阅读说明：本技术 一种移动式储能电池参与分布式电源电能分配方法 (Method for distributing electric energy of distributed power supply by participation of mobile energy storage battery ) 是由 *** 费骏韬 朱寰 袁晓冬 李建林 王耿耿 孟高军 于 2019-11-07 设计创作，主要内容包括：本发明公开了一种移动式储能电池参与分布式电源电能分配方法,针对目前分布式电源并网时普遍存在的谐波、三相不平衡以及无功问题引起的电压问题,在考虑移动式储能电池的荷电状态的基础上,提出一种基于SOC反馈的移动式储能电池工作模式自适应控制策略,通过对电网中存在的电能质量问题设定优先级,根据移动式储能电池SOC状态自适应治理相应等级的电能质量问题。本发明将基于SOC反馈的移动式储能电池工作模式自适应治理技术,有效的改善电网的电能质量问题,延长移动式储能电池寿命。(The invention discloses a method for distributing electric energy of a mobile energy storage battery participating in distributed power supply, which aims at the voltage problem caused by harmonic wave, three-phase imbalance and reactive power problems commonly existing in the grid connection of the existing distributed power supply, provides a mobile energy storage battery working mode self-adaptive control strategy based on SOC feedback on the basis of considering the charge state of the mobile energy storage battery, sets priority for the electric energy quality problem existing in a power grid, and adaptively controls the electric energy quality problem of a corresponding grade according to the SOC state of the mobile energy storage battery. The invention effectively solves the problem of power quality of a power grid by adopting a mobile energy storage battery working mode self-adaptive management technology based on SOC feedback, and prolongs the service life of the mobile energy storage battery.)

1. A method for distributing electric energy of a mobile energy storage battery participating in a distributed power supply is applied to a power supply system simultaneously comprising two power supply sources of the mobile energy storage battery and the distributed power supply, and comprises the following steps of collecting electric energy quality related electric power data of the power supply system, calculating an adjustment target of each electric power data, establishing an electric energy distribution model of the energy storage battery and the distributed power supply, and calculating to obtain the output of the energy storage battery and the distributed power supply under the condition of meeting the constraint condition of the electric power system, wherein before the output of the energy storage battery and the distributed power supply is obtained through calculation, the electric energy quality problem which is preferentially solved is selected according to the state of the mobile energy storage battery:

(1) partitioning the charge state of the mobile energy storage battery according to the magnitude of the charge quantity;

(2) setting priorities for power quality problems in a power grid according to power quality treatment requirements of the power grid for the power grid in different time periods, dividing N power quality problems in the power grid into two priorities according to treatment urgency, respectively representing the two priorities by 1 and 0, and establishing a power quality problem priority matrix A:

A＝[A_N，A_N-1，A_N-2，…A₂，A₁]

(3) collecting the actual charge states of M mobile energy storage batteries to form a capacity matrix B of the mobile energy storage batteries participating in power quality control,

B＝[B_M，B_M-1，B_M-2，…B₂，B₁]

when the charge state of the mobile energy storage battery is in the partition with the minimum charge quantity in the step (1), the mobile energy storage battery is in a forbidden state, and the power supply state of the mobile energy storage battery is set to be 0;

(4) calculating the average value B of the elements in the capacity matrix B_avAccording to the average value B_avJudging which kind of power quality problem is preferentially treated by the mobile energy storage battery according to the charge state partition of the mobile energy storage battery, and when the average value B is_avWhen the voltage is less than the set threshold value, the battery stops discharging, and does not participate in power quality management of the power grid, so that the mobile energy storage battery is protected.

2. The method of claim 1, wherein the method comprises the steps of: the partitioning of the charge state of the mobile energy storage battery in the step (1) comprises a discharge priority area, a normal charge and discharge area, a charge priority area and a forbidden area, and the charge amount corresponding to each partition is reduced in sequence.

3. The method of claim 2, wherein the mobile energy storage battery participates in the distribution of power of the distributed power supply, and the method comprises the following steps: the charge states of the mobile energy storage battery are 65% -100%, 35% -65%, 10% -35% and 0-10% respectively corresponding to the discharge priority area, the normal charge and discharge area, the charge priority area and the forbidden area.

4. The method of claim 3, wherein the method comprises the steps of: the power quality problems in step (2) include harmonic, three-phase imbalance, voltage deviation, frequency deviation, voltage sag, voltage fluctuation and flicker, temporary or transient overvoltage, and inter-power system harmonic problems.

5. The method of claim 4, wherein the method comprises the steps of: according to the average value B described in step (4)_avThe method for judging the power quality problem of the mobile energy storage battery comprises the following steps:

(41) if B is judged for the first time_avThe problems of harmonic waves, three-phase imbalance, voltage deviation and frequency deviation are treated preferentially if the frequency deviation is more than 0.65, and the step (42) is carried out; if 0.65 > B_avIf the harmonic wave and three-phase imbalance problem is solved preferentially, jumping to the step (43); if 0.35 > B_avIf the harmonic wave is more than 0.1, the harmonic wave problem is preferably treated, and the step (44) is skipped;

(42) redetermining the average value B_avIf B is_avIf not, the voltage drop, voltage fluctuation and flicker, temporary or transient overvoltage and inter-harmonic problems of the power system are continuously treated until the treatment is finished; if 0.65 > B_avIf the voltage drop and voltage fluctuation and flicker problems are treated preferentially, and the step (45) is skipped; if 0.35 > B_avIf the voltage drop is more than 0.1, the voltage drop problem is preferably treated, and the step (46) is skipped;

(43) redetermining the average value B_avIf B is_avIf the voltage deviation and the frequency deviation are more than 0.35, continuing to treat the problems until the treatment is finished;

(44) redetermining the average value B_avIf B is_avIf more than 0.1, continuing to treat the three-phase imbalance problem until the treatment is finished; if average value B_avIf the voltage is lower than 0.1, the storage battery is stopped to participate in the power quality control;

(45) redetermining the average value B_avIf 0.65 > B_avIf the voltage is more than 0.35, continuing to treat the temporary or transient overvoltage and inter-harmonic problems of the power system until the treatment is finished;

(46) redetermining the average value B_avIf B is_avThe voltage drop problem is continuously treated until the treatment is finished when the voltage drop problem is more than 0.1; if average value B_avAnd if the voltage is lower than 0.1, the storage battery is stopped to participate in power supply.

6. The method of claim 1, wherein the method comprises the steps of: in the step (4), the set threshold is 0.1.

Technical Field

The invention relates to an electric energy scheduling method of an electric power system, in particular to a scheduling method of a mobile energy storage battery participating in electric energy distribution of a distributed power supply.

Background

With the large-scale grid connection of clean energy power generation represented by wind energy and solar energy, the safe operation of a power system is seriously threatened, and due to the volatility and randomness of wind power generation and solar power generation, and the wide use of power electronic devices in the current power grid and a large number of nonlinear loads, the problems of harmonic waves, reactive power, three-phase imbalance and other power quality in the power grid are serious, so that the serious challenge is brought to the safe stability of the power system. The traditional electric energy management means comprise an on-load tap changer, a shunt capacitor bank, an RLC passive filter and the like, the principle of the equipment is simple, the construction and maintenance costs are low, and the traditional electric energy management means have more defects in application. With the development of energy storage technology, the mobile energy storage battery becomes a key point of attention as a novel power quality management means of a power grid. However, how to efficiently manage the power quality of the power grid by using the existing energy storage resources on the premise of not damaging the service life of the mobile energy storage battery is a key problem of current research.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems, the invention provides a method for distributing electric energy of a mobile energy storage battery participating distributed power supply, which can be used for meeting the problem that the electric energy quality of a power grid is adaptively controlled at different time periods, effectively improving the electric energy quality of the power grid, prolonging the service life of the mobile energy storage battery and improving the economical efficiency of the mobile energy storage battery participating in the electric energy quality control.

The technical scheme is as follows: the technical scheme adopted by the invention is a method for distributing electric energy of a distributed power supply by a mobile energy storage battery, which is applied to a power supply system simultaneously comprising two power supply sources of the mobile energy storage battery and the distributed power supply. The conventional power distribution method comprises the steps of collecting power quality related power data of a power supply system; calculating an adjustment target of each power data; establishing an electric energy distribution model of an energy storage battery and a distributed power supply; and finally, calculating to obtain the output of the energy storage battery and the distributed power supply under the condition of meeting the constraint condition of the power system. Before calculating the output of the energy storage battery and the distributed power supply, the invention selects the electric energy quality problem to be solved preferentially according to the state of the mobile energy storage battery, and specifically comprises the following steps:

(1) partitioning the charge state of the mobile energy storage battery according to the magnitude of the charge quantity; the specific subareas are divided into a discharging priority area, a normal charging and discharging area, a charging priority area and a forbidden area, and the charge quantity corresponding to each subarea is reduced in sequence. Optimally, the charge states of the mobile energy storage batteries corresponding to the partitions are 65-100%, 35-65%, 10-35% and 0-10% respectively.

(2) Setting priorities for power quality problems in a power grid according to power quality treatment requirements of the power grid for the power grid in different time periods, dividing N power quality problems in the power grid into two priorities according to treatment urgency, respectively representing the two priorities by 1 and 0, and establishing a power quality problem priority matrix A:

A＝[A_N，A_N-1，A_N-2，…A₂，A₁]

the power quality problems include harmonic waves, three-phase imbalance, voltage deviation, frequency deviation, voltage sag, voltage fluctuation and flicker, temporary or transient overvoltage and inter-power system harmonic wave problems.

(3) Collecting the actual charge states of M mobile energy storage batteries to form a capacity matrix B of the mobile energy storage batteries participating in power quality control,

B＝[B_M，B_M-1，B_M-2，…B₂，B₁]

when the charge state of the mobile energy storage battery is in the partition with the minimum charge quantity in the step (1), the mobile energy storage battery is in a forbidden state, and the power supply state of the mobile energy storage battery is set to be 0;

(4) calculating the average value B of the elements in the capacity matrix B_avAccording to the average value B_avJudging which kind of power quality problem is preferentially treated by the mobile energy storage battery according to the charge state partition of the mobile energy storage battery, and when the average value B is_avWhen the voltage is less than the set threshold value, the battery stops discharging, and does not participate in power quality management of the power grid, so that the mobile energy storage battery is protected. The set threshold is 0.1.

Wherein said is based on the average value B_avThe method for judging the power quality problem of the mobile energy storage battery comprises the following steps:

(41) if B is judged for the first time_avThe problems of harmonic waves, three-phase imbalance, voltage deviation and frequency deviation are treated preferentially if the frequency deviation is more than 0.65, and the step (42) is carried out; if 0.65 > B_avIf the harmonic wave and three-phase imbalance problem is solved preferentially, jumping to the step (43); if 0.35 > B_avIf the harmonic wave is more than 0.1, the harmonic wave problem is preferably treated, and the step (44) is skipped;

(42) redetermining the average value B_avIf B is_avIf not, the voltage drop, voltage fluctuation and flicker, temporary or transient overvoltage and inter-harmonic problems of the power system are continuously treated until the treatment is finished; if 0.65 > B_avIf the voltage drop and voltage fluctuation and flicker problems are treated preferentially, and the step (45) is skipped; if 0.35 > B_avIf the voltage drop is more than 0.1, the voltage drop problem is preferably treated, and the step (46) is skipped;

(43) redetermining the average value B_avIf B is_avIf the voltage deviation and the frequency deviation are more than 0.35, continuing to treat the problems until the treatment is finished;

(44) redetermining the average value B_avIf B is_avIf more than 0.1, continuing to treat the three-phase imbalance problem until the treatment is finished; if average value B_avIf the voltage is lower than 0.1, the storage battery is stopped to participate in the power quality control;

(45) redetermining the average value B_avIf 0.65 > B_avIf the voltage is more than 0.35, continuing to treat the temporary or transient overvoltage and inter-harmonic problems of the power system until the treatment is finished;

(46) Redetermining the average value B_avIf B is_avThe voltage drop problem is continuously treated until the treatment is finished when the voltage drop problem is more than 0.1; if average value B_avAnd if the voltage is lower than 0.1, the storage battery is stopped to participate in power supply.

Has the advantages that: compared with the prior art, the invention firstly solves the problem of how to distribute the generated electric energy because the mobile energy storage battery can not meet all the electric energy quality requirements when the charge state is lower, and preferentially solves the electric energy with higher priority by utilizing the relatively lower capacity of the mobile energy storage battery in order to protect the service life of the battery. Meanwhile, by setting corresponding conditions, the problem of power quality of the power grid in self-adaptive treatment at different time periods is solved, the stability of the system is enhanced, and the utilization efficiency of the mobile energy storage battery is improved. Secondly, because the output of photovoltaic and wind power changes with the illumination intensity, the ambient temperature and the wind power, if a distributed power supply is directly adopted for power supply, the voltage of the auxiliary power supply is often unstable, and the auxiliary power supply is required to have a wide input voltage range. Therefore, the use cost of the distributed power supply during grid connection and the power supply reliability of the grid-connected inverter are considered, the mobile energy storage battery and the distributed power supply are coordinated to supply power to the grid-connected inverter, and uninterrupted power supply can be guaranteed when the output of the distributed power supply is unstable. In addition, the problem of repeated start and stop of the distributed power supply during independent power supply is solved by using the mobile energy storage battery.

Drawings

Fig. 1 is a SOC partition of a mobile energy storage battery according to the present invention;

fig. 2 is a flow chart of the mobile energy storage battery participating in power quality management according to the invention.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

The invention relates to a method for distributing electric energy of a mobile energy storage battery participating in distributed power supply, which is an electric energy distribution method based on SOC feedback mobile energy storage battery working mode self-adaptive control technology. According to the invention, before the output of the energy storage battery and the distributed power supply is obtained through conventional energy distribution calculation, the electric energy quality problem to be solved preferentially is selected according to the state of the mobile energy storage battery, so that the electric energy quality of the distributed power supply can be improved, the electric energy quality problem of a power grid is effectively improved, the grid connection cost of a grid-connected inverter is reduced, and the operation economy of the mobile energy storage battery is improved.

The invention provides a mobile energy storage battery working mode self-adaptive treatment method based on SOC feedback through analyzing the priority of the system power quality problem and the state of charge (SOC) of the mobile energy storage battery. The method specifically comprises the following steps:

(1) the service life of the mobile energy storage battery has important influence on the effect and the economy of the energy storage participating in the power quality management of the power grid, so that the mobile energy storage battery SOC is partitioned firstly in the invention, and the partition condition of the mobile energy storage battery SOC is shown in figure 1. The specific subareas are divided into a discharging priority area, a normal charging and discharging area, a charging priority area and a forbidden area, and the charge quantity corresponding to each subarea is reduced in sequence. Optimally, the charge states of the mobile energy storage batteries corresponding to the partitions are 65-100%, 35-65%, 10-35% and 0-10% respectively.

(2) Priority is set for the power quality problem in the power grid, so that the mobile energy storage battery can adaptively treat the power quality problems of different levels in different SOC states.

Among a plurality of power quality problems of the power system, the power quality problems can be divided into two high priorities and two low priorities according to treatment urgency, wherein the two high priorities and the two low priorities are respectively represented by 1 and 0, and when the treatment of the power quality problems with the high priorities is finished, the power quality problems with the lower priorities are treated. As shown in table 1 below, common power quality issues are first listed and given treatment priority. And establishing a power quality problem priority matrix A for N power quality problems in the power grid according to the set power quality treatment priority.

A＝[A_N，A_N-1，A_N-2，…A₂，A₁](1)

TABLE 1 priority of common Power quality issues in the grid

(3) During the charging and discharging process of the energy storage, the capacity of the energy storage battery participating in the power quality management is continuously changed, and a capacity matrix B of the mobile energy storage battery participating in the power quality management is established and refreshed so as to implement the power quality distribution control of the mobile energy storage battery management.

B＝[B_M，B_M-1，B_M-2，…B₂，B₁](2)

And forming a matrix B according to the actual SOC values of the M mobile energy storage batteries, wherein the less non-zero elements in the matrix B are, the stronger the capacity of the energy storage for governing the electric energy quality is. The actual SOC of the mobile energy storage battery is directly monitored and obtained by an SCADA software system, and therefore the working area for controlling the power quality is divided. And setting a state matrix B according to the capability of the mobile energy storage battery participating in the power quality control, and setting the capability of the energy storage battery participating in the power quality control to be 0-1 when the SOC of the mobile energy storage battery is more than 10% and the power can be normally supplied. The SOC of the mobile energy storage battery is about 80% under the condition of full charge, so the capacity range of participating in the electric energy quality control is generally 0.1-0.8. When the SOC of the mobile energy storage battery is lower than 10%, the mobile energy storage battery is protected, and when the mobile energy storage battery is in a forbidden state, the power supply state of the mobile energy storage battery is set to be 0.

(4) On the premise of not damaging the service life of the mobile energy storage battery, the effect of energy storage participating in the quality of electric energy is optimized. Calculating the average value B of the elements in the capacity matrix B_avAccording to the average value B_avJudging which kind of power quality problem is preferentially treated by the mobile energy storage battery according to the charge state partition of the mobile energy storage battery, and when the average value B is_avWhen the voltage is less than the set threshold value, the battery stops discharging, and does not participate in power quality management of the power grid, so that the mobile energy storage battery is protected. The set threshold is 0.1.

Wherein, the base is flatMean value B_avThe method for judging the power quality problem of the mobile energy storage battery comprises the following steps:

(41) if B is judged for the first time_avThe problems of harmonic waves, three-phase imbalance, voltage deviation and frequency deviation are treated preferentially if the frequency deviation is more than 0.65, and the step (42) is carried out; if 0.65 > B_avIf the harmonic wave and three-phase imbalance problem is solved preferentially, jumping to the step (43); if 0.35 > B_avIf the harmonic wave is more than 0.1, the harmonic wave problem is preferably treated, and the step (44) is skipped;

(42) redetermining the average value B_avIf B is_avIf not, the voltage drop, voltage fluctuation and flicker, temporary or transient overvoltage and inter-harmonic problems of the power system are continuously treated until the treatment is finished; if 0.65 > B_avIf the voltage drop and voltage fluctuation and flicker problems are treated preferentially, and the step (45) is skipped; if 0.35 > B_avIf the voltage drop is more than 0.1, the voltage drop problem is preferably treated, and the step (46) is skipped;

(43) redetermining the average value B_avIf B is_avIf the voltage deviation and the frequency deviation are more than 0.35, continuing to treat the problems until the treatment is finished;

(44) redetermining the average value B_avIf B is_avIf more than 0.1, continuing to treat the three-phase imbalance problem until the treatment is finished; if average value B_avIf the voltage is lower than 0.1, the storage battery is stopped to participate in the power quality control;

(45) redetermining the average value B_avIf 0.65 > B_avIf the voltage is more than 0.35, continuing to treat the temporary or transient overvoltage and inter-harmonic problems of the power system until the treatment is finished;

(46) redetermining the average value B_avIf B is_avThe voltage drop problem is continuously treated until the treatment is finished when the voltage drop problem is more than 0.1; if average value B_avAnd if the voltage is lower than 0.1, the storage battery is stopped to participate in power supply.

Because the output of photovoltaic and wind power fluctuates along with the change of illumination intensity, environment temperature and wind power, the input of the photovoltaic and wind power is often uncertain, and the problem of repeated starting and stopping can exist at the same time. The scheme for preferentially treating the power quality problem of the mobile energy storage battery can improve the treatment efficiency, prolong the service life of the battery, reduce the system cost and improve the economical efficiency of the power station operation.

The electric energy distribution method can reduce grid connection cost and improve the analysis of the operation economy of the mobile energy storage battery:

cost analysis of mobile energy storage battery

(a) Initial investment cost

The energy storage system mainly comprises a battery pack, a PCS (power conversion system), a BMS (battery management system), a monitoring system and the like. The initial investment cost calculation formula is as follows:

C₁＝k_pP_es+k_qQ_es(3)

in the formula: c₁Initial investment cost for the energy storage system; p_esThe rated power of the energy storage system; q_esIs the energy storage system capacity; k is a radical of_pThe cost coefficient related to the input and output peak power of the energy storage system is obtained; k is a radical of_qIs a cost factor related to the capacity of the energy storage system.

(b) Annual operating maintenance costs

The annual operation and maintenance cost of the energy storage system comprises the operation cost and the maintenance cost of the energy storage system, and mainly refers to daily and regular manual maintenance of the battery, such as fault prevention and elimination of the battery and a management system thereof, regular manual inspection of the battery and the like. The annual operating maintenance cost can be calculated according to equation (5):

C₂＝k_omQ_es(4)

in the formula: c₂Operating and maintaining costs for the energy storage system; k is a radical of_omIs the annual operation and maintenance cost coefficient of unit capacity.

(c) Replacement costs

When the battery energy storage life cycle is smaller than the actual project cycle, the battery energy storage life cycle needs to be replaced, and replacement cost mainly comes from the battery body.

The replacement cost of battery energy storage is:

C₃＝(1-α)^knk_qQ_es(5)

in the formula: c₃The cost of each replacement of the battery, α the annual reduction rate of the cost of the battery, k the number of times of replacement of the battery, and n the service life of the battery.

(d) Cost of disposal

The waste disposal cost refers to the cost required to be paid for processing the energy storage equipment after the life cycle of the equipment is finished, and is mainly the residual value of the equipment. The residual value of the equipment is related to the initial investment cost and the recovery coefficient and is a negative value, and the calculation formula is as follows.

C₄＝γC₁(6)

In the formula: c₄The energy storage system waste disposal cost; and y is the recovery coefficient of the energy storage system.

Second, analysis of power supply participated by mobile energy storage battery

(a) Reducing electricity consumption

Under the time-of-use electricity price mechanism, the user uses the distributed power supply to charge the stored energy in the off-peak electricity price period through the energy storage system, and supplies power for the grid-connected inverter in the peak electricity price period, so that the peak-to-valley difference arbitrage is realized, the electricity purchasing cost is reduced, and the profit is as follows:

in the formula: m is m discharge periods in one day; n is n charging periods in a day; w_fiDischarging the electric quantity for the ith discharge period; e.g. of the type_iThe electricity price for the user in the ith discharging period; w_ciCharging the electric quantity for the ith charging period; e.g. of the type_jThe electricity price for the user in the jth charging period; n is_dThe average annual running days of the energy storage system.

(b) Reliability benefits

If only the distributed power supply is used for supplying power to the grid-connected inverter, when a power failure accident occurs, equipment damage can be caused, equipment starting cost is recovered, and loss of the grid-connected inverter caused by working efficiency of the grid-connected inverter is reduced. The following formula is used to calculate the reliability gains.

E₂＝ΔrP_esΔt (8)

In the formula: e₂After an energy storage system is built for a user, the benefit brought by the improvement of the power supply reliability is realized; delta r is the loss of 1h of power failure of unit capacity of a user; and delta t is the average annual power failure time after the reduced power failure load is converted into the rated power of the energy storage system after the energy storage system is built.

Considering that the surplus capacity of the stored energy after the quality of the electric energy is controlled is used for supplying power to the grid-connected inverter, the cost of the mobile energy storage battery is multiplied by an average coefficient, and is taken as 0.1, and the maximum value of the economic benefit after the stored energy is used for participating in the power supply of the distributed grid-connected inverter is taken as

max[(E₁+E₂)-0.1(C₁+C₂+C₃+C₄)](9)

The model can be solved under the constraint condition to obtain the maximization of the economic benefit. From the cost analysis formula, the economic benefit of the distributed combined energy storage power station system is increased along with the increase of the annual average running days (service life) of the energy storage system, the income brought by the improvement of the power supply reliability, the reduction of the abandonment cost of the energy storage system and the reduction of the recovery coefficient of the energy storage system. Therefore, the method for distributing the electric energy of the distributed power supply by the mobile energy storage battery has considerable economic benefits.