CN115603366A - Thermal power generating unit isolated network operation control method with participation of electric boiler heat storage device - Google Patents

Abstract

The invention discloses a method for controlling the isolated grid operation of a thermal power unit with the participation of an electric boiler heat storage device, belonging to the technical field of isolated grid operation control of a thermal power unit in a power grid, and judging whether the thermal power unit is in an isolated grid operation state; after the thermal power unit is triggered in the isolated grid , DEH load switching and electric boiler heat storage device load switching control adopt the isolated grid operation control method of thermal power units with the participation of electric boiler heat storage devices, which can monitor the power grid and unit operating status in real time. When the thermal power unit is running in an isolated grid, the system makes timely decisions and switches the electric boiler on and off according to the boundary conditions, which reduces the deviation between the output of the thermal power unit and the factory load, reduces the disturbance of the isolated grid to the boiler and steam turbine, and the thermal power unit can be transferred to the isolated grid stably. At the same time, with the participation of the electric boiler heat storage device, the heat supply for residents is effectively guaranteed.

Description

A control method for isolated grid operation of thermal power units with the participation of electric boiler heat storage devices

technical field

The invention relates to the technical field of isolated grid operation control of thermal power units in a power grid, and more specifically, relates to a method for controlling isolated grid operation of thermal power units with the participation of an electric boiler heat storage device.

Background technique

With the advancement of the new power system construction process, the proportion of new energy installed capacity is gradually increasing, and the proportion of thermal power units is gradually decreasing. Facing the strong uncertainty of the high proportion of new energy power generation, the power system adjustment ability is obviously insufficient, and the power system operation stability mechanism is more serious. It is difficult to ensure the safe operation of the power grid under complex fault conditions such as extreme weather and system disturbances. Heat storage devices such as electric boilers have been widely used in the research and application of thermal power flexibility transformation due to their fast adjustment ability and strong energy storage capacity. Since the pilot project of flexibility transformation of thermal power units was launched in 2016, there have been more than 30 power plants in the northern region Equipped with an electric boiler heat storage device, however, as a highly flexible electrical load, the electric boiler heat storage device quickly participates in coordinated regulation when the grid line fails, maintaining the power and load balance of the boiler and steam turbine, so that the unit The isolated grid runs with electric heat load, avoiding the shutdown of the unit, and improving the value of rapid grid connection and heating economy of the unit have not been fully understood. In the event of a grid failure, the heat storage device is used to quickly participate in coordinated adjustment, so that the unit is isolated with electric heat load The research and application of the operation and guarantee of heating for residents, and the rapid connection of the unit to the grid after the fault is removed have not yet been carried out.

Contents of the invention

The purpose of the present invention is to provide a thermal power unit isolated grid operation control method with the participation of the electric boiler heat storage device, so that when the power grid fails, the unit can stably transfer to the isolated grid operation state, and automatically match according to the output of the unit before the isolated grid The operation mode of the heat storage device of the electric boiler effectively guarantees the heating function of the residents.

In order to achieve the above object, the present invention adopts the following technical solution: a method for controlling the isolated grid operation of a thermal power unit with the participation of an electric boiler heat storage device, which is characterized in that it includes the following steps:

The first step is to judge whether the thermal power unit is in the isolated grid operation state;

The second step, DEH load switching and electric boiler heat storage device load switching control

(1) DEH load switching

After the thermal power unit is triggered in the isolated grid, DEH cuts off the remote DCS remote control, and the turbo generator immediately switches to the speed control mode to ensure that the speed change during the entire transition process is within the allowable range, and maintains a stable speed after the transition process ends; when the thermal power unit After entering the isolated grid operation, the primary frequency regulation of the thermal power unit will automatically switch to the mode of no speed dead zone;

(2) Switching of electric boiler heat storage device

By calculating the deviation between the output of the thermal power unit before the isolated grid and the sum of the heat storage device of the electric boiler and other utility loads, record Pn as the output of the thermal power unit before the isolated grid, and Pz as the heat storage device of the electric boiler and other utility loads The sum, Py is the allowable deviation of unit load;

After the isolated grid is triggered, when Pn-Pz≤Py, the heat storage device of the electric boiler maintains the original operation;

When Pn-Pz>Py, start a set of electric boiler heat storage device load to balance the output of the unit;

When Pn-Pz<-Py, it is necessary to stop the load of a set of electric boiler heat storage device to balance the output of the unit.

In the first step, the isolated grid trigger criterion for judging whether the thermal power unit is in the isolated grid operation state is as follows:

The two busbars between the power plant and the substation are busbar A and busbar B, and the following two lines refer to busbar A and busbar B; each busbar has three-phase current, and the three-phase current of busbar A is respectively IAa, IAb and IAc, the three-phase current of bus B are IBa, IBb and IBc respectively;

(1) The sudden changes in the power of the two lines are greater than the start-up fixed value P ₀ ;

Power mutation start criterion: ΔP=P _t-0.2s -P _t , ΔP≥P ₀

Among them, P _t is the effective value of the current power, P _t-0.2s is the effective value of the power before tripping, ΔP is the power mutation value, and P ₀ is the starting value of the power mutation before the accident;

(2) The current mutations of the two lines are both greater than the start-up fixed value I ₀ ;

Start-up criterion for current sudden change: ΔI=I _t-20ms -I _t , ΔI≥I ₀ ;

Among them, I _t is the current effective value of the current, I _t-20ms is the effective value of the current before one cycle, ΔI is the current mutation amount, and I ₀ is the starting value of the current mutation amount;

(3) 0.2s before the line fault, the power sum of the two lines is greater than or equal to the set value P _s1 , P _t-0.2s ≥ P _s1 , where P _s1 is the power setting value before the fault;

(4) After the line fault, the power sum of the two lines is less than or equal to the power setting value P _s2 , P _{t ≤} P _s2 , where P _s2 is the power setting value after the fault;

(5) The two-phase or three-phase current of both lines is less than the operating current I _s , I _t ≤ I _s , where I _s is the fixed value of the operating current;

(6) Both lines have two-phase or three-phase current mutations greater than the fixed value I ₀ ;

After the above (1)-(6) conditions are met at the same time, the isolated grid operation signal is triggered.

In the first step, after the unit is triggered by the isolated grid, the DEH cuts off the remote DCS remote control, and the turbo generator immediately switches to the speed control mode to ensure that the speed of the entire transition process is less than 3090r/min.

Through the above-mentioned design scheme, the present invention can bring the following beneficial effects: the isolated grid operation control method of the thermal power unit with the participation of the electric boiler heat storage device can monitor the operating status of the power grid and the unit in real time, and when complex faults such as extreme weather and system disturbance When the thermal power unit is running in an isolated grid, the system makes timely decisions and switches the electric boiler on and off according to the boundary conditions, which reduces the deviation between the output of the unit and the factory load, reduces the disturbance of the isolated grid to the boiler and turbine, and the unit can be transferred to the isolated grid stably At the same time, with the participation of the electric boiler heat storage device, the heat supply for residents is effectively guaranteed.

Description of drawings

The accompanying drawings here are used to provide a further understanding of the present invention and constitute a part of the application of the present invention. The schematic embodiments of the present invention and their descriptions are used to understand the present invention and do not constitute improper limitations of the present invention. In the accompanying drawings :

Figure 1 is a block diagram of the power system structure based on the isolated grid operation control method of thermal power units with the participation of electric boiler heat storage devices.

Fig. 2 is a flow chart of the control method for the isolated grid operation of the thermal power unit with the participation of the heat storage device of the electric boiler.

Figure 3 is a logic diagram of triggering criteria for an isolated network.

detailed description

In order to make the purpose, features, and advantages of the present invention more obvious and understandable, the technical solutions in the present invention are clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the present invention is not limited by the following examples, and the specific implementation manner can be determined according to the technical solutions of the present invention and actual conditions. In order not to obscure the essence of the present invention, well-known methods, procedures, procedures, components and circuits have not been described in detail.

As shown in Figure 1, the isolated grid operation control system of the thermal power unit with the participation of the electric boiler heat storage device adopts Hollysys K series controllers to realize the integration with the steam turbine DEH control system (that is, the digital electric hydraulic control system of the steam turbine (Digital Electric Hydraulic Control System)), the electric Acquisition, operation and control of boiler heat storage device control system, electrical ECS control system (ie Electric Control System) data. Hollysys K-CU03 main controller and the corresponding fast IO module can achieve the whole process from signal collection, operation to execution of action command output within 40ms, and can realize the control from power grid failure to the operation of the isolated grid live boiler heat storage device. Rapidity requirements.

The isolated network operation control system of the thermal power unit with the participation of the electric boiler heat storage device, through data interaction with the ECS system, detects the operating conditions of the two 220KV incoming lines. Criterion, automatically judge whether the power plant is in the isolated grid state, and trigger the isolated grid operation signal. Through data interaction with the control system of the electric boiler heat storage device, the operation mode of the electric boiler heat storage device is automatically matched according to the operation status of the electric boiler heat storage device and the output of the thermal power unit before the isolated grid. Through the data interaction of the steam turbine DEH control system, the stable control of the steam turbine after the thermal power unit is isolated from the grid is realized.

The specific implementation process is shown in Figure 2. Among them, Pn is the output of the thermal power unit in front of the isolated grid, Pz is the sum of the heat storage device of the electric boiler and other utility loads, and Py is the allowable deviation of the unit load.

The first step is to judge whether the thermal power unit is in the isolated grid operation state, and the trigger criterion of the isolated grid is shown in logic diagram 3.

In order to ensure reliable power supply, two busbars are usually designed between the power plant and the substation, which are counted as A busbar and B busbar. The following two lines refer to A busbar and B busbar. There are three-phase currents on each bus, the three-phase currents of the A bus are IAa, IAb and IAc respectively, and the three-phase currents of the B bus are IBa, IBb and IBc respectively;

(1) The power mutations of the two lines are greater than the start-up setting value P ₀

Power mutation start criterion: ΔP=P _t-0.2s -P _t , ΔP≥P ₀

Among them, P _t is the effective value of the current power, P _t-0.2s is the effective value of the power before tripping, ΔP is the power mutation value, and P ₀ is the starting value of the power mutation before the accident.

(2) The current mutations of the two lines are greater than the start-up setting value I ₀

Start-up criterion for current sudden change: ΔI=I _t-20ms -I _t , ΔI≥I ₀

Among them, I _t is the current RMS value, I _t-20ms is the current RMS value before one cycle, ΔI is the current mutation amount, and I ₀ is the starting value of the current mutation amount.

(3) 0.2s before the line fault, the power sum of the two lines is greater than or equal to the set value P _s1 , P _t-0.2s ≥ P _s1 , where P _s1 is the power setting value before the fault;

(4) After a line fault, the power sum of the two lines is less than or equal to the power setting value P _s2 , P _{t ≤} P _s2 , where P _s2 is the power setting value after the fault.

(5) The two-phase or three-phase currents of busbar A and busbar B are less than the operating current I _s , I _t ≤ I _s , where the operating current of I _s is a fixed value.

(6) Both A bus and B bus have two-phase or three-phase current mutations greater than the fixed value I ₀ ;

When the above conditions are satisfied at the same time, the isolated grid operation signal is triggered.

The second step, DEH load switching and electric boiler heat storage device load switching control

(1) DEH load switching

After the thermal power unit is triggered by the isolated grid, the DEH cuts off the remote DCS remote control, and the turbo generator immediately switches to the speed control mode to ensure that the speed change during the entire transition process is within the allowable range (less than 3090r/min), and it will be maintained after the transition process ends. The speed is stable. When the thermal power unit enters the isolated grid operation, the primary frequency regulation of the thermal power unit will automatically switch to the mode of no-speed dead zone.

(2) Switching of electric pan heat storage device

By calculating the deviation between the output of the thermal power unit before the isolated grid and the sum of the heat storage device of the electric boiler and other utility loads, record Pn as the output of the thermal power unit before the isolated grid, and Pz as the heat storage device of the electric boiler and other utility loads The sum, Py is the allowable deviation of thermal power unit load.

After the isolated grid is triggered, if Pn-Pz≤Py, it means that the difference between the output of the thermal power unit and the sum of the heat storage device of the electric boiler and other utility loads is within the controllable range, and the heat storage device of the electric boiler maintains the original operation;

If Pn-Pz>Py, it means that the sum of thermal power unit output, electric boiler heat storage device and other utility loads is not within the controllable range. At this time, thermal power unit output is greater than electric boiler heat storage device and other utility loads. And, it is necessary to start a set of electric boiler heat storage device load to balance the output of the unit;

If Pn-Pz<-Py, it means that the sum of thermal power unit output, electric boiler heat storage device and other utility loads is not within the controllable range. At this time, thermal power unit output is smaller than electric boiler heat storage device and other utility loads In sum, it is necessary to stop the load of a set of electric boiler heat storage device to balance the output of the unit.

Compared with the prior art, the improvement of the technical solution of the present invention:

When the thermal power unit runs in isolation due to complex faults such as extreme weather and system disturbances, the thermal power unit will instantly drop the electrical load, which will cause the output and load of the boiler and steam turbine to be unbalanced, resulting in overspeeding of the steam turbine and overpressure of the boiler steam pressure , steam overheating and a series of problems, it is difficult for the thermal power unit to maintain zero output operation and has to be shut down, making it difficult to play its effective power support role. The isolated-grid operation control system of thermal power units with the participation of electric boiler heat storage devices can monitor the operating status of the power grid and thermal power units at all times. When complex faults such as extreme weather and system disturbances cause thermal power units to operate in isolation, the system makes timely decisions, and Switching electric boilers according to the boundary conditions reduces the deviation of the output of the thermal power unit and the sum of the heat storage device of the electric boiler and other factory power loads, reduces the disturbance of the isolated grid to the boiler and steam turbine, and the thermal power unit can be stably transferred to the isolated grid. , At the same time, with the participation of the electric boiler heat storage device, the heat supply for residents is effectively guaranteed.

Claims (3)

1. A thermal power unit isolated network operation control method under the participation of an electric boiler heat storage device, is characterized in that, comprising the steps: The first step is to judge whether the thermal power unit is in the isolated grid operation state; The second step, DEH load switching and electric boiler heat storage device load switching control (1) DEH load switching After the thermal power unit is triggered in the isolated grid, DEH cuts off the remote DCS remote control, and the turbo generator immediately switches to the speed control mode to ensure that the speed change during the entire transition process is within the allowable range, and maintains a stable speed after the transition process ends; when the thermal power unit After entering the isolated grid operation, the primary frequency regulation of the thermal power unit will automatically switch to the mode of no speed dead zone; (2) Switching of electric boiler heat storage device By calculating the deviation between the output of the thermal power unit before the isolated grid and the sum of the heat storage device of the electric boiler and other utility loads, record Pn as the output of the thermal power unit before the isolated grid, and Pz as the heat storage device of the electric boiler and other utility loads The sum, Py is the allowable deviation of unit load; After the isolated grid is triggered, when Pn-Pz≤Py, the heat storage device of the electric boiler maintains the original operation; When Pn-Pz>Py, start a set of electric boiler heat storage device load to balance the output of the unit; When Pn-Pz<-Py, it is necessary to stop the load of a set of electric boiler heat storage device to balance the output of the unit. 2. the thermal power unit isolated network operation control method under the participation of a kind of electric boiler heat storage device according to claim 1, is characterized in that, in the first step, the isolated network trigger judgment of judging whether the thermal power unit is in the isolated network operation state According to the following: The two busbars between the power plant and the substation are busbar A and busbar B, and the following two lines refer to busbar A and busbar B; each busbar has three-phase current, and the three-phase current of busbar A is respectively IAa, IAb and IAc, the three-phase current of bus B are IBa, IBb and IBc respectively; (1) The sudden changes in the power of the two lines are greater than the start-up fixed value P ₀ ; Power mutation start criterion: ΔP=P _t-0.2s -P _t , ΔP≥P ₀ Among them, P _t is the effective value of the current power, P _t-0.2s is the effective value of the power before tripping, ΔP is the power mutation value, and P ₀ is the starting value of the power mutation before the accident; (2) The current mutations of the two lines are both greater than the start-up fixed value I ₀ ; Start-up criterion for current sudden change: ΔI=I _t-20ms -I _t , ΔI≥I ₀ ; Among them, I _t is the current effective value of the current, I _t-20ms is the effective value of the current before one cycle, ΔI is the current mutation amount, and I ₀ is the starting value of the current mutation amount; (3) 0.2s before the line fault, the power sum of the two lines is greater than or equal to the set value P _s1 , P _t-0.2s ≥ P _s1 , where P _s1 is the power setting value before the fault; (4) After the line fault, the power sum of the two lines is less than or equal to the power setting value P _s2 , P _{t ≤} P _s2 , where P _s2 is the power setting value after the fault; (5) The two-phase or three-phase current of both lines is less than the operating current I _s , I _t ≤ I _s , where I _s is the fixed value of the operating current; (6) Both lines have two-phase or three-phase current mutations greater than the fixed value I ₀ ; After the above (1)-(6) conditions are met at the same time, the isolated grid operation signal is triggered. 3. The thermal power unit isolated grid operation control method with the participation of the electric boiler heat storage device according to claim 1, characterized in that: in the first step, after the unit is triggered in the isolated grid, the DEH cuts off the remote DCS remote control, and the steam turbine generates electricity The machine immediately switches to the speed control mode to ensure that the speed of the entire transition process is less than 3090r/min.

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