CN113054633B - Time-limited current quick-break protection fixed value optimization method for power distribution network access of energy storage power station - Google Patents
Time-limited current quick-break protection fixed value optimization method for power distribution network access of energy storage power station Download PDFInfo
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Abstract
本发明公开了一种储能电站接入配电网的限时电流速断保护定值优化方法。该方法为：首先定义临界电流、最远短路电流、达标电流，根据配电网参数及储能电站输出电流的最大限制值计算临界电流；然后比较临界电流与最远短路电流的大小关系，判断储能电站输出短路电流是否达到最大电流限制；最后根据储能电站输出短路电流是否达限，确定优化因子α，对储能电站接入点上游线路的限时电流速断保护定值进行优化。本发明无需限制储能电站的接入容量和接入位置，能够在储能电站充电、备用、放电三种工作状态下进行动作，适用性强、可靠性高。
The invention discloses a method for optimizing the setting value of time-limited current quick-break protection for an energy storage power station connected to a distribution network. The method is as follows: first, define the critical current, the farthest short-circuit current and the up-to-standard current, and calculate the critical current according to the parameters of the distribution network and the maximum limit value of the output current of the energy storage power station; then compare the magnitude relationship between the critical current and the farthest short-circuit current to determine Whether the output short-circuit current of the energy storage power station reaches the maximum current limit; finally, according to whether the output short-circuit current of the energy storage power station reaches the limit, the optimization factor α is determined, and the time-limited current quick-break protection setting of the upstream line of the energy storage power station access point is optimized. The invention does not need to limit the access capacity and the access position of the energy storage power station, can operate in the three working states of charging, standby and discharge of the energy storage power station, and has strong applicability and high reliability.
Description
技术领域technical field
本发明属于配电自动化领域，特别是一种储能电站接入配电网的限时电流速断保护 定值优化方法。The invention belongs to the field of distribution automation, in particular to a fixed value optimization method for time-limited current quick-break protection of an energy storage power station connected to a distribution network.
背景技术Background technique
随着电力系统的不断发展，能源问题也不断突出，可再生能源以分布式电源的形式 逐渐推广应用，在改善了电力能源产业结构的同时也改变了传统电力系统集中式供电的 格局。但无论是以大容量、高参数机组发电，通过超高压、远距离输电形成大电网供电的传统电力生产模式供电，还是容量较小、分布较为分散的新兴可再生能源模式供电， 都离不开与储能系统的配合。With the continuous development of the power system, energy problems are also becoming more and more prominent. The renewable energy is gradually popularized and applied in the form of distributed power sources, which not only improves the power energy industry structure, but also changes the centralized power supply pattern of the traditional power system. However, whether it is powered by large-capacity, high-parameter units, the traditional power production mode that forms a large grid power supply through ultra-high voltage and long-distance power transmission, or the emerging renewable energy mode with smaller capacity and more dispersed distribution, it is inseparable from the power supply. Cooperate with energy storage system.
储能系统的典型应用场景包括集中式新能源+储能系统、电源侧调频储能、电网侧储能、分布式及微网储能以及用户侧应用。近年来，储能电站因其削峰填谷、提高供电 稳定性等作用，在配电系统中的应用越来越广泛，丰富了配电网的供电结构的同时也给 配电网的安全运行带来了新的问题。Typical application scenarios of energy storage systems include centralized new energy + energy storage systems, power-side frequency modulation energy storage, grid-side energy storage, distributed and micro-grid energy storage, and user-side applications. In recent years, energy storage power stations have become more and more widely used in power distribution systems due to their functions such as shaving peaks and filling valleys and improving power supply stability. brings new problems.
配电网的继电保护是以配电网的放射性结构、单电源供电的特点为基础而设计的， 以三段式电流保护为主，储能电站的接入使得配电网由单电源供电变为多电源供电，而 储能电站又区别于常规电源，其故障特性受其控制策略影响极大，特别对于储能电站接入点上游线路的限时电流速断保护定值整定而言，如果采用常规的定值整定方式，会导 致保护的灵敏度降低，出现拒动现象，威胁配电网的供电安全。The relay protection of the distribution network is designed based on the radioactive structure of the distribution network and the characteristics of a single power supply. It is mainly based on three-stage current protection. It becomes a multi-power supply, and the energy storage power station is different from the conventional power supply. Its fault characteristics are greatly affected by its control strategy, especially for the setting of the time-limited current quick-break protection setting of the upstream line of the energy storage power station access point. The conventional fixed value setting method will lead to the reduction of the sensitivity of the protection, and the phenomenon of refusal to operate, which threatens the power supply security of the distribution network.
发明内容SUMMARY OF THE INVENTION
本发明目的在于提供一种适用性强、可靠性高的储能电站接入配电网的限时电流速 断保护定值优化方法。The purpose of the present invention is to provide a time-limited current quick-break protection setting optimization method for an energy storage power station with strong applicability and high reliability connected to a distribution network.
实现本发明目的的技术解决方案为：一种储能电站接入配电网的限时电流速断保护 定值优化方法，包括以下步骤：The technical solution for realizing the purpose of the present invention is: a method for optimizing the fixed value of time-limited current quick-break protection for an energy storage power station connected to a distribution network, comprising the following steps:
步骤1、构建储能电站等效模型，定义临界电流、最远短路电流、达标电流，根 据配电网参数及储能电站输出电流的最大限制值计算临界电流；
步骤2、比较临界电流与最远短路电流的大小关系，判断储能电站输出短路电流是否达到最大电流限制；
步骤3、根据储能电站输出短路电流是否达限，确定优化因子α，对储能电站接 入点上游线路的限时电流速断保护定值进行优化。
进一步地，步骤1中所述的构建储能电站等效模型，具体如下：Further, the construction of the equivalent model of the energy storage power station described in
根据采用恒功率控制的储能电站控制策略及工作特性，建立储能电站等效模型为：According to the control strategy and working characteristics of the energy storage power station using constant power control, the equivalent model of the energy storage power station is established as follows:
式中，SN为储能电站额定功率，EG为储能电站出口相电压，IG为储能电站输出相 电流，IN为储能电站额定相电流。In the formula, SN is the rated power of the energy storage station, EG is the outlet phase voltage of the energy storage station, IG is the output phase current of the energy storage station, and I N is the rated phase current of the energy storage station.
进一步地，步骤1中所述的定义临界电流、最远短路电流、达标电流，具体如下：Further, the definition of critical current, farthest short-circuit current, and up-to-standard current described in
临界电流的定义为：设定IN为储能电站额定电流，则储能电站输出电流恰好达到最 大电流限制时，即2倍额定电流2IN时流过储能电站接入点上游线路保护的电流，其计算式为：The definition of critical current is: set I N as the rated current of the energy storage power station, when the output current of the energy storage power station just reaches the maximum current limit, that is, when twice the rated current 2IN flows through the protection of the upstream line of the access point of the energy storage power station. current, which is calculated as:
式中，I1'为临界电流，E为储能电站额定相电压，ZS为系统电源阻抗，Z1为储能 电站接入点上游线路阻抗；In the formula, I 1 ' is the critical current, E is the rated phase voltage of the energy storage power station, Z S is the system power supply impedance, and Z 1 is the upstream line impedance of the energy storage power station access point;
最远短路电流的定义为：储能电站接入点上游线路的限时电流速断保护的保护范围 末端发生短路故障时，流过储能电站接入点上游线路保护的电流；The farthest short-circuit current is defined as: the protection range of the time-limited current quick-break protection of the upstream line of the energy storage power station access point When a short-circuit fault occurs at the end, the current flowing through the protection of the upstream line of the energy storage power station access point;
达标电流的定义为：限时电流速断保护灵敏度恰好满足要求时，储能电站接入点上 游线路限时电流速断保护的定值，其计算式为：The definition of up-to-standard current is: when the sensitivity of the time-limited current quick-break protection just meets the requirements, the fixed value of the time-limited current quick-break protection of the upstream line of the access point of the energy storage power station, and its calculation formula is:
式中，ID为达标电流，I1m为储能电站接入点上游线路末端两相短路时流过储能电站接入点上游线路保护的电流，Ksen为满足要求的灵敏度。In the formula, I D is the up-to-standard current, I 1m is the current flowing through the protection of the upstream line of the access point of the energy storage power station when the two-phase short-circuit at the end of the upstream line of the energy storage power station access point, and K sen is the sensitivity that meets the requirements.
进一步地，步骤2中所述的比较临界电流与最远短路电流的大小关系来判断储能电 站输出短路电流是否达到最大电流限制，具体如下：Further, the magnitude relation of the comparison critical current and the farthest short-circuit current described in
步骤2.1、定义k点为临界电流对应短路点，k点与储能电站接入点下游线路首端之间的阻抗计算式为：Step 2.1. Define point k as the short-circuit point corresponding to the critical current. The impedance calculation formula between point k and the head end of the downstream line of the access point of the energy storage power station is:
式中，Z2为储能电站接入点下游线路阻抗，β'为常数；In the formula, Z 2 is the downstream line impedance of the access point of the energy storage power station, and β' is a constant;
根据上式计算出β'，若β'≥1，则储能电站输出电流必定达限；若β'＜1，则进入步骤2.2；Calculate β' according to the above formula. If β'≥1, the output current of the energy storage power station must reach the limit; if β'<1, go to step 2.2;
步骤2.2、设定最远短路电流小于临界电流，则最远短路电流的计算式为：Step 2.2. Set the farthest short-circuit current to be less than the critical current, then the calculation formula of the farthest short-circuit current is:
上式中，I″1为最远短路电流，β为常数；In the above formula, I″ 1 is the farthest short-circuit current, and β is a constant;
将β'作为β代入上式计算出最远短路电流I″1，然后将最远短路电流I″1与临界电流I1' 进行比较，若仍满足I″1＜I1'，则储能电站输出电流未达限；若I″1≥I1'，则储能电站输出 电流达限。Substitute β' as β into the above formula to calculate the farthest short-circuit current I″ 1 , and then compare the farthest short-circuit current I″ 1 with the critical current I 1 ′, if I″ 1 <I 1 ' is still satisfied, the energy storage The output current of the power station has not reached the limit; if I″ 1 ≥ I 1 ', the output current of the energy storage power station has reached the limit.
进一步地，步骤3所述的根据储能电站输出短路电流是否达限，确定优化因子α，对储能电站接入点上游线路的限时电流速断保护定值进行优化，具体如下：Further, according to
步骤3.1、定义h点为达标电流对应短路点，则h点与储能电站接入点下游线路首端之间的阻抗计算式为：Step 3.1. Define point h as the short-circuit point corresponding to the up-to-standard current, then the impedance calculation formula between point h and the head end of the downstream line of the access point of the energy storage power station is:
式中，SN为储能电站额定容量，βD为常数；In the formula, S N is the rated capacity of the energy storage power station, and β D is a constant;
步骤3.2、根据储能电站输出电流是否达限，确定优化因子α，计算出储能电站接入点下游线路的电流速断保护定值：Step 3.2, according to whether the output current of the energy storage power station reaches the limit, determine the optimization factor α, and calculate the current quick-break protection setting value of the downstream line of the access point of the energy storage power station:
式中，
步骤3.3、对储能电站接入点上游线路的限时电流速断保护定值进行优化，公式为：Step 3.3, optimize the time-limited current quick-break protection setting of the upstream line of the access point of the energy storage power station, the formula is:
式中，
本发明与现有技术相比，其显著优点在于：(1)从修改保护定值的角度出发来进行保护方案的优化，不必因保护要求而限制储能电站的接入容量和接入位置，适用性强； (2)综合考虑了储能电站的控制策略和工作特性，构建了储能电站的等效模型，使得 改进后的保护在储能电站充电、备用、放电三种工作状态下都能可靠动作，可靠性高。Compared with the prior art, the present invention has significant advantages as follows: (1) the protection scheme is optimized from the perspective of modifying the protection setting, and it is not necessary to limit the access capacity and access position of the energy storage power station due to protection requirements; Strong applicability; (2) The control strategy and working characteristics of the energy storage power station are comprehensively considered, and the equivalent model of the energy storage power station is constructed, so that the improved protection can be used in the three working states of the energy storage power station: charging, standby and discharging. Reliable action and high reliability.
附图说明Description of drawings
图1为本发明储能电站接入配电网的限时电流速断保护定值优化方法的流程示意图。FIG. 1 is a schematic flow chart of the method for optimizing the setting value of the time-limited current quick-break protection for the connection of the energy storage power station to the distribution network according to the present invention.
图2为本发明中PQ控制的储能电站的整体结构框图。FIG. 2 is a block diagram of the overall structure of the PQ-controlled energy storage power station in the present invention.
图3为本发明中典型含储能电站的配电网的拓扑结构图。FIG. 3 is a topological structure diagram of a typical distribution network including an energy storage power station in the present invention.
图4为本发明中储能电站接入点下游线路短路时的等值电路图。FIG. 4 is an equivalent circuit diagram when the downstream line of the access point of the energy storage power station in the present invention is short-circuited.
图5为本发明中储能电站上游线路限时电流速断保护定值优化整体流程图。FIG. 5 is the overall flow chart of the optimization of the setting value of the time-limited current quick-break protection of the upstream line of the energy storage power station in the present invention.
具体实施方式Detailed ways
本发明储能电站接入配电网的限时电流速断保护定值优化方法，包括以下步骤：The time-limited current quick-break protection setting optimization method for an energy storage power station connected to a distribution network of the present invention includes the following steps:
步骤1、构建储能电站等效模型，定义临界电流、最远短路电流、达标电流，根 据配电网参数及储能电站输出电流的最大限制值计算临界电流；
步骤2、比较临界电流与最远短路电流的大小关系，判断储能电站输出短路电流是否达到最大电流限制；
步骤3、根据储能电站输出短路电流是否达限，确定优化因子α，对储能电站接 入点上游线路的限时电流速断保护定值进行优化。
进一步地，步骤1中所述的构建储能电站等效模型，具体如下：Further, the construction of the equivalent model of the energy storage power station described in
根据采用恒功率控制的储能电站控制策略及工作特性，建立储能电站等效模型为：According to the control strategy and working characteristics of the energy storage power station using constant power control, the equivalent model of the energy storage power station is established as follows:
式中，SN为储能电站额定功率，EG为储能电站出口相电压，IG为储能电站输出 相电流，IN为储能电站额定相电流。In the formula, SN is the rated power of the energy storage station, EG is the outlet phase voltage of the energy storage station, IG is the output phase current of the energy storage station, and I N is the rated phase current of the energy storage station.
进一步地，步骤1中所述的定义临界电流、最远短路电流、达标电流，具体如下：Further, the definition of critical current, farthest short-circuit current, and up-to-standard current described in
临界电流的定义为：设定IN为储能电站额定电流，则储能电站输出电流恰好达到最 大电流限制时，即2倍额定电流2IN时流过储能电站接入点上游线路保护的电流，其计算式为：The definition of critical current is: set I N as the rated current of the energy storage power station, when the output current of the energy storage power station just reaches the maximum current limit, that is, when twice the rated current 2IN flows through the protection of the upstream line of the access point of the energy storage power station. current, which is calculated as:
式中，I1'为临界电流，E为储能电站额定相电压，ZS为系统电源阻抗，Z1为储能 电站接入点上游线路阻抗；In the formula, I 1 ' is the critical current, E is the rated phase voltage of the energy storage power station, Z S is the system power supply impedance, and Z 1 is the upstream line impedance of the energy storage power station access point;
最远短路电流的定义为：储能电站接入点上游线路的限时电流速断保护的保护范围 末端发生短路故障时，流过储能电站接入点上游线路保护的电流；The farthest short-circuit current is defined as: the protection range of the time-limited current quick-break protection of the upstream line of the energy storage power station access point When a short-circuit fault occurs at the end, the current flowing through the protection of the upstream line of the energy storage power station access point;
达标电流的定义为：限时电流速断保护灵敏度恰好满足要求时，储能电站接入点上 游线路限时电流速断保护的定值，其计算式为：The definition of up-to-standard current is: when the sensitivity of the time-limited current quick-break protection just meets the requirements, the fixed value of the time-limited current quick-break protection of the upstream line of the access point of the energy storage power station, and its calculation formula is:
式中，ID为达标电流，I1m为储能电站接入点上游线路末端两相短路时流过储能电站接入点上游线路保护的电流，Ksen为满足要求的灵敏度，取值为1.3。In the formula, I D is the current that reaches the standard, I 1m is the current flowing through the protection of the upstream line of the access point of the energy storage power station when the two-phase short-circuit at the end of the upstream line of the energy storage power station access point, K sen is the sensitivity that meets the requirements, and the value is 1.3.
进一步地，步骤2所述的比较临界电流与最远短路电流的大小关系，判断储能电站输出短路电流是否达到最大电流限制，具体如下：Further, comparing the magnitude relationship between the critical current and the farthest short-circuit current described in
步骤2.1、定义k点为临界电流对应短路点，k点与储能电站接入点下游线路首端之间的阻抗计算式为：Step 2.1. Define point k as the short-circuit point corresponding to the critical current. The impedance calculation formula between point k and the head end of the downstream line of the access point of the energy storage power station is:
式中，Z2为储能电站接入点下游线路阻抗，β'为常数；In the formula, Z 2 is the downstream line impedance of the access point of the energy storage power station, and β' is a constant;
根据上式计算出β'，若β'≥1，则储能电站输出电流必定达限；若β'＜1，则进入步骤2.2；Calculate β' according to the above formula. If β'≥1, the output current of the energy storage power station must reach the limit; if β'<1, go to step 2.2;
步骤2.2、设定最远短路电流小于临界电流，则最远短路电流的计算式为：Step 2.2. Set the farthest short-circuit current to be less than the critical current, then the calculation formula of the farthest short-circuit current is:
式中，I″1为最远短路电流，β为常数；In the formula, I″ 1 is the farthest short-circuit current, and β is a constant;
将β'作为β代入上式计算出最远短路电流I″1，然后将最远短路电流I″1与临界电流I1' 进行比较，若仍满足I″1＜I1'，则储能电站输出电流未达限；若I″1≥I1'，则储能电站输出 电流达限。Substitute β' as β into the above formula to calculate the farthest short-circuit current I″ 1 , and then compare the farthest short-circuit current I″ 1 with the critical current I 1 ′, if I″ 1 <I 1 ' is still satisfied, the energy storage The output current of the power station has not reached the limit; if I″ 1 ≥ I 1 ', the output current of the energy storage power station has reached the limit.
进一步地，步骤3所述的根据储能电站输出短路电流是否达限，确定优化因子α，对储能电站接入点上游线路的限时电流速断保护定值进行优化，具体如下：Further, according to
步骤3.1、定义h点为达标电流对应短路点，则h点与储能电站接入点下游线路首端之间的阻抗计算式为：Step 3.1. Define point h as the short-circuit point corresponding to the up-to-standard current, then the impedance calculation formula between point h and the head end of the downstream line of the access point of the energy storage power station is:
式中，SN为储能电站额定容量，βD为常数；In the formula, S N is the rated capacity of the energy storage power station, and β D is a constant;
步骤3.2、根据储能电站输出电流是否达限，确定优化因子α，计算出储能电站接入点下游线路的电流速断保护定值：Step 3.2, according to whether the output current of the energy storage power station reaches the limit, determine the optimization factor α, and calculate the current quick-break protection setting value of the downstream line of the access point of the energy storage power station:
式中，
步骤3.3、对储能电站接入点上游线路的限时电流速断保护定值进行优化，公式为：Step 3.3, optimize the time-limited current quick-break protection setting of the upstream line of the access point of the energy storage power station, the formula is:
式中，
下面结合附图和具体实施例对本发明作进一步的详细说明。The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
实施例Example
结合图1，本发明一种储能电站接入配电网的限时电流速断保护定值优化方法，包括以下步骤：With reference to Fig. 1, a method for optimizing the setting value of time-limited current quick-break protection for an energy storage power station connected to a distribution network of the present invention includes the following steps:
步骤1、构建储能电站等效模型，定义临界电流、最远短路电流、达标电流，根据 配电网参数及储能电站输出电流的最大限制值计算临界电流，具体如下：
储能电站的故障特性取决于其逆变器的控制策略，一般采用的控制策略是恒功率控制(PQ控制)，PQ控制的储能电站的整体结构图如图2所示。PQ控制下的储能电 站可以看作一个恒功率输出电源，其有功功率和和无功功率可以实时跟踪参考信号， 其实质为将有功功率与无功功率解耦控制，对电流采用PI控制，保持输出恒定。将电 网中的abc坐标系下的电压、电流经abc/dq转换得到d轴、q轴分量，利用dq坐标系 下的电压、电流分量计算得到有功功率P和无功功率Q的测量值。将有功功率和无功功 率参考值Pref、Qref与有功功率、无功功率实际测量值进行比较，得到有功无功偏差， 经过PI控制器产生电流dq坐标系下的电流参考值IL.ref与经过实际测量值进行比较，产 生dq坐标系下经PI环节得到的电压参考值uref，用来控制SPWM(正弦脉宽调制器) 产生触发脉冲，得到逆变器的驱动信号，从而实现控制逆变器输出恒定功率的目的。 储能电站的输出电流受逆变器输出电流限制在额定电流的2倍以下，当输出电流未达最 大输出电流时，储能电站维持输出功率S不变，出口电压下降时，输出电流将增大。 当储能电站输出电流达到最大电流限制之后，随着出口的电压的降低，输出功率也随 之下降。储能电站的工作状态一般分为三种：充电、放电和备用。充电状态下其工作 特性相当于一个负载，根据以上特性，建立放电状态的储能电站等效模型为：The fault characteristics of the energy storage power station depend on the control strategy of its inverter. The control strategy generally used is constant power control (PQ control). The overall structure of the energy storage power station under PQ control is shown in Figure 2. The energy storage power station under PQ control can be regarded as a constant power output power supply, and its active power and reactive power can track the reference signal in real time. keep the output constant. The voltage and current in the abc coordinate system in the power grid are converted by abc/dq to obtain the d-axis and q-axis components, and the measured values of active power P and reactive power Q are calculated by using the voltage and current components in the dq coordinate system. The active and reactive power reference values P ref and Q ref are compared with the actual measured values of active power and reactive power to obtain the active and reactive power deviation, and the current reference value IL in the current dq coordinate system is generated through the PI controller . The ref is compared with the actual measured value to generate the voltage reference value u ref obtained by the PI link in the dq coordinate system, which is used to control the SPWM (sinusoidal pulse width modulator) to generate the trigger pulse and obtain the drive signal of the inverter, so as to realize The purpose of controlling the inverter to output constant power. The output current of the energy storage power station is limited by the inverter output current to be less than 2 times the rated current. When the output current does not reach the maximum output current, the energy storage power station maintains the output power S unchanged. When the outlet voltage drops, the output current will increase. big. When the output current of the energy storage power station reaches the maximum current limit, as the voltage at the outlet decreases, the output power also decreases. The working state of the energy storage power station is generally divided into three types: charging, discharging and standby. Its working characteristics in the charging state are equivalent to a load. According to the above characteristics, the equivalent model of the energy storage power station in the discharging state is established as follows:
式中，SN为储能电站额定功率，EG为储能电站出口相电压，IG为储能电站输出 相电流，IN为储能电站额定相电流。In the formula, SN is the rated power of the energy storage station, EG is the outlet phase voltage of the energy storage station, IG is the output phase current of the energy storage station, and I N is the rated phase current of the energy storage station.
进一步地，构建了典型的含储能电站的配电网拓扑图如图3所示，由于配电网的辐射状结构，任意配电网络均可通过阻抗串并联原理(将线路等效为等值阻抗)等效为典 型配电网拓扑。对于储能电站接入点上游线路的限时电流速断保护而言，其整定原则 为躲过下级线路的电流速断保护定值，即Further, a typical topology of the distribution network with energy storage power stations is constructed, as shown in Figure 3. Due to the radial structure of the distribution network, any distribution network can pass the impedance series-parallel principle (equivalent lines to equal value impedance) is equivalent to a typical distribution network topology. For the time-limited current quick-break protection of the upstream line of the access point of the energy storage power station, the setting principle is to avoid the current quick-break protection setting of the lower line, that is,
式中，
由于储能电站接入后配电网变为多源网络，储能电站接入点上游线路保护处测得的电流值小于储能电站接入点下游线路保护处测得的电流值，如果仍沿用此整定方 式，会使储能电站接入点上游线路的限时电流速断保护灵敏度减小，出现拒动情况。Since the distribution network becomes a multi-source network after the energy storage power station is connected, the current value measured at the upstream line protection point of the energy storage power station access point is smaller than the current value measured at the downstream line protection point of the energy storage power station access point. Continuing this setting method will reduce the sensitivity of the time-limited current quick-break protection of the upstream line of the access point of the energy storage power station, resulting in a refusal to operate.
进一步地，根据图3所示的典型拓扑图，可得故障发生在储能电站接入点下游线路时的等值电路图，如图4所示，图中β为短路点与储能电站接入点下游线路首端之间的 阻抗占储能电站接入点下游线路总阻抗的百分比值，后文算式推导均从图4所示等值电 路而得。Further, according to the typical topology diagram shown in Figure 3, the equivalent circuit diagram when the fault occurs in the downstream line of the access point of the energy storage power station can be obtained, as shown in Figure 4, in the figure β is the short-circuit point and the access point of the energy storage power station. The impedance between the head ends of the downstream line at the point accounts for the percentage value of the total impedance of the downstream line at the access point of the energy storage power station. The following formulas are derived from the equivalent circuit shown in Figure 4.
进一步地，定义临界电流、最远短路电流、达标电流，具体如下：Further, define the critical current, the farthest short-circuit current, and the up-to-standard current, as follows:
临界电流的定义为：设定IN为储能电站额定电流，则储能电站输出电流恰好达到最 大电流限制时，即2倍额定电流2IN时流过储能电站接入点上游线路保护的电流，其计算式为：The definition of critical current is: set I N as the rated current of the energy storage power station, when the output current of the energy storage power station just reaches the maximum current limit, that is, when twice the rated current 2IN flows through the protection of the upstream line of the access point of the energy storage power station. current, which is calculated as:
式中，I1'为临界电流，E为储能电站额定相电压，ZS为系统电源阻抗，Z1为储能 电站接入点上游线路阻抗；定义k点为临界电流对应短路点，显然，短路点位于临界短 路点k下游时，储能电站提供的短路电流小于2IN；短路点位于临界短路点k上游时， 储能电站提高的短路电流等于2IN。In the formula, I 1 ' is the critical current, E is the rated phase voltage of the energy storage power station, Z S is the system power supply impedance, and Z 1 is the upstream line impedance of the access point of the energy storage power station; point k is defined as the short-circuit point corresponding to the critical current, obviously , when the short-circuit point is downstream of the critical short-circuit point k, the short-circuit current provided by the energy storage power station is less than 2IN; when the short - circuit point is upstream of the critical short-circuit point k, the short-circuit current increased by the energy storage station is equal to 2IN .
最远短路电流的定义为：储能电站接入点上游线路的限时电流速断保护的保护范围 末端发生短路故障时，流过储能电站接入点上游线路保护的电流；定义j点为最远短路电流对应短路点，当最远短路电流小于临界电流时，保护范围末端j点在临界短路点k 下游，储能电站所提供的短路电流小于2IN；当最远短路电流大于临界电流时，保护范 围末端j点在临界短路点k上游，储能电站提高的短路电流等于2IN，据此分为两种情 况进行优化。The farthest short-circuit current is defined as: when a short-circuit fault occurs at the end of the protection range of the time-limited current quick-break protection of the upstream line of the energy storage power station access point, the current flowing through the protection of the upstream line of the energy storage power station access point; point j is defined as the farthest The short-circuit current corresponds to the short-circuit point. When the farthest short-circuit current is less than the critical current, point j at the end of the protection range is downstream of the critical short-circuit point k, and the short-circuit current provided by the energy storage power station is less than 2IN; when the farthest short - circuit current is greater than the critical current, The point j at the end of the protection range is upstream of the critical short-circuit point k, and the short-circuit current increased by the energy storage power station is equal to 2IN , which is divided into two cases for optimization.
达标电流的定义为：限时电流速断保护灵敏度恰好满足要求时，储能电站接入点上 游线路限时电流速断保护的定值，其计算式为：The definition of up-to-standard current is: when the sensitivity of the time-limited current quick-break protection just meets the requirements, the fixed value of the time-limited current quick-break protection of the upstream line of the access point of the energy storage power station, and its calculation formula is:
式中，ID为达标电流，I1m为储能电站接入点上游线路末端两相短路时流过储能电站接入点上游线路保护的电流，Ksen为满足要求的灵敏度，取值为1.3。In the formula, I D is the current that reaches the standard, I 1m is the current flowing through the protection of the upstream line of the access point of the energy storage power station when the two-phase short-circuit at the end of the upstream line of the energy storage power station access point, K sen is the sensitivity that meets the requirements, and the value is 1.3.
步骤2、比较临界电流与最远短路电流的大小关系，判断储能电站输出短路电流是否达到最大电流限制，具体如下：
步骤2.1、定义k点为临界电流对应短路点，k点与储能电站接入点下游线路首端之间的阻抗计算式为：Step 2.1. Define point k as the short-circuit point corresponding to the critical current. The impedance calculation formula between point k and the head end of the downstream line of the access point of the energy storage power station is:
式中，Z2为储能电站接入点下游线路阻抗，β'为常数；In the formula, Z 2 is the downstream line impedance of the access point of the energy storage power station, and β' is a constant;
根据上式计算出β'，若β'≥1，则储能电站输出电流必定达限；若β'＜1，则进入步骤2.2；Calculate β' according to the above formula. If β'≥1, the output current of the energy storage power station must reach the limit; if β'<1, go to step 2.2;
步骤2.2、设定最远短路电流小于临界电流，则最远短路电流的计算式为：Step 2.2. Set the farthest short-circuit current to be less than the critical current, then the calculation formula of the farthest short-circuit current is:
式中，I″1为最远短路电流，β为常数；In the formula, I″ 1 is the farthest short-circuit current, and β is a constant;
将β'作为β代入上式计算出最远短路电流I″1，然后将最远短路电流I″1与临界电流I1' 进行比较，若仍满足I″1＜I1'，则储能电站输出电流未达限；若I″1≥I1'，则储能电站输出 电流达限。Substitute β' as β into the above formula to calculate the farthest short-circuit current I″ 1 , and then compare the farthest short-circuit current I″ 1 with the critical current I 1 ′, if I″ 1 <I 1 ' is still satisfied, the energy storage The output current of the power station has not reached the limit; if I″ 1 ≥ I 1 ', the output current of the energy storage power station has reached the limit.
步骤3、根据储能电站输出短路电流是否达限，确定优化因子α，对储能电站接入点上游线路的限时电流速断保护定值进行优化，结合图5，具体如下：
步骤3.1、定义h点为达标电流对应短路点，则h点与储能电站接入点下游线路首端之间的阻抗计算式为：Step 3.1. Define point h as the short-circuit point corresponding to the up-to-standard current, then the impedance calculation formula between point h and the head end of the downstream line of the access point of the energy storage power station is:
式中，SN为储能电站额定容量，βD为常数，根据上式可解得βD；In the formula, S N is the rated capacity of the energy storage power station, β D is a constant, and β D can be solved according to the above formula;
步骤3.2、根据储能电站输出电流是否达限，确定优化因子α，计算出储能电站接入点下游线路的电流速断保护定值：Step 3.2, according to whether the output current of the energy storage power station reaches the limit, determine the optimization factor α, and calculate the current quick-break protection setting value of the downstream line of the access point of the energy storage power station:
在储能电站输出电流未达限时，根据式：When the output current of the energy storage power station does not reach the limit, according to the formula:
得βD对应的最远短路电流，利用此最远短路电流求解得的优化因子α上限会偏小，有利于增加保护灵敏度，由于最远短路电流对应储能电站接入点上游线路限时电 流速断保护的保护范围末端，其值与实际整定值相等，为保证灵敏度要求，优化过后 的定值需小于此时βD所对应的最远短路电流值，引入优化因子α后的整定式为：To obtain the farthest short-circuit current corresponding to β D , the upper limit of the optimization factor α obtained by using this farthest short-circuit current will be small, which is beneficial to increase the protection sensitivity. Because the farthest short-circuit current corresponds to the time-limited current fast break of the upstream line of the energy storage power station access point At the end of the protection range of protection, its value is equal to the actual setting value. In order to ensure the sensitivity requirements, the optimized setting value should be smaller than the farthest short-circuit current value corresponding to β D at this time. The setting formula after introducing the optimization factor α is:
此时有：At this point there are:
当储能电站处于充电或备用状态时，储能电站接入点下游线路发生故障，储能电站提供的短路电流为0，储能电站接入点上游线路限时电流速断保护定值根据上述过程 修改过，此情况下其保护范围可能会超过储能电站接入点下游线路电流速断保护，导 致误动作。储能电站处于充电或备用状态时的储能电站接入点下游线路电流速断保护 保护整定值为：When the energy storage power station is in the charging or standby state, the downstream line of the energy storage power station access point fails, the short-circuit current provided by the energy storage power station is 0, and the time-limited current quick-break protection setting of the upstream line of the energy storage power station access point is modified according to the above process. However, in this case, its protection range may exceed the current quick-break protection of the downstream line of the access point of the energy storage power station, resulting in malfunction. When the energy storage power station is in the charging or standby state, the current quick-break protection of the downstream line of the energy storage power station access point. The protection setting value is:
因此保护1处电流Ⅱ段的保护整定值必须不小于储能电站处于充电或备用状态时保 护2处电流Ⅰ段的保护整定值，即
为同时保证灵敏度与选择性，优化因子取上下限的中间值，即：In order to ensure the sensitivity and selectivity at the same time, the optimization factor takes the middle value of the upper and lower limits, namely:
结合储能电站输出电流未达限时储能电站接入点下游线路的电流速断保护定值整定 式：Combined with the current quick-break protection setting formula of the downstream line of the access point of the energy storage power station when the output current of the energy storage power station does not reach the limit:
上式中
步骤3.3、对储能电站接入点上游线路的限时电流速断保护定值进行优化，公式为：Step 3.3, optimize the time-limited current quick-break protection setting of the upstream line of the access point of the energy storage power station, the formula is:
在储能电站输出电流达限时，根据式：When the output current of the energy storage power station reaches the limit, according to the formula:
得βD对应的最远短路电流，类似储能电站输出电流未达限情况，可得优化因子α上限：The farthest short-circuit current corresponding to β D can be obtained. Similar to the case where the output current of the energy storage power station does not reach the limit, the upper limit of the optimization factor α can be obtained:
为保证保护的选择性，需要考虑储能电站处于备用或充电状态时的防止误动，此处的整定原则亦与储能电站输出电流未达限情况类似，有：In order to ensure the selectivity of protection, it is necessary to consider the prevention of misoperation when the energy storage power station is in standby or charging state. The setting principle here is also similar to the case where the output current of the energy storage power station does not reach the limit, as follows:
为同时保证灵敏度与选择性，优化因子取上下限的中间值，即：In order to ensure the sensitivity and selectivity at the same time, the optimization factor takes the middle value of the upper and lower limits, namely:
结合储能电站输出电流未达限时储能电站接入点下游线路的电流速断保护定值整定 式：Combined with the current quick-break protection setting formula of the downstream line of the access point of the energy storage power station when the output current of the energy storage power station does not reach the limit:
可通过式：Passable:
求得储能电站输出电流达限时的优化整定值。Obtain the optimal setting value when the output current of the energy storage power station reaches the limit.
经定值优化过后的储能电站接入点上游线路限时电流速断保护可保证在储能电站 的各个工作状态下不会发生误动、拒动，能够可靠动作。The time-limited current quick-break protection of the upstream line of the access point of the energy storage power station after the optimization of the fixed value can ensure that there will be no malfunction or refusal to operate under each working state of the energy storage power station, and it can operate reliably.
以两个实际配电网参数为例，采用上述流程对其保护定值进行优化，配电网参数如下表1所示：Taking two actual distribution network parameters as an example, the above process is used to optimize their protection settings. The distribution network parameters are shown in Table 1 below:
表1Table 1
优化结果如下表2所示：The optimization results are shown in Table 2 below:
表2Table 2
由优化结果可见，对于2个配电网络而言，储能电站接入后，按原有整定方式所得的储能电站接入点上游线路限时电流速断保护灵敏度均不能满足要求，采用本发明所 述方法进行优化后，灵敏度均达到了要求，并且在储能电站由放电状态切换至充电或 备用状态时，储能电站接入点上游线路限时电流速断保护不会超越保护范围越级跳 闸，优化后的储能电站接入点上游线路限时电流速断保护在储能电站的各种工作状态 下均不会发生误动、拒动，能够可靠动作。It can be seen from the optimization results that for the two power distribution networks, after the energy storage power station is connected, the time-limited current quick-break protection sensitivity of the upstream line of the energy storage power station access point obtained by the original setting method cannot meet the requirements. After the optimization of the above method, the sensitivity all meet the requirements, and when the energy storage power station is switched from the discharge state to the charging or standby state, the time-limited current quick-break protection of the upstream line of the energy storage power station access point will not exceed the protection range. The time-limited current quick-break protection of the upstream line of the energy storage power station access point will not malfunction or refuse to operate under various working conditions of the energy storage power station, and can operate reliably.
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