CN112910016A - Frequency modulation control method for power distribution network - Google Patents

Abstract

The embodiment of the invention discloses a frequency modulation control method for a power distribution network. The method comprises the following steps: calculating the regional control deviation of the power distribution network, the expected dynamic frequency modulation capability of the thermal power generating unit and the expected dynamic frequency modulation capability of the energy storage power station group according to the frequency modulation requirement of the system, and determining the dynamic distribution coefficient of the thermal power generating unit between the thermal power generating unit and the energy storage power station group according to the regional control deviation of the power distribution network, the expected dynamic frequency modulation capability of the thermal power generating unit and the expected dynamic frequency modulation capability of the energy storage power station group; determining a dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group according to the regional control deviation of the power distribution network, the expected dynamic frequency modulation capability of the thermal power unit and the expected dynamic frequency modulation capability of the energy storage power station group; and determining the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group according to the dynamic distribution coefficient of the energy storage power station group between the thermal power generating unit and the energy storage power station group. Therefore, respective frequency modulation output of the energy storage power station group and the thermal power generating unit can be determined, and advantage complementation is achieved.

Description

A kind of frequency regulation control method of distribution network

technical field

The embodiments of the present invention relate to the technical field of automatic power generation control of power systems, and in particular, to a frequency regulation control method of a distribution network.

Background technique

The frequency of the AC power system is one of the most important indicators to measure the power quality, and it is an important control parameter for the operation of the power system. However, with the large-scale integration of distributed power sources such as wind power and photovoltaics into the power grid, the randomness and uncertainty of their output have brought an impact on the power grid. Conventional frequency regulation resources have been unable to meet the grid’s demand for frequency regulation, and the grid’s availability of frequency regulation resources Capacity, response speed and response accuracy all put forward higher requirements.

At present, the traditional frequency modulation units are mainly thermal power units and hydropower units. The traditional thermal power units participating in frequency regulation have inherent defects such as long response time, slow response speed, and low ramp rate. In the case of limited frequency regulation capacity, the frequency regulation control capability for short periods is limited. The frequency regulation capacity and performance of hydroelectric units are also easily affected and restricted by seasons and regions. In addition, such frequency-modulating units are generally rotating mechanical equipment, which is affected by mechanical inertia and physical wear, which not only restricts the further improvement of power quality and grid security, but also increases the maintenance and management costs of the units in the later period.

SUMMARY OF THE INVENTION

The invention provides a frequency regulation control method for a distribution network, so as to realize the frequency regulation requirements of the distribution network, considering the regional control deviation and the expected dynamic frequency regulation capability of each frequency regulation power supply, to determine the dynamic distribution coefficient of the regional control deviation among the frequency regulation power supplies to Determine the FM output of each FM power supply, and finally realize the complementary advantages of each FM power supply.

An embodiment of the present invention provides a frequency regulation control method for a distribution network, the control method comprising:

Calculate the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit, the modified upper limit of the frequency regulation power of each energy storage power station and the lower limit of the modified frequency regulation power of each energy storage power station;

Calculate the expected dynamic frequency modulation capability of each energy storage power station according to the modified upper limit of the frequency modulation power of each energy storage power station and the modified lower limit of the frequency modulation power of each energy storage power station;

Calculate the expected dynamic frequency regulation capability of the energy storage power station group according to the expected dynamic frequency regulation capability of each energy storage power station;

According to the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group, it is determined that the thermal power unit is located between the thermal power unit and the energy storage power station group dynamic distribution coefficient between

According to the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group The dynamic distribution coefficient between groups;

The dynamic distribution coefficient between each energy storage power station in the energy storage power station group is determined according to the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group.

Optionally, the calculating the regional control deviation of the power distribution network includes:

Obtain the power fluctuation and frequency fluctuation of the tie line;

The regional control deviation of the distribution network is calculated from the tie line power fluctuation and the frequency fluctuation.

The calculation formula of the regional control deviation of the distribution network is:

A _ce =ΔP _t +BΔf

Among them, A _ce represents the regional control deviation, ΔP _t represents the deviation between the actual measured value of the exchange power of all tie lines in the control area and the sum of the transaction plan value; Δf represents the difference between the system frequency value and the rated value; represents the control The frequency response coefficient of the area.

Optionally, the calculation formula of the expected dynamic frequency modulation capability of the thermal power unit is:

表示火电机组j的上调的最大发电功率；

表示火电机组j的下调的最小发电功率；T_com表示自动发电控制指令的调度周期；

表示火电机组j功率的上调速率；

表示火电机组j功率的下调速率。Among them, D _aa.g (t) represents the expected dynamic frequency modulation capability of thermal power unit at time t; P _gj (t) represents the active power actually emitted by thermal power unit j at time t;

Indicates the increased maximum power generation of thermal power unit j;

Represents the down-regulated minimum generating power of thermal power unit j; T _com represents the dispatch cycle of the automatic power generation control command;

Indicates the rate of increase in the power of thermal power unit j;

Indicates the down-regulation rate of thermal power unit j power.

Optionally, the calculation formula of the modified upper limit of the frequency regulation power of each energy storage power station is:

表示第i个储能电站修正后的调频功率上限；P_bess,N表示储能电池额定充放电功率；K₁、K₂为人为设定的调节参数；in,

Represents the upper limit of the frequency regulation power after the revision of the i-th energy storage power station; P _bess,N represents the rated charge and discharge power of the energy storage battery; K ₁ and K ₂ are the adjustment parameters set artificially;

The calculation formula of the modified frequency regulation power lower limit of each energy storage power station is:

表示第i个储能电站修正后的调频功率下限。in,

Indicates the revised lower limit of the frequency regulation power of the i-th energy storage power station.

Optionally, the calculation formula of the expected dynamic frequency regulation capability of each energy storage power station is:

表示第i个储能电站修正后的调频功率上限；

表示第i个储能电站修正后的调频功率下限；

表示第i个储能电站功率的放电速率；T_com表示自动发电控制指令的调度周期；

表示第i个储能电站功率的充电速率。Among them, D _aa.i (t) represents the expected dynamic frequency regulation capability of the ith energy storage power station at time t; P _bess.i (t) represents the frequency regulation power of the ith energy storage power station at time t;

Represents the revised upper limit of the frequency regulation power of the i-th energy storage power station;

Indicates the revised lower limit of the frequency regulation power of the i-th energy storage power station;

Represents the discharge rate of the power of the i-th energy storage power station; T _com represents the dispatch cycle of the automatic power generation control command;

Indicates the charging rate of the power of the i-th energy storage power station.

Optionally, calculating the expected dynamic frequency regulation capability of the energy storage power station group according to the expected dynamic frequency regulation capability of each energy storage power station includes:

The sum of the expected dynamic frequency regulation capability of each energy storage power station in the energy storage power station group is equal to the expected dynamic frequency regulation capability of the energy storage power station group.

Optionally, the dynamic distribution coefficient of the thermal power unit between the thermal power unit and the energy storage power station group, and the dynamic distribution of the energy storage power station group between the thermal power unit and the energy storage power station group. The formulas for calculating the distribution coefficient are:

A _ce.g =αA _ce ,α∈[0,1]

A _ce.bess =(1-α)A _ce

表示t时刻区域控制偏差的相对严重程度；

表示t时刻火电机组在所有调频设备中关于动态可调能力的占比；β_l表示

对火电机组动态分配系数的影响程度；D_aa.g(t)表示t时刻火电机组的预期动态调频能力；D_aa.bess(t)表示t时刻储能电站群的预期动态调频能力。Among them, A _ce.g represents the value dynamically allocated to all thermal power units, A _ce.bess represents the value dynamically allocated to the energy storage power station group, α represents the ACE dynamic allocation coefficient of the thermal power unit, and 1-α represents the energy storage power station group ACE dynamic allocation coefficient;

represents the relative severity of the regional control deviation at time t;

Represents the proportion of the dynamic adjustment capability of thermal power units in all frequency modulation equipment at time t; β _l represents

The degree of influence on the dynamic distribution coefficient of thermal power units; D _aa.g (t) represents the expected dynamic frequency regulation capability of the thermal power unit at time t; D _aa.bess (t) represents the expected dynamic frequency regulation capability of the energy storage power station group at time t.

Optionally, the dynamic distribution coefficient between each energy storage power station in the energy storage power station group is determined according to the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group, include:

According to the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group, the expected dynamic frequency regulation capability of the energy storage power station group, and the energy storage power station in the energy storage power station group The expected dynamic frequency regulation capability determines the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group.

Optionally, the calculation formula of the dynamic distribution coefficient between the energy storage power stations in the energy storage power station group is:

A _ce.i = p _i A _ce.bess

表示第i个储能电站的动态调频能力在储能电站群中的占比。Among them, A _ce.i represents the value dynamically allocated to the ith energy storage power station in the energy storage power station group, pi represents the dynamic allocation coefficient of the _ith energy storage power station in the energy storage power station group,

Indicates the proportion of the dynamic frequency regulation capability of the i-th energy storage power station in the energy storage power station group.

The invention provides a frequency regulation control method for a distribution network, according to the frequency regulation requirements of the system, the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group are calculated, and according to the distribution network The regional control deviation of the network, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group determine the dynamic distribution coefficient of the thermal power unit between the thermal power unit and the energy storage power station group; according to the regional control of the distribution network The deviation, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group determine the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group; The dynamic distribution coefficient among the energy storage power station groups determines the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group. From this, the dynamic distribution coefficient of the regional control deviation between the energy storage power station group and the thermal power unit can be determined, so as to determine the respective frequency modulation outputs of the energy storage power station group and the thermal power unit, and finally realize the reasonable distribution of the energy storage power station group and the thermal power unit, and The effect of complementary advantages.

Description of drawings

1 is a flowchart of a method for controlling frequency regulation of a distribution network in an embodiment of the present invention;

FIG. 2 is a block diagram of an AGC control system of a power grid with participation of an energy storage power station group in an embodiment of the present invention;

3 is a schematic diagram of ACE interval division and SOC interval division in an embodiment of the present invention;

FIG. 4 is a schematic diagram of frequency fluctuation under two situations of a dynamic power allocation strategy and a fixed-proportion allocation strategy in an embodiment of the present invention;

5 is a schematic diagram of the frequency fluctuation of the traditional frequency-modulating unit in the embodiment of the present invention under the comparison of the dynamic power allocation strategy and the fixed-proportion allocation strategy;

6 is a schematic diagram of the frequency fluctuation of the No. 1 energy storage power station in the embodiment of the present invention under the comparison of the dynamic power allocation strategy and the fixed-proportion allocation strategy;

7 is a schematic diagram of the frequency fluctuation of No. 2 energy storage power station in the embodiment of the present invention under the comparison of the dynamic power allocation strategy and the fixed-proportion allocation strategy;

8 is a schematic diagram of the SOC change of No. 1 energy storage power station in an embodiment of the present invention under two conditions of a dynamic power allocation strategy and a fixed-proportion allocation strategy;

FIG. 9 is a schematic diagram of SOC changes of No. 2 energy storage power station in the embodiment of the present invention under two conditions of a dynamic power allocation strategy and a fixed-proportion allocation strategy.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all structures related to the present invention.

The embodiment of the present invention provides a frequency regulation control method for a power distribution network, so as to determine the dynamic distribution coefficient of the regional control deviation among the frequency regulation power sources according to the frequency regulation requirements of the system, considering the regional control deviation and the expected dynamic frequency regulation capability of each frequency regulation power supply In order to determine the FM output of each FM power supply, and finally realize the complementary advantages of each FM power supply.

The frequency of the power system reflects the balance between the generated active power and the load. The power grid frequency modulation method mainly includes primary frequency modulation and secondary frequency modulation. The secondary frequency modulation is also called Automatic Generation Control (AGC). control.

The frequency-modulated power supply may include thermal power units and energy storage power stations, and the energy storage power station group includes a plurality of energy storage power stations. Energy storage power stations can be electrochemical energy storage power stations, lithium-ion batteries, sodium-sulfur batteries, vanadium flow batteries, flywheel energy storage, super capacitors, etc. A breakthrough has been achieved, and the basic conditions for engineering application have been obtained. Among them, the output characteristics of the electrochemical energy storage power station have the following characteristics: short response time, fast speed, and the fastest full power output can be achieved in the millisecond time range; in terms of precise control, stable output can be maintained at any power point; two-way adjustment In terms of capability, the adjustment direction is flexible and variable, and it appears as a load when charging and a power source when discharging. Using the energy storage power station with the above characteristics to assist the conventional frequency regulation unit to participate in the frequency regulation of the power grid can significantly improve the frequency recovery speed of the system, reduce the maximum frequency difference, effectively reduce the operating frequency of the traditional frequency regulation unit, reduce mechanical wear and rotational reserve capacity.

FIG. 1 is a flowchart of a method for controlling frequency regulation of a distribution network provided in an embodiment of the present invention. This embodiment is applicable to the implementation process of the frequency regulation control method for the distribution network. Referring to FIG. 1 , it specifically includes the following steps:

Step 110: Calculate the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit, the upper limit of the frequency regulation power after each energy storage power station correction, and the lower limit of the frequency regulation power after the correction of each energy storage power station;

Among them, the area control error (ACE) of the distribution network is used to characterize the frequency regulation demand of the distribution network system. Generally, the greater the regional control deviation, the greater the output demand of the frequency modulation power supply to a certain extent.

The Dynamic Adjustment Ability (DAA) of the FM power supply shows the current support ability of each FM power supply to the frequency. Therefore, the dynamic frequency adjustment ability of each FM power supply needs to be considered when allocating the output of each FM power supply. The dynamic frequency modulation capability of the FM power supply reflects the power input and output capabilities of various FM devices in the scheduling period. Exemplarily, in this embodiment, DAA is defined as: the maximum power adjustment amount of the FM power supply in one AGC command scheduling period. For example, when the frequency-modulated power source is a thermal power unit, the dynamic frequency modulation capability of the thermal power unit reflects the maximum power adjustment amount of the thermal power unit in an AGC command dispatch cycle; when the frequency-modulated power source is an energy storage power station group, the dynamic frequency modulation capability of the energy storage power station group reflects the energy storage. The maximum power adjustment amount of the power station group in one AGC command scheduling cycle.

Step 120: Calculate the expected dynamic frequency modulation capability of each energy storage power station according to the modified upper limit of the frequency modulation power of each energy storage power station and the modified lower limit of the frequency modulation power of each energy storage power station.

Among them, the expected dynamic frequency regulation capability of each energy storage power station reflects the power input and output capabilities of each energy storage power station in its respective dispatch period.

Step 130: Calculate the expected dynamic frequency regulation capability of the energy storage power station group according to the expected dynamic frequency regulation capability of each energy storage power station.

Among them, the expected dynamic frequency regulation capability of the energy storage power station group reflects the maximum power adjustment amount of the energy storage power station group in an AGC command dispatch cycle.

Step 140: Determine the dynamic distribution coefficient of the thermal power unit between the thermal power unit and the energy storage power station group according to the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group.

Among them, by determining the dynamic distribution coefficient of the thermal power unit between the thermal power unit and the energy storage power station group, the value of the regional control deviation dynamically allocated to the thermal power unit can be determined, so that the frequency modulation output of the thermal power unit can be determined.

Step 150: Determine the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group according to the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capacity of the energy storage power station group.

Among them, by determining the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group, the value of the regional control deviation dynamically allocated to the energy storage power station group can be determined, so that the frequency regulation output of the energy storage power station group can be determined.

Step 160: Determine the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group according to the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group.

Specifically, according to the dynamic allocation coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group, the value of the regional control deviation dynamically allocated to the energy storage power station group, that is, the value allocated to all the energy storage power stations, can be determined. Then, according to the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group, the dynamic distribution coefficient between the energy storage power stations in the energy storage power station group can be determined, and then dynamically allocated to all the energy storage power stations according to the regional control deviation. The value of the energy storage station can further determine the frequency modulation output of each energy storage station in the energy storage station group.

In the technical solution of this embodiment, the working principle of the frequency regulation control method for the distribution network: first, calculate the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit, and the corrected upper limit of the frequency regulation power of each energy storage power station. and the revised lower limit of frequency regulation power of each energy storage power station. Then, according to the modified upper limit of frequency regulation power of each energy storage power station and the lower limit of modified frequency regulation power of each energy storage power station, first calculate the expected dynamic frequency regulation capacity of each energy storage power station, and then calculate the energy storage power station according to the expected dynamic frequency regulation capacity of each energy storage power station. The expected dynamic frequency regulation capability of the power station group. Finally, according to the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group, the dynamic distribution coefficient and storage capacity of the thermal power unit between the thermal power unit and the energy storage power station group are calculated respectively. The dynamic distribution coefficient of the thermal power station group between the thermal power station group and the energy storage power station group, so the frequency modulation output of the thermal power station can be determined according to the dynamic distribution coefficient of the thermal power station group between the thermal power station group and the energy storage power station group. The dynamic distribution coefficient of the group between thermal power units and energy storage power stations can determine the frequency modulation output of the energy storage power station group, so as to realize the complementary advantages between the energy storage power station group and the thermal power station group. In addition, the dynamic distribution coefficient between the energy storage power stations in the energy storage power station group can be determined according to the dynamic distribution coefficient of the energy storage power station group between the thermal power station group and the energy storage power station group, so that each storage power station in the energy storage power station group can be further determined. The frequency modulation output of the power station. It can be seen from this that, according to the frequency regulation demand of the distribution network, considering the actual regional control deviation and the expected dynamic frequency regulation capability of each frequency regulation power supply, determine the dynamic distribution coefficient of the regional control deviation between the energy storage power station group and the thermal power unit, so as to determine the storage The frequency regulation output of the energy storage power station group and the thermal power unit can finally realize the reasonable distribution of the energy storage power station group and the thermal power unit, and achieve the effect of complementary advantages.

The technical scheme of this embodiment calculates the regional control deviation of the distribution network, the expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group according to the frequency regulation requirements of the system, and according to the regional control deviation of the distribution network, The expected dynamic frequency regulation capability of the thermal power unit and the expected dynamic frequency regulation capability of the energy storage power station group determine the dynamic distribution coefficient of the thermal power unit between the thermal power unit and the energy storage power station group; The dynamic frequency regulation capability and the expected dynamic frequency regulation capability of the energy storage power station group determine the dynamic distribution coefficient of the energy storage power station group between the thermal power generation unit and the energy storage power station group; The dynamic distribution coefficient of is to determine the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group. From this, the dynamic distribution coefficient of the regional control deviation between the energy storage power station group and the thermal power unit can be determined, so as to determine the respective frequency modulation outputs of the energy storage power station group and the thermal power unit, and finally realize the reasonable distribution of the energy storage power station group and the thermal power unit, and The effect of complementary advantages.

FIG. 2 is a block diagram of a power grid AGC control system with participation of an energy storage power station group provided in an embodiment of the present invention. Optionally, calculate the regional control deviation of the distribution network, including:

Obtain the power fluctuation and frequency fluctuation of the tie line;

Calculate the regional control deviation of the distribution network according to the power fluctuation and frequency fluctuation of the tie line.

Specifically, before calculating the regional control deviation of the distribution network, a frequency regulation control area including the participation of the energy storage power station group is established in the automatic power generation control system AGC. Among them, the block diagram of the grid AGC control system with the participation of the energy storage power station group is shown in Figure 2.

After establishing the frequency regulation control area with the participation of the energy storage power station group in the automatic power generation control system AGC, measure the power fluctuation and frequency fluctuation of the tie line in the frequency regulation control area, and calculate the area of the distribution network according to the obtained tie line power fluctuation and frequency fluctuation. Control deviation.

FIG. 3 is a schematic diagram of ACE interval division and SOC interval division provided in an embodiment of the present invention. Optionally, the calculation formula of the regional control deviation of the distribution network is:

A _ce =ΔP _t +BΔf

Among them, A _ce represents the regional control deviation, ΔP _t represents the deviation between the actual measured value of the exchange power of all tie lines in the control area and the sum of the transaction plan value; Δf represents the difference between the system frequency value and the rated value; represents the control The frequency response coefficient of the zone in MW/Hz.

Among them, the absolute value of the regional control deviation ACE of the distribution network represents the frequency regulation demand of the distribution network. In order to further understand the frequency regulation demand of the distribution network, the absolute value of ACE is divided into intervals. Specifically, referring to FIG. 3 , the absolute value of ACE is divided into the following state intervals: FM dead zone [0, A _{ce, min} ), normal FM zone [A _{ce, min} , A _{ce, mid} ), and sub-emergency FM zone [A ce, mid ] _ce,mid ,A _ce,max ) and the emergency FM region [A _ce,max ,∞). Among them, A _ce,min is the demarcation point between the FM dead zone and the normal FM zone, A _ce,mid is the demarcation point between the normal FM zone and the sub-emergency FM zone, and A _ce,max is the sub-emergency FM zone and the emergency FM zone. Demarcation point between FM regions.

FIG. 4 is a schematic diagram of frequency fluctuation under two conditions of a dynamic power allocation strategy and a fixed-proportion allocation strategy provided by an embodiment of the present invention. Referring to Figure 4, the curve L1 is the frequency fluctuation curve of the distribution network under the dynamic power allocation strategy, and the curve L2 is the frequency fluctuation curve of the distribution network under the fixed proportion allocation strategy. It can be seen from Figure 4 that the distribution network under the dynamic power allocation strategy The maximum transient frequency difference of the grid is relatively small. The dynamic allocation strategy is the dynamic frequency modulation described in the embodiment of the present invention.

Optionally, the dynamic distribution coefficient between the energy storage power stations in the energy storage power station group is determined according to the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group, including:

According to the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group, the expected dynamic frequency modulation capability of the energy storage power station group, and the expected dynamic frequency modulation capability of each energy storage power station in the energy storage power station group The dynamic distribution coefficient among the energy storage power stations.

Among them, the determination of the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group is mainly based on the consideration of their respective dynamic frequency regulation capability DAA.

In an embodiment, the specific implementation process of the frequency regulation control method for the distribution network includes the following steps, specifically:

The first step is to establish a frequency regulation control area with the participation of the energy storage power station group in the automatic power generation control system. Among them, the block diagram of the grid AGC control system with the participation of the energy storage power station group is shown in Figure 2. The control method of the energy storage power station group participating in the secondary frequency regulation is generally based on the area control deviation ACE or the area regulation requirement (ARR) signal Both allocation modes. The main difference between the two control methods of ACE and ARR is that the latter is converted by a PI controller. The ACE or ARR signal is then allocated to FM power according to different participation factors. In order to maximize the advantage of the fast frequency regulation of the energy storage power station, the present invention adopts the frequency regulation control method based on the ACE signal.

The second step is to measure the power fluctuation of the tie line and the frequency fluctuation to calculate the regional control deviation ACE, and divide the ACE into intervals. Refer to Figure 3 for the specific interval division. The third step is to integrate the charging and discharging power of each energy storage power station to calculate the respective state of charge SOC. Since overcharge and overdischarge will affect the life of the energy storage battery, the output of the energy storage power station needs to consider the SOC limit during the operation of the energy storage power station, and the SOC is divided into intervals, as shown in Figure 3.

Among them, the calculation formula of S _OC,i is:

Among them, S _OC,i (t) represents the state of charge of the ith energy storage power station at time t; E _ini,i represents the initial capacity of the ith energy storage power station; P _bess,i (t) represents the ith energy storage station The frequency modulation power of the energy storage power station at time t is assumed to be positive when discharging and negative when charging; EN _,i represents the rated capacity of the i-th energy storage power station.

The fourth step is to calculate the upper and lower limits of the modified frequency regulation power of each energy storage power station according to the division of the SOC interval.

Considering the influence of SOC, the upper limit of frequency regulation power of each energy storage power station is revised. The calculation formula of the revised upper limit of the frequency regulation power of each energy storage power station is:

表示第i个储能电站修正后的调频功率上限；P_besS,N表示储能电池额定充放电功率；K₁、K₂为人为设定的调节参数。in,

Represents the upper limit of the frequency regulation power after the correction of the i-th energy storage power station; P _besS,N represents the rated charge and discharge power of the energy storage battery; K ₁ , K ₂ are the adjustment parameters set artificially.

Considering the influence of SOC, the lower limit of the frequency regulation power of each energy storage power station is revised. The calculation formula of the revised lower limit of frequency regulation power of each energy storage power station is:

表示第i个储能电站修正后的调频功率下限，为负值；S_OC,i表示第i个储能电站在t时刻的荷电状态。in,

Represents the revised lower limit of the frequency regulation power of the i-th energy storage power station, which is a negative value; S _OC,i represents the state of charge of the i-th energy storage power station at time t.

The fifth step is to calculate the expected dynamic frequency regulation DAA of the thermal power unit and the energy storage power station group respectively.

The dynamic frequency modulation capability DAA of the FM power supply should be able to reflect the power input and output capabilities of various FM equipment in the scheduling period. In this embodiment, DAA is defined as: the maximum power adjustment amount of the frequency-modulated power supply in one AGC command scheduling cycle.

The formula for calculating the expected dynamic frequency modulation capability of thermal power units is:

表示火电机组j的上调的最大发电功率；

表示火电机组j的下调的最小发电功率；T_com表示自动发电控制指令的调度周期(单位：s)；

表示火电机组j功率的上调速率(单位：MW/min)；

表示火电机组j功率的下调速率(单位：MW/min)。Among them, D _aa.g (t) represents the expected dynamic frequency modulation capability of thermal power unit at time t; P _gj (t) represents the active power actually emitted by thermal power unit j at time t;

Indicates the increased maximum power generation of thermal power unit j;

Represents the reduced minimum power generation of thermal power unit j; T _com represents the dispatch cycle of the automatic power generation control command (unit: s);

Indicates the rate of increase of thermal power unit j power (unit: MW/min);

Indicates the down-regulation rate of thermal power unit j power (unit: MW/min).

Among them, the thermal power unit has a low ramp rate, so the expected dynamic frequency modulation capability of the thermal power unit is mainly affected by the ramp rate.

The calculation formula of the expected dynamic frequency regulation capacity of each energy storage power station is:

表示第i个储能电站修正后的调频功率上限；

表示第i个储能电站修正后的调频功率下限；

表示第i个储能电站功率的放电速率；T_com表示自动发电控制指令的调度周期；

表示第i个储能电站功率的充电速率。Among them, D _aa.i (t) represents the expected dynamic frequency regulation capability of the ith energy storage power station at time t; P _bess.i (t) represents the frequency regulation power of the ith energy storage power station at time t;

Represents the revised upper limit of the frequency regulation power of the i-th energy storage power station;

Indicates the revised lower limit of the frequency regulation power of the i-th energy storage power station;

Represents the discharge rate of the power of the i-th energy storage power station; T _com represents the dispatch cycle of the automatic power generation control command;

Indicates the charging rate of the power of the i-th energy storage power station.

The calculation formula of the expected dynamic frequency regulation capability of the energy storage power station group is:

Among them, D _aa,bess (t) represents the expected dynamic frequency modulation power of the energy storage power station group at time t.

Usually, the output response speed of the energy storage power station is very fast, so the expected dynamic frequency regulation capability of the energy storage power station is mainly limited by its own state of charge SOC.

The sixth step is to calculate and determine the dynamic distribution coefficient of the regional control deviation ACE in the energy storage power station group and the traditional frequency modulation unit.

Specifically, the calculation formulas of the dynamic distribution coefficient between the thermal power unit and the energy storage power station group, and the dynamic distribution coefficient of the energy storage power station group between the thermal power unit and the energy storage power station group are:

A _ce.g =αA _ce ,α∈[0,1]

A _ce.bess =(1-α)A _ce

表示t时刻区域控制偏差的相对严重程度；

表示t时刻火电机组在所有调频设备中关于动态可调能力的占比；β_l表示

对火电机组动态分配系数的影响程度；D_aa.g(t)表示t时刻火电机组的预期动态调频能力；D_aa.bess(t)表示t时刻储能电站群的预期动态调频能力。Among them, A _ce.g represents the value dynamically allocated to all thermal power units, A _ce.bess represents the value dynamically allocated to the energy storage power station group, α represents the ACE dynamic allocation coefficient of the thermal power unit, and 1-α represents the energy storage power station group ACE dynamic allocation coefficient;

represents the relative severity of the regional control deviation at time t;

Represents the proportion of the dynamic adjustment capability of thermal power units in all frequency modulation equipment at time t; β _l represents

The degree of influence on the dynamic distribution coefficient of thermal power units; D _aa.g (t) represents the expected dynamic frequency regulation capability of the thermal power unit at time t; D _aa.bess (t) represents the expected dynamic frequency regulation capability of the energy storage power station group at time t.

的计算公式为：where the relative severity of regional control deviations

The calculation formula is:

Specifically, when the absolute value of the interval control deviation |A _ce (t)| belongs to the FM dead zone [0, A _{ce, min} ), the distribution coefficient is not considered, and the output adjustment of the FM power supply is 0; when the interval control deviation When the absolute value of |A _ce (t)| belongs to the normal frequency modulation region [A _ce,min ,A _ce,min ), l=1, and when the absolute value of the interval control deviation |A _ce (t)| belongs to the sub-emergency frequency modulation In the area [A _ce,mid ,A _ce,max ), l=2, the value of parameter β _l is determined according to the real-time working conditions of the distribution network and the frequency modulation power supply; when the absolute value of the interval control deviation |A _ce (t) |When it belongs to the emergency frequency regulation area [A _ce,max ,∞), the distribution coefficient is no longer considered, and the energy storage power station and thermal power unit directly output according to the maximum frequency regulation power.

Among them, the determination of the dynamic distribution coefficient of the regional control deviation ACE in the energy storage power station group and traditional frequency regulation units (such as thermal power units) is mainly based on the relative severity of the regional control deviation and the dynamic frequency regulation capability of the frequency regulation power supply.

The greater the regional control deviation, the greater the output demand of the frequency modulation power supply to a certain extent. On the basis of considering the limited capacity of energy storage power stations, when the demand for frequency regulation of the distribution network is large, it is hoped to make full use of the advantages of fast response of energy storage power stations. The dynamic frequency modulation capability of the FM power supply shows the current support ability of each FM power supply to the frequency, and this indicator naturally needs to be considered when allocating the output of each power supply. Moreover, the relative severity of the regional control deviation and the dynamic frequency regulation capability of the FM power supply have different influences on the distribution coefficient in different ACE states, and appropriate adjustments should be made according to the actual situation.

The seventh step is to calculate and determine the dynamic distribution coefficient of ACE among the energy storage power stations in the energy storage power station group. The determination of the dynamic distribution coefficient among the energy storage power stations is mainly based on the consideration of their respective dynamic frequency regulation capability DAA. The calculation formula is as follows:

A _ce.i = p _i A _ce.bess

表示第i个储能电站的动态调频能力在储能电站群中的占比，在此处可直接等同于各储能电站ACE的动态分配系数。Among them, A _ce.i represents the value dynamically allocated to the ith energy storage power station in the energy storage power station group, and pi represents the dynamic allocation coefficient of the _ith energy storage power station in the energy storage power station group.

It represents the proportion of the dynamic frequency regulation capability of the i-th energy storage power station in the energy storage power station group, which can be directly equivalent to the dynamic distribution coefficient of each energy storage power station ACE here.

The eighth step, according to the dynamic distribution coefficient between the energy storage power station group and the thermal power unit calculated in steps 1 to 7, and the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group, reasonably determine the output of each frequency modulation power source.

In addition, FIG. 5 is a schematic diagram of the frequency fluctuation of the traditional frequency modulation unit provided by the embodiment of the present invention under the dynamic power allocation strategy and the fixed-proportion allocation strategy. Referring to FIG. 5, the curve P1 is the traditional frequency modulation unit under the dynamic power allocation strategy. The frequency fluctuation curve of the distribution network, the curve P2 is the frequency fluctuation curve of the distribution network under the fixed proportion allocation strategy of the traditional frequency regulation unit. 6 is a schematic diagram of the frequency fluctuation of the No. 1 energy storage power station provided by the embodiment of the present invention under two situations of a dynamic power distribution strategy and a fixed-proportion allocation strategy. Referring to FIG. 6, the curve P3 is the No. 1 energy storage power station in the dynamic power distribution. The frequency fluctuation curve of the distribution network under the strategy, the curve P4 is the frequency fluctuation curve of the distribution network under the fixed-proportion allocation strategy of the No. 1 energy storage power station. 7 is a schematic diagram of the frequency fluctuation of the No. 2 energy storage power station provided by the embodiment of the present invention under the comparison of the dynamic power allocation strategy and the fixed-proportion allocation strategy. Referring to FIG. 7 , the curve P5 is the No. 2 energy storage power station in the dynamic power allocation. The distribution network frequency fluctuation curve under the strategy, curve P6 is the distribution network frequency fluctuation curve of the No. 2 energy storage power station under the fixed proportion allocation strategy. It can be seen from Fig. 5-Fig. 7, referring to Fig. 5, under the dynamic power distribution strategy, the frequency regulation output of traditional frequency regulation units (such as thermal power units) is relatively smaller than the frequency regulation output under the fixed proportion allocation strategy; with reference to Fig. 6 or Fig. 7, The frequency regulation output of the energy storage power station under the dynamic power allocation strategy is relatively larger than the frequency regulation output under the fixed proportion allocation strategy; from the longitudinal comparison of Figure 6 and Figure 7, it can be seen that the frequency regulation of No. 1 energy storage power station under the dynamic power allocation strategy The output is greater than the frequency modulation output of No. 2 energy storage power station, but the frequency modulation output of the two energy storage power stations changes the same under the fixed-proportion allocation strategy.

8 is a schematic diagram of SOC changes of No. 1 energy storage power station under two conditions of a dynamic power allocation strategy and a fixed-proportion allocation strategy provided by an embodiment of the present invention, and the curve S1 is the SOC of No. 1 energy storage power station under the dynamic power allocation strategy. Change curve, curve S2 is the SOC change curve of No. 1 energy storage power station under the fixed proportion allocation strategy. FIG. 9 is a schematic diagram of SOC changes of No. 2 energy storage power station under two situations of a dynamic power allocation strategy and a fixed-proportion allocation strategy provided by an embodiment of the present invention, and curve S3 is the SOC of No. 2 energy storage power station under the dynamic power allocation strategy. Change curve, curve S4 is the SOC change curve of No. 2 energy storage power station under the fixed proportion allocation strategy. It can be seen from Figure 8 and Figure 9 that under the dynamic power allocation strategy, the SOC of the energy storage power station decreases faster and the drop value is larger; the longitudinal comparison of Figure 8 and Figure 9 shows that the SOC of No. 1 energy storage power station under the dynamic power allocation strategy The decrease is higher than that of No. 2 energy storage power station, and the SOC changes of the two energy storage power stations are the same under the fixed proportion allocation strategy.

Based on the analysis of the above results, under the dynamic power allocation strategy, due to the different settings of the initial SOC values of the two energy storage power stations, the energy storage output based on the dynamic perception of SOC is different. However, the proportional allocation strategy does not consider the influence of SOC at all, the output rules are single, and there is a lack of interaction with the power grid and the energy storage state itself, so it is difficult to give full play to the real advantages of the energy storage power station group participating in AGC. The dynamic power allocation strategy overcomes the above shortcomings, not only improves the frequency regulation effect of the power grid, but also flexibly maintains the SOC of the energy storage power station.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention. The scope is determined by the scope of the appended claims.

Claims (10)

1. A frequency modulation control method for a power distribution network is characterized by comprising the following steps:

respectively calculating the regional control deviation of the power distribution network, the expected dynamic frequency modulation capability of the thermal power generating unit, the modified upper frequency modulation power limit of each energy storage power station and the modified lower frequency modulation power limit of each energy storage power station;

calculating the expected dynamic frequency modulation capacity of each energy storage power station according to the corrected upper frequency modulation power limit of each energy storage power station and the corrected lower frequency modulation power limit of each energy storage power station;

calculating the expected dynamic frequency modulation capability of the energy storage power station group according to the expected dynamic frequency modulation capability of each energy storage power station;

determining a dynamic distribution coefficient of the thermal power generating unit between the thermal power generating unit and the energy storage power station group according to the regional control deviation of the power distribution network, the expected dynamic frequency modulation capability of the thermal power generating unit and the expected dynamic frequency modulation capability of the energy storage power station group;

determining a dynamic distribution coefficient of the energy storage power station group between the thermal power generating unit and the energy storage power station group according to the regional control deviation of the power distribution network, the expected dynamic frequency modulation capability of the thermal power generating unit and the expected dynamic frequency modulation capability of the energy storage power station group;

and determining the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group according to the dynamic distribution coefficient of the energy storage power station group between the thermal power generating unit and the energy storage power station group.

2. The method for frequency modulation control of a power distribution network according to claim 1, wherein said calculating a regional control deviation of said power distribution network comprises:

acquiring power fluctuation and frequency fluctuation of a tie line;

and calculating the regional control deviation of the power distribution network according to the power fluctuation and the frequency fluctuation of the tie line.

3. A frequency modulation control method for a power distribution network according to claim 2, wherein the calculation formula of the regional control deviation of the power distribution network is as follows:

A_ce＝ΔP_t+BΔf

wherein A is_ceIndicating regional control deviation, Δ P_tA deviation representing the sum of the actual measured values of the exchange power of all the links of the control area and the sum of the planned values of the trade; Δ f represents the difference between the system frequency value and the nominal value; representing the frequency response coefficients of the control zone.

4. The power distribution network frequency modulation control method according to claim 1, wherein the expected dynamic frequency modulation capability calculation formula of the thermal power generating unit is as follows:

wherein D is_aa.g(t) representing the expected dynamic frequency modulation capacity of the thermal power generating unit at the moment t; p_g.j(t) representing the active power actually generated by the thermal power generating unit j at the moment t;

representing the maximum generating power of the up regulation of the thermal power generating unit j;

representing a down-regulated minimum generated power of the thermal power generating unit j; t is_comA scheduling period representing an automatic power generation control command;

representing the up-regulation rate of j power of the thermal power generating unit;

and expressing the downward regulation rate of j power of the thermal power generating unit.

5. The power distribution network frequency modulation control method according to claim 1, wherein the calculation formula of the modified frequency modulation power upper limit of each energy storage power station is as follows:

wherein,

representing the upper limit of the frequency modulation power of the ith energy storage power station after correction; s_OC,iIndicates the ith binThe charge state of the energy power station at the moment t; p_bess,NRepresenting the rated charge and discharge power of the energy storage battery; k₁、K₂A human being is a set adjustment parameter;

the calculation formula of the corrected lower limit of the frequency modulation power of each energy storage power station is as follows:

wherein,

and (4) representing the corrected lower limit of the frequency modulation power of the ith energy storage power station.

6. The power distribution network frequency modulation control method according to claim 1, wherein the calculation formula of the expected dynamic frequency modulation capability of each energy storage power station is as follows:

wherein D is_aa.i(t) represents the expected dynamic frequency modulation capacity of the ith energy storage power station at the moment t; p_bess.i(t) the frequency modulation power of the ith energy storage power station at the time t is represented;

representing the upper limit of the frequency modulation power of the ith energy storage power station after correction;

representing the lower limit of the frequency modulation power of the ith energy storage power station after correction;

the discharge rate of the ith energy storage power station power is represented; t is_comA scheduling period representing an automatic power generation control command;

representing the charging rate of the ith energy storage plant power.

7. The power distribution network frequency modulation control method according to claim 1, wherein the calculating the expected dynamic frequency modulation capability of the energy storage power station group according to the expected dynamic frequency modulation capability of each energy storage power station comprises:

the sum of the expected dynamic frequency modulation capacities of the energy storage power stations in the energy storage power station group is equal to the expected dynamic frequency modulation capacity of the energy storage power station group.

8. The power distribution network frequency modulation control method according to claim 1, wherein the calculation formulas of the dynamic distribution coefficient of the thermal power generating unit between the thermal power generating unit and the energy storage power station group and the dynamic distribution coefficient of the energy storage power station group between the thermal power generating unit and the energy storage power station group are respectively:

A_ce.g＝αA_ce,α∈[0,1]

A_ce.bess＝(1-α)A_ce

wherein A is_ce.gRepresenting a value, A, dynamically allocated to all thermal power units_ce.bessExpressing the value dynamically allocated to the energy storage power station group, alpha expressing the ACE dynamic allocation coefficient of the thermal power generating unit, 1-alpha expressing the ACE dynamic allocation coefficient of the energy storage power station group；

Indicating the relative severity of the regional control deviation at time t;

representing the occupation ratio of the thermal power generating unit in all frequency modulation equipment at the moment t on the dynamic adjustable capacity; beta is a_lTo represent

Influence degree on dynamic distribution coefficient of the thermal power generating unit; d_aa.g(t) representing the expected dynamic frequency modulation capacity of the thermal power generating unit at the moment t; d_aa.bessAnd (t) represents the expected dynamic frequency modulation capability of the energy storage power station group at the time t.

9. The method for controlling frequency modulation of a power distribution network according to claim 1, wherein the determining the dynamic distribution coefficients among the energy storage power stations in the energy storage power station group according to the dynamic distribution coefficients of the energy storage power station group between the thermal power generating unit and the energy storage power station group comprises:

and determining the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group according to the dynamic distribution coefficient of the energy storage power station group between the thermal power generating unit and the energy storage power station group, the expected dynamic frequency modulation capability of the energy storage power station group and the expected dynamic frequency modulation capability of each energy storage power station in the energy storage power station group.

10. The power distribution network frequency modulation control method according to claim 9, wherein the calculation formula of the dynamic distribution coefficient among the energy storage power stations in the energy storage power station group is as follows:

A_ce.i＝p_iA_ce.bess

wherein A is_ce.iRepresenting the value, p, dynamically allocated to the i-th energy storage station in the group of energy storage stations_iThe dynamic distribution coefficient of the ith energy storage power station in the energy storage power station group is shown,

and the occupation ratio of the dynamic frequency modulation capacity of the ith energy storage power station in the energy storage power station group is shown.

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