Catalog
One 、 summary
Two 、 adopt DER Distributed power flow management
3、 ... and 、 Motivational case studies
Four 、Python Code implementation
5、 ... and 、 result
Traditionally , Electricity is generated by large power plants at the transmission voltage level , Medium and low voltage distribution network （DNs） Is regarded as a power sink . However , In the past few decades , A lot of distributed energy （DER）, For example, distributed generators and new controllable loads have been and are being installed in DNs in . Distribution system operator （DSO） One of the most important modern challenges is to control the tide , To avoid violating power quality constraints . In order to alleviate these key power quality problems and achieve more efficient grid utilization , Can control most DER, Such as residential PV （PV） Crew .
Based on the available communication and monitoring infrastructure ,DER The control scheme can be roughly divided into “ Centralized ”、“ Distributed ” and “ Local ”. In a centralized solution , The measurement data from the sensor is collected by a central control unit , The central control unit calculates each DER The best set point for , And convey command signals . Distributed control schemes require limited communication , And it can achieve near optimal system performance without any centralized computing unit . The communication link can only be used between key nodes , Compared with centralized scheme , This method is more economical . However , The main control architecture defines a local control scheme that does not require any communication , And included in DN The most scalable and practical solution implemented in . Every DER Rely on local measurements to adjust their set points according to certain predetermined rules . The analysis we present in this paper is applicable to local systems with a fully decentralized architecture DER Control plan . In presenting our results , We pay particular attention to strategies designed to control reactive power flow and avoid violating voltage amplitude constraints . Local Volt/VAr The controller differs in the control algorithm and the required local measurements . In this work , We consider the graph 1 General policy categories represented in , Voltage amplitude measurement is used as input , By using the static droop function DER Required setpoint for reactive power injection . This setpoint can be filtered before being used as a reference for the power inverter controller . chart 2 A simple example of this pure local feedback law for reactive power control is reported .
chart 2
To further stimulate our research , And emphasize the importance of the proposed analysis , We briefly investigated the figure 2 Standardized voltage reported in / Stability of reactive power curve , Among them, we have determined the design parameters according to the recommendations of several modern power grid codes . According to these criteria , high （ low ） The local voltage amplitude will trigger reactive power consumption （ Inject ）. Absorption of reactive power （ produce ） Local overpressure is relieved （ Undervoltage ）. However , As the following example shows , The feedback mode is unstable in the operation area ： Let's consider the graph 3 Reference distribution network shown 1, It features four distributed generators （DG） Connect to Cigre Reference low voltage test system . We set all active and reactive loads and active power feeds to set all 19 Of nodes PV Set to a constant value . By setting the initial DG The reactive power injection is set to a random value to initialize the simulation , Then adjust according to the control curve . therefore , In the following power flow calculation , All nodes are treated as PQ node . Pictured 4 Shown , Reactive power injection does not converge , They are in a continuous limit cycle . Select the time interval between update steps , So that all inverter dynamics are attenuated between subsequent setpoint updates . This simple example inspires us to study this local voltage / Study on the stability of reactive power control scheme . The important thing is to pay attention , In this example and the rest of this article , We assume that DER Adjust its reactive power injection regularly according to its measured value , also t Is the index of this iterative update . The actual absolute time between iterations does not affect our analysis , As long as the time is longer than the stability time of the power converter and the power grid dynamics .
chart 4
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