Hydroelectric generating set AGC and primary frequency control adjustment collaborative control method

Abstract

A hydroelectric generating set AGC and primary frequency control adjustment collaborative control method, comprising: introducing a governor primary frequency control action guide vane control deviation YPFC into a monitoring system of a hydroelectric generating set, incorporating the corresponding relationship between active power and guide vane opening under different working heads of the hydroelectric generating set into an AGC power control algorithm, performing AGC to track real-time the working head of the set and performing power-guide vane opening conversion and guide vane opening-power conversion on the basis of the working head of the hydroelectric generating set. The function of hydroelectric generating set AGC and primary frequency control in stabilizing the system load frequency can be fully but not excessively exerted. By means of the method, the function of AGC and primary frequency control in ensuring safe and stable operation of the system can be fully exerted, and faster adjustment of the unit can be achieved, thereby reducing guide vane servomotor fluctuation and active power frequency fluctuation during AGC and primary frequency control, reducing the operational intensity of control machinery of the set and the consumption of governor operating oil pressure, significantly reducing the maintenance costs, and reducing the risk of active power frequency oscillation in the system.

Description

A coordinated control method for AGC and primary frequency regulation of hydropower units Technical Field

[0001] The present invention relates to the technical field of power system regulation, and in particular to a method for coordinated control of an AGC and a primary frequency regulation variable of a hydropower unit. Background Art

[0002] Active power and frequency regulation of hydropower units are accomplished through the combined efforts of the speed control system and the monitoring and control system (AGC). The monitoring system performs closed-loop active power control and serves as the upper-level active power control system for the speed control system. When active closed-loop regulation is engaged and the power setpoint or feedback value changes, closed-loop regulation is performed based on the power deviation, issuing guide vane opening increase or decrease commands to the speed control system until the power setpoint and power feedback values ​​are equalized again. Primary frequency regulation of hydropower units is primarily accomplished by the speed governor. When the speed governor detects that the unit frequency (when the unit is grid-connected, the governor unit frequency is equal to the grid frequency) exceeds the primary frequency regulation dead zone (typically 50±0.05Hz) set by the speed governor, the speed governor controls the unit to increase or decrease the guide vane opening according to the set permanent slip coefficient bp (power regulation rate ep) until the unit frequency returns to within the primary frequency regulation dead zone, thereby achieving primary frequency regulation power regulation. If the unit frequency exceeds the dead zone frequency of the primary frequency regulation action by △f, then for the speed governor whose working mode is the opening closed loop mode, the change in the guide vane opening of the primary frequency regulation action is However, since the guide vane opening and active power of the turbine generator set are nonlinear, its primary frequency regulation power adjustment amount is not only related to △f but also related to the current working head and load conditions of the unit.

[0003] In summary, the AGC (Automatic Guided Controller) regulates active power, while the primary frequency regulator regulates opening. When adjusted independently, both can stably control the unit to the new operating condition required by the system. However, when the AGC and primary frequency regulator are adjusted simultaneously, their inconsistent regulation targets may lead to frequent adjustments that prevent the unit from achieving a stable state. For example, after the primary frequency regulator is activated, the speed regulator controls the guide vanes to open or close, causing the unit power to change. When the unit power changes to a level greater than the set power regulation deadband relative to the AGC power setting, the AGC will issue guide vane opening increase or decrease commands to the speed regulator to restore the deviation between the unit power setting and the power setting to within the power regulation deadband. However, because the guide vane opening adjusted by the AGC deviates from the guide vane opening target set by the primary frequency regulator, the primary frequency regulator will continue to open or close the guide vanes, repeating this process.

[0004] In order to enable the monitoring system (AGC) and primary frequency regulation to simultaneously regulate the unit to quickly and stably reach the new operating conditions required by the system, it is necessary to study the coordinated regulation mode of the monitoring system (AGC) and primary frequency regulation. The current coordinated regulation modes of the monitoring system (AGC) and primary frequency regulation mainly include the following:

[0005] 1) During a frequency modulation action, the speed regulator shields the AGC / monitoring system related adjustment instructions, and the AGC / monitoring system only tracks the actual value;

[0006] 2) In the case of a primary frequency modulation action, there are AGC / monitoring system related adjustment instructions, which execute the AGC / monitoring system instructions and lock the primary frequency modulation function;

[0007] 3) In case of a frequency modulation action, if there is an AGC / monitoring system related adjustment instruction, the AGC / monitoring system instruction will be executed; during the AGC / monitoring system adjustment period, if there is a frequency modulation action, the AGC instruction will be locked and a frequency modulation will be executed;

[0008] 4) The primary frequency modulation is superimposed on the AGC in the same direction and in the opposite direction; the primary frequency modulation is superimposed on the AGC in the same direction and blocks the primary frequency modulation in the opposite direction; the primary frequency modulation is superimposed on the AGC in the same direction and blocks the AGC in the opposite direction.

[0009] As shown in Figure 1, under the AGC closed-loop power regulation mode, the unit's primary frequency regulation and AGC action interact. When a system frequency deviation occurs, the primary frequency regulation is activated, causing the unit power to change, while the system's set power value has not yet been updated and remains at the original value. At this point, the unit power change has formed a power deviation, and the monitoring system will automatically adjust the power to the set power. In this case, the monitoring system's adjustments have a negative effect.

[0010] In order to ensure the effectiveness of primary frequency regulation, the technical measures generally adopted in reality are: before the AGC system sets the power value and receives the new power setting value or when the power setting value does not change, the AGC power regulation of the unit should be stopped. The disadvantage of this measure is that when the AGC and primary frequency regulation are activated at the same time, the AGC instructions cannot be executed. When the primary frequency regulation of some power plants is activated, the operator will not be able to adjust the load, and the controllability of the unit will be reduced, posing a safety risk. Similarly, in order to ensure the regulation effect of the AGC, the primary frequency regulation function of the speed regulator must be shielded when the AGC is activated. This does not meet the requirement that "other power or frequency control systems of the grid-connected power supply [such as automatic generation control (AGC), active power closed-loop regulation, etc.] should be coordinated with the primary frequency regulation and should not limit the primary frequency regulation function."

[0011] In the approach shown in Figure 2, the frequency feedback signal is introduced into the on-site control unit of the monitoring system. The monitoring system then tracks the governor's primary frequency regulation active power regulation in real time. When power monitoring or AGC power regulation is required, the monitoring system or AGC first superimposes the governor's primary frequency regulation active power regulation. Frequency regulation power correction logic is designed to meet the requirements of multiple power grid operating modes, thereby achieving superposition of active power / frequency control within the monitoring and speed regulation systems. However, due to the nonlinearity of the guide vane opening and active power of the turbine generator set, the change in active power corresponding to increasing or decreasing the same guide vane opening at the same head is inconsistent. Therefore, this approach's frequency regulation power correction logic is difficult to achieve sufficient accuracy. Under frequency and power disturbances, the primary frequency regulation and AGC operate simultaneously, making it difficult for the monitoring system or AGC to accurately track the governor's primary frequency regulation active power regulation. Therefore, this approach fails to achieve complete mathematical superposition of the primary frequency regulation and AGC regulation, achieving only partial superposition (either failing to fully utilize the AGC and primary frequency regulation's respective regulation capabilities, or over-utilizing both the AGC and primary frequency regulation capabilities).

[0012] Summary of the Invention

[0013] The technical problem to be solved by the present invention is to provide a method for coordinated control of the AGC and primary frequency regulation adjustment amount of a hydropower unit, so as to solve the problems that when the AGC and primary frequency regulation of the hydropower unit are adjusted simultaneously, the primary frequency regulation or AGC function must be shielded (restricted), and when the AGC and primary frequency regulation are adjusted simultaneously, only partial superposition of the adjustment amount can be achieved and the effect of the primary frequency regulation or AGC adjustment amount on system stability cannot be fully exerted.

[0014] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0015] A method for coordinating the control of the AGC and primary frequency regulation of a hydropower unit includes: connecting the speed governor primary frequency regulation action guide vane control deviation Y in the hydropower unit monitoring system; PFC The corresponding relationship between the active power and guide vane opening under different working water heads of the hydropower unit is added to the AGC power control algorithm. The AGC tracks the working water head of the unit in real time and can perform power-guide vane opening conversion and guide vane opening-power conversion according to the working water head of the hydropower unit.

[0016] The above-mentioned governor primary frequency modulation action guide vane control deviation Y PFC When the hydropower unit is connected to the grid, the unit power corresponding to the guide vane opening Y0 is P0. If the primary frequency regulation does not work, Y PFC =0, and there is no AGC active power increase or decrease instruction, then Y AGC =0.

[0017] The speed regulator detects that the deviation between the unit frequency f and f0 exceeds the primary frequency dead zone E. f, once the frequency modulation action is taken, the speed regulator will output the frequency modulation guide vane control deviation Y PFC , adjust the turbine generator to adjust the guide vane opening from Y0 to Y PFC+ Y0, the active power of the unit also changes accordingly; at the same time, the active power P0 detected by the monitoring system is converted into Y0 through active power-guide vane conversion, and Y0 is superimposed on Y PFC Then we get Y1, which is converted from guide vane to active power to get Pe. Since there is no AGC active power increase or decrease instruction, P ref =0, then Pe = P1, because P1 is converted into Y2 by the active guide vane, so Y2 = Y1, and Y AGC =Y2-Y1, so at this time AGC has no adjustment opening instruction output; the primary frequency regulation of the unit operates normally, and AGC does not affect the primary frequency regulation operation.

[0018] The above AGC active power increase and decrease instruction P ref ≠0, then P1=Pe+P ref , then P1≠Pe, P1 is converted by active guide vanes to obtain Y2, then Y2≠Y1, then Y AGC =Y2-Y1≠0, at this time, the AGC has an opening command output to the governor hydraulic servo system, and the power of the turbine generator set will change; at the same time, if the governor detects that the deviation between the unit frequency f and f0 does not exceed the primary frequency regulation dead zone E f , the primary frequency regulation does not work, the speed governor primary frequency regulation guide vane control deviation Y PFC =0, the normal operation of AGC is not affected by primary frequency modulation;

[0019] When the speed regulator detects that the deviation between the unit frequency f and f0 exceeds the primary frequency dead zone E f , once the frequency modulation action is taken, the speed regulator will output the frequency modulation guide vane control deviation Y PFC At the same time, if the AGC active power increase or decrease instruction P ref ≠0, then P1=Pe+P ref , then P1≠Pe, P1 is converted by active guide vanes to obtain Y2, then Y2≠Y1, then Y AGC =Y2-Y1≠0, at this time, the AGC has an opening command output to the governor hydraulic servo system. At this time, the command received by the governor hydraulic servo system is the superposition of the AGC adjustment and the primary frequency adjustment amount, that is: Y0+Y PFC +Y AGC .

[0020] The present invention provides a method for coordinated control of the AGC and primary frequency regulation of a hydropower unit, which can realize a technical method of mathematical superposition of the AGC regulation amount and the primary frequency regulation regulation amount, so as to fully but not excessively play the role of the AGC and primary frequency regulation of the hydropower unit in stabilizing the load frequency of the system; through this method, not only can the role of AGC and primary frequency regulation in the safe and stable operation of the system be fully played, but also faster adjustment of the unit can be achieved, and the fluctuation of the guide vane relay and the active frequency during the adjustment process of AGC and primary frequency regulation can be reduced, which can reduce the operating intensity of the mechanical part of the unit control and the consumption of the speed regulator operating oil pressure, can greatly reduce the maintenance cost, and reduce the risk of active frequency oscillation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings and examples:

[0022] Figure 1 is the relationship diagram of the current primary frequency regulation and monitoring system of hydropower units;

[0023] Figure 2 is the second diagram of the relationship between the primary frequency regulation and monitoring system of the current hydropower unit;

[0024] FIG3 is a diagram of a coordinated control system of the AGC and primary frequency regulation of a hydropower unit according to the present invention;

[0025] FIG4 is a MATLAB simulation diagram of a primary frequency modulation superimposed on a co-directional AGC active power instruction in an embodiment;

[0026] FIG5 is a MATLAB simulation diagram of a primary frequency modulation superimposed reverse AGC active power instruction in an embodiment;

[0027] FIG6 is a MATLAB simulation diagram of an AGC superimposed primary frequency modulation reverse active power instruction in an embodiment;

[0028] FIG7 is a MATLAB simulation diagram of the AGC superimposed primary frequency modulation co-directional active power instruction in the embodiment. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0030] As shown in FIG3 , a method for cooperatively controlling the AGC and primary frequency regulation of a hydropower unit includes: connecting the speed governor primary frequency regulation action guide vane control deviation Y to the hydropower unit monitoring system. PFC The corresponding relationship between the active power and guide vane opening under different working water heads of the hydropower unit is added to the AGC power control algorithm. The AGC tracks the working water head of the unit in real time and can perform power-guide vane opening conversion and guide vane opening-power conversion according to the working water head of the hydropower unit.

[0031] The above-mentioned governor primary frequency modulation action guide vane control deviation Y PFCWhen the hydropower unit is connected to the grid, the unit power corresponding to the guide vane opening Y0 is P0. If the primary frequency regulation does not work, Y PFC =0, and there is no AGC active power increase or decrease instruction, then Y AGC =0, at this time the unit operates normally and stably without adjustment.

[0032] The speed regulator detects that the deviation between the unit frequency f and f0 exceeds the primary frequency dead zone E. f , once the frequency modulation action is taken, the speed regulator will output the frequency modulation guide vane control deviation Y PFC , adjust the turbine generator to adjust the guide vane opening from Y0 to Y PFC+ Y0, the active power of the unit also changes accordingly; at the same time, the active power P0 detected by the monitoring system is converted into Y0 through active power-guide vane conversion, and Y0 is superimposed on Y PFC Then we get Y1, which is converted from guide vane to active power to get Pe. Since there is no AGC active power increase or decrease instruction, P ref =0, then Pe = P1, because P1 is converted into Y2 by the active guide vane, so Y2 = Y1, and Y AGC =Y2- Y1, so at this time AGC has no adjustment opening instruction output; the primary frequency regulation of the unit operates normally, and AGC does not affect the primary frequency regulation action.

[0033] The above AGC active power increase and decrease instruction P ref ≠0, then P1=Pe+P ref , then P1≠Pe, P1 is converted by active guide vanes to obtain Y2, then Y2≠Y1, then Y AGC =Y2-Y1≠0, at this time, the AGC has an opening command output to the governor hydraulic servo system, and the power of the turbine generator set will change; at the same time, if the governor detects that the deviation between the unit frequency f and f0 does not exceed the primary frequency regulation dead zone E f , the primary frequency regulation does not work, the speed governor primary frequency regulation guide vane control deviation Y PFC =0, the normal operation of AGC is not affected by primary frequency modulation;

[0034] When the speed regulator detects that the deviation between the unit frequency f and f0 exceeds the primary frequency dead zone E f , once the frequency modulation action is taken, the speed regulator will output the frequency modulation guide vane control deviation Y PFC At the same time, if the AGC active power increase or decrease instruction P ref ≠0, then P1=Pe+P ref , then P1≠Pe, P1 is converted into Y by active guide vane 2， Then Y2≠Y1, then Y AGC=Y2-Y1≠0, at this time, the AGC has an opening command output to the governor hydraulic servo system. At this time, the command received by the governor hydraulic servo system is the superposition of the AGC adjustment and the primary frequency adjustment amount, that is: Y0+Y PFC +Y AGC ; That is, the complete superposition of the two adjustment amounts is achieved.

[0035] Example: According to Figure 3, a simulation model was built in MATLAB / Simlnk to simulate the joint regulation of AGC and primary frequency regulation of a hydropower unit under a certain head. The rated active power of the unit is 700MW, and the primary frequency regulation parameters of the speed regulator are: bp = 0.04, K P =8, K I =8, K D =0; the speed control hydraulic system relay reaction time constant Ty = 0.2, the unit inertia time Ta = 12, the generator en = 1.0, the turbine rigid model water flow inertia time constant Tw = 0.6, the active power-guide vane relationship is shown in Table 1; the simulation results of the combined regulation of AGC and primary frequency regulation are shown in Figures 4 to 7; the simulation results show that the combined regulation of AGC and primary frequency regulation can achieve the superposition of the two regulation amounts.

[0036] Table 1. Active guide vane relationship table for simulation model

Claims

1. A method for coordinated control of AGC and primary frequency regulation of a hydropower unit, characterized in that: Including the guide vane control deviation Y of the speed governor primary frequency regulation action connected to the hydropower unit monitoring system PFC The corresponding relationship between the active power and guide vane opening under different working water heads of the hydropower unit is added to the AGC power control algorithm. The AGC tracks the working water head of the unit in real time and can perform power-guide vane opening conversion and guide vane opening-power conversion according to the working water head of the hydropower unit.

2. A method for coordinated control of AGC and primary frequency regulation of a hydropower unit according to claim 1, characterized in that: The speed governor primary frequency modulation action guide vane control deviation Y PFC When the hydropower unit is connected to the grid, the unit power corresponding to the guide vane opening Y0 is P0. If the primary frequency regulation does not work, Y PFC =0, and if there is no AGC active power increase or decrease instruction, Y AGC =0.

3. A method for coordinated control of AGC and primary frequency regulation of a hydropower unit according to claim 2, characterized in that: The speed regulator detects that the deviation between the unit frequency f and f0 exceeds the primary frequency regulation dead zone E. f , once the frequency modulation action is taken, the speed regulator will output the frequency modulation guide vane control deviation Y PFC , adjust the turbine generator to adjust the guide vane opening from Y0 to Y PFC+ Y0, the unit active power also changes accordingly; at the same time, the active power P0 detected by the monitoring system is converted into Y0 through active power-guide vane conversion, and Y0 is superimposed on Y PFC Then, Y1 is converted from the guide vane to active power to obtain Pe. Since there is no AGC active power increase or decrease instruction, P ref =0, then Pe = P1, because P1 is converted into Y2 by the active guide vane, so Y2 = Y1, and Y AGC =Y2-Y1, so at this time AGC has no adjustment opening command output; the primary frequency regulation of the unit operates normally, and AGC does not affect the primary frequency regulation action.

4. A method for coordinated control of AGC and primary frequency regulation of a hydropower unit according to claim 3, characterized in that: The AGC active power increase and decrease instruction P ref ≠0, then P1=Pe+P ref , then P1≠Pe, P1 is converted by active guide vanes to obtain Y2, then Y2≠Y1, then Y AGC =Y2-Y1≠0, at this time, the AGC has an opening command output to the governor hydraulic follow-up system, and the power of the turbine generator set will change; at the same time, if the governor detects that the deviation between the unit frequency f and f0 does not exceed the primary frequency regulation dead zone E f , the primary frequency regulation does not work, the primary frequency regulation guide vane control deviation Y of the speed regulator PFC =0, the normal operation of AGC is not affected by primary frequency modulation; When the speed regulator detects that the deviation between the unit frequency f and f0 exceeds the primary frequency regulation dead zone E f , once the frequency modulation action is taken, the speed regulator will output the frequency modulation guide vane control deviation Y PFC At the same time, if the AGC active power increase or decrease instruction P ref ≠0, then P1=Pe+P ref , then P1≠Pe, P1 is converted by active guide vanes to obtain Y2, then Y2≠Y1, then Y AGC =Y2-Y1≠0, at this time, the AGC has an opening command output to the governor hydraulic servo system. At this time, the command received by the governor hydraulic servo system is the superposition of the AGC adjustment and the primary frequency regulation, that is, Y0+Y PFC +Y AGC .

Images