RU2697510C1 - Method for controlling composition and loading of generators of a power plant with own loads, operating in isolation and in parallel to a receiving power system - Google Patents

Abstract

FIELD: power engineering.SUBSTANCE: use: in electric power engineering. In parallel mode of power plant with receiving power system for planned interval of constancy of composition of generators included into operation, maximum load of power plant is predicted, composition of the generators connected to operation is determined and put into operation, which is necessary for its coverage, as well as output to the receiving PS of surplus capacity. Part of generators is switched to mode of constant power output with total power equal to maximum allowed for transmission to receiving power system. Other part is switched to the group control mode or to the control mode with share participation in power of the master generator. Power control of said generators is carried out based on the condition of equality of power transmitted to the receiving power system and total power of the other connected generators not included in the number of generators of group control. In case of prohibition of parallel operation, generators are unloaded to level of zero overflow in receiving power system and switches are disconnected in fixed section of electric connections of power plant with receiving power system, generators of power plant are switched to frequency control mode. In case of disturbance of electric connections of power plant with receiving power system or normal mode, switches are cut off in fixed cross section of electric connections of power plant with receiving power system with simultaneous disconnection of generators operating with constant load. Adjust power of remaining generators of power plant in frequency control mode. When the prohibition for parallel operation is removed and conditions for normal mode are restored, the power plant is restored to restore the mode of parallel operation of the power plant to the receiving power system, the required composition, loading and modes of controlling power of generators of both sets of generators are restored.EFFECT: power plant output of maximum available or maximum permissible power for transmission to the receiving power system without reduction of reliability of power supply of own consumers and operation of the power plant itself.1 cl, 2 dwg

Description

The PROPOSED INVENTION relates to the field of electric power and can be used in electric power systems, electric networks when controlling the modes of power output to the receiving power system by electric stations with their own loads.

KNOWN METHOD OF COMPOSITION AND LOAD POWER GENERATORS with its own load, operate in isolation from the external POWER SYSTEMS (STR 59012820.29.240.001-2011 Standard Organization (Joint Stock Company "System Operator of Unified Energy System". The automatic emergency control of power systems regimes. Emergency control of power systems. The status of the process. Conditions for the creation of an object. Norms and requirements. Official publication. S.19-23) in which,

the minimum number of turned-on generators is determined by the maximum load on the constancy interval of turned-on generators and reserve power (according to the n-1 criterion), which ensures the reliability of power supply to consumers during an emergency shutdown of the most powerful of the generators

,

,

where Рнmax is the maximum load on the constancy interval of the switched-on generators, Ррз is the reserve power, kн is the safety factor for the generator power, taking into account the measurement error and the error in predicting the load power.

The method is as follows

для интервала постоянства включенных генераторов.• According to retrospective data is determined

for the interval of constancy of the included generators.

• The optimal composition of the included generators is selected, sufficient to carry the load and an additional generator with a capacity of at least the largest of the generators required to cover the load.

• The generators are synchronized and switched on under load, with the total power being regulated by primary speed control and the secondary frequency regulation, and the total power distribution between the generators is carried out by group power control or by shared participation of the driven generators in the power of the lead generator.

In the event of emergency power imbalances, in order to prevent the generators from shutting down and extinguishing the station, a quick shutdown of part of the generators (during load shedding) or part of the load (during power surge, AChP, DAR) is used.

HOWEVER THE SPECIFIED METHOD has the following disadvantages:

• the impossibility of using excess installed capacity of the power plant (low installed capacity utilization factor - KIUM) for generating electricity, which reduces its economic efficiency, including increases the payback period;

• the need to disconnect part of the load during emergency power imbalances, which reduces the reliability of power supply to consumers; shutdown of power units of a power plant that are sensitive to power surges / discharges, followed by repayment of the power plant and shutdown of consumers, which also reduces the reliability of their power supply.

In addition, the METHOD FOR MANAGING THE COMPOSITION AND DOWNLOADING OF ELECTRIC POWER GENERATORS WITH OWN LOADS, OPERATING PARALLELLY WITH THE RECEIVING ENERGY SYSTEM, MAINTAINING SUSTAINABLE SLEEPING IS OFF. (STO _59012820.29.240.001-2011 Organization standard (OPEN JOINT STOCK COMPANY “SYSTEM OPERATOR OF A UNIFIED ENERGY SYSTEM”). Automatic emergency control of power system modes. Emergency automation of power systems. Conditions for organizing the process. Conditions for creating an object. Norms and requirements. Publication. Official publication. .17-18), in which

• Synchronize a stand-alone power plant with a receiving power system.

• Turn on additional generators with synchronization, introduce them into the group power control generators, transfer the group power control of generators to the regime of regulating power flow into the receiving power system.

• Increase the setpoint of the group power regulator to the allowed value of the power flow through the power plant communications with the receiving power system.

• In the event of disturbances in the normal mode, in order to prevent disturbances in stability or the development of an accident, disconnect the electrical connections providing a parallel operation mode (if necessary, with the disconnection of part of the generators).

Two variants of the method are used:

a) With constant cross-sectional flow

( Rsch = Rzad = const),

where Rsch is the power transmitted over the cross section of the electric connection with the receiving power system, Rsad is the specified value of the transmitted power.

c) With flow restriction

( Rsech < Rzad ),

moreover, the positive flow corresponds to the mode of issuing excess power to the power system to the receiving power system.

The method increases (KIUM) the economic efficiency of the station.

HOWEVER, THE SPECIFIED METHOD does not provide the required reliability of the power plant and the power supply of its consumers, because in case of violations of the normal mode (including deep drops in voltage or frequency in the power system) due to the inevitable unbalanced division of the network, a power drop and unbalance occur on the shafts of the generators of the power plant, if the permissible level is exceeded, the power plant generators are disconnected and the load is disconnected.

In addition, the METHOD of controlling a multi-unit power generation system with its own loads, operating both in an island (isolated from an external power supply) mode and in parallel with an external power supply (US patent No. 7.122.916 B2, class H02J 3/04 (2006.1) ), in which the control system gives control actions on the power regulation to each generator and on the transitions between the parallel operation mode and the isolated operation mode (by turning on / off the mains switch).

The method is as follows:

The control system measures the frequency and power consumed from the external supply network to change the number of running generators and regulate the generated power depending on the specified operating mode, according to the program, controls the start / stop of the generators according to the planned schedule, adjusts their power according to the specified load profile, following the schedule own loading or cutting off of peaks of loading. In this case, the control system designates one of the generators as the lead generator, and the remaining generators as slave generators, controls the power of the lead generator according to the natural frequency, natural frequency and frequency of the external network when synchronizing with the external network, as well as the power consumed from the external power supply network in parallel operation. The load of the master generator is used to control the load of the slave generators.

HOWEVER THE SPECIFIED METHOD has the following disadvantages:

• The possibility of an emergency transition from parallel operation to the island mode of operation of a multi-unit power generation system with a balanced load is not provided to limit the supply of short-circuit currents in the external and internal electrical network, to prevent the occurrence of shock moments on the shafts of synchronous generators of the multi-unit power generation system, and to eliminate the effect of the multi-unit power generation systems for the operation of protection devices and automation of an external set and.

• Possibility of erroneous start-ups / shutdowns of generators according to the planned schedule with irregularity of the power consumption mode, typical for low-power power supply systems.

Additionally, a METHOD OF COMPOSITION AND LOAD POWER GENERATORS with its own load, work in parallel with the receiving power, with the division NETWORK on a balanced cross-section for Disturbance (including the deeper reduction in frequency or voltage in the power system) (STO _59012820. 29.240.001-2011 Organization Standard (OPEN JOINT STOCK COMPANY “SYSTEM OPERATOR OF A UNIFIED ENERGY SYSTEM”), which is a prototype of the proposed method, in which the station operates in parallel whose power is selected to the receiving power system in the power network of the receiving power system from the number of possible sections with a load as close as possible to the power output to the receiving power system. If the normal mode is violated, the network is divided by the selected section, the power control of the power plant is switched to the secondary frequency control mode. conditions for normal parallel operation of the station with the receiving ES synchronize the station with the receiving ES, restore fully electrical connection in the cross section used for division, transfer the group regulation of generators into the mode of regulation of power flow with a given setting.

HOWEVER THE SPECIFIED METHOD has the following disadvantages:

• the impossibility of accurately balancing the generation and load of the power plant, which, due to the presence of residual unbalance, threatens to develop a violation of the normal regime;

• the need to control the topology and mode of part of the electrical network of the receiving power system; the complexity, often not overcome, of the search and implementation of the necessary sections;

• loss of the possibility of local control of the power plant regime, which significantly complicates and increases the cost of the control system, increases the payback period of the power plant.

THE PROBLEM (TECHNICAL RESULT) OF THE PROPOSED INVENTION IS to ensure high use of the installed capacity of the power plant, reliable operation of the power plant and power supply to consumers, local control over the parallel operation of the power plant with the receiving power system.

 The posed problem is solved due to the fact that in the known METHOD the composition, the load control of the generators of the power plant in the mode of its parallel operation with the receiving power system are carried out separately for two groups of generators, one of which provides for covering the own loads of the power plant, and the second - the distribution of power to the receiving power system . In the event of prohibitions on parallel operation, disruptions in the electrical connection of the power plant with the receiving power system or normal operation in the receiving power system, unloading or disconnecting of the second group of generators with the circuit breakers of the fixed section of the electrical connections of the power plant and the receiving power system disconnected, they ensure balanced separation of the power plant with its own loads from the receiving power system.

Figure 1 shows an example of a simplified single-line diagram of a power plant with its own loads and a power line connecting the power plant with the receiving power system, and control devices for the composition and loading of the generators of the power plant, representing the implementation of the proposed method;

Figure 2 presents the balance of power and energy for a power plant with its own loads associated with the receiving power system, on the interval of constancy of the composition of the working generators, as applied to the example of FIG. 1.

The circuit of FIG. 1 contains:

- generators (primary engine with a synchronous generator, represented on the diagram by the symbol of the synchronous generator and referred to hereinafter as the generator) 1 and 2, operating in the mode of constant power output,

- generators 3 and 4, which are in the group power control mode or in the control mode with a share in the power of the lead generator,

- the busbar of the power plant 5,

- generator switches 6 - 9,

- switches of the connected load 10 and 11,

- switches 12 and 13 of the power line 14,

- communication channel 15,

- measuring points of the operational parameters of the power plant 16-21,

- setpoint issued by the generators 1 and 2 power 22,

- block control modes of the generators 23,

- group regulator of active power of 24 generators 3 and 4,

- synchronizer 25 of the power plant and the receiving power system 26.

Figure 2 marked:

– суммарная мощность генераторов 1 и 2 электростанции, работающих на выдачу постоянной мощности в энергосистему 26;

- the total capacity of the generators 1 and 2 of the power plant, working to issue constant power to the power system 26;

– разрешённая обменная мощность между электростанцией и энергосистемой 26;

- permitted exchange power between the power plant and the power system 26;

– максимальная мощность нагрузки электростанции;

- maximum power load of the power plant;

– суммарная располагаемая мощность генераторов 1 – 4 электростанции;

- the total available capacity of the generators 1 - 4 power plants;

– суммарная мощность генераторов 1 – 4 электростанции;

- total capacity of generators 1 - 4 power plants;

– обменная энергия электростанции и энергосистемы 26;

- exchange energy of the power plant and power system 26;

– энергия, потреблённая собственными нагрузками электростанции.

- energy consumed by the own loads of the power plant.

METHOD (1) CARRIED OUT BY THE FOLLOWING IMAGE:

a. In parallel operation of a power plant with a receiving power system

Assume that in the preceding interval of constancy of the composition of the working generators indicated in FIG. 2, only one generator 4 was operating in the mode of regulating the delivery of zero power to the receiving power system, i.e. following the power plant’s own loads. Generators 1, 2, and 3 are turned off.

Control unit 23:

(ФИГ.2) для планируемого интервала времени постоянства состава включенных в работу генераторов,- according to retrospective data predicts the maximum own load of the power plant

(FIG. 2) for the planned time interval for the constancy of the composition of the generators included in the work,

с коэффициентом

, определяет минимально достаточный состав генераторов электростанции для покрытия максимума собственной нагрузки (3 и 4), - on the condition that the total available capacity of the power plant generators exceeds the predicted maximum own load

with coefficient

determines the minimum sufficient composition of the power plant generators to cover the maximum own load (3 and 4),

- turns on the disconnected generator 5 for parallel operation with synchronization,

- introduces included 3.4 generators into group power control generators with maintaining zero overflow along section S1, which ensures that the power plant follows its own load.

Provided that not all generators of the power plant were turned on and put into operation following the generation of the power plant at its own load, control unit 23:

) с учетом ограничения на передаваемую мощность по сечению S1, определяет минимально достаточный состав генераторов электростанции (1, 2) для выдачи в приемную энергосистему мощности, максимально близкой к разрешённой обменной мощности с приемной энергосистемой 26, но не превосходящую её, - in order to maximize the use of the installed capacity of the power plant to generate electricity (

), taking into account the limitation on the transmitted power over the cross-section S1, determines the minimum sufficient composition of the power plant generators (1, 2) for supplying to the receiving power system the power that is as close as possible to the allowed exchange power with the receiving power system 26, but not exceeding it,

не превышения над разрешённой обменной мощности электростанции с приемной энергосистемой 26 и условия

не превышения над суммарной располагаемой мощностью генераторов, включённых в режим выдачи мощности в приемную энергосистему 26,- turns on switched-off generators 1,2 for parallel operation with synchronization and loads them to a total level equal to the setpoint of the power delivery adjuster in the receiving power system 22, selected subject to the conditions

not exceeding the permitted exchange capacity of a power plant with a receiving power system 26 and conditions

not exceeding the total available power of the generators included in the mode of power output to the receiving power system 26,

(Рг1,г2 – Рвыд = 0), что обеспечивает следование генерации электростанции за собственной нагрузкой и поддержание стабильности мощности, выдаваемой электростанцией в приёмную энергосистему 26.- puts the generators included in the group 3.4 power control generators into the mode of maintaining the overflow along section S1 equal to

(Pr1, r2 - Rvyd = 0), which ensures that the power plant follows its own load and maintains the stability of the power supplied by the power plant to the receiving power system 26.

, равного уставке задатчика выдачи мощности в приёмную энергосистему 22, выбранной при соблюдении условия (

) не превышения разрешённой обменной мощности электростанции с приемной энергосистемой 26. По сравнению с режимом изолированной работы использование установленной мощности электростанции выше на величину

, ограниченную условием выдачи максимальной мощности в приемную энергосистему

.As a result, the generators 1 and 2 (FIG. 2) are loaded to the total level

equal to the setpoint of the generator for power output to the receiving power system 22, selected subject to the conditions (

) not exceeding the permitted exchange capacity of a power plant with a receiving power system 26. Compared with the mode of isolated operation, the use of the installed capacity of a power plant is higher by an amount

limited by the condition of maximum power output to the receiving power system

.

b. In the event of a violation of the electrical connections of the power plant and the receiving power system or normal operation

в энергосистему 26.The electrical connection of the power plant and the power system 26 is made according to a fixed cross-section S1 in the power plant’s electric network by turning off switch 12 while simultaneously unloading and disconnecting 5 from switches 6 and 7 of generators 1 and 2 operating in power output mode

into the power system 26.

Trips of circuit breaker 12 and generators 1 and 2 The control unit 23 gives a command to the group active power controller 24 to put the generators 3 and 4 into frequency control mode.

) с количеством генераторов и выдаваемой ими мощностью, обеспечивающими бесперебойность электроснабжения потребителей.As a result, the power plant is separated from the power system 26 in a balanced way (

) with the number of generators and the power they provide, ensuring uninterrupted power supply to consumers.

c. In the event of a ban on the parallel operation of the power plant and the receiving power system

The prohibition of parallel operation of the power plant with the receiving power system is formed in the receiving power system 26 or at the power plant, as well as if the communication channel 15 is broken. Through the communication channel 15 or directly from the power station, the ban goes to the control unit 23.

Control unit 23:

- unloads the generators 1 and 2 to zero, controlling the power at the measurement points 6, 7 and 12,

- gives commands to turn off the switch 12, breaking the electrical connection between the power plant and the receiving power system 26 via the power line 14 at a fixed cross-section S1 in the electric network of the power station, and disconnecting the switches 6 and 7 of the generators 1 and 2 from the busbar of the power station 5,

- gives a command to the group regulator of active power 24 to put the generators 3 and 4 into the frequency control mode.

с количеством генераторов и мощностью, обеспечивающими бесперебойность электроснабжения потребителей

с учётом погрешности измерений и ошибки прогнозирования мощности на текущем интервале времени постоянства состава включенных в работу генераторов.The power plant is separated from the power system 26 in a balanced manner

with the number of generators and power, ensuring uninterrupted power supply to consumers

taking into account the measurement error and the power prediction error in the current time interval of the constancy of the composition of the generators included in the work.

d. When restoring the conditions of parallel operation (lifting the ban on parallel operation) of the power plant and the receiving power system

The ban on the parallel operation of the power plant with the receiving power system is removed to the control unit 23.

The control unit 23 gives a command to the synchronizer 25 to perform active synchronization of the power plant with the receiving power system 26 by group control of the power of the generators 3 and 4.

When the conditions for accurate synchronization between the power plant and the receiving power system 26 are fulfilled, the synchronizer gives the command to turn on the switch 12, creating an electrical connection between the power plant and the receiving power system 26 via transmission line 14.

After turning on the power plant for parallel operation with the receiving power system 26 Control unit 23:

- includes, with synchronization, previously switched off generators 1 and 2, allocated for the constant power output mode equal to the setpoint of the power output setter 22 in the receiving power system 26.

- puts the generators 1 and 2 into constant power output mode and loads them up to values equal to the setpoint of the power delivery setpoint 22 in the receiving power system 26, controlling the power values at the measurement points 16, 17 and 21.

As a result, the parallel operation mode of the power plant with the receiving power system and the delivery of excess power to the power system generators 1 and 2 to the power system are restored.

Thus, in contrast to the prototype, the proposed method provides high utilization of the installed capacity of the power plant, reliable operation of the power plant and power supply to consumers, local control over the parallel operation of the power plant with the receiving power system (since the control system uses only the parameters of the equipment, mode and device available at the power plant itself).

Claims (1)

A method for controlling the composition and loading of generators of a power plant with its own loads, operating in isolation and in parallel with the receiving power system, which consists in the fact that in the mode of parallel operation of the power plant with the receiving power system for the planned interval of constancy of the composition of the generators included in the operation, the maximum load of the power plant is predicted, determined and introduced the work necessary for its coverage, as well as the issuance of excess power to the ES receiving station, the composition of the generators included in the work, p generators are put into group regulation mode or regulation mode with shared participation in the power of the lead generator, the generators are loaded to the level of the required power output to the receiving power system, when there is a ban on parallel operation, the generators are unloaded to the level of zero flow to the receiving power system and the circuit breakers are cut off in section zero flow, the generators of the power plant are put into frequency control mode, if there are disturbances in the electrical connections of the power plant with the reception disconnect circuit breakers with a zero or close to zero flow, switch the power control of the power plant generators into frequency control mode, remove the ban on parallel operation and restore the conditions for normal operation, synchronize the power station with the receiving power system, transfer the generator load control to control mode of a given overflow, characterized in that the transfer of generators into group control mode or in p the hedgehog with shared participation in the power of the lead generator is carried out only for the part of the included generators that is sufficient to cover the load of the power plant’s own consumers, the power regulation of the generators is carried out on the condition that the power transmitted to the receiving power system is equal to the total power of the remaining included generators not included in the number of generators group regulation, moreover, these generators are transferred to the mode of constant power output with a total power equal to maxim If it is allowed to transfer to the receiving power system, if there is a disturbance in the power plant’s electrical connections with the receiving power system or in normal mode, the power plant’s electrical connection with the receiving power system is disconnected while the generators operating at constant load are disconnected, group regulation of the remaining generators is switched to frequency control mode, if a ban occurs for parallel operation unload generators working with constant load to zero and turn off electrical connection of the power plant with the receiving power system, group control is switched to frequency control mode, when conditions for parallel operation are restored (lifting the ban on parallel operation and eliminating the causes of normal operation), the power station is synchronized with the receiving power system by switching the group control of generators into active synchronization mode with fulfilling the conditions for accurate synchronization and include the rest, previously opened for parallel operation with synchronization li ne generators.

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