CN-122000929-A - Multi-mode frequency support control method for optical storage power station considering time-of-use electricity price

CN122000929ACN 122000929 ACN122000929 ACN 122000929ACN-122000929-A

Abstract

The application discloses a multi-mode frequency support control method of an optical storage power station considering time-of-use electricity price, which synthesizes multi-source information, the combined criterion of 'time-sharing electricity price-supply and demand relation-power grid demand' is constructed, and the multi-mode self-adaptive cooperative control and active support of the optical storage power station are realized. The photovoltaic side is switched between a maximum power point tracking mode and an active standby mode to provide controllable power margin, the energy storage side realizes reasonable power distribution and quick frequency support among multiple energy storage units by introducing charge state balance and frequency droop control, and the energy storage charge state threshold is dynamically adjusted according to the electricity price level and the running state of a power grid, so that the economic running is ensured, and meanwhile, the frequency adjustment capability is reserved. According to the application, the economical efficiency and the power grid frequency active support requirement can be considered under different electricity price time periods and operation conditions, the frequency response speed, the available active support margin and the system operation stability of the optical storage power station are improved, and the optical storage power station has good engineering application value.

Inventors

HAN HUA
ZHANG LONGZHENG
CHEN SHIMIAO
HOU XIAOCHAO
LIU DENIAN
XIN XIAOZHE
SUN YAO
SU MEI

Assignees

中南大学

Dates

Publication Date: 20260508
Application Date: 20260129

Claims (7)

1. The multi-mode frequency support control method of the optical storage power station considering the time-of-use electricity price is characterized by comprising the following steps of: S1, multi-source information acquisition and state quantity calculation; s2, designing a photovoltaic working mode, wherein the photovoltaic working mode comprises an MPPT control mode and an active standby control mode; s3, energy storage side DC-DC control; S4, controlling a light accumulation unit converter; s5, adjusting an SOC threshold value based on power grid requirements; s6, mode judgment of a 'time-sharing electricity price-supply and demand relation' combined criterion.
2. The multi-mode frequency support control method of an optical storage station taking into account time-of-use electricity prices according to claim 1, wherein step S1 is specifically as follows: The following multi-source information is collected and updated: Time-of-use electricity price level lambda (t); photovoltaic power generation output P pv ; Near end load demand P L The frequency f of the grid-connected point is calculated with the rated frequency f n ; The state of charge SOC i of the i-th energy storage unit.
3. The multi-mode frequency support control method of an optical storage station taking into account time-of-use electricity prices according to claim 1, wherein step S2 is specifically as follows: The photovoltaic working mode adopts PV dual-mode control, namely MPPT control mode and active standby control mode, and is expressed as follows: (1); Wherein, V pv_ref is the voltage given value controlled by PV, V mppt is the maximum power output of PV obtained by MPPT algorithm at this moment, k vp and k vi are the proportional and integral coefficients controlled by PI, s is Laplacian, V dc_ref is the DC capacitor voltage given value, V dc is the DC capacitor voltage, and EN is the mode switching logic signal.
4. The multi-mode frequency support control method of an optical storage station taking into account time-of-use electricity prices according to claim 1, wherein step S3 is specifically as follows: The energy storage side DC-DC control is specifically realized as follows: (2); Wherein i ess_ref is an energy storage output current given value, k pp and k pi are PI proportion and integral coefficients of an energy storage PI power loop respectively, P ess_ref is an energy storage output power given value, P ess is an energy storage output, m is an active droop coefficient, ω n is a frequency reference value, ω is an output frequency, sgn (·) is a sign function, n is used for balancing SOCs among a plurality of ESUs, and SOC i represents the SOC state of the ith ESU.
5. The multi-mode frequency support control method of an optical storage station taking into account time-of-use electricity prices according to claim 1, wherein step S4 is specifically as follows: The light reservoir unit converter is controlled by adopting self-adaptive droop control, and the light reservoir unit converter is concretely as follows: (3); Wherein ω is the output frequency, ω n is the reference value of the frequency, k acp and k aci are the PI ratio and integral coefficient, s is the laplace operator, V dc_ref is the given value of the dc capacitor voltage, V dc is the dc capacitor voltage, EN is the mode switching logic signal, P ref and P are the given value of the active power and the calculated value of the active power, and the voltage of the light-accumulating unit converter is controlled to be E n .
6. The multi-mode frequency support control method of an optical storage station taking into account time-of-use electricity prices according to claim 1, wherein step S5 is specifically as follows: The SOC threshold adjustment is specifically as follows: during the electricity price valley period: The energy storage device is actively charged to reduce the electricity consumption cost, the charging threshold value of the state of charge (SOC) of the energy storage device is adjusted to avoid excessive fluctuation of the power grid frequency, and the energy storage device can provide active power grid support by reserving power margin, which is expressed as: (4); wherein, SOC th is a state of charge threshold, A is a power reserve coefficient between frequency and state of charge SOC, f is a grid-connected point frequency, and f n is a rated frequency; during peak electricity price period: in the scenario of supply and demand, when the grid frequency is too low, by increasing the SOC th of the energy storage device, the energy storage device can release more power to support the grid operation, expressed as: (5); In the scenario of supply less than demand, the energy storage discharges to reduce the electricity purchasing cost, adjusts the SOC th to support the grid at the same time, even when the grid frequency is reduced, expressed as: (6); during the level value period: And the SOC th is subjected to power standby adjustment on the basis of energy storage charge and discharge on the basis of the standard frequency of the power grid, so that the active supporting capacity of the power grid is improved.
7. The multi-mode frequency support control method of an optical storage station taking into account time-of-use electricity prices according to claim 1, wherein step S6 is specifically as follows: According to lambda (t) and power balance relation And determining a system operation mode by the frequency difference deltaf.

Description

Multi-mode frequency support control method for optical storage power station considering time-of-use electricity price Technical Field The invention belongs to the field of new energy grid connection and power electronic control, and particularly relates to a multi-mode frequency support control method of an optical storage power station considering time-of-use electricity price, which is suitable for grid connection operation of a centralized/group string optical storage power station containing multiple energy storage units. Background The requirements of modern power grids on new energy stations are changing from "passive grid-connection" to "active support", especially when the frequency is disturbed, requiring fast active support. Under a time-of-use electricity price (peak/flat/valley) mechanism, the photovoltaic power station can increase operation profits by purchasing electricity during electricity price periods and selling electricity during high electricity price periods. However, the existing multi-operation mode strategy considering time-of-use electricity price tends to focus on economy, and is difficult to actively buffer frequency fluctuation when a power grid is disturbed, and on the other hand, control only from frequency support can further cause the decrease of electricity price sleeve benefit capability and the unbalanced aggravation of energy storage SOC, so that sustainable support capability is weakened. Meanwhile, the existing multi-mode control considering the time-of-use electricity price is mostly 'passive adaptation', so that the fluctuation of frequency is difficult to 'naturally and actively' buffer, and the transition from passive support to active support needs to be realized. Therefore, a control scheme is needed that can simultaneously consider the economic operation under the time-of-use electricity price and the active support of the power grid frequency, and can maintain the balance of the SOC and promote the available support margin under the condition of multiple energy storage units. The invention of China with the publication number of CN104065095A discloses an auxiliary primary frequency modulation optimization control method of a battery energy storage system, which is characterized by comprising the following steps of obtaining the power shortage of primary frequency modulation and the frequency deviation change rate of a power grid, obtaining the adjustment proportion coefficient of the battery energy storage system, calculating the output power value of the battery energy storage system, determining the correction time and the correction degree of the charge state of a battery, and correcting. The method provided by the invention overcomes the defect of insufficient power change of the generator set, and is beneficial to faster recovery of the power grid frequency due to the high response speed of the energy storage system. After the frequency modulation is finished, on the premise of not causing a dead zone beyond the power grid frequency, the SOC of the battery is corrected, the smooth proceeding of the next frequency modulation process is ensured, the time-of-use electricity price condition is comprehensively considered, the charging cost of energy storage is reduced, and the reverse discharge income is increased. The technology of the application compared with the technology of the patent is as follows: The patent provides a battery energy storage system auxiliary primary frequency modulation optimal control method, which is used for acquiring power grid frequency deviation and change rate, obtaining a frequency modulation proportionality coefficient by fuzzy reasoning so as to calculate frequency modulation output power of an energy storage system, and correcting the charge state of the energy storage system by combining time-of-use electricity price when frequency modulation is finished or the energy storage system does not participate in frequency modulation. The control object of the scheme is mainly a battery energy storage system, the time-of-use electricity price is mainly used for SOC correction after frequency modulation and operation economy optimization, and the problem that photovoltaic side power mode switching and light storage are cooperatively involved in frequency support is not involved. In the multi-mode frequency support control scheme of the optical storage power station considering the time-of-use electricity price, which is provided by the invention, not only is the frequency modulation control carried out on an energy storage system carried out, but also the switching between a photovoltaic side MPPT mode and an active standby mode is introduced, so that a photovoltaic has controllable power margin to participate in frequency support, and meanwhile, the time-of-use electricity price, the supply and demand relation of the power station and the frequency requirement of a power grid are taken together as operation mode criteria, and th