Cold Region Power System and Voltage Automatic Control Method

Abstract

The present invention relates to the technical field of power grid power supply and power distribution, and specifically to a cold-region power system and voltage automatic control method, including: in the process of controlling the voltage of each distribution area by using a PID control algorithm, the voltage error of each distribution area is fed back to an energy storage subsystem, the energy storage subsystem responds according to the error, and after the energy storage subsystem responds, the voltage error of each distribution area is calculated again, and the change of the voltage error of each distribution area before and after the energy storage subsystem responds is fed back to the distribution subsystem, and the distribution subsystem responds according to the change of the voltage error; each time the energy storage subsystem and the distribution subsystem respond once, the control parameters of each distribution area are adjusted according to the voltage error and voltage change of each distribution area. The present invention supplies power to the power grid by reasonably investing in energy storage equipment, and maintains the stability of the power grid by reasonable scheduling and automatic control of voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply and distribution of power grids, and in particular to a cold-region power system and an automatic voltage control method. Background Art

[0002] Extreme low temperatures in cold regions can affect the efficiency and reliability of power generation equipment. For example, water flow in hydroelectric power plants is reduced, and the use of renewable energy sources such as wind, solar and geothermal energy in cold regions is restricted. For example, solar photovoltaic panels may become less efficient at low temperatures, and wind turbines may be damaged by ice and snow. In addition, energy storage equipment is inefficient and unstable in low temperature environments. At the same time, electricity demand in cold regions may increase sharply in winter.

[0003] Under the above-mentioned constraints, in a power grid that includes the above-mentioned various power generation equipment, unreasonable power distribution plans and unreasonable use of energy storage equipment make it difficult to maintain a balanced power supply to users when power demand surges. For example, there may be a voltage imbalance in the power grid, resulting in insufficient voltage, and in severe cases, large-scale power outages may occur. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a cold region power system and a voltage automatic control method.

[0005] A voltage automatic control method of the present invention adopts the following technical solution:

[0006] An embodiment of the present invention provides a voltage automatic control method, the method comprising the following steps:

[0007] Use PID control algorithm to control the voltage in each distribution area;

[0008] During the PID control process, the voltage error of each distribution area is fed back to the energy storage subsystem, and the energy storage subsystem responds according to the error. After the energy storage subsystem responds, the voltage error of each distribution area is calculated again, and the change of the voltage error of each distribution area before and after the energy storage subsystem responds is fed back to the distribution subsystem, and the distribution subsystem responds according to the change of the voltage error; after each energy storage subsystem and the distribution subsystem respond once, the control parameters of the PID control algorithm of each distribution area are adjusted according to the voltage error and voltage change of each distribution area;

[0009] The responses of the energy storage subsystem include: controlling the energy storage device to be switched in or out of the power grid; the responses of the distribution subsystem include: controlling the power distribution device to be switched on or off;

[0010] The power generation equipment in the power grid includes hydroelectric generators, wind turbines, geothermal generators, and photovoltaic panels.

[0011] Preferably, after the energy storage subsystem and the distribution subsystem respectively respond several times, the specific steps included are as follows:

[0012] Record the frequency a1 of each energy storage device switching into the power grid and the change b1 of the voltage of all distribution areas before and after each switching in the energy storage subsystem from the first response to several responses; record the frequency a2 of each distribution device in the distribution subsystem switching on or off and the change b2 of the voltage of all distribution areas before and after each switching on or off; filter out the energy storage devices that need to remain in the switched-on state and the distribution devices that need to remain in the switched-on or switched-off state according to a1, b1, a2 and a2; the energy storage devices that remain in the switched-on state remain in the switched-on state all the time; the distribution devices that need to remain in the switched-on or switched-off state remain in the normally open or normally closed state all the time.

[0013] Preferably, the energy storage subsystem responds according to the error, including the following specific steps:

[0014] The voltage errors of all distribution areas are summed up and recorded as the missing voltage. The energy storage devices in the power grid are cut in and out according to the size of the missing voltage. The total power of the energy storage devices cut in is positively correlated with the missing voltage, and the total power of the energy storage devices cut out is negatively correlated with the missing voltage.

[0015] Preferably, the power distribution subsystem responds according to the change of the voltage error, including the following specific steps:

[0016] According to the change of voltage error in each distribution area before and after the energy storage subsystem responds, invalid response areas are screened out from all distribution areas, and all distribution areas outside the invalid response areas are recorded as valid response areas. The opening and closing of the distribution equipment are controlled to distribute the grid power from the valid response areas to the invalid response areas.

[0017] Preferably, each time the energy storage subsystem and the distribution subsystem respond once, the control parameters of the PID control algorithm of each distribution area are adjusted according to the voltage error and voltage variation of each distribution area, and the specific steps include the following:

[0018] After the energy storage subsystem and the distribution subsystem respond once, the voltage of each distribution area is recorded as I1, the voltage error of each distribution area is recorded as D1, the voltage of each distribution area before each response of the energy storage subsystem is recorded as I2, and the absolute value of the difference between I1 and I2 is recorded as the voltage change of each distribution area after the energy storage subsystem and the distribution subsystem respond once;

[0019] Adjusting the control parameter KP in the PID control algorithm according to the voltage variation comprises the following steps: when the ratio of the voltage variation to I1+I2 is in a preset first interval, not adjusting the control parameter KP; when the ratio of the voltage variation to I1+I2 is on the left or right side of the preset first interval, increasing or decreasing the control parameter KP by a preset percentage;

[0020] Adjusting the control parameter KI in the PID control algorithm according to D1 includes the following steps: when the ratio of D1 to the rated voltage of each distribution area is in a preset second interval, the control parameter KI is not adjusted; when the ratio of D1 to the rated voltage of each distribution area is on the left or right side of the preset second interval, the control parameter KP is increased or decreased by a preset percentage.

[0021] Preferably, the specific steps of screening out the energy storage equipment that needs to be kept in the cut-in state and the power distribution equipment that needs to be kept in the open or closed state according to a1, b1, a2, and b2 include the following:

[0022] During the response process, when each energy storage device is connected to the grid, the average value of the voltage change b1 in all distribution areas is recorded as c1. The power regulation intensity d1 of each energy storage device is obtained based on c1 and a1. d1 is positively correlated with c1 and a1.

[0023] In the process of several responses, the average value of the voltage change b2 of all distribution areas after each distribution device is opened or closed is recorded as c2, and the power dispatching strength d2 of each distribution device is obtained according to c2 and a2; d2 is positively correlated with c2 and a2;

[0024] The energy storage device whose power regulation strength d1 is greater than the preset first threshold is used as the energy storage device that maintains the cut-in state unchanged; the distribution device whose power dispatching strength d2 is preset to the second threshold is used as the distribution device that needs to maintain the open or closed state unchanged.

[0025] Preferably, the voltage error of each power distribution area is equal to the absolute value of the difference between the measured voltage and the rated voltage.

[0026] Preferably, when the mean value of the voltage errors of all the power distribution areas is less than a third preset threshold, the cut-out energy storage device is charged, otherwise the cut-out energy storage device is not charged.

[0027] Preferably, the switching in and out of the energy storage device in the power grid according to the magnitude of the missing voltage comprises the following specific steps:

[0028] First, the working efficiency of each energy storage device is obtained, where the working efficiency refers to the ratio of the average discharge amount per hour to the average charge amount per hour of the energy storage device in the historical time;

[0029] Energy storage devices are switched in order of work efficiency from high to low, and the total power of all switched-in energy storage devices is calculated. When the ratio of the total power to the missing voltage is greater than f×th0, the energy storage devices that have been switched into the power grid before the energy storage subsystem responds are switched out of the power grid in order of work efficiency from low to high. At the same time, after each energy storage device is switched out, another energy storage device is switched in. When the difference between the total power of all switched-in energy storage devices and the total power of the switched-out energy storage devices and the ratio of the missing voltage is greater than or equal to th0, switching in and out is stopped;

[0030] th0 is equal to the average value of the maximum current allowed to pass through the distribution equipment in all distribution areas, and f is a preset value less than 1.

[0031] An embodiment of the present invention provides a cold-region power system, including a voltage acquisition module, a voltage control module, an energy storage subsystem and a distribution subsystem, wherein the voltage acquisition module uses a voltmeter to collect the voltage of each distribution area, the energy storage subsystem includes all energy storage devices in the power grid; the distribution subsystem includes the distribution equipment in the power grid; the voltage control module includes a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the above-mentioned voltage automatic control method when executing the computer program.

[0032] The beneficial effects of the technical solution of the present invention are:

[0033] The PID control algorithm is used to control the voltage of each distribution area; it can ensure the stable change of the distribution area so that the power grid can return to a steady state.

[0034] During the PID control process, the voltage error of each distribution area is fed back to the energy storage subsystem, and the energy storage subsystem responds according to the error; so that the energy storage device can be used reasonably according to the voltage error of the PID control process when supplying power to the grid;

[0035] After the energy storage subsystem responds, the voltage error of each distribution area is calculated again, and the change of the voltage error of each distribution area before and after the energy storage subsystem responds is fed back to the distribution subsystem, and the distribution subsystem responds according to the change of the voltage error; it is ensured that the voltage error of the PID control process and the power supply of the energy storage equipment are combined when dispatching electricity, so that the power dispatch plan is reasonable and in line with the power consumption of the distribution area;

[0036] Whenever the energy storage subsystem and the distribution subsystem respond once, the control parameters of the PID control algorithm of each distribution area are adjusted according to the voltage error and voltage change of each distribution area; the present invention adjusts the control parameters of the PID control algorithm once every time the energy storage subsystem and the distribution subsystem respond once, so that the voltage control process is combined with the power supply situation of the specific energy storage device and the power distribution situation of the distribution device. At the same time, the control result of the PID control algorithm, that is, the voltage error, feeds back the power supply situation of the energy storage device and the power distribution situation of the distribution device, so that the power supply, distribution and voltage control form a complementary whole, so that the energy storage device is reasonably used and combined with a suitable distribution plan, so that the user's power supply balance and voltage stability can still be maintained when the power demand surges. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A flowchart of the steps of a voltage automatic control method provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a voltage automatic control method proposed by the present invention, its specific implementation, structure, features and effects, in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0040] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0041] A specific scheme of a voltage automatic control method provided by the present invention is described in detail below with reference to the accompanying drawings.

[0042] Embodiment 1:

[0043] See also Figure 1 , which shows a flow chart of the steps of a voltage automatic control method provided by an embodiment of the present invention, the method comprising the following steps:

[0044] Step S001: Use a PID control algorithm to control the voltage of each power distribution area.

[0045] Under low temperature conditions in cold regions, the power grid is greatly affected. For example, the efficiency of power generation equipment such as hydropower generators, wind power generators, geothermal generators, thermal power generators, photovoltaic panels, etc. in the power grid is not high. Without the introduction of new power generation equipment, the demand for electricity surges in low temperature weather, which can easily lead to insufficient voltage at the user end and even cause large-scale power outages.

[0046] This embodiment uses the PID control algorithm to regulate the voltage at the user end. Specifically, first record the rated voltage at the user end (i.e., the voltage that can maintain the user's normal power consumption for a long time, for example, the residential user end is 220 volts, and the rated voltage of some production enterprise user ends is 380 volts because they power large-scale production equipment). Then use a voltmeter to measure the voltage used by each user end in actual production and life. The voltage at the user end is controlled by the PID algorithm to change to the rated voltage.

[0047] It should be noted that, considering the huge number of users in the power grid, if the voltage of each user is controlled, the amount of data collection and data processing will be relatively large. Considering that there are many types of users, such as residential users and corporate users, different types of users require different rated voltages, such as 220 volts and 380 volts; even the rated voltages of different production equipment among corporate users are different, which leads to the need to classify the types of users in the power grid and investigate the equipment used, which greatly increases the workload.

[0048] Therefore, in this embodiment, voltage control is performed on a per-distribution area basis, wherein a distribution area refers to: a collection of some electricity users in a power grid, and these users are distributed electricity together by distribution equipment (such as distribution cabinets or transformers), and different distribution areas have different distribution equipment. In this embodiment, all users connected to each distribution cabinet are regarded as a distribution area. In other embodiments, all users connected to each low-voltage transformer (a transformer that converts medium voltages such as 10 kV or 20 kV into low voltages such as 220 V or 380 V) can be regarded as a distribution area; in other embodiments, when voltage regulation is performed for large-scale power grid users at the city level, all users connected to high-voltage transformers can be regarded as a distribution area. In some other embodiments, considering that the structure of the power grid is relatively complex, all electricity users can be artificially divided into different distribution areas.

[0049] Obtain the rated voltage of each distribution area (that is, the voltage that can maintain normal production of all users in the power supply area. In this embodiment, the rated output voltage of the distribution equipment corresponding to the distribution area is used as the rated voltage of the distribution area). At the same time, use a voltmeter to collect the output voltage of the distribution equipment corresponding to the distribution area in real time (recorded as the voltage of the distribution area). Use the PID algorithm to control the voltage of each distribution area to change to the rated voltage to maintain the stability of electricity consumption in each distribution area. The control parameters of the PID algorithm corresponding to each distribution area are adjusted by experts. The PID control algorithm is a well-known technology. This embodiment will not repeat its specific working principle and the method for adjusting its control parameters.

[0050] Step S002: During the PID control process, the voltage error of each distribution area is fed back to the energy storage subsystem, and the energy storage subsystem responds according to the error.

[0051] In the process of using the PID control algorithm to control the voltage of each distribution area to change to the rated voltage, additional electric energy needs to be provided to the power grid to avoid the situation where the voltage cannot obviously approach the rated voltage for a long time under the PID control algorithm, so as to restore and maintain the steady state of the power grid in a timely and rapid manner.

[0052] This embodiment takes into account that when the grid voltage decreases due to an increase in user electricity demand, all the power generation equipment in the grid has been connected to the grid for use, so this embodiment does not consider the situation where new power generation equipment is added to the grid. This embodiment provides additional electric energy to the grid by inserting energy storage equipment into the grid. The energy storage equipment includes: battery equipment such as lithium-ion batteries and lead-acid batteries, pumped storage power stations, compressed air energy storage equipment, flywheel energy storage equipment, thermal energy storage equipment, and the like. In other embodiments, if there are additional power generation equipment in the grid that has not been put into use, the power generation equipment can also be cut into the grid as a (non-rechargeable) energy storage device.

[0053] All energy storage devices and their charging, discharging, grid-connection and grid-exit processes constitute the energy storage subsystem in the grid.

[0054] Specifically, during the PID control process, the voltage error of each distribution area is fed back to the energy storage subsystem in real time, for example, through the Internet of Things technology. The purpose is to build a linkage system with a feedback mechanism between the PID control process and the grid energy storage subsystem, and the two work together to efficiently maintain grid stability.

[0055] In this embodiment, the error of the voltage of each distribution area is equal to the absolute value of the difference between the voltage of each distribution area and the rated voltage of each distribution area.

[0056] The energy storage subsystem responds according to the size of the error. The response of the energy storage subsystem includes: controlling the energy storage device to cut in or out of the grid. The error represents the voltage that the grid needs to provide additionally when the voltage changes to the rated voltage during the PID control process. These additional voltages need to be contributed by the energy storage device. Considering that the working efficiency of different energy storage devices will decrease to varying degrees under low temperature conditions in cold areas, not all energy storage devices can be cut into the grid. On the one hand, it is to avoid inefficient energy storage devices that will increase the burden on the grid, such as causing large power fluctuations to the grid; on the other hand, it is to avoid cutting all energy storage devices into the grid or unreasonably cutting some energy storage devices into the grid. When the grid becomes unstable again, the remaining energy storage devices cannot maintain the stability of the grid, or some of the energy storage devices that have been cut in are exhausted too early and cannot be put into use again, resulting in the grid being unable to remain stable.

[0057] Therefore, this embodiment enables the energy storage device in the energy storage subsystem to switch in or out in response to the voltage error in the PID control process, so that the voltage control and the switching in or out of the energy storage device cooperate with each other, so that the power grid can reliably restore voltage stability.

[0058] Step S003: After the energy storage subsystem responds, the voltage error of each distribution area is calculated again, and the change of the voltage error of each distribution area before and after the energy storage subsystem responds is fed back to the distribution subsystem, and the distribution subsystem responds according to the change of the voltage error.

[0059] After the energy storage device in the energy storage subsystem responds to switching in and out, the voltage of each distribution area is obtained again, and the voltage error of each distribution area is calculated.

[0060] The difference between the voltage error of each distribution area before the energy storage subsystem responds and the voltage error of each distribution area after the energy storage subsystem responds is taken as the change of voltage error of each distribution area. The change of voltage error is fed back to the distribution subsystem, and the distribution subsystem responds according to the change of voltage error of each distribution area.

[0061] The distribution subsystem is composed of distribution equipment in the power grid. The response of the distribution subsystem includes: controlling the opening or closing of the distribution equipment. The distribution equipment in this embodiment refers to the distribution cabinet or the isolating switch (or circuit breaker) in the distribution cabinet, and its opening and closing is used to control whether power is supplied to the distribution area (that is, to realize power dispatching).

[0062] In other embodiments, if the distribution area is divided according to the transformer, the response of the distribution subsystem at this time includes switching on and off the transformer, and the power dispatch of the distribution area is achieved by switching on and off the transformer.

[0063] It should be noted that in order to achieve power dispatch in the power grid, the opening and closing of the isolating switch in the distribution cabinet can control whether the power input to the distribution cabinet (from the previous transformer) can be output to other distribution cabinets. Therefore, the isolating switch in the distribution cabinet can be used to dispatch the power input to one distribution area to another distribution area. In summary, the core function of the distribution subsystem is to dispatch power to different distribution areas.

[0064] The purpose of the above process is to take into account that the power demand of each distribution area is different, and the distribution of energy storage devices in the power grid is also uncertain, that is, the distribution of energy storage devices is not associated with the distribution area, which results in the additional power energy provided by the energy storage device to the power grid for eliminating voltage errors cannot be accurately distributed to each distribution area. In the above process, the distribution subsystem responds to the change of the voltage error in each distribution area. On the basis of using the PID control algorithm and combining the energy storage device to restore the steady state of the power grid voltage, on the one hand, the distribution subsystem is introduced to ensure that the power energy provided by the energy storage device can be dispatched, and on the other hand, the dispatching process is adapted to the change of the voltage error in each distribution area, that is, to ensure that the dispatching process is adapted to the power consumption of each distribution area, to avoid blind power dispatching resulting in unbalanced power distribution and the situation that the voltage in some distribution areas cannot be changed to the rated voltage for a long time under PID control, thereby further ensuring that the power grid can reasonably and reliably restore the steady state.

[0065] As an example, the distribution subsystem responds to the change of the voltage error in each distribution area, including the following specific steps:

[0066] According to the change of voltage error in each distribution area before and after the energy storage subsystem responds, invalid response areas are screened out from all distribution areas, and all distribution areas outside the invalid response areas are recorded as valid response areas. The opening and closing of the distribution equipment are controlled to distribute the grid power from the valid response areas to the invalid response areas.

[0067] Step S004: After the energy storage subsystem and the power distribution subsystem respond once, the control parameters of the PID control algorithm of each power distribution area are adjusted according to the voltage error and voltage variation of each power distribution area.

[0068] After the energy storage subsystem and power distribution subsystem respond once, they provide power sources for the PID control process from the two aspects of power supply and distribution, so that the voltage in the PID control process can quickly and stably reach the rated voltage.

[0069] However, the response of the energy storage subsystem and the distribution subsystem belongs to macro-control for each distribution area, which can maintain the macro-stability of the power grid as a whole. However, the voltage in different distribution areas may still be unstable when changing to the rated voltage. For example, the voltage in some distribution areas changes faster, while some changes slower. The voltage in some distribution areas even increases sharply in a short period of time and exceeds the rated voltage. These unstable voltage changes in all distribution areas still hinder the recovery of the power grid, which in turn causes the voltage in each distribution area to fail to recover to the rated voltage in time.

[0070] In this embodiment, the voltage error after the energy storage subsystem and the distribution subsystem respond is used to adjust the control parameters of the PID control algorithm of each distribution area, and the voltage is adjusted once using the PID algorithm based on the adjusted control parameters, so as to timely restore the voltage of each distribution area to the rated voltage.

[0071] Then, when the energy storage subsystem and the distribution subsystem respond again, the control parameters of the PID control algorithm of each distribution area are adjusted according to the voltage error after the second response. And so on, until the voltage of all distribution areas is stabilized at the rated voltage.

[0072] In this process, the control parameters are adjusted through the voltage error after the energy storage subsystem and the distribution subsystem respond successively. During the PID control process, coordination is formed with the power grid in terms of power supply and distribution, so that the voltage control depends on the power grid, and the power grid makes adjustments (power supply adjustment and distribution adjustment) according to the voltage control results, so that the power grid can restore the voltage in a timely and reliable manner under a reasonable power distribution plan and the allocation and use of energy storage equipment, thereby maintaining the stability of the entire power grid.

[0073] As an example, after the energy storage subsystem and the distribution subsystem each respond once, the control parameters of the PID control algorithm of each distribution area are adjusted according to the voltage error, including the specific method of:

[0074] In this embodiment, the distribution subsystem also responds once after the energy storage subsystem responds once. After the energy storage subsystem and the distribution subsystem respond once, the voltage of each distribution area is recorded as I1, the voltage error of each distribution area is recorded as D1, and the voltage of each distribution area before each response of the energy storage subsystem is recorded as I2. The absolute value of the difference between I1 and I2 is recorded as the voltage change of each distribution area after the energy storage subsystem and the distribution subsystem respond once. This voltage change represents the voltage fluctuation change of each distribution area in the process from before the energy storage subsystem responds to after the energy storage subsystem and the distribution subsystem respond successively; the voltage error D1 describes the difference between the voltage of each distribution area and the rated voltage after the energy storage subsystem and the distribution subsystem respond once.

[0075] For the PID control process corresponding to each distribution area, when the voltage change is small, the control parameter KP in the PID control algorithm needs to be appropriately increased to ensure that the PID control algorithm can control the voltage in the distribution area to quickly reach the rated voltage with a large amplitude. When the voltage change is large, the control parameter KP in the PID control algorithm needs to be appropriately smaller to avoid excessive voltage fluctuations during the PID control process, which affects the stability of the entire power grid. Specifically, in this embodiment, when the ratio of the voltage change to I1+I2 is less than 0.4, the control parameter KP in the PID control algorithm is increased by 10%, and when the ratio of the voltage change to I1+I2 is greater than 0.6, the control parameter KP is reduced by 10%; when the ratio of the voltage change to I1+I2 is greater than or equal to 0.4 and less than or equal to 0.6, the control parameter KP is not adjusted.

[0076] When the voltage error D1 is small, it means that the voltage of each distribution area is basically close to the rated voltage. At this time, the control parameter KI in the PID control algorithm can be increased to reduce the voltage oscillation above and below the rated voltage. When the voltage error D1 is large, it means that after the energy storage subsystem and the distribution subsystem respond, the voltage of each distribution area still has no obvious and rapid trend of approaching the rated voltage. At this time, the control parameter KI in the PID control algorithm can be reduced to eliminate the error and quickly change the voltage to the rated voltage. Specifically, when the ratio of D1 to the rated voltage is less than 0.2, the control parameter KI is increased by 10%, and when the ratio of D1 to the rated voltage is greater than 0.4, the control parameter KI is reduced by 10%. In other cases (that is, when the ratio is in the [0.2, 0.4] interval), the control parameter KI is not adjusted.

[0077] The above KP and KI are two control parameters of the PID control algorithm, respectively representing the proportional control line and the integral control term. All the judgment thresholds set in this embodiment are examples, and other judgment thresholds can be set in other embodiments, which are not specifically limited in this embodiment.

[0078] Embodiment 2:

[0079] After the energy storage subsystem and the distribution subsystem respond several times, for example, 8 times. In other embodiments, other values ​​of the number of responses can be set, which are not specifically limited in this embodiment. For example, when the average value of the voltage of all distribution areas is greater than 80% of the average rated voltage of all distribution areas, it means that the voltage imbalance is not too serious, and it can be set to 5 times. If it is less than 50%, it means that the grid voltage imbalance is more serious, and it can be set to 12 times.

[0080] After several responses, the steps involved are as follows:

[0081] Record the frequency a1 of each energy storage device switching into the grid during the process from the first response to several responses of the energy storage subsystem, as well as the absolute value of the difference between the average voltage of all distribution areas before and after each switching (recorded as the change b1 of all distribution areas);

[0082] Record the disconnection frequency a2 of each distribution device in the distribution subsystem, and the change b2 of the voltage in all distribution areas before and after each opening or closing; filter out the energy storage devices that need to remain in the cut-in state and the distribution devices that need to remain in the disconnected state according to a1, b1, a2, and b2; the energy storage devices that remain in the cut-in state remain in the cut-in state until the power is completely discharged; the distribution devices that need to remain in the disconnected state remain in the normally open state.

[0083] It should be noted that the above only considers the disconnectable frequency a2. When considering the closed state, the above process also needs to record the closing frequency of each distribution device in the distribution subsystem (when considering the closed state, the closing frequency is also recorded as a2 for the convenience of description). Similarly, when considering the closed state, the distribution devices that need to keep the closed state unchanged are screened out according to a1, b1, a2, and b2 (that is, these distribution devices always remain in the normally closed state). If the opening and closing frequencies of the same distribution device are the same, it does not participate in the above calculation (that is, it does not need to be regarded as a normally open or normally closed device).

[0084] In the above process, some energy storage devices and distribution devices are kept unchanged in a specific state according to the voltage changes before and after the energy storage subsystem and the distribution subsystem respond. These devices play an important role in both the distribution and dispatch of the power grid. Keeping them in the corresponding state (cut-in, normally open or normally closed state) can avoid the problem of repeated response of these devices, which saves response time and avoids excessive and frequent input of unimportant equipment that is greatly affected by low temperatures in cold areas and is not adapted to power demand under low temperatures into the power grid, thereby further maintaining the stability of the power grid.

[0085] As an example, according to a1, b1, a2, and b2, the energy storage equipment that needs to remain in the cut-in state and the power distribution equipment that needs to remain open or closed are screened out, and the specific steps are as follows:

[0086] During the several responses of the energy storage subsystem and the distribution subsystem, the average value of the voltage change b1 of all distribution areas after each energy storage device is switched on is recorded as c1. The power regulation intensity d1 of each energy storage device is obtained based on c1 and a1; d1 is positively correlated with c1 and a1.

[0087] The calculation formula of d1 in this embodiment is:

[0088]

[0089] Where D represents the average of the rated voltages of all distribution areas, and N1 represents the total frequency of all energy storage devices switching on during several response processes. The purpose of dividing by D and N1 in the above formula is to eliminate the dimension. In other embodiments, the multiplication sign in the above formula can be changed to a plus sign.

[0090] The average value of the voltage change b2 of all distribution areas after each distribution device is opened or closed several times is recorded as c2. The power dispatching intensity d2 of each distribution device is obtained based on c2 and a2; d2 is positively correlated with c2 and a2.

[0091] The calculation formula of d2 in this embodiment is:

[0092]

[0093] N2 represents the total number of times all the power distribution devices are turned on and off during the response process. In other embodiments, the multiplication sign in the above formula can be changed to a plus sign.

[0094] The greater the power regulation intensity d1 and the power dispatching intensity d2, the greater the role of energy storage equipment and distribution equipment in the response process of several energy storage subsystems and distribution subsystems.

[0095] Therefore, the energy storage device whose power regulation intensity d1 is greater than the preset first threshold is used as the energy storage device that maintains the cut-in state unchanged; the power distribution device whose power dispatch intensity d2 is preset to the second threshold is used as the power distribution device that needs to remain open or closed unchanged. This embodiment is described by taking the preset first threshold equal to 0.3 and the preset second threshold equal to 0.4 as an example. Other values ​​can be set in other embodiments, and this embodiment does not specifically limit it.

[0096] Embodiment three:

[0097] As a preferred example, the energy storage subsystem responds according to the error size, including the following specific steps:

[0098] The voltage errors of all distribution areas are summed up and recorded as the missing voltage. The energy storage device in the power grid is cut in or out according to the size of the missing voltage. The power of the energy storage device cut in is positively correlated with the missing voltage, and the power of the energy storage device cut out is negatively correlated with the missing voltage.

[0099] As an example, the energy storage device in the power grid is switched in or out according to the magnitude of the missing voltage, including the following method:

[0100] First, the working efficiency of each energy storage device is obtained. The working efficiency refers to the ratio of the average discharge per hour to the average charge per hour in the historical time of the energy storage device (for example, from January to April and from October to December of the current year. The specific time can be set according to the time when the local low temperature weather arrives).

[0101] The energy storage devices are switched on in descending order of working efficiency, and the total power of all switched-on energy storage devices is calculated. When the ratio of the total power to the missing voltage is greater than 0.8×th0, the energy storage devices that were previously switched on to the grid (before this response) are switched off from the grid in descending order of working efficiency. At the same time, after each energy storage device is switched off, another energy storage device is switched on. When the difference between the total power of all switched-on energy storage devices and the total power of the switched-off energy storage devices and the ratio of the missing voltage is greater than or equal to th0, switching on and off is stopped.

[0102] That is, when the difference between the total power of all switched-in energy storage devices and the total power of switched-out energy storage devices is greater than or equal to the product of the missing voltage and th0, the energy storage subsystem can provide a suitable power source for voltage adjustment in each distribution area.

[0103] In this embodiment, th0 is equal to the average value of the maximum current allowed to pass through the power distribution equipment in all power distribution areas.

[0104] The above process cuts energy storage devices that still have high efficiency in low temperature environments into the power grid, and cuts energy storage devices that have low efficiency in low temperature environments out of the power grid, thereby maintaining the stability of the power grid.

[0105] In the above process, when the amount of electricity stored in the energy storage device is less than 10%, it does not need to be connected to the grid. At the same time, when the amount of electricity stored in the energy storage device in the grid is less than 10%, it must be cut off from the grid in time.

[0106] As an optional example, the energy storage subsystem responds according to the error size, including the following specific steps:

[0107] Multiple energy storage devices with the largest remaining power and a ratio of the sum of their power to the missing voltage greater than th0 are switched into the grid, and the energy storage devices that have been switched into the grid are not switched out of the grid until the power is less than 10%.

[0108] Embodiment 4:

[0109] The distribution subsystem responds to the change in voltage error, including the following specific steps:

[0110] The difference between the voltage error of each distribution area before the energy storage subsystem responds and the voltage error of each distribution area after the energy storage subsystem responds is taken as the error change of each distribution area, and the mean of the error change of all distribution areas is obtained. The distribution areas with error changes less than the mean are taken as invalid response areas. The voltage error changes in these areas are small after the energy storage equipment is cut into the power grid. It is necessary to dispatch power to these distribution areas to maintain power grid balance and steady state.

[0111] All distribution areas outside the invalid response area are recorded as valid response areas, and the opening and closing of the distribution equipment are controlled to distribute the grid power from the valid response area to the invalid response area.

[0112] As an example, a specific distribution method is: dispatching power from the first N3 response valid areas with the largest error changes to the N4 response invalid areas with the smallest error changes by closing and opening the distribution equipment.

[0113] The specific power dispatching method depends on the connection relationship and connection mode of the power grid structure between different distribution areas. At the same time, power dispatching of the power grid is a well-known and commonly used technology, and the specific process will not be repeated in this embodiment.

[0114] Wherein N3 represents half of the number of effective response areas, and N4 represents half of the number of ineffective response areas. Other embodiments are set to other values, which are not specifically limited in this embodiment.

[0115] Embodiment five:

[0116] When the mean value of the voltage errors of all the power distribution areas is less than the third preset threshold, the switched-out energy storage device is charged; otherwise, the switched-out energy storage device is not charged.

[0117] The purpose is to prevent the energy storage equipment that is cut out when the voltage error is large and the power demand increases from becoming a grid load, thereby bringing additional user pressure to the grid.

[0118] This embodiment is described by taking the example that the third preset threshold is equal to 30% of the rated voltage of all power distribution areas.

[0119] Embodiment six:

[0120] This embodiment provides a cold region power system, including a voltage acquisition module, a voltage control module, an energy storage subsystem and a power distribution subsystem.

[0121] The voltage acquisition module uses a voltmeter to collect the voltage of each distribution area. The energy storage subsystem includes all energy storage devices in the power grid, which can be switched in and out of the power grid. The distribution subsystem includes all distribution devices, which are used to allocate and dispatch electricity for each distribution area. The voltage control module includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above-mentioned voltage automatic control method are performed.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A voltage automatic control method, characterized in that: The method comprises the following steps: Use PID control algorithm to control the voltage in each distribution area; During the PID control process, the voltage error of each distribution area is fed back to the energy storage subsystem, and the energy storage subsystem responds according to the error. After the energy storage subsystem responds, the voltage error of each distribution area is calculated again, and the change of the voltage error of each distribution area before and after the energy storage subsystem responds is fed back to the distribution subsystem, and the distribution subsystem responds according to the change of the voltage error. After each energy storage subsystem and the distribution subsystem respond once, the control parameters of the PID control algorithm of each distribution area are adjusted according to the voltage error and voltage change of each distribution area, thereby realizing several responses and control parameter adjustments of the energy storage subsystem and the distribution subsystem. The responses of the energy storage subsystem include: controlling the energy storage device to be switched in or out of the power grid; the responses of the distribution subsystem include: controlling the power distribution device to be switched on or off; The power generation equipment in the power grid includes hydroelectric generators, wind turbines, geothermal generators, and photovoltaic panels; After each energy storage subsystem and distribution subsystem respond once, the control parameters of the PID control algorithm of each distribution area are adjusted according to the voltage error and voltage variation of each distribution area. The specific steps include the following: After the energy storage subsystem and the distribution subsystem respond once, the voltage of each distribution area is recorded as I1, the voltage error of each distribution area is recorded as D1, the voltage of each distribution area before each response of the energy storage subsystem is recorded as I2, and the absolute value of the difference between I1 and I2 is recorded as the voltage change of each distribution area after the energy storage subsystem and the distribution subsystem respond once; Adjusting the control parameter KP in the PID control algorithm according to the voltage variation comprises the following steps: when the ratio of the voltage variation to I1+I2 is in a preset first interval, not adjusting the control parameter KP; when the ratio of the voltage variation to I1+I2 is on the left or right side of the preset first interval, increasing or decreasing the control parameter KP by a preset percentage; Adjusting the control parameter KI in the PID control algorithm according to D1 includes the following steps: when the ratio of D1 to the rated voltage of each distribution area is in a preset second interval, the control parameter KI is not adjusted; when the ratio of D1 to the rated voltage of each distribution area is on the left or right side of the preset second interval, the control parameter KP is increased or decreased by a preset percentage.

2. The voltage automatic control method according to claim 1, characterized in that: After the energy storage subsystem and the distribution subsystem respond several times respectively, the frequency a1 of each energy storage device switching into the power grid and the change b1 of the voltage of all distribution areas before and after each switching in the energy storage subsystem from the first response to several responses are recorded; the frequency a2 of each distribution device in the distribution subsystem switching on or off and the change b2 of the voltage of all distribution areas before and after each switching on or off are recorded; the energy storage devices that need to keep the switching on state unchanged and the distribution devices that need to keep the opening or closing state unchanged are screened out according to a1, b1, a2 and b2; the energy storage devices that keep the switching on state unchanged always keep the switching on state; the distribution devices that need to keep the opening or closing state unchanged always keep the normally open or normally closed state.

3. The voltage automatic control method according to claim 1, characterized in that: The energy storage subsystem responds according to the error, including the following specific steps: The voltage errors of all distribution areas are summed up and recorded as the missing voltage. The energy storage devices in the power grid are cut in and out according to the size of the missing voltage. The total power of the energy storage devices cut in is positively correlated with the missing voltage, and the total power of the energy storage devices cut out is negatively correlated with the missing voltage.

4. The voltage automatic control method according to claim 1, characterized in that: The power distribution subsystem responds according to the change of the voltage error, including the following specific steps: According to the change of voltage error in each distribution area before and after the energy storage subsystem responds, invalid response areas are screened out from all distribution areas, and all distribution areas outside the invalid response areas are recorded as valid response areas. The opening and closing of the distribution equipment are controlled to distribute the grid power from the valid response areas to the invalid response areas.

5. The voltage automatic control method according to claim 2, characterized in that: The specific steps of selecting the energy storage equipment that needs to be kept in the cut-in state and the power distribution equipment that needs to be kept in the open or closed state according to a1, b1, a2, and b2 are as follows: During the response process, when each energy storage device is connected to the grid, the average value of the voltage change b1 in all distribution areas is recorded as c1. The power regulation intensity d1 of each energy storage device is obtained based on c1 and a1. d1 is positively correlated with c1 and a1. In the process of several responses, the average value of the voltage change b2 of all distribution areas after each distribution device is opened or closed is recorded as c2, and the power dispatching strength d2 of each distribution device is obtained according to c2 and a2; d2 is positively correlated with c2 and a2; The energy storage device whose power regulation strength d1 is greater than the preset first threshold is used as the energy storage device that maintains the cut-in state unchanged; the distribution device whose power dispatching strength d2 is preset to the second threshold is used as the distribution device that needs to maintain the open or closed state unchanged.

6. The voltage automatic control method according to claim 1, characterized in that: The voltage error of each power distribution area is equal to the absolute value of the difference between the measured voltage and the rated voltage.

7. The voltage automatic control method according to claim 1, characterized in that: When the mean value of the voltage errors of all the power distribution areas is less than a third preset threshold, the switched-out energy storage device is charged; otherwise, the switched-out energy storage device is not charged.

8. The voltage automatic control method according to claim 3, characterized in that: The specific steps of switching in and out the energy storage device in the power grid according to the magnitude of the missing voltage are as follows: First, the working efficiency of each energy storage device is obtained, where the working efficiency refers to the ratio of the average discharge amount per hour to the average charge amount per hour of the energy storage device in the historical time; Energy storage devices are switched in order of work efficiency from high to low, and the total power of all switched-in energy storage devices is calculated. When the ratio of the total power to the missing voltage is greater than f×th0, the energy storage devices that have been switched into the power grid before the energy storage subsystem responds are switched out of the power grid in order of work efficiency from low to high. At the same time, after each energy storage device is switched out, another energy storage device is switched in. When the difference between the total power of all switched-in energy storage devices and the total power of the switched-out energy storage devices and the ratio of the missing voltage is greater than or equal to th0, switching in and out is stopped; th0 is equal to the average value of the maximum current allowed to pass through the distribution equipment in all distribution areas, and f is a preset value less than 1.

9. A cold-region power system, comprising a voltage acquisition module, a voltage control module, an energy storage subsystem and a distribution subsystem, wherein the voltage acquisition module uses a voltmeter to collect the voltage of each distribution area, the energy storage subsystem includes all energy storage devices in the power grid; the distribution subsystem includes the distribution equipment in the power grid; the voltage control module includes a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the voltage automatic control method according to any one of claims 1 to 8 are implemented.

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