WO2017118175A1 - Emergency control method applicable to wind-photovoltaic power station - Google Patents

Abstract

An emergency control method applicable to a wind-photovoltaic power station, belonging to the field of electrical power systems and the automation thereof. In the method, the emergency control capability of an energy storage apparatus of a wind-photovoltaic power station is preferentially used when an emergency machine set removal command is implemented, so as to reduce the power loss of machine sets, and the performance difference of all the machine sets of the wind-photovoltaic power station and a machine set repair cycle are comprehensively considered, to remove the machine sets at the lowest economic cost. The method can improve the utilization ratio of a device on the premise of guaranteeing the safety and stability of a power grid, thereby reducing the economic cost when a wind-photovoltaic power station performs emergency control.

Description

Emergency control method suitable for wind power station Technical field

The invention belongs to the field of power systems and their automation technology, and more particularly relates to an emergency control method suitable for a wind power station.

Background technique

With the development and utilization of wind farms and photovoltaic power plants (hereinafter referred to as wind power stations), the safety and stability of power grids and photovoltaic power plants need to be deployed as cutting machine execution stations. At present, the cutting machine measures are based on the whole field or the feeder line, and are executed according to the principle of minimum overcutting, in which the performance of different units (inverters), the maintenance period and whether or not they are equipped with energy storage equipment are not considered too much. . Therefore, such a cutting strategy tends to bring excessive economic losses to the wind power station.

Actual operation of wind power stations often contains a variety of units, and the performance of different units is greatly different. In emergency control, if the units with superior performance are first removed, the risk of uncontrollable wind and light power stations will be aggravated. Can lead to unplanned off-network. At the same time, if the unit that is about to reach the maintenance cycle can be cut off preferentially, it will inevitably increase the actual utilization hours of the wind power station equipment and increase the operating efficiency of the wind and light power station.

With the popularity of energy storage devices, more and more wind power plants will be equipped with a certain capacity of energy storage equipment. If you can make full use of the performance of energy storage equipment for rapid charge and discharge, and participate in grid emergency control, not only can you achieve better control results, but also reduce the actual cutting capacity of wind and light power stations, thereby improving economy. Nevertheless, how to verify the security and economical uniformity in the implementation of emergency control is still a problem to be solved by those skilled in the art.

Summary of the invention

The object of the present invention is to provide an emergency control method for improving the economy of a wind power station for the problem of economical shortage in the emergency control of the wind power station, and not only realize the energy storage equipment to participate in the emergency control, but also reduce the actual cutting machine of the wind power station. Quantity, while achieving comprehensive consideration of unit performance, fault ride-through capability, The economical optimal cutting plan for unit maintenance to reduce the economic loss of wind and light power stations. .

Specifically, the present invention is implemented by the following technical solutions, including the following steps:

1) The stability control device collects the current and voltage of the local high-voltage side of the local wind power main transformer, calculates the power of the wind power station, and communicates with the EMS system of the wind power station to obtain the unit type, current output and continuous running time of each unit, and collect energy storage and grid. The current and voltage on the high voltage side of the transformer, calculate the power of the energy storage device, and communicate with the energy storage control system in real time to obtain the current output and current power of the energy storage device;

If the power supply of the wind power station and the power of the energy storage device calculated by the stability control device are inconsistent with the current output of each unit obtained through the EMS system and the current output of the energy storage device obtained through the energy storage control system, the safety and stability control system to the power grid is obtained. The alarm is as follows:

|P _T -ΣP _EMS -P _S |>P _Er

|P _ST -Ps|>P _Er

In the above formula, P _T and P _ST are respectively the power of the wind power station and the power of the energy storage device calculated by the stability control device, and the ΣP _EMS is the sum of the current outputs of the units acquired by each EMS system, and the Ps is the energy storage. energy storage device of the control system acquires a current output, P _Er is the allowable error power threshold;

If the stability control device receives an emergency cutting command from the grid safety and stability control system, proceed to step 2); the emergency cutting command contains the power ΔP to be cut and the required cut-off time ts;

2) If there is no energy storage device available at the wind power station at this time, go directly to step 3), otherwise:

First, evaluate the adjustable amount ΔPs of the energy storage device for this emergency control as follows:

If the energy storage device is currently charging, then:

If the energy storage device is currently in a discharged state, then:

Where dp/dt is the maximum adjustment speed of the energy storage device, Psmax is the maximum charging power of the energy storage device, Qmax is the upper limit of the energy storage device, Q is the current capacity of the energy storage device, and T is the emergency cutting command. The maximum time that the device must be operated;

Then, the stability control device sends the command of ΔP _s to the energy storage control system. If the energy storage device can complete the emergency control separately, the method ends; otherwise, the remaining cutting power ΔP-ΔP _{s is taken} as a new requirement. The cut power ΔP, proceeds to step 3);

3) Calculate the cutting cost of each unit. The cutting cost is estimated according to the lost power. The calculation formula of the cutting cost generated by the kth unit cutting machine is:

W _k =(1+α _k +β _k )*P _k +W _0k /T _k

Among them, P _k is the current output power of the kth unit, T _k is the running time after the last maintenance of the kth unit, and α _k is the cutting cost factor of the kth unit considering the adjustment performance of the unit. The better the regulation performance, The higher the cost factor of the cutting machine; β _k is the cutting cost factor of the k-th unit considering the fault traversing ability. The better the fault traversing performance, the higher the cost factor; W _0k is the kth unit of the electric power representation. Fixed maintenance costs;

4) Sort all units according to the cutting machine cost W _k from small to large, and preferentially cut off the minimum cost of the cutting machine until the accumulated power of the removed unit ∑P _sum >ΔP, and the cutting machine ends.

A further feature of the above technical solution is that the values of α _k and β _k in the step 3) are in the range of 0 to 1.

The beneficial effects of the invention are as follows: the invention preferentially utilizes the emergency control capability of the energy storage device of the wind power station when implementing the emergency cutting machine command, reduces the power loss of the unit, and comprehensively considers the performance difference of each unit of the wind power station and the maintenance period of the unit, according to The principle of the least economic cost is cut. The invention can improve the utilization rate of the equipment and reduce the economic cost when the wind power station performs the emergency control under the premise of ensuring the safety and stability of the power grid.

DRAWINGS

Figure 1 shows a typical configuration of a wind power station.

2 is a flow chart of the method of the present invention.

detailed description

The present invention will be further described in detail below with reference to the accompanying drawings in conjunction with examples.

Example 1:

A typical configuration of a wind power station to which an embodiment of the present invention is applied is shown in FIG. The stability control device of the wind power station needs to collect the on-grid current and voltage of the local high-voltage side of the main wind power transformer to calculate the power of the wind power station, and also collect the current and voltage of the high-voltage side of the energy storage grid-connected transformer to calculate the power of the energy storage device. At the same time, the stability control device also needs to communicate with the EMS system of various units and the energy storage control system of the energy storage device. Each EMS system sends relevant information of each unit to the stability control device, including the unit type, current output, and continuous running time. Wait. The energy storage control system also generates the current state of the energy storage device to the stability control device, including information such as current output and current power.

The flow of this embodiment is shown in FIG. 2, specifically:

Step 1 in Figure 2 describes the stability control device collecting the local wind current and voltage on the high-voltage side of the local wind power main transformer, calculating the power of the wind power station, and communicating with the EMS system of the wind power station to obtain the unit type, current output and continuous running time of each unit. Collecting the current and voltage on the high voltage side of the energy storage grid-connected transformer, calculating the power of the energy storage device, and communicating with the energy storage control system in real time to obtain the current output and current power of the energy storage device.

If the power supply of the wind power station and the power of the energy storage device calculated by the stability control device are inconsistent with the current output of each unit obtained through the EMS system and the current output of the energy storage device obtained through the energy storage control system, the safety and stability control system to the power grid is obtained. The alarm is as follows:

|P _T -ΣP _EMS -P _S |>P _Er

|P _ST -Ps|>P _Er

In the above formula, P _T and P _ST are respectively the power of the wind power station and the power of the energy storage device calculated by the stability control device, and the ΣP _EMS is the sum of the current outputs of the units acquired by each EMS system, and the Ps is the energy storage. The current output of the energy storage device obtained by the control system, P _Er is the power tolerance error threshold;

If the stability control device receives an emergency cutting command from the grid safety and stability control system, proceed to step 2; the emergency cutting command contains the power ΔP to be cut and the required cut-off time ts;

Step 2 in Figure 2 describes that if there is no energy storage device available at the wind power plant at this time, go directly to step 3). Otherwise, first, evaluate the adjustable amount ΔPs of the energy storage device for this emergency control, as follows: Shown as follows:

If the energy storage device is currently charging, then:

If the energy storage device is currently in a discharged state, then:

Where dp/dt is the maximum adjustment speed of the energy storage device, Psmax is the maximum charging power of the energy storage device, Qmax is the upper limit of the energy storage device, Q is the current capacity of the energy storage device, and T is the emergency cutting command. The maximum time that the device must be running.

Then, the stability control device sends the command of ΔP _s to the energy storage control system. If the energy storage device can complete the emergency control separately, the method ends; otherwise, the remaining cutting power ΔP-ΔP _{s is taken} as a new requirement. The cut power ΔP is entered into step 3.

Step 3 of Figure 2 depicts the calculation of the cost per machine. In order to ensure the economical efficiency of the cutting machine, it is necessary to evaluate the cutting cost of each unit, and the cutting machine cost is estimated according to the lost power after conversion.

Assume that the wind farm contains three types of units: ordinary asynchronous unit type, double-fed unit type and direct drive unit type. Among them, the wind farm contains i ordinary asynchronous units (numbered from the first unit to the i-th unit), and j double-feed units (numbered from the i+1 unit to the i+j unit), n straight Drive unit (numbered from i+j+1 unit to i+j+n unit). The running time of each unit after the last overhaul is T ₁ , T ₂ ... T _i , T _i+1 ... T _i+j , T _i+j+1 ... T _i+j+n . Each unit output power _{P 1, P 2 ...... P i} , P i + 1 ... P i + j, P i + j + 1 ... P i + j + n. The start-stop cost of the common asynchronous unit is W ₀₁ , the start-stop cost of the double-fed unit is W ₀₂ , and the start-stop cost of the direct-drive unit is W ₀₃ . The cost factors of conventional asynchronous generators, doubly-fed units and direct-drive units considering the regulation performance are α _A , α _B , α _C ; the cost factors for considering the fault ride-through capability are β _A , β _B , β _C. α _A , α _B , α _C and β _A , β _B , β _{C have} a value range of 0 to 1, and the specific size wind farm operators are set according to actual needs. According to the actual operating experience, there are generally: α _A <α _B <α _C , β _A <β _B <β _C .

Thus, the cutting cost of the i-th ordinary asynchronous unit is:

W _i =(1+α _i +β _i )*P _i +W ₀₁ /T _i

The cutting cost of the i+j double-fed unit is:

W _i+j =(1+α _i+j +β _i+j )*P _i+j +W ₀₂ /T _i+j

The cutting cost of the i+j+n direct drive unit is:

W _i+j+n =(1+α _i+j+n +β _i+j+n )*P _i+j+n +W ₀₃ /T _i+j+n

α _i and β _i are the cutting cost factor of the i-th ordinary asynchronous unit considering the adjustment performance and the cutting cost factor considering the fault traversing ability; α _i+j and β _i+j are the i+j doubly-fed asynchronous unit Consider the cost factor of the adjustment performance and the cost factor of the cutter considering the fault ride-through capability; α _i+j+n and β _i+j+n are the cutting machines for the i++j+n direct drive asynchronous unit considering the adjustment performance The cost factor and the cost factor of the cutter considering the fault ride-through capability.

Therefore, the formula that can be summarized as the cost of cutting the machine produced by the kth unit cutting machine is:

W _k =(1+α _k +β _k )*P _k +W _0k /T _k

Among them, P _k is the current output power of the kth unit, T _k is the running time after the last maintenance of the kth unit, and α _k is the cutting cost factor of the kth unit considering the adjustment performance of the unit. The better the regulation performance, The higher the cost factor of the cutting machine; β _k is the cutting cost factor of the k-th unit considering the fault traversing ability. The better the fault traversing performance, the higher the cost factor; W _0k is the kth unit of the electric power representation. Fixed maintenance costs.

The first term 1*P _{k in the} formula represents the power loss directly lost after the machine is cut, the second term α _k *P _k represents the indirect adjustable power of the loss after cutting, and the third term β _k *P _k represents the machine after cutting The loss of power that can be used for fault traversal, the fourth item W _0k /T indicates that the fixed maintenance cost of the unit is spread to the power in the running time.

Step 4 in Figure 2 describes that all units are sorted according to the cutter cost W _k from small to large, and the minimum cut-off cost is maximized until the accumulated power of the cut unit ∑P _sum >ΔP, and the cutting machine ends.

Although the invention has been disclosed above in the preferred embodiments, the embodiments are not intended to limit the invention. Any equivalent variation or refinement made, without departing from the spirit and scope of the present invention, also belongs to the present invention. The scope of protection. Therefore, the scope of protection of the present invention should be defined by the content defined in the claims of the present application.

Claims (2)

1. An emergency control method suitable for a wind power station, characterized in that the method comprises the following steps:

   1) The stability control device collects the current and voltage of the local high-voltage side of the local wind power main transformer, calculates the power of the wind power station, and communicates with the EMS system of the wind power station to obtain the unit type, current output and continuous running time of each unit, and collect energy storage and grid. The current and voltage on the high voltage side of the transformer, calculate the power of the energy storage device, and communicate with the energy storage control system in real time to obtain the current output and current power of the energy storage device;

   If the power supply of the wind power station and the power of the energy storage device calculated by the stability control device are inconsistent with the current output of each unit obtained through the EMS system and the current output of the energy storage device obtained through the energy storage control system, the safety and stability control system to the power grid is obtained. The alarm is as follows:

   |P _T -ΣP _EMS -P _S |>P _Er

   |P _ST -Ps|>P _Er

   In the above formula, P _T, P _ST are Internet access power energy storage device and power plant scenery stability control calculation means, ΣP _EMS for the unit obtained by each of the current output of the EMS system and, Ps through storage The current output of the energy storage device obtained by the control system, P _Er is the power tolerance error threshold;

   If the stability control device receives an emergency cutting command from the grid safety and stability control system, proceed to step 2); the emergency cutting command contains the power ΔP to be cut and the required cut-off time ts;

   2) If there is no energy storage device available at the wind power station at this time, go directly to step 3), otherwise:

   First, evaluate the adjustable amount ΔPs of the energy storage device for this emergency control as follows:

   If the energy storage device is currently charging, then:

   

   If the energy storage device is currently in a discharged state, then:

   

   Where dp/dt is the maximum adjustment speed of the energy storage device, Psmax is the maximum charging power of the energy storage device, Qmax is the upper limit of the energy storage device, Q is the current capacity of the energy storage device, and T is the emergency cutting command. The maximum time that the device must be operated;

   Then, the stability control device sends the command of ΔP _s to the energy storage control system. If the energy storage device can complete the emergency control separately, the method ends; otherwise, the remaining cutting power ΔP-ΔP _{s is taken} as a new requirement. The cut power ΔP, proceeds to step 3);

   3) Calculate the cutting cost of each unit. The cutting cost is estimated according to the lost power. The calculation formula of the cutting cost generated by the kth unit cutting machine is:

   W _k =(1+α _k +β _k )*P _k +W _0k /T _k

   Among them, P _k is the current output power of the kth unit, T _k is the running time after the last maintenance of the kth unit, and α _k is the cutting cost factor of the kth unit considering the adjustment performance of the unit. The better the regulation performance, The higher the cost factor of the cutting machine; β _k is the cutting cost factor of the k-th unit considering the fault traversing ability. The better the fault traversing performance, the higher the cost factor; W _0k is the kth unit of the electric power representation. Fixed maintenance costs;

   4) Sort all units according to the cutting machine cost W _k from small to large, and preferentially cut off the minimum cost of the cutting machine until the accumulated power of the removed unit ∑P _sum >ΔP, and the cutting machine ends.
2. The emergency control method for a wind power station according to claim 1, wherein the values of α _k and β _k in the step 3) are in the range of 0 to 1.

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