dwg

Description

The invention relates to the field of electrical engineering, in particular to high-voltage regulated electrical complexes, and can be used in high-voltage electric networks with a voltage of 110 ÷ 750 kV to compensate for reactive power and voltage stabilization.

Known traditional means of compensation and regulation of reactive power in electrical networks - synchronous compensators (SC) and static thyristor compensators (STK).

SCs are rotating electric machines requiring enclosed spaces and ongoing qualified service.

An analogue of the invention according to the purpose and partly according to the composition of the equipment is an STK containing a three-phase power inductance regulated by successive thyristor switches and a capacitor bank connected in parallel with it [1]. There are no moving elements in the STK, but the STK, like the SK, needs cooling, indoors, and special maintenance, since the regulating means in them are high-voltage thyristor switches with a rated power that prevents short-term and emergency overloads that are inevitable in operation. In addition, STK (as well as SK) can not be performed on a voltage of 110 ÷ 750 kV, which requires connecting them to an intermediate transformer at full power or to the tertiary winding of existing autotransformers (which is not always possible in existing networks). In both the first and second cases, the efficiency of reactive power regulation on the high-voltage side is significantly reduced. In addition, in the first case, the cost of equipment, installation and operation increases.

At the same time, there is a new type of controlled power inductance - a magnetization controlled reactor [2], on the basis of which a reactive power source (IRM) is created, devoid of the above disadvantages and capable of replacing SC and STK in networks of 110 ÷ 750 kV.

Also known is the IRM, which includes, in addition to other electrical devices, a three-phase group of magnetically controlled reactors [3]. The analogue provides an increase in the efficiency of regulation of reactive power in high-voltage electric networks, a decrease in the cost of installed equipment and an increase in its reliability. However, it has reduced functionality due to the need to use the substation's own needs network for supplying a bias source.

The closest in purpose and composition of the equipment (prototype) is an IRM, consisting of an adjustable inductance - controlled by magnetizing a three-phase reactor, which is directly connected to a high voltage network, and a capacitor bank, also connected to a high voltage network with sectioning through switches or to control windings [ four]. Magnetization is carried out by using a controlled rectifier, fed by a single-phase voltage from the control windings or from the auxiliary system of the substation. The prototype provides an increase in the efficiency of regulation of reactive power in high-voltage electrical networks, reducing the cost of installed equipment.

However, it has the following disadvantages: reduced reliability when supplying only one controlled rectifier from the auxiliary system of the substation, and not autonomously (from the reactor), deterioration of the rectifier operation when powered from a single-phase voltage of the control windings, the occurrence of asymmetry in the reactor current and an increase in the level of higher harmonics in the current reduced functionality.

The aim of the invention is to eliminate these disadvantages, increase reliability and increase the functionality of the IRM.

This goal is achieved by the fact that a reactive power source containing a three-phase bias controlled magnetization reactor with 6 rods, on each of which there is a network winding connected to a high voltage network, and a control winding connected to the network, a three-phase capacitor bank made of two sections, filters of the 5th and 7th harmonics connected to the control windings, a controlled rectifier connected at the output to the control windings, and an automatic control system, a second additional controlled rectifier, main and additional three-phase power transformer of controlled rectifiers. The control winding of the reactor of each of the 6 rods is made of three parts, while the parts of the control windings are connected in three open double triangles and connected to the output of a controlled rectifier, with power transformers of controlled rectifiers and with filters of the 5th and 7th harmonics.

Schematic diagram of the IRM is shown in figure 1. Figure 2 shows the location of the windings on the rods of a three-phase magnetically controlled reactor magnetization, the connection diagram of the network windings and shows the inputs of the reactor, figure 3 shows the connection diagram of the parts of the control windings of the reactor, figure 4 - connection diagram of the windings of the power transformer controlled rectifiers.

Two sections of a three-phase capacitor bank 7 and 8 are connected to the buses of a three-phase network 110 ÷ 750 kV through section switches 1-3 and 4-6 and, through switches 9-11, a three-phase magnetization controlled reactor 12.

The automatic control system of self-propelled guns 13 connected voltage sensors of the phases of the network 110 ÷ 750 kV - voltage transformers 14-16 and current sensors of the reactor - current transformers 17-19. Self-propelled guns 13 is connected to the reactor 12 for automatic (if necessary manual) regulation of the bias current and reactive power of the reactor and to section switches 1-3 and 4-6. In addition, low-power AC and DC voltage sources (“≈” and “=”) are connected to the ACS 13 to power the ACS and regulate the preliminary magnetization of the reactor rods in the mode of disconnecting the IRM from the high-voltage network.

A circuit variant with a common three-phase switch and an IRM disconnector is also possible (not shown in FIG. 1).

The reactor 12 inputs "+" and "-" is connected to the corresponding output inputs of the main controlled rectifier 20 and additional 21, which are controlled by the system 13 and receive three-phase power through the main three-phase transformer 22 and additional 23 from two three-phase systems a1-b1-c1 and a2 -b2-c2 created by the control windings of the reactor. The 5th and 7th harmonics 24 and 25 are connected to the three-phase system a1-b1-c1.

The reactor 12 has 6 rods 26-31 with network windings 32-37 and control windings. Each of the 6 control windings has three parts, i.e. There are 18 parts of control windings 38-55. To reduce the additional losses due to circulating currents in parallel branches, the three parts of the control winding of each rod should be identical. To do this, they must be made by winding simultaneously with three wires (similar to bifilar winding). To simplify the description, it is assumed that all windings have the same type of winding (all windings have a left winding), the beginning of each winding is marked with an asterisk.

The windings of neighboring rods 32-33, 34-35 and 36-37, paired in parallel, are connected to a star and connected to the network inputs A, B and C and neutral input 0.

Parts of the control windings are connected in 6 open triangles connected in parallel in pairs.

The first open triangle is composed of serially connected parts of the control windings 38, 44 and 50 of the first 26, third 28 and fifth 30 rods, the second of the parts of the windings 43, 49 and 55 of the rods 27, 29 and 31 (counter to the parts of the windings of the first triangle). The end of the winding portion 50 and the beginning of the winding portion 55 are connected together and connected to the inlet of the “+” reactor. The beginning of the winding portion 38 and the end of the winding portion 43 are also interconnected and connected to the inlet of the reactor “-”.

The third open triangle is composed of parts of the windings 45, 51 and 39 of the third 28, fifth 30 and first 26 rods, and the fourth is made of parts of the windings 48, 54 and 42 of the fourth 29, sixth 31 and second 27 rods, the end of part of the winding 39 and the beginning of the part windings 42 are connected to the input of the reactor “+”, and the beginning of the part of the winding 45 and the end of the part of the winding 48 to the input “-”.

Similarly, the fifth open triangle is composed of parts of the windings 52, 40 and 49 of the fifth 30, the first 26 and third 28 rods, and the sixth of the parts of the windings 53, 41 and 47 of the sixth 31, the second 27 and the fourth 29 rods, the end of the part of the winding 46 and the beginning parts of the winding 47 are connected to the input of the reactor "+", and the beginning of the winding 52 and the end of the winding 53 are connected to the input "-".

The end of the winding portion 38 and the beginning of the winding portion 43 are connected to the inputs of the reactor A1, the end of the winding portion 45 and the beginning of the winding portion 48 are connected to the inputs of the reactor b1, the end of the winding portion 52 and the beginning of the winding portion 53 are connected to the inputs of the reactor c1. The inputs of the reactor a1, b1 and c1 form a three-phase voltage system for connecting LC filters 24 and 25 and powering the converter - a controlled rectifier of the bias system 22.

The beginning of the winding portion 39 and the end of the winding portion 42 are connected to the inputs of the reactor a2, the beginning of the winding portion 46 and the end of the winding portion 47 are connected to the inputs of the reactor b2, the beginning of the winding portion 50 and the end of the winding portion 55 are connected to the inputs of the reactor c2. The reactor inlets a2, b2 and c2 form an additional three-phase voltage system.

The primary windings 56-58 are connected to three-phase voltage systems a1-b1-c1 and a2-b2-c2 by three-phase power transformers 22 and 23 with three-phase voltage converters - controlled rectifiers 20 and 21 from the secondary windings 59-61 connected into a triangle.

In the IRM, the magnetization controlled reactor 12 can be three-phase or in the form of a three-phase group of single-phase reactors.

Power transformers 22 and 23 of controlled rectifiers can be three-phase or in the form of three-phase groups of single-phase transformers.

Capacitor banks 7 and 8 can be connected to three-phase voltage systems a1-b1-c1 and a2-b2-c2.

IRM works as follows.

At full network load (in the daytime) due to a voltage drop, there is a lack of reactive power and a decrease in network voltage. ACS 13, having received the relevant information from voltage transformers 14-16, generates and transmits signals to turn on by switches 1-3 and 4-6 two sections of capacitor banks and reduce to zero the bias voltage of reactor 12. As a result, reactor 12 reduces its current to a minimum - goes into idle mode, and the IRM goes into the mode of outputting maximum reactive power to the network from two sections of the capacitor bank 7 and 8. In this mode, there is no voltage at the “+” and “-” inputs, the reactor works as an idle transformer move, and inputs a1-b1-c1 and a2-b2-c2 is equal to the voltage 2U _p × K _Tp - dual voltage control windings 38-55 (U _p - phase voltage network, K _Tp - transformation coefficient control network winding and winding) .

With a decrease in load and its absence (for example, at night), the network has excess reactive power due to the presence of a distributed network capacity to the ground. An increased voltage occurs in the network, to reduce which an IRM is necessary in the mode of reactive power consumption. In this case, the automatic control system automatically ensures operation in the mode of reactive power consumed by the IRM when the sectional switches 1-6 are turned off and the reactor 12 is turned on at full power. In this mode, the controlled rectifiers 20 and 21, fed from the reactor through transformers 22 and 23 with a symmetric three-phase current, are loaded at full capacity. The double open triangles of the parts of the control windings actually go into an operation mode similar to the work of bridge circuits: the direct current and bias circuits and the alternating current supply circuit of the transformers electrically work independently. In this mode, as in all load modes, the reactor actually works as a reactor-transformer.

In intermediate modes, when the load in the network changes, the voltage changes, recorded by voltage transformers 14-16 for transmission of self-propelled guns 13, which, by adjusting the bias current of the reactor and turning on or off the battery sections of capacitors 7 and 8, automatically maintains the mains voltage within the limits established in the self-propelled guns . The included LC filters 24 and 25 provide the necessary reduction in the level of higher harmonics in the reactor current.

When the reactor power changes from idle to nominal, only one bias source can operate (transformer 22 and converter 20), and in maximum power and short-term overload conditions, a parallel additional bias source (transformer 23 and converter 21) is connected to operation.

An additional source (21 and 23) is also used as a backup in case of repair of a magnetization source or emergency shutdown of a transformer or converter in case of damage.

An additional source (21 and 23) is used when it is necessary to increase the speed of the reactor (when turning on the reactor, recruiting and dumping power). In this case, the rectifier output of the additional bias source is switched on in series with the output of the main rectifier 20 (transition to the bias forcing mode).

Thus, the use of an additional source (21 and 23) expands the functionality of the proposed IRM and the reliability of its operation, which distinguishes it from known analogues.

The difference between the proposed IRM and the known devices is that the circuit allows galvanic coupling of all control windings and all transformer and converter circuits to a grounding point, which eliminates the occurrence of an unacceptable "floating potential" induced by capacitive or inductive spurious connections with the high voltage side, which is dangerous due to possible discharges and breakdowns of isolation. The proposed scheme makes it possible to supply rectifiers with a symmetric three-phase voltage from the control windings (the effect of this is to improve the working conditions of the rectifiers and reduce the higher harmonics in the current of the reactor windings) and at the same time simplify the design of the rectifiers due to the fact that the potential of the rectifiers is the earth potential, not high potential winding control.

The performance of the IRM and its high technical and economic indicators are confirmed by calculations, mathematical modeling, and test results of similar devices. In the near future, it is planned to manufacture prototypes of the IRM for mass production.

Literature

1. Bias-controlled electrical reactors. Sat articles. Ed. doctors of those. sciences prof. A.M. Bryantseva. - M .: “Sign”. 2004.

2. Static thyristor compensators for power systems and power supply networks. Bortnik I.M. et al. Electricity, 1985, No. 2.

3. Patent for the invention of the Russian Federation No. 2132581 according to the application No. 98100385, priority of the invention 06.01.98. Published: 06/27/99 in bull. Number 18.

4. Patent for the invention of the Russian Federation No. 2282912 by application No. 2004121712, priority of the invention July 16, 2004. Published: August 27, 2006 in bull. Number 24.

Claims (1)

Reactive power source containing a three-phase magnetization controlled reactor with 6 rods, each of which has a network winding connected to a high voltage network, and a control winding, a three-phase capacitor bank made of two sections and connected to the network or to the control windings, fifth filters and seventh harmonics connected to the control windings, a controlled rectifier connected at the output to the control windings, and an automatic control system, characterized in that in the source of active power, a second additional controlled rectifier was introduced, the main and additional three-phase power transformer of controlled rectifiers, the control winding of the reactor of each of the 6 rods is made of three parts, while the parts of the control windings are connected in three open double triangles and connected to the output of the controlled rectifier, with power transformers controlled rectifiers and with filters of the fifth and seventh harmonics.

Images