A method for optimizing the performance of primary frequency regulation under the opening mode of a hydropower unit

Abstract

The invention discloses a method for optimizing the primary frequency regulation performance of a hydropower unit under an opening mode, comprising: when the unit is connected to the grid and operated, a speed regulation system obtains the current frequency value of the system by measuring f(i) to determine whether the primary frequency regulation of the unit is in action; when the speed regulation system determines that the primary frequency regulation of the unit is in action, the speed regulation system simultaneously collects a characteristic parameter K1 of the unit and an operating water head parameter K2 and adjusts the primary frequency regulation action amount of the unit according to the current characteristics of the unit and the operating water head information, thereby achieving the goal of optimizing the primary frequency regulation performance of the unit; the method solves the technical problems in the prior art that, for a hydropower unit operated under an opening mode, due to the nonlinear characteristics of the hydropower unit, usually different units have large differences in active power changes under different operating water heads, and for a unit with a large head change, the requirement for the primary frequency regulation load change is usually not met when the unit is operated at a low water level; the overall regulation performance of the unit is seriously deteriorated, and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of primary frequency regulation of hydropower units, and in particular relates to a method for optimizing primary frequency regulation performance under an opening mode of a hydropower unit. Background Art

[0002] With the large-scale commissioning of large and medium-sized hydropower units, the proportion of hydropower units in the power grid is also increasing. The problem of hydropower units affecting the frequency stability of the power system is gradually reflected. The quality of regulation and the reliability of operation of hydropower units directly affect the safe and reliable operation and power quality of hydropower units and even the entire power system. In the power grid, the demand for electricity by users and the electricity generated by power generation enterprises must be balanced. When an imbalance occurs, the power grid must be adjusted. The main means of adjustment are primary frequency regulation and automatic power generation control. During the operation of the hydropower unit, primary frequency regulation control is a basic function of the hydropower unit speed regulation system. When the change in the grid frequency exceeds the frequency dead zone, the hydropower unit speed regulation system changes the load of the unit according to the frequency change. Due to the advantages of high operating reliability and strong regulation stability, the opening mode has always been the main operating mode of the hydropower unit speed regulation system. For hydropower units operating in the opening mode, when the permanent slip rate is constant, the primary frequency regulation adjustment is determined by the frequency deviation, and the grid frequency deviation is generally small, so the primary frequency regulation adjustment is relatively small. At the same time, affected by the nonlinearity of load regulation of hydropower units, when the operating water heads of the units are different, under the same permanent slip rate and the same grid frequency deviation, the primary frequency regulation performance of the units varies greatly.

[0003] Generally speaking, for hydropower units with large operating head changes, when operating in the opening mode, the primary frequency regulation performance under high head and low head operating conditions is quite different. For hydropower units operating in the opening mode, when the grid frequency reaches or exceeds the primary frequency regulation dead zone, regardless of the size of the unit's operating head, its primary frequency regulation action opening (increasing or decreasing the opening) is proportional to the permanent slip rate and frequency deviation. Due to the nonlinear characteristics of hydropower units, the active power changes of different units under different operating heads are usually quite different. For units with large head changes, they usually cannot meet the requirements of the primary frequency regulation load change when operating at low water levels. On the other hand, affected by various factors such as water, machinery, and electricity in the operating environment, although the primary frequency regulation performance of the hydropower unit speed control system is greatly improved when operating in the power mode, the overall regulation performance of the unit is seriously deteriorated. Summary of the invention

[0004] The technical problem to be solved by the present invention is as follows: a method for optimizing the primary frequency regulation performance under the opening mode of a hydropower unit is provided to solve the technical problems in the prior art that, for hydropower units operating under the opening mode, due to the nonlinear characteristics of the hydropower units, the active power changes of different units under different operating heads are usually quite different, and for units subject to large head changes, the requirements for the primary frequency regulation load change are usually not met when operating at a low water level; although the primary frequency regulation performance of the hydropower unit speed control system is greatly improved when operating in the power mode, the overall regulation performance of the unit is seriously deteriorated.

[0005] Technical solution of the present invention:

[0006] A method for optimizing the primary frequency regulation performance of a hydropower unit under an opening mode, characterized in that it comprises: when the unit is connected to the grid and operated, a speed regulation system obtains the current frequency value of the system by measuring f(i) to determine whether the primary frequency regulation of the unit is in operation; when the speed regulation system determines that the primary frequency regulation of the unit is in operation, the speed regulation system simultaneously collects the characteristic parameter K1 of the unit and the operating head parameter K2 of the operating head and adjusts the primary frequency regulation action amount of the unit according to the current characteristics of the unit and the operating head information, thereby achieving the goal of optimizing the primary frequency regulation performance of the unit.

[0007] The method for the speed regulation system to determine whether the primary frequency regulation of the unit is in operation by measuring the current frequency value of the system as f(i) is:

[0008] When |f ed -f(i)|≤f sq When the speed control system determines that the unit primary frequency regulation does not work, then

[0009] A(i)=A G (i)'=A G (i)

[0010] Where: A(i) is the current operating opening value of the unit; A G (i) The opening set value of the monitoring system calculated for the speed control system; A G (i)' is the superposition value of the primary frequency modulation action value and the opening of the monitoring system;

[0011] When |f ed -f(i)|≥f sq When the speed control system determines the unit's primary frequency regulation action, the speed control system collects the unit's characteristic parameter K1 and the operating head parameter K2 and adjusts the unit's primary frequency regulation action amount according to the current unit's characteristics and operating head information. The formula is:

[0012]

[0013] Where: A(i) is the current guide vane opening value of the unit; A G (i) The given value of the guide vane opening of the monitoring system calculated for the speed control system; AG (i)' is the superposition value of the primary frequency modulation action value and the given guide vane opening of the monitoring system; A max is the maximum opening of the guide vane of the unit; f ed is the rated frequency of the system; f(i) is the actual frequency of the power grid; b p is the permanent slip rate set for the unit; K1 is the characteristic parameter of the current unit; K2 is the operating head parameter of the unit.

[0014] For impulse hydropower units, axial-flow propeller hydropower units and mixed-flow hydropower units with a head variation of less than 15 meters, K1=1.10~1.15; for axial-flow fixed-propeller hydropower units and mixed-flow hydropower units with a head variation of greater than or equal to 15 meters and less than 30 meters, K1=1.25~1.30; for mixed-flow hydropower units with a head variation of greater than or equal to 30 meters, K1=1.40~1.45.

[0015] The method for determining the unit operating head parameter K2 is:

[0016] when hour,

[0017]

[0018] when hour,

[0019] K2=1.0;

[0020] when hour,

[0021]

[0022] when hour,

[0023]

[0024] K2 is the current unit operating head parameter; H i H is the current operating water head of the unit; max H is the maximum operating water head of the unit; min H is the minimum operating water head of the unit; r It is the rated operating head of the unit.

[0025] The primary frequency modulation action value includes an increase value or a decrease value.

[0026] Beneficial effects of the present invention:

[0027] The present invention is for hydropower units operating in the opening mode. Affected by the nonlinear characteristics of the hydropower units, the present invention has the problems of poor primary frequency regulation performance and large integral power variation under different water head operating conditions. The present invention does not change the permanent slip rate of the hydropower unit and the calculation method of the primary frequency regulation frequency deviation. By superimposing the characteristic parameters of the unit and the operating water head parameters, the present invention adjusts (increases or decreases) the primary frequency regulation integral power by dynamically calculating the primary frequency regulation action amount, thereby achieving the purpose of optimizing the primary frequency regulation performance of the hydropower unit. The present invention is a practical and efficient method in the field of hydropower unit control.

[0028] The present invention solves the technical problems that, for hydropower units operating in the opening mode in the prior art, due to the nonlinear characteristics of the hydropower units, the active power changes of different units under different operating heads are usually quite different, and for units with large head changes, the requirements for the primary frequency regulation load change are usually not met when operating at low water levels; although the primary frequency regulation performance of the hydropower unit speed regulation system is greatly improved when operating in the power mode, the overall regulation performance of the unit is seriously deteriorated. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0030] The optimization method of the frequency regulation performance of the hydropower unit speed control system under the opening mode is as follows: During the normal operation of the unit connected to the grid, A(i) is the current operating opening value of the unit, and A G (i) is the active power command value P issued by the speed control system through the power plant monitoring system G (i) and the corresponding calculated guide vane opening given value; A G (i)' is the guide vane opening calculation output value corresponding to the superposition of the active power value and the primary frequency regulation action value (increase or decrease) issued by the speed control system; f(i) is the current frequency value of the system; b p The permanent slip rate set for the unit; f ed is the rated frequency of the system; f sq It is the dead zone of primary frequency regulation of the unit.

[0031] When the unit is connected to the grid, the speed control system obtains the current system frequency value f(i) through measurement, and determines whether the unit's primary frequency regulation is in effect:

[0032] 1. When |f ed -f(i)|≤f sq When the speed control system determines that the unit primary frequency regulation does not work, then A(i) = A G (i)'=A G (i)

[0033] Where: A(i) is the current operating opening value of the unit;

[0034] A G (i) The opening setpoint of the monitoring system calculated for the speed control system;

[0035] A G (i)' is the superposition value of the primary frequency modulation action value and the opening of the monitoring system;

[0036] 2. When |f ed -f(i)|≥f sq When the speed control system determines the unit's primary frequency regulation action, the speed control system collects the unit's characteristic parameter K1 and the operating head parameter K2 and adjusts the unit's primary frequency regulation action amount according to the current unit's characteristics and its operating head information. Then:

[0037]

[0038] Where: A(i) is the current guide vane opening value of the unit;

[0039] A G (i) The set value of the guide vane opening of the monitoring system calculated for the speed control system;

[0040] A G (i)' is the superposition value of the primary frequency regulation action value and the given guide vane opening of the monitoring system;

[0041] A max is the maximum opening of the guide vane of the unit;

[0042] f ed is the system rated frequency;

[0043] f(i) is the current actual frequency of the power grid;

[0044] b p The permanent slip rate set for the unit;

[0045] K1 is the characteristic parameter of the current unit;

[0046] K2 is the unit operating head parameter;

[0047] K1 in the above formula is the characteristic parameter of the currently operating unit. For impulse hydropower units, axial-flow propeller hydropower units and mixed-flow hydropower units with a head amplitude less than 15 meters, K1=1.10~1.15; for axial-flow fixed-propeller hydropower units and mixed-flow hydropower units with a head amplitude greater than or equal to 15 meters and less than 30 meters, K1=1.25~1.30; for mixed-flow hydropower units with a head amplitude greater than or equal to 30 meters, K1=1.40~1.45.

[0048] K2 in the above formula is determined according to the following rules:

[0049] ⑴ When hour,

[0050]

[0051] (2) When hour,

[0052] K2=1.0;

[0053] ⑶ When hour,

[0054]

[0055] (4) When hour,

[0056]

[0057] Among them: K2 is the current unit operating head parameter;

[0058] H i The current operating water head of the unit;

[0059] H max is the maximum operating water head of the unit;

[0060] H min is the minimum operating water head of the unit;

[0061] H r is the rated operating water head of the unit;

[0062] Therefore, during the primary frequency regulation action, the speed control system needs to collect the performance characteristics and operating head information of the unit, and then determine the unit's primary frequency regulation action amount after calculation based on the current operating unit characteristic parameter K1 and the unit's operating head parameter K2, so as to achieve the goal of optimizing the unit's primary frequency regulation performance.

Claims

1. A method for optimizing the frequency regulation performance of a hydropower unit under the opening mode, characterized in that: It includes: When the unit is connected to the grid, the speed control system obtains the current system frequency value f(i) by measuring to determine whether the unit's primary frequency regulation is in effect. When the speed control system determines that the unit's primary frequency regulation is in effect, it simultaneously collects the unit's characteristic parameter K1 and the operating water head parameter K2 and adjusts the unit's primary frequency regulation action amount according to the current unit's characteristics and operating water head information, thereby achieving the goal of optimizing the unit's primary frequency regulation performance. The method for the speed regulation system to determine whether the primary frequency regulation of the unit is in operation by measuring the current frequency value of the system as f(i) is: When |f ed -f(i)≤f sq When the speed control system determines that the unit primary frequency regulation does not work, then A(i) = A G (i)'=A G (i) Where: A(i) is the current operating opening value of the unit; A G (i) The opening set value of the monitoring system calculated for the speed control system; A G (i)' is the superposition value of the primary frequency modulation action value and the opening of the monitoring system; When |f ed -f(i)≥f sq When the speed control system determines that the unit is in primary frequency regulation action; f sq It is the dead zone of primary frequency regulation of the unit; The speed control system collects the unit characteristic parameter K1 and the operating head parameter K2 and adjusts the unit's primary frequency regulation action amount according to the current unit characteristics and operating head information. The formula is: Where: A(i) is the current guide vane opening value of the unit; A G (i) The given value of the guide vane opening of the monitoring system calculated for the speed control system; A G (i)' is the superposition value of the primary frequency modulation action value and the given guide vane opening of the monitoring system; A max is the maximum opening of the guide vane of the unit; f ed is the rated frequency of the system; f(i) is the actual frequency of the power grid; b p is the permanent slip rate set for the unit; K1 is the characteristic parameter of the current unit; K2 is the operating head parameter of the unit.

2. The method for optimizing the frequency regulation performance of a hydropower unit under the opening mode according to claim 1 is characterized in that: The value of the unit characteristic parameter K1 is determined as follows: for impulse hydropower units, axial-flow propeller hydropower units and mixed-flow hydropower units with a head amplitude less than 15 meters, K1=1.10~1.15; for axial-flow fixed-propeller hydropower units and mixed-flow hydropower units with a head amplitude greater than or equal to 15 meters and less than 30 meters, K1=1.25~1.30; for mixed-flow hydropower units with a head amplitude greater than or equal to 30 meters, K1=1.40~1.

45.

3. The method for optimizing the primary frequency regulation performance under the opening mode of a hydropower unit according to claim 1, characterized in that: The method for determining the unit operating head parameter K2 is: hour, when hour, K2＝1.0； when hour, when hour, K2 is the current unit operating head parameter; H i H is the current operating water head of the unit; max H is the maximum operating water head of the unit; min H is the minimum operating water head of the unit; r It is the rated operating head of the unit.

4. The method for optimizing the primary frequency regulation performance under the opening mode of a hydropower unit according to claim 1, characterized in that: The primary frequency modulation action value includes an increase value or a decrease value.

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