A safety and stability control method for thermal stability instability of a nuclear power unit

Abstract

The present application relates to a kind of nuclear power unit thermal stability instability safety stability control method of nuclear power unit thermal stability regulation technology field, after receiving the power plant outgoing line current, voltage and circuit breaker position information by nuclear power plant safety control master station, when it is judged that nuclear power plant outgoing line occurs thermal stability, does not occur transient stability problem, the adjustment output value of each allowed regulating unit is calculated, then the overload on line is distributed to each allowed regulating unit according to specific method, reduce the power generation of nuclear power plant by the joint control of generator, steam turbine and nuclear reactor control system and solve overload problem. By the joint control of steam turbine side and nuclear island side, nuclear power unit output can be adjusted, nuclear power unit can be cut off as far as possible, achieve the effect of not cutting machine or cutting machine less, improve the safety and stability of power grid and nuclear power unit operation.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of nuclear power unit thermal stability loss of stability safety stability control method, belong to nuclear power unit thermal stability regulation technical field. BACKGROUND

[0002] The current conventional for the situation of thermal stability loss of stability of power plant outgoing line, generally take the measure of directly removing power plant unit. This safety stability control measure has little effect on the unit of non-nuclear power plant, but for nuclear power plant, since the requirement of nuclear power unit to safety is extremely high, control system is complex, emergency machine removal is a severe test to the operation personnel and safety system of nuclear power plant, nuclear power plant does not cut machine, less cut machine for nuclear power can greatly improve the safety and stability of power grid and nuclear power unit operation. How to avoid not cutting machine or less cutting machine is the problem that designers and operators need to consider.

[0003] Related technical field prior art such as: a nuclear power station safety stability machine removal round control method (ZL201710814206.1): provide the machine removal round control method of nuclear power unit when nuclear power station adopts machine removal mode for safety stability control, mainly provide the selection and sorting of nuclear power plant internal safety control machine removal, and does not give the safety stability control device and internal control process of nuclear power unit after loss of stability for safety stability control.

[0004] Related technical field prior art such as: safety stability control method for nuclear power unit out-of-step oscillation (ZL201510035267.9), safety stability control method based on nuclear power unit out-of-step oscillation (ZL201510035159.1), these two patents provide the overall control process of nuclear power plant internal steam turbine regulating system and reactor control system after machine removal of safety stability control device action under the condition of nuclear power unit out-of-step oscillation, this method is not applicable to the situation of thermal stability loss of stability of nuclear power plant outgoing line.

[0005] The above invention patents do not involve the safety stability control under the condition of thermal stability loss of stability of nuclear power plant outgoing line.

[0006] The safety stability control method for thermal stability loss of stability of nuclear power unit provided by the present application can avoid removing nuclear power unit as much as possible, achieve the effect of not cutting machine or less cutting machine, and improve the safety and stability of power grid and nuclear power unit operation. SUMMARY

[0007] In order to solve the above problems existing in the prior art, the present application provides a safety stability control method for thermal stability loss of stability of nuclear power unit.

[0008] The technical scheme of the present application is as follows:

[0009] A safety and stability control method for thermal stability instability of a nuclear power unit, comprising the following steps:

[0010] Step one, the safety control master station receives the outgoing line current, voltage and circuit breaker position information collected by the safety control sub-station, and performs fault discrimination;

[0011] Step two, when the outgoing line of the nuclear power plant has thermal stability but no transient stability problem, the overload adjustment coefficient of the power plant is calculated, and the outgoing line overload is distributed to each allowed regulating unit or allowed cutting unit according to a specific method;

[0012] Step three, the nuclear power unit output is adjusted through the joint control of the steam turbine side and the nuclear island side to solve the outgoing line overload problem.

[0013] In step two, the allowed regulating unit is a unit that can adjust power through the steam turbine speed regulation system and the nuclear reactor control system; and the allowed cutting unit is a unit that can be urgently cut through the steam turbine speed regulation system and the nuclear reactor control system.

[0014] In step two, the overload adjustment coefficient K is calculated:

[0015] K = sum of outgoing line overload power of the power plant / sum of adjustable power of all allowed regulating units;

[0016] According to the overload adjustment coefficient K, the power reduction value of each allowed regulating unit is calculated, and the overload is distributed to the allowed regulating unit according to the power reduction value according to the following method:

[0017] When 0 < K ≤ 0.2, 0 < the power reduction value of each allowed regulating unit ≤ 20% Pn, and the power reduction operation power of the allowed regulating unit is set to 20% Pn; further optimization calculation: assuming that the priority order of m allowed regulating units is 1, 2, …, m, the power reduction regulation command is issued to the r units with the highest priority order, and r should satisfy the following conditions, r ≤ m and ∑Pn r-1 * 20% ≤ sum of outgoing line overload power of the power plant ≤ ∑

[0018] Pn r * 20%; the power reduction value of 20% Pn is issued to the r units with the highest order;

[0019] When 0.2 < K ≤ 0.5, 20% Pn < the power reduction value of each allowed regulating unit ≤ 50% Pn, and the power reduction operation power of the allowed regulating unit is set to 50% Pn; further optimization calculation: assuming that the priority order of m allowed regulating units is 1, 2, …, m, the power reduction regulation command is issued to the r units with the highest priority order, and r should satisfy the following conditions, r ≤ m and ∑Pn r-1 * 50% ≤ sum of outgoing line overload power of the power plant ≤ ∑Pn r* 50%; the 50% Pn power reduction value is issued to the r units with the highest priority;

[0020] When K > 0.5, the cut-off part allows the unit to be cut off; the control host computer re-computes the number of cut-off units; assuming that the priority order of t units allowed to be cut off is 1, 2,..., t, the cut-off command is issued to the s units with the highest priority, which should satisfy the following conditions: s ≤ t and ∑Pn s-1 ≤ the sum of the overload power of the power plant outgoing line ≤ ∑Pn s ; the cut-off command is issued to the s units with the highest priority.

[0021] In step three, according to the control adjustment command, the specific control measures taken by the turbine and reactor control system are:

[0022] When 0 < K ≤ 0.2, the r units with the highest priority receive a 20% Pn power reduction value, and the power generation output is reduced; the turbine bypass exhaust system gradually opens the valve as the generator load decreases; under the control of the reactor control system, the nuclear reactor power is automatically set to 80% Pn, the control rod is inserted to reduce the nuclear power, and the reactor can be re-powered and connected to the grid after the power grid is restored; if a fault occurs in the control system during the waiting period for the power grid to recover, the generator set is tripped, the turbine is manually shut down, and the nuclear reactor enters a hot shutdown state waiting for the power grid to recover;

[0023] When 0.2 < K ≤ 0.5, the r units with the highest priority receive a 50% Pn power reduction value, and the power generation output is reduced; the turbine bypass exhaust system gradually opens the valve as the generator load decreases; under the control of the reactor control system, the nuclear reactor power is automatically set to 50% Pn, and the control rod is inserted to reduce the nuclear power; after the nuclear power is successfully reduced from 100% Pn to 50% Pn, the reactor maintains 50% Pn operation and waits for the power grid to recover; if a fault occurs in the control system or the operating time exceeds 50% Pn during the waiting period for the power grid to recover, the generator set is tripped, the turbine is manually shut down, and the nuclear reactor enters a hot shutdown state waiting for the power grid to recover;

[0024] When K > 0.5, the s units with the highest priority receive a cut-off command, the GCB is tripped, the auxiliary load is supplied by the high-voltage side power grid, and the turbine bypass exhaust system discharges excess steam to the condenser; the nuclear power is automatically set to 30% Pn, and the control rod is inserted to reduce the nuclear power; when the nuclear power is successfully reduced from 100% Pn to 30% Pn, the turbine is manually shut down, and the nuclear reactor maintains 30% Pn low-power operation and waits for the power grid to recover; if a fault occurs in the control system or the operating time exceeds 30% Pn during the waiting period for the power grid to recover, the nuclear reactor enters a hot shutdown state waiting for the power grid to recover.

[0025] The present application has the following advantages:

[0026] The safety and stability control method for thermal stability instability of a nuclear power unit has the following steps: after receiving the power plant outgoing line current, voltage and circuit breaker position information from the safety and control substation acquisition device, the safety and control master station of the nuclear power plant judges whether the power plant outgoing line has thermal stability instability or transient stability instability, calculates the adjustment output value of each adjustable unit, distributes the overload on the line to each adjustable unit or each cut-off unit according to a specific method, and reduces the power generation of the nuclear power plant through the joint control and adjustment of the generator, turbine and nuclear reactor control system to solve the overload problem. By jointly controlling and adjusting the output of the nuclear power unit on the turbine side and the nuclear island side, the nuclear power unit can be cut off as little as possible to achieve the effect of not cutting off the unit or cutting off the unit as little as possible, thereby improving the safety and stability of the power grid and the nuclear power unit. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 is a flow chart of the safety and stability control method of the present application;

[0028] Fig. 2 is a flow chart of the joint control of the turbine side and the nuclear island side in the embodiment of the present application. DETAILED DESCRIPTION

[0029] The present application will be described in detail below in conjunction with the drawings and specific embodiments.

[0030] Referring to Figs. 1-2 A safety and stability control method for thermal stability instability of a nuclear power unit, comprising the following steps:

[0031] Step 1: The safety and control master station of the nuclear power plant receives the power plant outgoing line current, voltage and circuit breaker position information sent by the safety and control substation acquisition device, judges whether the power plant outgoing line has thermal stability instability or transient stability instability in combination with the line current, voltage and circuit breaker position information collected by the safety and control master station, receives the current and voltage information sent by the safety and control substation acquisition device of the nuclear power unit, and calculates the allowable power reduction value of the adjustable unit and the allowable power cut-off value of the cut-off unit. The adjustable unit is a unit that can be power adjusted through the turbine speed regulation system and the nuclear reactor control system. The cut-off unit is a unit that can be emergency cut-off through the turbine speed regulation system and the nuclear reactor control system.

[0032] Step 2: When the power plant outgoing line has thermal stability instability and does not have transient stability instability, the overload adjustment coefficient of the power plant is calculated, and the overload on the outgoing line is distributed to each adjustable unit or each cut-off unit according to a specific method. Specifically:

[0033] Calculate the overload adjustment coefficient K: assuming that the overload adjustment coefficient of the nuclear power plant is K, K is the ratio of the sum of the overload power of the plant out line and the sum of the adjustable power of all the allowed units, that is, K = the sum of the overload power of the plant out line / the sum of the adjustable power of all the allowed units;

[0034] When 0 < K ≤ 0.2, 0 < the power reduction value of each allowed unit ≤ 20%Pn, the allowed unit is set to run at 20%Pn; If 20%Pn power reduction operation command is issued to all the allowed units in any overload condition, it will cause a certain amount of overshoot, causing unnecessary loss of the benefit of the nuclear power plant, so further optimization calculation is needed; Assuming that the priority order of m allowed units is 1, 2 …… m, in order to minimize the number of units and reduce losses, only the power reduction adjustment command is issued to the first r units in the priority order, r should meet the following conditions, r ≤ m and ∑Pn r-1 * 20% ≤ the sum of the overload power of the plant out line ≤ ∑Pn r * 20%; Then the 20%Pn power reduction value is issued to the first r units in the order, and the nuclear power unit output is adjusted through the joint control of the generator, turbine side and nuclear island side;

[0035] When 0.2 < K ≤ 0.5, 20%Pn < the power reduction value of each allowed unit ≤ 50%Pn, the allowed unit is set to run at 50%Pn; If 50%Pn power reduction operation command is issued to all the allowed units in any overload condition, it will cause a certain amount of overshoot, causing unnecessary loss of the benefit of the nuclear power plant, so further optimization calculation is needed; Assuming that the priority order of m allowed units is 1, 2 …… m, in order to minimize the number of units and reduce losses, only the power reduction adjustment command is issued to the first r units in the priority order, r should meet the following conditions, r ≤ m and ∑Pn r-1 * 50% ≤ the sum of the overload power of the plant out line ≤ ∑Pn r * 50%; Then the 50%Pn power reduction value is issued to the first r units in the order, and the nuclear power unit output is adjusted through the joint control of the generator, turbine side and nuclear island side;

[0036] Since the power of the turbine and the nuclear reactor cannot be lower than 50%Pn when running at low power, when K > 0.5, part of the allowed units need to be removed to solve the overload problem: if the unit removal command is issued to all the allowed units, it will cause a certain amount of overshoot, causing unnecessary loss of the benefit of the nuclear power plant, and the safety control host needs to recalculate the number of units to be removed; Assuming that the priority order of t allowed units is 1, 2 …… t, in order to minimize the number of units and reduce losses, only the unit removal command is issued to the first s units in the priority order, s should meet the following conditions, s ≤ t and ∑Pn s-1≤ Sum of the overload power of the power plant out line ≤∑Pn s Then the generator unit with the highest priority is ordered to be shut down, and the nuclear power unit output is adjusted through the joint control of the generator, turbine side and nuclear island side.

[0037] Step three, adjust the nuclear power unit output through the joint control of the generator, turbine side and nuclear island side to solve the out line overload problem. Because the received control adjustment commands are different, the control measures taken by the turbine and reactor control systems are also different:

[0038] When 0

[0039] 0.2

[0040] When K>0.5, the generator unit with the highest priority receives the shut down command, the GCB is tripped, the plant load is supplied by the high voltage side power grid, the turbine bypass exhaust system is actuated to discharge excess steam to the condenser, and the nuclear power is automatically adjusted to 30%Pn and the control rods are inserted to reduce the nuclear power. When the nuclear power is successfully reduced from 100%Pn to 30%Pn, the turbine is manually stopped, the nuclear reactor is maintained at a low power of 30%Pn, and the reactor can be re-powered and connected to the grid after the power grid is restored. If the control system fails or the running time exceeds 30%Pn during the waiting period for the power grid to be restored, the nuclear reactor enters a hot shutdown state and waits for the power grid to be restored.

[0041] After the fault is eliminated and the power grid is restored, the control rods are raised, the reactor is re-powered, and the grid is connected.

[0042] The above merely illustrates the embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, which are made by using the content of the present application specification and drawings, are also included in the patent protection scope of the present application.

Claims

1. A safe and stable control method for thermal instability of a nuclear power unit, characterized in that, Includes the following steps: Step 1: The security control master station receives the outgoing line current, voltage, and circuit breaker location information collected by the security control substation and performs fault diagnosis. Step 2: When thermal stability occurs at the nuclear power plant outgoing line but no transient stability problem occurs, calculate the overload regulation coefficient of the power plant and distribute the outgoing line overload to each unit that can be regulated or the unit that can be cut off according to a specific method. Step 3: Adjust the output of the nuclear power unit through joint control on the turbine side and the nuclear island side to solve the overload problem of the outgoing lines; In step two, the units that can be adjusted are those whose power can be regulated by the turbine speed regulation system and the nuclear reactor control system; the units that can be cut off are those that can be cut off in an emergency by the turbine speed regulation system and the nuclear reactor control system. In step two, the overload adjustment coefficient K is calculated: K = Sum of overload power of power plant outgoing lines / Sum of adjustable power of all adjustable generating units; Calculate the power reduction value for each allowable generator unit based on the overload adjustment coefficient K, and issue the overload amount to the allowable generator units according to the following method based on the power reduction value: When 0 < K ≤ 0.2, then 0 < power reduction value of each allowable unit ≤ 20% Pn, and the power reduction operation of the allowable unit is set at 20% Pn; assuming the priority order of m allowable units is 1, 2...m, the power reduction adjustment command is issued to the r units with the highest priority, and r should satisfy the following condition: r ≤ m and ∑Pn r-1 *20%≤Sum of overload power of power plant outgoing lines≤∑Pn r *20%; Send the 20% reduction in power value of Pn to the r units ranked first; When 0.2 < K ≤ 0.5, then 20%Pn < the power reduction value of each allowable regulating unit ≤ 50%Pn, and the power reduction operation of the allowable regulating unit is set at 50%Pn; assuming the priority order of m allowable regulating units is 1, 2...m, the power reduction regulation command is issued to the r units with the highest priority, and r should meet the following condition: r ≤ m and ∑Pn r-1 *50%≤Sum of overload power of power plant outgoing lines≤∑Pn r *50%; Send the 50% reduction in power value of Pn to the r units ranked first; When K > 0.5, some of the permitted units are cut off; the security control host recalculates the number of units to be cut off; assuming the priority order of the t permitted units is 1, 2...t, the cut-off command is issued to the s units with the highest priority, where s should satisfy the following condition: s ≤ t and ∑Pn s-1 ≤Sum of overload power of power plant outgoing lines≤∑Pn s The switchover command is issued to the top s units in the sequence.

2. The safe and stable control method for thermal instability of a nuclear power unit as described in claim 1, characterized in that: In step three, the specific control measures taken by the turbine and reactor control systems according to the control and adjustment commands are as follows: When 0 < K ≤ 0.2, after the first r generating units receive a power reduction value of 20% Pn, their power output is reduced, and the turbine bypass emission system gradually opens its valves as the generator load decreases. Under the control of the reactor control system, the nuclear reactor power is automatically set at 80% Pn, and control rods are inserted to reduce nuclear power. After the grid is restored, the reactor can resume power output and reconnect to the grid. If the control system fails while waiting for the grid to be restored, the generating units are tripped, the turbine is manually shut down, and the nuclear reactor enters a hot shutdown state to wait for the grid to be restored. When 0.2 < K ≤ 0.5, after the first r units in the sequence receive a power reduction value of 50% Pn, the power generation output is reduced, and the turbine bypass emission system gradually opens the valves as the generator load decreases. Under the control of the reactor control system, the nuclear reactor power is automatically set at 50% Pn, and the control rods are inserted to reduce the nuclear power. After the nuclear power is successfully reduced from 100% Pn to 50% Pn, the reactor maintains 50% Pn operation and waits for the grid to be restored before it can resume power generation and grid connection. If the control system fails or the 50% Pn operation time is exceeded while waiting for the grid to be restored, the generator unit is tripped, the turbine is manually shut down, and the nuclear reactor enters a hot shutdown operation state to wait for the grid to be restored. When K > 0.5, after the top s units receive the trip command, the GCB is disconnected, the plant auxiliary load is supplied by the high-voltage side of the step-up transformer grid, and the turbine bypass emission system activates to discharge excess steam to the condenser; the nuclear power is automatically set to 30%Pn, and the control rods are inserted to reduce the nuclear power; when the nuclear power successfully drops from 100%Pn to 30%Pn, the turbine is manually shut down, and the nuclear reactor maintains low-power operation at 30%Pn, waiting for the grid to be restored before the reactor can resume power increase and grid connection; if the control system fails or the 30%Pn operation time exceeds the period of waiting for grid restoration, the nuclear reactor enters a hot shutdown operation state to wait for grid restoration.

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