CN110429669A - A kind of main website side control method for frequency of AGC and primary frequency modulation coordination - Google Patents

Abstract

The invention proposes a main station side frequency control method in which AGC and primary frequency modulation are coordinated, and belongs to the technical field of power system active power control. This method first calculates the regional control deviation of the power grid and the AGC frequency regulation demand; traverses all AGC available units, and judges whether the unit is in the primary frequency regulation state and exceeds the set number of AGC cycles; The speed deviation is used to divide the available units into groups; for units belonging to different groups, different methods are used to calculate and issue AGC control commands. The present invention considers the relationship between the operating state of the unit and the state of the current power grid when distributing the AGC control command, ensures the execution of the unit's primary frequency modulation control process, and avoids the deterioration of frequency quality caused by the conflict between the primary frequency modulation and AGC control.

Description

A Master Station Side Frequency Control Method Coordinated by AGC and Primary Frequency Modulation

technical field

The invention belongs to the technical field of power system active power control, and in particular relates to a main station side frequency control method in which AGC and primary frequency modulation are coordinated.

Background technique

Grid frequency is one of the important indicators of power quality. It reflects the balance between active power and load. Ensuring grid frequency stability is conducive to the safety and economic benefits of equipment at multiple levels such as source, grid, and load. One of the most important tasks of the scheduling agency.

In grid frequency control, primary frequency regulation and AGC (automatic generation control) (automatic generation control) have played an important role. The primary frequency regulation is to use the differential adjustment characteristics of the generator set governor to adjust the power of the generator when the frequency deviation is large, so as to improve the unbalanced situation of power generation and reduce the frequency deviation; AGC is to send power to the generator set through the dispatching mechanism Instructions to adjust the active output of the generator set to achieve the goal of reducing the frequency deviation and the transmission power deviation of the tie line. In comparison, primary frequency modulation has the characteristics of fast action speed, but its action range is relatively small, and it is impossible to achieve no-difference adjustment of frequency; AGC can realize no-difference adjustment of frequency, but its action speed is relatively slow. Therefore, the coordinated control of primary frequency modulation and AGC is crucial to grid frequency control.

Since the control objectives, implementation methods, control process, and time scales of primary frequency modulation and AGC are different, the requirements for the power regulation direction of the generator set may be inconsistent. In an emergency, this may lead to reverse adjustment and over-adjustment of the unit, resulting in slow frequency recovery and repeated oscillations, and even further deterioration of frequency quality, resulting in the expansion of the accident.

In order to solve this problem, the patent "a power grid frequency adjustment method coordinated with primary frequency regulation" (patent application number: CN201410700043.0), "optimized control system and method for ensuring primary frequency regulation action under AGC mode of thermal power unit" (patent Application number: CN201610119319.5), "coordinated control method of primary frequency modulation and AGC of thermal power units" (patent application number: CN201610461880.1) discloses a variety of coordinated control methods of primary frequency modulation and AGC of thermal power units, aiming at The control strategy is improved. When the primary frequency regulation is opposite to the AGC control direction, the primary frequency regulation process can be carried out smoothly, so as to meet the assessment requirements of the dispatching organization for primary frequency regulation, and ensure the frequency stability and fault recovery of the power grid. The above methods are all strategic optimizations carried out on the power plant side.

However, due to regulatory and technical reasons, there are still some power plants that do not have a reasonable coordination control function between primary frequency regulation and AGC. The above-mentioned conflict between primary frequency regulation and AGC may still occur, which will seriously threaten the frequency security of the power grid.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and propose a master station side frequency control method in which AGC and primary frequency modulation are coordinated. The present invention considers the relationship between the operating state of the unit and the state of the current power grid when distributing the AGC control command, ensures the execution of the unit's primary frequency modulation control process, and avoids the deterioration of frequency quality caused by the conflict between the primary frequency modulation and AGC control.

The present invention proposes a master station side frequency control method coordinated with AGC and primary frequency modulation, comprising the following steps:

1) At the beginning of the current AGC cycle, read the frequency deviation data of the power grid area and the transmission power deviation data of the tie line, and calculate the control deviation of the grid area and the AGC frequency modulation demand; the specific steps are as follows:

1-1) Denote the AGC cycle as T, the current AGC cycle start time as t, read the frequency deviation data Δf(t) of the power grid area at time t and the transmission power deviation data ΔP _tie (t) of the tie line at time t, and calculate the power grid at time t Regional control deviation ACE(t)=BΔf(t)+ΔP _tie (t), where B is the regional frequency deviation coefficient of the power grid;

1-2) Calculate AGC frequency modulation demand at time t ΔP _R (t)=K _P ACE(t)+K _I IACE(t);

Among them, K _P and K _I are the gain coefficients of the proportional component and the integral component respectively; IACE(t) is the integral component of the regional control deviation at time t, and the calculation expression is as follows:

IACE(t)=IACE(t-T)+T×ACE(t)

Among them, t-T is the start time of the previous AGC cycle; the initial value of IACE(t) at the start time of the first AGC cycle is 0;

2) Traverse all AGC available units, read the local frequency modulation signal and speed data of the unit, and judge whether the unit is in a frequency modulation state for more than M AGC cycles; the specific steps are as follows:

2-1) For the AGC available unit whose unit serial number is i, read the local primary frequency modulation signal F _Local,i (t) of the unit at time t; F _Local,i (t)=1 means that the AGC available unit whose unit serial number is i It is in the state of primary frequency regulation at time t, and F _Local,i (t)=0 means that the unit is not in the state of primary frequency regulation at time t;

2-2) Supplementary judgment is made on the primary frequency regulation state of the unit in step 2-1) by using the rotational speed data; the specific method is as follows:

2-2-1) For the AGC available unit with unit number i, read the speed data ω _i (t) of the unit at time t, and calculate the speed deviation of the unit at time t Δω _i (t)=ω _i (t)-ω _n , where ω _n is the rated speed of the unit;

2-2-2) For the AGC available unit whose unit serial number is i, compare the speed deviation Δω _i (t) with the corresponding primary frequency regulation action threshold of the unit Compare: if Then it is judged that the unit is in a frequency regulation state at time t but there is data missing or error in F _Local,i (t), and the remote primary frequency regulation flag of the unit at time t is set as F _Remote,i (t)=1; otherwise, it is judged that the unit t If it is not in the state of primary frequency regulation at all times, the remote primary frequency regulation of the unit at time t is marked as F _{Remote, i} (t)=0;

2-3) For the AGC available unit whose unit serial number is i, if it exists Then the unit is in a frequency regulation state at time t for more than M AGC cycles, and the first frequency regulation flag at time t of the unit is set as F _i (t)=1; if there is and Then the unit is in a frequency regulation state at time t for more than M AGC cycles, but F _Local,i (t) has data missing or wrong, and the unit frequency regulation flag at time t is set to F _i (t) = 1; otherwise, the The first frequency modulation flag of the unit at time t is set to F _i (t) = 0;

3) According to the AGC frequency regulation demand ΔP _R (t) at time t, the primary frequency regulation status of AGC available units at time t, and the unit speed deviation Δω _i (t), divide all AGC available units into control groups; the specific steps are as follows:

3-1) For the AGC available unit whose serial number is i, if the unit is not in the state of primary frequency regulation at time t or is in the state of primary frequency regulation for less than M AGC cycles, that is, the primary frequency regulation flag F _i (t) = 0, then set The unit is classified into the control group A, enter step 4-1);

3-2) For the AGC available unit whose unit number is i, if the unit is in a frequency modulation state at time t and has exceeded M AGC cycles, that is, the frequency modulation flag F _i (t) = 1, and the direction of the frequency modulation action is the same as that of the AGC action If the directions are the same, that is, Δω _i (t)×ΔP _R (t)≥0, then the unit is classified into the control group A and enters step 4-1);

3-3) For the AGC available unit whose unit number is i, if the unit is in a frequency modulation state at time t and has exceeded M AGC cycles, that is, the frequency modulation flag F _i (t) = 1, and the direction of the frequency modulation action is the same as that of the AGC action If the directions are inconsistent, that is, Δω _i (t)×ΔP _R (t)<0, then the unit is classified into control group B and enters step 4-2);

4) According to the result of step 3), take corresponding AGC instructions for different groups of units:

4-1) For the units belonging to the control group A, the AGC frequency regulation demand is distributed proportionally according to the available frequency regulation capacity, and is superimposed with the current actual output of the unit and set as the current AGC cycle AGC command; the calculation expression is as follows:

P _cmd,j (t)=P _g,j (t)+ΔP _R,j (t),j=1,2,...,J

Among them, P _cmd,j (t) is the AGC command of unit j belonging to control group A at time t in the current AGC cycle, and P _g,j (t) is the current actual output of unit j belonging to control group A at time t , ΔP _R,j (t) is the AGC frequency regulation demand allocated to the units belonging to the control group A at time jt, P _avail,j (t) is the available frequency regulation capacity of the units belonging to the control group A at time jt, and P _j are the output upper limit and lower limit of unit j belonging to control group A respectively, j is the serial number of the unit belonging to control group A, and J is the total number of units belonging to control group A;

4-2) For the unit belonging to the control group B, update the current AGC cycle AGC command of the unit to the actual output average value within 10 seconds before the unit participates in a frequency regulation action; the calculation expression is as follows:

Among them, P _cmd,k (t) is the AGC instruction of unit k belonging to control group B at time t in the current AGC cycle, t ^* is the moment when unit k belonging to control group B starts frequency regulation, Δt is 10 seconds, k is the serial number of the unit belonging to the control group B, and K is the total number of units belonging to the control group B;

5) When the next AGC period arrives, return to step 1).

Features and beneficial effects of the present invention are:

The invention can ensure the execution of the primary frequency modulation control process of the generating set when the primary frequency modulation and AGC control directions are inconsistent, and fully exert the positive effect of the primary frequency modulation on frequency stability, while not affecting the execution of the AGC function in other states. Another advantage of the present invention is that it does not depend on the coordinated control strategy of primary frequency regulation and AGC on the generating set side, and can play a role in generating sets adopting different coordinated control strategies, ensuring the mutual support of the whole network generating sets in frequency emergencies and contribute.

Description of drawings

Fig. 1 is the overall flowchart of the method of the present invention.

Detailed ways

A master station-side frequency control method in which AGC and primary frequency modulation are coordinated by the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

A master station-side frequency control method for coordination between AGC and primary frequency modulation proposed by the present invention, the overall process is shown in Figure 1, including the following steps:

1) At the beginning of the current AGC cycle, read the grid area frequency deviation data and tie line transmission power deviation data from the data acquisition and monitoring control system, and calculate the grid area control deviation and AGC frequency modulation requirements. Specific steps are as follows:

1-1) Denote the AGC cycle as T, the current AGC cycle start time as t, and read the frequency deviation data Δf(t) (unit: Hz) of the power grid area at time t from the data acquisition and monitoring control system and the tie line transmission at time t Power deviation data ΔP _tie (t) (unit: MW), calculate grid area control deviation ACE (t) = BΔf (t) + ΔP _tie (t) at time t, where B is grid area frequency deviation coefficient (unit: MW/ Hz).

1-2) Calculate AGC frequency modulation demand ΔP _R (t)=K _P ACE (t)+K _I IACE (t) at time t, wherein K _P and K _I are proportional component and integral component gain coefficient respectively (two coefficients The value range is usually between -1 and 0), IACE(t) is the integral component of the regional control deviation at time t, and the calculation expression is as follows:

IACE(t)=IACE(t-T)+T×ACE(t)

Among them, t-T is the start time of the last AGC cycle; the initial value of IACE(t) is 0 at the start time of the first AGC cycle.

2) Traverse all AGC available units, read the local primary frequency modulation signal and speed data of the unit from the remote terminal device of the power plant, and judge whether the unit is in the primary frequency modulation state exceeding M (M is a positive number, the recommended value is 5~10) AGC cycle. Specific steps are as follows:

2-1) For the AGC available unit whose unit serial number is i, read the local primary frequency modulation signal F _Local,i (t) of the unit at time t from the remote terminal device of the power plant. In particular, F _Local,i (t)=1 indicates that the AGC available unit with unit number i is in the primary frequency regulation state at time t, and F _Local,i (t)=0 indicates that the AGC available unit with unit number i is not in the primary frequency regulation state at time t.

2-2) Considering that the data transmitted through the remote terminal device may have missing or incorrect data, the rotation speed data is used to supplement the primary frequency regulation status of the unit in step 2-1). The specific method is as follows:

Step 2-2) is to prepare data for the results in verification 2-1) (the verification step is 2-3)). When the result in 2-1) is 1, the calculation result of 2-2) does not play a role in the control strategy, but it should still be calculated in order to maintain the validity of the data.

2-2-1) For the AGC available unit with unit number i, read the speed data ω _i (t) (unit: r/min) of the unit at time t from the remote terminal device of the power plant, and calculate the speed deviation Δω of the unit at time t _i (t)=ω _i (t)-ω _n , where ω _n is the rated speed of the unit, generally 3000r/min. Especially for a unit with multiple speed data, the average or median value of the speed data at time t is selected as the speed data at this time to calculate the speed deviation.

2-2-2) For the AGC available unit whose unit serial number is i, compare the speed deviation Δω _i (t) with the corresponding primary frequency regulation action threshold of the unit Compare: if Then it is judged that the unit may be in the state of primary frequency regulation at time t but there is data missing or error in F _Local,i (t), and the remote primary frequency regulation flag of the unit at time t is set as F _Remote,i (t)=1; otherwise, it is judged that the unit If the time t is not in the state of primary frequency regulation, the remote primary frequency regulation of the unit at time t is marked as F _Remote,i (t)=0. In particular, for hydroelectric units (including pumped storage), Generally take 3r/min, for other units, Generally take 2r/min.

2-3) For the available unit of AGC whose unit serial number is i, if there is Then it is considered that the unit is in a frequency regulation state at time t for more than M AGC cycles, and the first frequency regulation flag at time t of the unit is set as F _i (t)=1; if there is but Then it is considered that the unit is in a frequency regulation state at time t for more than M AGC cycles, but F _Local,i (t) has data missing or wrong, and the first frequency regulation flag of the unit at time t is still set as F _i (t) = 1; otherwise Set the unit's primary frequency modulation flag to F _i (t)=0.

3) According to the AGC frequency regulation demand ΔP _R (t) at time t, the primary frequency regulation status of AGC available units at time t, and the unit speed deviation Δω _i (t), divide the control groups of all AGC available units. Specific steps are as follows:

3-1) For the AGC available unit whose serial number is i, if the unit is not in the state of primary frequency regulation at time t or is in the state of primary frequency regulation for less than M AGC cycles, that is, the primary frequency regulation flag F _i (t) = 0, then set The unit is classified into control group A, and enters step 4-1).

3-2) For the AGC available unit whose unit number is i, if the unit is in a frequency modulation state at time t and has exceeded M AGC cycles, that is, the frequency modulation flag F _i (t) = 1, and the direction of the frequency modulation action is the same as that of the AGC action If the directions are the same, that is, Δω _i (t)×ΔP _R (t)≥0, then the unit is classified into control group A and enters step 4-1).

3-3) For the AGC available unit whose unit number is i, if the unit is in a frequency modulation state at time t and has exceeded M AGC cycles, that is, the frequency modulation flag F _i (t) = 1, and the direction of the frequency modulation action is the same as that of the AGC action If the directions are inconsistent, that is, Δω _i (t)×ΔP _R (t)<0, then the unit is classified into control group B and enters step 4-2).

4) According to the result of step 3), take corresponding AGC instructions for different groups of units:

4-1) For the units belonging to the control group A, the AGC frequency regulation demand is distributed proportionally according to the available frequency regulation capacity, and is superimposed with the current actual output of the unit and set as the current AGC cycle AGC command; the calculation formula is as follows:

P _cmd,j (t)=P _g,j (t)+ΔP _R,j (t),j=1,2,...,J

Among them, P _cmd,j (t) is the AGC command (unit: MW) of unit j belonging to control group A at time t in the current AGC cycle, and P _g,j (t) is the command of unit j belonging to control group A The current actual output at time t (unit: MW), ΔP _R,j (t) is the AGC frequency regulation demand (unit: MW) assigned by the units belonging to the control group A at time jt, and P _avail,j (t) is the The available frequency regulation capacity (unit: MW) of the units in group A at time jt, and P _j are the upper limit and lower limit of output of unit j belonging to control group A, respectively, j is the serial number of units belonging to control group A, and J is the total number of units belonging to control group A.

4-2) For the unit belonging to the control group B, update the current AGC cycle AGC command of the unit to the actual output average value within 10 seconds before the unit participates in a frequency regulation action; the calculation formula is as follows:

Among them, P _cmd,k (t) is the AGC command (unit: MW) of unit k belonging to the control group B at time t in the current AGC period, and t ^* is the time when unit k belonging to the control group B starts a frequency regulation, Δt is 10 seconds, k is the serial number of the units belonging to the control group B, and K is the total number of units belonging to the control group B.

5) When the next AGC period arrives, return to step 1).

Claims (1)

1. A master station side frequency control method coordinated by AGC and primary frequency modulation, is characterized in that, comprises the following steps: 1) At the beginning of the current AGC cycle, read the frequency deviation data of the power grid area and the transmission power deviation data of the tie line, and calculate the control deviation of the grid area and the AGC frequency modulation demand; the specific steps are as follows: 1-1) Denote the AGC cycle as T, the current AGC cycle start time as t, read the frequency deviation data Δf(t) of the power grid area at time t and the transmission power deviation data ΔP _tie (t) of the tie line at time t, and calculate the power grid at time t Regional control deviation ACE(t)=BΔf(t)+ΔP _tie (t), where B is the regional frequency deviation coefficient of the power grid; 1-2) Calculate AGC frequency modulation demand at time t ΔP _R (t)=K _P ACE(t)+K _I IACE(t); Among them, K _P and K _I are the gain coefficients of the proportional component and the integral component respectively; IACE(t) is the integral component of the regional control deviation at time t, and the calculation expression is as follows: IACE(t)=IACE(t-T)+T×ACE(t) Among them, t-T is the start time of the previous AGC cycle; the initial value of IACE(t) at the start time of the first AGC cycle is 0; 2) Traverse all AGC available units, read the local frequency modulation signal and speed data of the unit, and judge whether the unit is in a frequency modulation state for more than M AGC cycles; the specific steps are as follows: 2-1) For the AGC available unit whose unit serial number is i, read the local primary frequency modulation signal F _Local,i (t) of the unit at time t; F _Local,i (t)=1 means that the AGC available unit whose unit serial number is i It is in the state of primary frequency regulation at time t, and F _Local,i (t)=0 means that the unit is not in the state of primary frequency regulation at time t; 2-2) Supplementary judgment is made on the primary frequency regulation state of the unit in step 2-1) by using the rotational speed data; the specific method is as follows: 2-2-1) For the AGC available unit with unit number i, read the speed data ω _i (t) of the unit at time t, and calculate the speed deviation of the unit at time t Δω _i (t)=ω _i (t)-ω _n , where ω _n is the rated speed of the unit; 2-2-2) For the AGC available unit whose unit serial number is i, compare the speed deviation Δω _i (t) with the corresponding primary frequency regulation action threshold of the unit Compare: if Then it is judged that the unit is in a frequency regulation state at time t but there is data missing or error in F _Local,i (t), and the remote primary frequency regulation flag of the unit at time t is set as F _Remote,i (t)=1; otherwise, it is judged that the unit t If it is not in the state of primary frequency regulation at all times, the remote primary frequency regulation of the unit at time t is marked as F _{Remote, i} (t)=0; 2-3) For the AGC available unit whose unit serial number is i, if it exists Then the unit is in a frequency regulation state at time t for more than M AGC cycles, and the first frequency regulation flag at time t of the unit is set as F _i (t)=1; if there is and Then the unit is in a frequency regulation state at time t for more than M AGC cycles, but F _Local,i (t) has data missing or wrong, and the unit frequency regulation flag at time t is set to F _i (t) = 1; otherwise, the The first frequency modulation flag of the unit at time t is set to F _i (t) = 0; 3) According to the AGC frequency regulation demand ΔP _R (t) at time t, the primary frequency regulation status of AGC available units at time t, and the unit speed deviation Δω _i (t), divide all AGC available units into control groups; the specific steps are as follows: 3-1) For the AGC available unit whose serial number is i, if the unit is not in the state of primary frequency regulation at time t or is in the state of primary frequency regulation for less than M AGC cycles, that is, the primary frequency regulation flag F _i (t) = 0, then set The unit is classified into the control group A, enter step 4-1); 3-2) For the AGC available unit whose unit number is i, if the unit is in a frequency modulation state at time t and has exceeded M AGC cycles, that is, the frequency modulation flag F _i (t) = 1, and the direction of the frequency modulation action is the same as that of the AGC action If the directions are the same, that is, Δω _i (t)×ΔP _R (t)≥0, then the unit is classified into the control group A and enters step 4-1); 3-3) For the AGC available unit whose unit number is i, if the unit is in a frequency modulation state at time t and has exceeded M AGC cycles, that is, the frequency modulation flag F _i (t) = 1, and the direction of the frequency modulation action is the same as that of the AGC action If the directions are inconsistent, that is, Δω _i (t)×ΔP _R (t)<0, then the unit is classified into control group B and enters step 4-2); 4) According to the result of step 3), take corresponding AGC instructions for different groups of units: 4-1) For the units belonging to the control group A, the AGC frequency regulation demand is distributed proportionally according to the available frequency regulation capacity, and is superimposed with the current actual output of the unit and set as the current AGC cycle AGC command; the calculation expression is as follows: P _cmd,j (t)=P _g,j (t)+ΔP _R,j (t),j=1,2,...,J Among them, P _cmd,j (t) is the AGC command of unit j belonging to control group A at time t in the current AGC cycle, and P _g,j (t) is the current actual output of unit j belonging to control group A at time t , ΔP _R,j (t) is the AGC frequency regulation demand allocated to the units belonging to the control group A at time jt, P _avail,j (t) is the available frequency regulation capacity of the units belonging to the control group A at time jt, and P _j are the output upper limit and lower limit of unit j belonging to control group A respectively, j is the serial number of the unit belonging to control group A, and J is the total number of units belonging to control group A; 4-2) For the unit belonging to the control group B, update the current AGC cycle AGC command of the unit to the actual output average value within 10 seconds before the unit participates in a frequency regulation action; the calculation expression is as follows: Among them, P _cmd,k (t) is the AGC instruction of unit k belonging to control group B at time t in the current AGC cycle, t ^* is the moment when unit k belonging to control group B starts frequency regulation, Δt is 10 seconds, k is the serial number of the unit belonging to the control group B, and K is the total number of units belonging to the control group B; 5) When the next AGC period arrives, return to step 1).