A Sub-period Control Method and Device for Photovoltaic AVC Sub-station Considering Assessment Rules

Abstract

The present application provides a method and device for sub-period control of a photovoltaic AVC substation considering assessment rules, which relates to the technical field of automatic voltage control of power grids. The method determines the control time period in which the photovoltaic AVC substation is currently located according to the moment when an AVC master station instruction of the power grid dispatching center is received and the assessment rules; determines the control mode in which the photovoltaic AVC substation is currently located according to the control time period in which the photovoltaic AVC substation is currently located, and performs adjustment control according to the control mode in which the photovoltaic AVC substation is currently located. In this way, different control modes are adapted in different time periods according to the assessment rules, which not only meets the needs of the voltage safety of the station itself, but also meets the requirements of the dispatching master station for reactive voltage regulation of new energy stations, and at the same time can give full play to the role of the station's independent optimization of voltage regulation, so that the three promote each other, improve the safety margin of the station voltage, and avoid the generation of assessment fees.

Description

Technical Field

[0001] This application relates to the technical field of automatic voltage control of power grids, and particularly to a method and device for sub-period control of a photovoltaic AVC substation considering assessment rules. Background Art

[0002] New energy power stations are power stations that generate electricity using renewable energy or pollution-free energy, aiming to replace traditional fossil energy power generation and reduce environmental pollution and global warming. Solar photovoltaic power stations use solar energy as the energy source and convert it into electrical energy through photovoltaic panels for power generation. With the proposal of China's dual-carbon goal, before 2030, carbon dioxide emissions will be controlled at the peak and efforts will be made to reach the peak as soon as possible. Before 2060, through various means, carbon dioxide emissions will be offset by the carbon dioxide absorbed through technologies such as afforestation and carbon capture, achieving net-zero emissions. To achieve this goal, a new round of photovoltaic power station construction is in full swing. Due to its own characteristics, the power generation of photovoltaic power stations is intermittent and volatile, resulting in unstable voltage of photovoltaic power stations. To ensure the stability of the substation voltage, an AVC (Automatic Voltage Control) substation is generally installed in the photovoltaic power station, which receives the instructions issued by the AVC master station system of the power grid control center and then regulates the reactive power equipment in the station to make the voltage / reactive power at the grid connection point meet the requirements of the power grid.

[0003] The AVC master station of the power grid control center generates control instructions periodically and sends them to the AVC substation of the photovoltaic power station. This period is generally no more than 5 minutes. To better constrain the substation to adjust the voltage and reactive power according to the instructions of the master station, the master station AVC system will evaluate and assess the adjustment effect of the AVC substation of the photovoltaic power station.

[0004] Currently, most AVC substations of photovoltaic power stations adopt a mode of following the control instructions of the master station to adjust the voltage of the substation. Although the ideas of emergency control and optimal control have been proposed, in order to better meet the requirements of the master station control instructions and avoid the generation of assessment fees, emergency control and optimal control have not fully played their roles, so that various control modes restrict each other and cannot form a joint force to achieve a higher level of reactive power and voltage regulation. Therefore, it is urgent to solve this technical problem. Summary of the Invention

[0005] In view of the above problems, the present application is proposed to provide a time-division control method and device for a photovoltaic AVC substation considering assessment rules, which can overcome the above problems or at least partially solve the above problems. Different control modes are adapted according to the assessment rules in different time periods, which can not only meet the needs of the voltage safety of the station itself, but also meet the requirements of the dispatching master station for reactive voltage regulation of new energy power stations. At the same time, it can give full play to the role of the station's independent optimized voltage regulation, so that the three promote each other, improve the safety margin of the station voltage, and avoid assessment fees at the same time. The technical solutions are as follows:

[0006] In a first aspect, a time-division control method for a photovoltaic AVC substation considering assessment rules is provided, including:

[0007] Determine the current control time period of the photovoltaic AVC substation according to the received instruction time of the AVC master station of the power grid control center and the assessment rules;

[0008] Determine the current control mode of the photovoltaic AVC substation according to the current control time period of the photovoltaic AVC substation, and perform adjustment and control according to the current control mode of the photovoltaic AVC substation.

[0009] In a second aspect, a time-division control device for a photovoltaic AVC substation considering assessment rules is provided, including:

[0010] A determination unit for determining the current control time period of the photovoltaic AVC substation according to the received instruction time of the AVC master station of the power grid control center and the assessment rules;

[0011] A control unit for determining the current control mode of the photovoltaic AVC substation according to the current control time period of the photovoltaic AVC substation, and performing adjustment and control according to the current control mode of the photovoltaic AVC substation.

[0012] By means of the above technical solutions, the time-division control method and device for a photovoltaic AVC substation considering assessment rules provided by the embodiments of the present application determine the current control time period of the photovoltaic AVC substation according to the received instruction time of the AVC master station of the power grid control center and the assessment rules; determine the current control mode of the photovoltaic AVC substation according to the current control time period of the photovoltaic AVC substation, and perform adjustment and control according to the current control mode of the photovoltaic AVC substation. In this way, different control modes are adapted according to the assessment rules in different time periods, which can not only meet the needs of the voltage safety of the station itself, but also meet the requirements of the dispatching master station for reactive voltage regulation of new energy power stations. At the same time, it can give full play to the role of the station's independent optimized voltage regulation, so that the three promote each other, improve the safety margin of the station voltage, and avoid assessment fees at the same time. Description of the Drawings

[0013] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments of the present application.

[0014] Figure 1 Shows a flowchart of a time - segmented control method for a photovoltaic AVC sub - station considering assessment rules provided by an embodiment of the present application;

[0015] Figure 2 Shows a schematic diagram of the control time period provided by an embodiment of the present application;

[0016] Figure 3a Shows a flowchart of a time - segmented control method for a photovoltaic AVC sub - station considering assessment rules provided by another embodiment of the present application;

[0017] Figure 3b Shows a schematic diagram of the combination of the control time period and the control mode provided by an embodiment of the present application;

[0018] Figure 4 Shows a structural diagram of a time - segmented control device for a photovoltaic AVC sub - station considering assessment rules provided by an embodiment of the present application. Detailed implementation manners

[0019] The following will describe the exemplary embodiments of the present application in more detail with reference to the drawings. Although the exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0020] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present application are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that such use can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order different from those illustrated or described herein. In addition, the term "including" and its variants should be interpreted as open - ended terms meaning "including but not limited to".

[0021] To solve the above - mentioned technical problems, an embodiment of the present application provides a time - segmented control method for a photovoltaic AVC sub - station considering assessment rules, as Figure 1 shown, the time - segmented control method for a photovoltaic AVC sub - station considering assessment rules may include the following steps S101 and S102:

[0022] Step S101, determine the current control time period of the photovoltaic AVC sub - station according to the moment when the AVC master station instruction of the power grid dispatching center is received and the assessment rules.

[0023] In this step, the assessment rules can be set according to actual requirements, and this embodiment does not limit this.

[0024] For example, assume that the instruction issuing period of the AVC master station is T c , as shown in Figure 2 , the moment when the PV AVC sub-station receives the latest control instruction from the AVC master station is T0. According to the assessment rules, the PV AVC sub-station has a time of T adj to make adjustments. Let T1 = T0 + T adj , then the control time period of the PV AVC sub-station from T0 to T1 is the adjustment time period; according to the assessment rules, the AVC master station will collect data for a duration of T exam for assessment calculation. Let T2 = T1 + T exam , then the control time period of the PV AVC sub-station from T1 to T2 is the assessment time period; let T afexam = T c - (T adj + T exam ), then the time period from T2 to T2 + T afexam is the post-assessment time period. If the next round of AVC master station instruction is issued at time T3 and T3 < T2 + T afexam , then the time period from T2 to T3 is the post-assessment time period. According to this method, the control period of the PV AVC sub-station is divided into three time periods: the adjustment time period, the assessment time period, and the post-assessment time period.

[0025] Step S102: Determine the current control mode of the PV AVC sub-station according to the current control time period it is in, and perform adjustment control according to the current control mode of the PV AVC sub-station.

[0026] In this step, the control modes of the PV AVC sub-station generally include an emergency control mode, a correction control mode, and an optimization control mode. For the busbar equipment B i in the booster station, its upper voltage safety limit is U i sup, its lower voltage safety limit is U i sdn, and the busbar voltage value of B i is U i real. When U i real >= U i sup or U i real <= U i sdn, the PV AVC sub-station enters the emergency control mode; for the inverter equipment G i of the PV power station, its upper voltage safety limit is UG i sup, its lower safety limit is UG i sdn, and the terminal voltage of the inverter equipment is UGi real, count all UGs i real > UG i The number of inverter devices of sup is N gup , count all UGs i real < UG i The number of inverter devices of sdn is N gdn , set the emergency control inverter threshold number of the photovoltaic AVC substation to N safe , when N gup >= N safe or N gdn >= N safe When this happens, the photovoltaic AVC substation enters the emergency control mode. The traditional photovoltaic AVC substation determines whether the photovoltaic AVC substation is in the correction control mode or the optimization control mode according to the voltage control dead zone U dead and the balance control dead zone U bal to determine whether the photovoltaic AVC substation is in the correction control mode or the optimization control mode. In this embodiment, the control time period in which the AVC substation is located will be fully considered to finally determine the control mode of the AVC substation.

[0027] This embodiment adapts different control modes in different time periods according to the assessment rules, which not only meets the needs of the voltage safety of the station itself, but also meets the requirements of the dispatching master station for the reactive voltage regulation of new energy stations. At the same time, it can give full play to the role of the station's independent optimization of voltage regulation, so that the three promote each other, improve the voltage safety margin of the station, and avoid generating assessment fees.

[0028] In the embodiment of the present application, a possible implementation manner is provided. The control time period mentioned above may include any one of the adjustment time period, the assessment time period, and the post-assessment time period;

[0029] In step S101, according to the received instruction time of the AVC master station of the power grid dispatching center and the assessment rules, determine the current control time period of the photovoltaic AVC substation, which may specifically include the following steps A1 and A2:

[0030] Step A1, set the instruction issuing period of the AVC master station to T c , the moment when the photovoltaic AVC substation receives the latest control instruction of the AVC master station is T0. According to the assessment rules, the photovoltaic AVC substation has T adj time to adjust. Let T1 = T0 + T adj , then the control time period of the photovoltaic AVC substation from T0 to T1 is the adjustment time period; according to the assessment rules, the AVC master station will collect data for T exam duration for assessment calculation. Let T2 = T1 + T exam , then the control time period of the photovoltaic AVC substation from T1 to T2 is the assessment time period; let T afexam = Tc -(T adj +T exam ), then the time period from time T2 to T2 + T afexam is the post-assessment time period. If the next round of AVC master station instruction is issued at time T3 and T3 < T2 + T afexam , then the time period from T2 to T3 is the post-assessment time period;

[0031] Step A2: Determine the current control time period of the PV AVC substation according to the defined adjustment time period, assessment time period, and post-assessment time period.

[0032] In this embodiment, the current control time period of the PV AVC substation can be determined according to the assessment rules, so that different control modes can be adapted in different time periods.

[0033] In an embodiment of the present application, a possible implementation manner is provided. The aforementioned control modes may include any one of an emergency control mode, a correction control mode, and an optimization control mode;

[0034] In step S102, according to the current control time period of the PV AVC substation, determine the current control mode of the PV AVC substation, and perform adjustment control according to the current control mode of the PV AVC substation. Specifically, it may include the following steps B1:

[0035] Step B1: When the PV AVC substation is currently in the adjustment time period, determine the current control mode of the PV AVC substation. When the PV AVC substation is currently in the emergency control mode, if the voltage regulation requirement of the PV AVC substation itself is opposite to the instruction issued by the dispatching AVC master station, temporarily discard the instruction issued by the dispatching AVC master station, and adjust the voltage of the bus or inverter equipment exceeding the safety limit in the PV station to the normal range as the target; when the PV AVC substation is not currently in the emergency control mode, assume that the voltage instruction issued by the dispatching AVC master station is U set , and the control voltage of the PV AVC substation is U real , and the control dead zone of the PV AVC substation is U dead . When |U set - U real | >= U dead , the PV AVC substation enters the correction control mode, and the PV AVC substation follows the instruction issued by the AVC master station for adjustment. When |U set - U real | < U dead , the PV AVC substation does not perform optimization control either, but enters the instruction leveling stage in the correction control mode, that is, issue leveling instructions to each reactive power device.

[0036] In an embodiment of the present application, a possible implementation manner is provided. In step S102, according to the current control time period in which the photovoltaic AVC substation is located, the current control mode of the photovoltaic AVC substation is determined, and adjustment control is performed according to the current control mode of the photovoltaic AVC substation. Specifically, the following steps B2 may further be included:

[0037] Step B2, when the photovoltaic AVC substation is currently in the assessment time period, determine the current control mode of the photovoltaic AVC substation. When the photovoltaic AVC substation is currently in the emergency control mode, adjust according to the emergency control mode; when the photovoltaic AVC substation is not currently in the emergency control mode and |U set -U real | >= U dead , the photovoltaic AVC substation enters the correction control mode. The photovoltaic AVC substation follows the instructions issued by the AVC master station for adjustment, and issues corresponding adjustment instructions to each reactive power device. When |U set -U real | < U dead , a flat adjustment instruction is issued to each reactive power device.

[0038] In an embodiment of the present application, a possible implementation manner is provided. In step S102, according to the current control time period in which the photovoltaic AVC substation is located, the current control mode of the photovoltaic AVC substation is determined, and adjustment control is performed according to the current control mode of the photovoltaic AVC substation. Specifically, the following steps B3 may further be included:

[0039] Step B3, when the photovoltaic AVC substation is currently in the post-assessment time period, determine the current control mode of the photovoltaic AVC substation. When the photovoltaic AVC substation is currently in the emergency control mode, adjust according to the emergency control mode; when the photovoltaic AVC substation is not currently in the emergency control mode, set the upper operation limit of the current control bus of the photovoltaic AVC substation as U runup , the lower operation limit as U rundn , and the control voltage of the photovoltaic AVC substation as U real . When U real < U runup -2*U dead and U real > U rundn +2*U dead , that is, the control voltage of the photovoltaic AVC substation is within the normal operation upper and lower limits, it is considered that the photovoltaic AVC substation enters the optimization control mode, and control is performed according to the optimization control mode to eliminate the reactive power circulation of the main transformer and optimize the reactive power distribution within the substation yard.

[0040] In an embodiment of the present application, a possible implementation is provided. When the photovoltaic AVC substation adjusts and controls according to the emergency control mode, when the main transformer high-voltage side bus exceeds the safety limit, it is determined whether the adjustment direction of the instruction issued by the dispatching main station AVC to the photovoltaic AVC substation is consistent with the bus adjustment direction for adjusting the main transformer high-voltage side bus back to the normal range. When the two are consistent, the instruction U issued by the main station AVC is still followed set for adjustment. If the adjustment directions of the two are inconsistent, the instruction issued by the main station AVC is temporarily discarded, and the adjustment is carried out with the goal of adjusting the main transformer high-voltage side bus voltage to the normal range. If the high-voltage side bus voltage U real >=U sup , U sup is the voltage safety upper limit, the target value of the photovoltaic AVC substation is adjusted to U sup -2×U dead . If the high-voltage side bus voltage U real <=U sdn , U sdn is the voltage safety lower limit, the target value of the photovoltaic AVC substation is adjusted to U sdn +2×U dead . After the photovoltaic AVC substation determines the adjustment target value, the reactive power equipment in the station is adjusted to reach the target. When the main transformer low-voltage side bus voltage exceeds the safety limit, it is determined whether the instruction issued by the dispatching AVC main station is consistent with the adjustment direction of the photovoltaic AVC substation for adjusting the main transformer low-voltage side bus to the normal range. If the two are consistent, the instruction U issued by the dispatching AVC main station is still followed set for adjustment. If the adjustment directions of the two are inconsistent, for the over-limit low-voltage bus B i , its voltage safety upper limit is U i sup, its voltage safety lower limit is U i sdn, the bus voltage value is U i real. If U i real>=U i sup, U lset =U i sup-2×U i dead, U i dead is the control dead zone of the bus B i , and it is converted to the high-voltage side U hset =U lset ×U real / U i real, where U hset is the high-voltage side voltage setting target pre-estimation value, U real is the main transformer high-voltage side bus voltage. If U hset >=U sup -2×U dead , Uhset = U sup - 2×U dead If U hset <= U sdn + 2×U dead U hset = U sdn + 2×U dead Considering the maximum step limit of voltage regulation, if U hset >= U real + U maxstep U hset = U real + U maxstep If U hset <= U real - U maxstep U hset = U real - U maxstep Thus, the control target value U of the PV AVC substation is calculated hset When U i real <= U i sdn, U lset = U i sdn + 2×U i dead, and it is converted to the high voltage side to get U hset = U lset ×U real / U i real. Considering the upper limit U of the main transformer high voltage side bus voltage sup and the lower limit U of the voltage sdn constraints and the voltage regulation step limit, U hset is obtained. The PV AVC substation adjusts each reactive power device in the station with U hset as the target; when the terminal voltages of a certain number of PV inverters exceed the safety limit, in the same way, when the instruction issued by the dispatching AVC master station is consistent with the adjustment direction to adjust the terminal voltage of the PV inverter back to the normal range, the instruction of the dispatching AVC master station is used as the control target. When the two are inconsistent, the control instruction of the dispatching AVC master station is temporarily discarded. Let the maximum voltage regulation step of the PV AVC substation be U maxstep . Adjust with the maximum regulation step as the step. If it is to increase the inverter voltage, then U hset = U real + U maxstep . If it is to decrease the inverter voltage, then U hset = U real - U maxstep . After verification by the upper limit U of the main transformer high voltage side bus voltage sup and the lower limit U of the voltage sdn , the final U hset, the PV AVC substation regulates the reactive power equipment in the substation with U hset as the target.

[0041] In an embodiment of the present application, a possible implementation is provided. When the PV AVC substation is controlled according to the correction control mode, it is regulated according to the control instruction U set of the dispatching AVC master station. The reactive power demand is obtained through sensitivity calculation, and the reactive power command values of each reactive power equipment are calculated according to the inverter priority regulation or equal margin regulation algorithm. The bus voltages of each voltage level in the step-up substation after the regulation of the PV AVC substation are estimated. Reactive power control instructions are issued to equipment such as inverters and ordinary SVG (Static Var Generator), and voltage control instructions are issued to equipment such as distributed synchronous condensers and network-forming SVG.

[0042] In an embodiment of the present application, a possible implementation is provided. When the PV AVC substation is controlled according to the optimization control mode, it eliminates the reactive power circulation of the main transformer through reactive power replacement and balances the reactive power distribution of each reactive power equipment. During the regulation process, since the optimization control mode only operates in the post-assessment time period, its regulation step size can be carried out according to the normal regulation step size of the PV AVC substation. At the same time, large fluctuations in the bus voltage on the high-voltage side need to be avoided. Therefore, the finally calculated reactive power injection on the high-voltage side should be 0 at this time. The reactive power optimization can be divided into two steps. First, the reactive power circulation between the main transformers is eliminated. For substations with multiple main transformers, two main transformers with the largest circulation can be selected for control. First, the circulation of these two main transformers is eliminated, and in the next round, two main transformers with the largest circulation are found until the circulation of the main transformers is eliminated. The second step is to balance the possible circulation of the reactive power equipment under each main transformer and perform reactive power replacement between fast reactive power regulation and slow reactive power regulation.

[0043] In an embodiment of the present application, a possible implementation is provided to determine the current control mode of the PV AVC substation, specifically including the following steps C1:

[0044] Step C1, for the bus equipment B i in the step-up substation, its voltage safety upper limit is U i sup, its voltage safety lower limit is U i sdn, and the bus voltage value of B i is U i real. When U i real >= U i sup or U i real <= U i sdn, the PV AVC substation enters the emergency control mode; for the inverter equipment G i of the PV power station, its voltage safety upper limit is UG isup, and its safety lower limit is UG i sdn, the terminal voltage of the inverter device is UG i real, count all UG i real > UG i The number of inverter devices with sup is N gup , count all UG i real < UG i The number of inverter devices with sdn is N gdn , set the emergency control inverter threshold number of the PV AVC substation as N safe , when N gup >= N safe or N gdn >= N safe , the PV AVC substation enters the emergency control mode.

[0045] In addition, the traditional PV AVC substation determines whether the PV AVC substation is in the correction control mode or the optimization control mode according to the voltage control dead zone U dead and the balance control dead zone U bal . In this embodiment, the control time period in which the AVC substation is located will be fully considered to finally determine the control mode of the AVC substation.

[0046] The above has introduced Figure 1 multiple implementation manners of each link of the embodiment shown in

[0047] Figure 3a The flowchart of the PV AVC substation time - segmented control method considering the assessment rules provided by another embodiment of the present application is shown.

[0048] In Figure 3a , the PV AVC substation judges the currently - owned control time period, judges whether it is an adjustment time period. If it is an adjustment time period, the PV AVC substation judges the currently - owned control mode (emergency control mode or correction control mode), and performs adjustment control according to the control mode in which the PV AVC substation is currently located, and continues the next - round judgment.

[0049] If it is not an adjustment time period, it judges whether it is an assessment time period. If it is an assessment time period, the PV AVC substation judges the currently - owned control mode (emergency control mode or correction control mode), and performs adjustment control according to the control mode in which the PV AVC substation is currently located, and continues the next - round judgment.

[0050] If it is not the assessment time period, it is the post-assessment time period. The PV AVC substation judges the current control mode (emergency control mode or optimization control mode) it belongs to, and performs adjustment control according to the control mode in which the PV AVC substation is currently located, and continues to make the next round of judgments. Here, different time periods are adapted to different control modes, such as Figure 3b shown

[0051] In Figure 3b , the adjustment time period is adapted to the emergency control mode and the correction control mode; the assessment time period is adapted to the emergency control mode and the correction control mode; the post-assessment time period is adapted to the emergency control mode and the optimization control mode.

[0052] In a specific embodiment, there is a PV power station with two main transformers, and the rated capacity is 150 MVA. The bus voltage level of the high-voltage side of the main transformer is 220 KV, the upper safety limit of the high-voltage side voltage of the main transformer is 236 KV, the lower safety limit of the high-voltage side voltage of the main transformer is 220 KV, the control dead zone is 0.5 KV, the bus voltage level of the low-voltage side of the main transformer is 35 kV, the upper safety limit of the low-voltage side voltage of the main transformer is 39 KV, the lower safety limit of the low-voltage side voltage of the main transformer is 33 KV, and the control dead zone is 0.2 KV. There are 300 inverters, and the installed capacity of each inverter is 0.5 MW, the rated terminal voltage is 0.315 KV, the upper voltage safety limit value is 0.340 KV, and the lower voltage safety limit value is 0.290 KV. The control period of the PV AVC substation is 30 seconds.

[0053] The current high-voltage side bus voltage of the PV power station is 230.0 KV, and the adjustment instruction sent by the main station AVC system is 229.0 KV. The PV AVC substation enters the adjustment time period. The reactive power of the high-voltage side of #1 main transformer is -4 Mvar, and the reactive power of the high-voltage side of #2 main transformer is 2 Mvar. There is a circulating current between #1 main transformer and #2 main transformer, resulting in inconsistent bus voltages of the two sections. The current voltage value of the 35 KV I-section bus is 35.5 KV, and the current voltage value of the 35 KV II-section bus is 34.5 KV. The terminal voltages of each inverter are all around 0.31 KV. The terminal voltages of some inverters under the 35 KV II-section bus are relatively low, around 0.3 KV. At this time, the PV AVC substation enters the correction control mode after judgment, and adjusts each reactive power device in the station to follow the instruction of 229.0 KV sent by the main station. After two rounds of adjustment, after 1 minute, the high-voltage side voltage of the station is stabilized at 229.3 KV. The PV AVC substation judges that the high-voltage side control bus voltage enters the control dead zone, and issues a flat adjustment instruction to each reactive power device in the station in the subsequent time.

[0054] Two minutes later, the PV AVC substation enters the assessment period. At this time, the voltage on the high-voltage side of the substation is about 229.3 KV. The PV AVC substation continues to send flat-regulation commands to each reactive power device in the substation. At this time, due to the sudden change in weather, the active power output of the inverters drops suddenly, and the reactive power output also changes. The voltages of some inverters change. The PV AVC substation detects that the voltages of 11 inverters under the 35 KV II section bus have dropped below the lower limit of 0.290 KV, exceeding the emergency control inverter threshold number 10 of the PV AVC substation. The PV AVC substation enters the emergency control mode. The AVC substation adjusts the reactive power of the SVG device in the substation to raise the voltage on the high-voltage side of the main transformer to 230.0 KV, and the voltages of the 11 over-limit inverters are also raised to about 0.305 KV. In the next control cycle, the PV AVC substation detects that the bus voltages are within the safe upper and lower limits, and enters the correction control mode again, adjusting the reactive power of each reactive power device to adjust the voltage of the high-voltage side bus to 229.20 KV. After that, the PV AVC substation sends flat-regulation commands to each reactive power device.

[0055] Four minutes later, the assessment period ends. The PV AVC substation enters the post-assessment period. It detects that the voltages of each bus device are within the safe upper and lower limits and enters the optimal control mode. By adjusting the output of the SVG devices under the #1 main transformer and the #2 main transformer, the reactive power on the high-voltage side of the #1 main transformer is adjusted to -1 Mvar, the reactive power on the high-voltage side of the #2 main transformer is adjusted to -1 Mvar, the voltage of the 35 KV I section bus is adjusted to 35.2 KV, the voltage of the 35 KV II section bus is adjusted to 35.0 KV, and the voltages of some inverters with low voltages under the 35 KV II section bus are also adjusted, rising from 0.300 KV to 0.305 KV. After that, the PV AVC substation sends flat-regulation commands to each reactive power device. Five minutes later, the PV AVC substation receives a new control command issued by the dispatching AVC master station and enters a new round of adjustment period to start a new round of control.

[0056] It should be noted that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application. In practical applications, all the above possible implementation manners can be combined arbitrarily to form possible embodiments of the present application, which will not be elaborated here one by one.

[0057] Based on the PV AVC substation time-division control method considering the assessment rules provided in the above embodiments, based on the same inventive concept, the embodiments of the present application also provide a PV AVC substation time-division control device considering the assessment rules.

[0058] Figure 4This is the structural diagram of the photovoltaic AVC substation time - segmented control device provided by the embodiments of the present application. As Figure 4 shown, the photovoltaic AVC substation time - segmented control device considering the assessment rules may specifically include a determination unit 410 and a control unit 420.

[0059] The determination unit 410 is configured to determine the current control time period of the photovoltaic AVC substation according to the received instruction time of the AVC master station in the power grid dispatching center and the assessment rules;

[0060] The control unit 420 is configured to determine the current control mode of the photovoltaic AVC substation according to the current control time period of the photovoltaic AVC substation, and perform adjustment control according to the current control mode of the photovoltaic AVC substation.

[0061] In a possible implementation manner provided by the embodiments of the present application, the control time period includes any one of an adjustment time period, an assessment time period, and a post - assessment time period; the determination unit 410 is further configured to:

[0062] Set the instruction issuance period of the AVC master station as T c , the time when the photovoltaic AVC substation receives the latest control instruction of the AVC master station is T0. According to the assessment rules, the photovoltaic AVC substation has T adj time to make adjustments. Set T1 = T0 + T adj , then the control time period of the photovoltaic AVC substation from T0 to T1 is the adjustment time period; according to the assessment rules, the AVC master station will collect data with a duration of T exam for assessment calculation. Set T2 = T1+T exam , then the control time period of the photovoltaic AVC substation from T1 to T2 is the assessment time period; let T afexam =T c -(T adj +T exam ), then the time period from T2 to T2 + T afexam is the post - assessment time period. If the next round of AVC master station instruction is issued at T3, and T3 < T2 + T afexam , then the time period from T2 to T3 is the post - assessment time period;

[0063] Determine the current control time period of the photovoltaic AVC substation according to the defined adjustment time period, assessment time period, and post - assessment time period.

[0064] In a possible implementation manner provided by the embodiments of the present application, the control mode includes any one of an emergency control mode, a correction control mode, and an optimization control mode; the control unit 420 is further configured to:

[0065] When the current photovoltaic AVC substation is in the adjustment time period, determine the current control mode of the photovoltaic AVC substation. When the photovoltaic AVC substation is in the emergency control mode, if the voltage regulation requirement of the photovoltaic AVC substation itself is opposite to the instruction issued by the dispatching AVC master station, temporarily discard the instruction issued by the dispatching AVC master station, and adjust with the goal of adjusting the voltage of the bus or inverter equipment exceeding the safety limit in the photovoltaic power station to the normal range; when the photovoltaic AVC substation is not in the emergency control mode, set the voltage instruction issued by the dispatching AVC master station as U set , and the control voltage of the photovoltaic AVC substation is U real , the control dead zone of the photovoltaic AVC substation is U dead , when |U set - U real | >= U dead , the photovoltaic AVC substation enters the correction control mode, and the photovoltaic AVC substation follows the instruction issued by the AVC master station for adjustment. When |U set - U real | < U dead , the photovoltaic AVC substation does not perform optimization control either, but enters the instruction flat adjustment stage under the correction control mode, that is, issue flat adjustment instructions to each reactive power device.

[0066] In a possible implementation provided in the embodiment of the present application, the control unit 420 is further configured to:

[0067] When the current photovoltaic AVC substation is in the assessment time period, determine the current control mode of the photovoltaic AVC substation. When the photovoltaic AVC substation is in the emergency control mode, adjust according to the emergency control mode; when the photovoltaic AVC substation is not in the emergency control mode and |U set - U real | >= U dead , the photovoltaic AVC substation enters the correction control mode, and the photovoltaic AVC substation follows the instruction issued by the AVC master station for adjustment, and issue corresponding adjustment instructions to each reactive power device. When |U set - U real | < U dead , issue flat adjustment instructions to each reactive power device.

[0068] In a possible implementation provided in the embodiment of the present application, the control unit 420 is further configured to:

[0069] When the current photovoltaic AVC substation is in the post-assessment time period, determine the current control mode of the photovoltaic AVC substation. When the photovoltaic AVC substation is in the emergency control mode, adjust according to the emergency control mode; when the photovoltaic AVC substation is not in the emergency control mode, set the upper limit of the operation of the control bus of the current photovoltaic AVC substation as U runup, the lower operating limit is U rundn , and the control voltage of the photovoltaic AVC substation is U real , when U real < U runup - 2*U dead and U real > U rundn + 2*U dead When the control voltage of the photovoltaic AVC substation is within the normal operating upper and lower limits, it is considered that the photovoltaic AVC substation enters the optimized control mode and is controlled according to the optimized control mode to eliminate the reactive power circulation of the main transformer and optimize the reactive power distribution within the substation yard.

[0070] In an embodiment of the present application, a possible implementation manner is provided, and the control unit 420 is further configured to:

[0071] When the photovoltaic AVC substation adjusts and controls according to the emergency control mode and the high-voltage side bus of the main transformer exceeds the safety limit, at this time, it is judged whether the adjustment direction of the instruction issued by the dispatching main station AVC to the photovoltaic AVC substation is consistent with the bus adjustment direction for adjusting the high-voltage side bus of the main transformer back to the normal range. When the two are consistent, the adjustment is still carried out according to the instruction U set issued by the main station AVC. If the adjustment directions of the two are inconsistent, the instruction issued by the main station AVC is temporarily discarded, and the adjustment is carried out with the goal of adjusting the high-voltage side bus voltage to the normal range. If the high-voltage side bus voltage U real >= U sup , U sup is the voltage safety upper limit, the target value of the photovoltaic AVC substation is adjusted to U sup - 2×U dead , if the high-voltage side bus voltage U real <= U sdn , U sdn is the voltage safety lower limit, the target value of the photovoltaic AVC substation is adjusted to U sdn + 2×U dead , after the photovoltaic AVC substation determines the adjustment target value, the reactive power equipment in the station is adjusted to reach the target; when the low-voltage side bus voltage of the main transformer exceeds the safety limit, it is judged whether the instruction issued by the dispatching AVC main station is consistent with the adjustment direction of the photovoltaic AVC substation for adjusting the low-voltage side bus of the main transformer to the normal range. If the two are consistent, the adjustment is still carried out according to the instruction U set issued by the dispatching AVC main station. If the adjustment directions of the two are inconsistent, for the over-limited low-voltage bus B i , its voltage safety upper limit is U i sup, its voltage safety lower limit is U i sdn, the bus voltage value is U i real, if U i real >= Ui sup, U lset = U i sup - 2×U i dead, U i dead is the control dead zone of bus bar B and is converted to the high - voltage side U i = U hset ×U lset / U real real, where U i is the target predicted value of the high - voltage side voltage setting, U hset is the bus bar voltage of the main transformer high - voltage side. If U real >= U hset - 2×U sup - 2×U dead , U hset = U sup - 2×U dead , if U hset <= U sdn + 2×U dead , U hset = U sdn + 2×U dead , considering the maximum step - size limit of voltage regulation. If U hset >= U real + U maxstep , U hset = U real + U maxstep , if U hset <= U real - U maxstep , U hset = U real - U maxstep , thus calculating the control target value U of the PV AVC sub - station hset , when U i real <= U i sdn, U lset = U i sdn + 2×U i dead and is converted to the high - voltage side to obtain U hset = U lset ×U real / U i real, considering the upper limit U sup of the main transformer high - voltage side bus bar voltage and the lower limit U sdn and the constraint of the voltage regulation step - size limit, U hset is obtained. The PV AVC sub - station uses U hsetTo regulate each reactive power device in the target regulating substation; when the terminal voltages of a certain number of PV inverters exceed the safety limit, in the same way, when the instruction issued by the dispatching AVC master station is consistent with the regulating direction to adjust the terminal voltage of the PV inverter back to the normal range, the instruction of the dispatching AVC master station is taken as the control target. When the two are inconsistent, the control instruction of the dispatching AVC master station is temporarily discarded. Let the maximum voltage regulation step of the PV AVC substation be U maxstep , and adjust in steps with the maximum regulation step as the step. If it is to increase the inverter voltage, then U hset = U real + U maxstep , if it is to decrease the inverter voltage, then U hset = U real - U maxstep , and after verification by the upper limit U sup and the lower limit U sdn of the bus voltage on the high-voltage side of the main transformer, the final U hset is obtained. The PV AVC substation regulates the reactive power devices in the substation with U hset as the target.

[0072] In a possible implementation provided in the embodiment of the present application, the control unit 420 is further configured to:

[0073] When the PV AVC substation is controlled according to the correction control mode, adjust according to the control instruction U set of the dispatching AVC master station. Calculate the reactive power demand through sensitivity calculation, calculate the reactive power command values of each reactive power device according to the inverter priority regulation or equal margin regulation algorithm, and estimate the bus voltages of each voltage level in the booster station after the PV AVC substation adjusts. Issue reactive power control instructions to the inverter and ordinary SVG devices, and issue voltage control instructions to the distributed synchronous condenser and network-forming SVG devices.

[0074] In a possible implementation provided in the embodiment of the present application, the control unit 420 is further configured to:

[0075] When the PV AVC substation is controlled according to the optimization control mode, it eliminates the main transformer reactive power circulation through reactive power replacement and balances the reactive power distribution of each reactive power device.

[0076] In a possible implementation provided in the embodiment of the present application, the control unit 420 is further configured to:

[0077] For the bus device B i in the booster station, its voltage safety upper limit is U i sup, its voltage safety lower limit is U i sdn, B i 's bus voltage value is U i real, when Ui real >= U i sup or U i real <= U i When the PV AVC substation enters the emergency control mode; for the inverter equipment G of the PV power station i , its upper voltage safety limit is UG i sup, and its lower safety limit is UG i sdn, and the terminal voltage of the inverter equipment is UG i real, and count all UG i real > UG i sup, the number of inverter equipment is N gup , and count all UGi r eal < UG i sdn, the number of inverter equipment is N gdn , and set the emergency control inverter threshold number of the PV AVC substation as N safe , when N gup >= N safe or N gdn >= N safe , the PV AVC substation enters the emergency control mode.

[0078] Those skilled in the art can clearly understand that the specific working processes of the systems, devices, and modules described above can refer to the corresponding processes in the foregoing method embodiments. For the sake of brevity, they are not described herein again.

[0079] Those of ordinary skill in the art can understand that the technical solution of the present application can essentially or all or part of the technical solution be embodied in the form of a software product. The computer software product is stored in a storage medium, which includes several program instructions for causing an electronic device (such as a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application when running the program instructions. And the foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs that can store program codes.

[0080] Alternatively, all or part of the steps of implementing the foregoing method embodiments can be completed by hardware related to program instructions (such as an electronic device such as a personal computer, a server, or a network device, etc.). The program instructions can be stored in a computer-readable storage medium. When the program instructions are executed by the processor of the electronic device, the electronic device executes all or part of the steps of the methods described in the embodiments of the present application.

[0081] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that within the spirit and principle of the present application, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the corresponding technical solutions to deviate from the protection scope of the present application.

Claims

1. A photovoltaic AVC substation time-sharing control method taking into account assessment rules, characterized in that: include: According to the command time and assessment rules received from the AVC master station of the power grid control center, the current control time period of the photovoltaic AVC substation is determined; According to the control time period of the photovoltaic AVC substation, the current control mode of the photovoltaic AVC substation is determined, and the photovoltaic AVC substation is adjusted and controlled according to the current control mode of the photovoltaic AVC substation; The control time period includes any time period among the adjustment time period, the assessment time period, and the post-assessment time period; The method of determining the current control time period of the photovoltaic AVC substation according to the received instruction time of the AVC master station of the power grid control center and the assessment rules includes: Assume that the instruction issuing cycle of the AVC master station is The time when the photovoltaic AVC substation receives the latest control instruction from the AVC master station is According to the assessment rules, the photovoltaic AVC substation has time to adjust, set , then from arrive The photovoltaic AVC substation control time period is the adjustment time period; according to the assessment rules, the AVC master station will collect The data of duration is used for assessment and calculation. , then from arrive The photovoltaic AVC substation control time period is the assessment time period; , then from Time has come The time period is the post-assessment time period. If the next round of AVC master station instructions are Issued at all times, and , then from arrive The time period is the time period after the assessment; According to the defined adjustment time period, assessment time period and post-assessment time period, determine the current control time period of the photovoltaic AVC substation; Wherein, the control mode includes any one of an emergency control mode, a correction control mode, and an optimization control mode; The method of determining the current control mode of the photovoltaic AVC substation according to the current control time period of the photovoltaic AVC substation, and performing adjustment and control according to the current control mode of the photovoltaic AVC substation, includes: When the photovoltaic AVC substation is currently in the adjustment time period, the current control mode of the photovoltaic AVC substation is determined. When the photovoltaic AVC substation is currently in the emergency control mode, if the photovoltaic AVC substation's own voltage regulation demand is opposite to the instruction issued by the dispatching AVC master station, the instruction issued by the dispatching AVC master station is temporarily abandoned, and the voltage of the bus or inverter equipment that exceeds the safety limit in the photovoltaic station is adjusted to the normal range; when the photovoltaic AVC substation is not currently in the emergency control mode, the voltage instruction issued by the dispatching AVC master station is set to , and the control voltage of the photovoltaic AVC substation is , the control dead zone of the photovoltaic AVC substation is ,when When the PV AVC substation enters the correction control mode, the PV AVC substation follows the instructions issued by the AVC master station to make adjustments. When the PV AVC substation does not perform optimization control, it enters the command leveling stage under the correction control mode, that is, it issues leveling commands to each reactive device.

2. The method according to claim 1, characterized in that The method of determining the current control mode of the photovoltaic AVC substation according to the current control time period of the photovoltaic AVC substation, and performing adjustment and control according to the current control mode of the photovoltaic AVC substation, includes: When the PV AVC substation is currently in the assessment period, determine the current control mode of the PV AVC substation. When the PV AVC substation is currently in the emergency control mode, adjust according to the emergency control mode. When the PV AVC substation is not currently in the emergency control mode and When the PV AVC substation enters the correction control mode, the PV AVC substation follows the instructions issued by the AVC master station to adjust and issue corresponding adjustment instructions to each reactive device. When the power is turned off, a leveling command is issued to each reactive equipment.

3. The method according to claim 1, characterized in that The method of determining the current control mode of the photovoltaic AVC substation according to the current control time period of the photovoltaic AVC substation, and performing adjustment and control according to the current control mode of the photovoltaic AVC substation, includes: When the PV AVC substation is currently in the post-assessment time period, determine the current control mode of the PV AVC substation. When the PV AVC substation is currently in the emergency control mode, adjust according to the emergency control mode. When the PV AVC substation is not currently in the emergency control mode, set the current upper limit of the operation of the PV AVC substation control busbar to , the lower limit of operation is , and the control voltage of the photovoltaic AVC substation is ,when and When the control voltage of the photovoltaic AVC substation is within the upper and lower limits of normal operation, it is considered that the photovoltaic AVC substation enters the optimization control mode and is controlled according to the optimization control mode to eliminate the reactive circulating current of the main transformer and optimize the reactive distribution in the station.

4. The method according to any one of claims 1 to 3, characterized in that When the PV AVC substation is regulated and controlled in the emergency control mode, the busbar on the high-voltage side of the main transformer exceeds the safety limit. At this time, it is determined whether the adjustment direction of the command issued by the dispatching master station AVC to the PV AVC substation is consistent with the busbar adjustment direction for adjusting the busbar on the high-voltage side of the main transformer back to the normal range. If the two are consistent, the command issued by the master station AVC is still followed. If the adjustment directions of the two are inconsistent, the command issued by the master station AVC is temporarily abandoned, and the bus voltage on the high-voltage side of the main transformer is adjusted to the normal range. >= , is the voltage safety upper limit, then the target value of the photovoltaic AVC substation is adjusted to , if the high-voltage bus voltage is <= , is the voltage safety lower limit, then the target value of the photovoltaic AVC substation is adjusted to After the photovoltaic AVC substation determines the adjustment target value, it adjusts the reactive equipment in the station to achieve the target; when the bus voltage on the low-voltage side of the main transformer exceeds the safety limit, it determines whether the instruction issued by the dispatching AVC master station is consistent with the adjustment direction of the photovoltaic AVC substation to adjust the low-voltage side bus of the main transformer to the normal range. If the two are consistent, it still follows the instruction issued by the dispatching AVC master station. If the two adjustment directions are inconsistent, the low-voltage busbar that exceeds the limit , the voltage safety upper limit is , the voltage safety lower limit is The bus voltage is ,if , , For bus The control dead zone is converted to the high voltage side ,in Set a target estimate for the high voltage side voltage, is the bus voltage on the high-voltage side of the main transformer, if , ,if , , considering the maximum step size limit of voltage regulation, if , ,if , , thereby calculating the control target value of the photovoltaic AVC substation ,when , , and convert it to the high-voltage side to obtain , considering the upper limit of bus voltage on the high voltage side of the main transformer and voltage lower limit After the constraints of and voltage regulation step size limit, we can get , PV AVC substation The reactive equipment in the station is regulated as the target; when the terminal voltage of a certain number of photovoltaic inverters exceeds the safety limit, in the same way, when the instruction issued by the dispatching AVC master station is consistent with the adjustment direction for adjusting the terminal voltage of the photovoltaic inverter back to the normal range, the instruction of the dispatching AVC master station is used as the control target. When the two are inconsistent, the control instruction of the dispatching AVC master station is temporarily abandoned. The maximum voltage regulation step of the photovoltaic AVC substation is set to , adjust with the maximum adjustment step size as the step size. If you want to increase the inverter voltage, then , if the inverter voltage is lowered, then and through the upper limit of the bus voltage on the high-voltage side of the main transformer and voltage lower limit After verification, the final , PV AVC substation The purpose is to adjust the reactive equipment within the station.

5. The method according to claim 4, characterized in that When the PV AVC substation is controlled in the correction control mode, it follows the control instructions of the dispatching AVC master station. Adjustment is performed, and reactive power demand is obtained through sensitivity calculation. The reactive power command value of each reactive device is calculated according to the inverter priority adjustment or equal margin adjustment algorithm, and the bus voltage of each voltage level in the booster station after adjustment by the photovoltaic AVC substation is estimated. Reactive power control commands are issued to inverters and ordinary SVG devices, and voltage control commands are issued to distributed phase-shifting condensers and grid-type SVG devices.

6. The method according to claim 5, characterized in that When the photovoltaic AVC substation is controlled according to the optimized control mode, it eliminates the reactive circulating current of the main transformer through reactive power replacement and balances the reactive power distribution of each reactive device.

7. The method according to any one of claims 1 to 3, characterized in that Determine the current control mode of the PV AVC substation, including: For busbar equipment in booster station , the voltage safety upper limit is , the voltage safety lower limit is , The bus voltage value is ,when >= or <= The photovoltaic AVC substation enters the emergency control mode; for the inverter equipment of the photovoltaic power station , the voltage safety upper limit is , and its lower safety limit is , the terminal voltage of the inverter equipment is , statistics all > The number of inverter devices is , statistics all < The number of inverter devices is , assuming that the threshold number of the emergency control inverter of the photovoltaic AVC substation is ,when or When the PV AVC substation enters the emergency control mode.

8. A photovoltaic AVC substation time-sharing control device taking into account assessment rules, characterized in that: include: A determination unit, used to determine the current control time period of the photovoltaic AVC substation according to the command time received from the AVC master station of the power grid control center and the assessment rules; A control unit, used to determine the current control mode of the photovoltaic AVC substation according to the current control time period of the photovoltaic AVC substation, and perform adjustment and control according to the current control mode of the photovoltaic AVC substation; The control time period includes any time period among the adjustment time period, the assessment time period, and the post-assessment time period; The determining unit is further configured to: Assume that the instruction issuing cycle of the AVC master station is The time when the photovoltaic AVC substation receives the latest control instruction from the AVC master station is According to the assessment rules, the photovoltaic AVC substation has time to adjust, set , then from arrive The photovoltaic AVC substation control time period is the adjustment time period; according to the assessment rules, the AVC master station will collect The data of duration is used for assessment and calculation. , then from arrive The photovoltaic AVC substation control time period is the assessment time period; , then from Time has come The time period is the post-assessment time period. If the next round of AVC master station instructions are Issued at all times, and , then from arrive The time period is the time period after the assessment; According to the defined adjustment time period, assessment time period and post-assessment time period, determine the current control time period of the photovoltaic AVC substation; Wherein, the control mode includes any one of an emergency control mode, a correction control mode, and an optimization control mode; The control unit is also used for: When the photovoltaic AVC substation is currently in the adjustment time period, the current control mode of the photovoltaic AVC substation is determined. When the photovoltaic AVC substation is currently in the emergency control mode, if the photovoltaic AVC substation's own voltage regulation demand is opposite to the instruction issued by the dispatching AVC master station, the instruction issued by the dispatching AVC master station is temporarily abandoned, and the voltage of the bus or inverter equipment that exceeds the safety limit in the photovoltaic station is adjusted to the normal range; when the photovoltaic AVC substation is not currently in the emergency control mode, the voltage instruction issued by the dispatching AVC master station is set to , and the control voltage of the photovoltaic AVC substation is , the control dead zone of the photovoltaic AVC substation is ,when When the PV AVC substation enters the correction control mode, the PV AVC substation follows the instructions issued by the AVC master station to make adjustments. When the PV AVC substation does not perform optimization control, it enters the command leveling stage under the correction control mode, that is, it issues leveling commands to each reactive device.

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