2020 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 27, …

1 2020 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 27, NO. 4, OCTOBER 2012 Analysis of voltage Profile Problems Due to thePenetration of distributed Generation in Low-VoltageSecondary Distribution NetworksPo-Chen Chen, Reynaldo Salcedo, Student Member, IEEE, Qingcheng Zhu, Member, IEEE,Francisco de Le n, Senior Member, IEEE, Dariusz Czarkowski, Member, IEEE, Zhong-Ping Jiang, Fellow, IEEE,Vitaly Spitsa, Member, IEEE,ZivanZabar, Senior Member, IEEE, and Resk Ebrahem Uosef, Member, IEEEA bstract This paper presents a comprehensive analysis of thepossible impacts of different penetration levels of distributed gen-eration (DG)

2 On voltage profiles in low- voltage secondary distri-bution networks. Detailed models of all system componentsareutilized in a study that performs hundreds of time-domain sim-ulations of large networked distribution systems using the Elec-tromagnetic Transients Program (EMTP). DGs are allocatedinaprobabilistic fashion to account forthe uncertainties of future in-stallations. The main contribution of this paper is the determina-tion of the maximum amount of DG that secondary distributionnetworks can withstand without exhibiting undervoltage and over- voltage problems or unexpected loaddisconnections.

3 This informa-tion is important for network planning engineers to facilitate theextension of the maximum penetration limit. The results show thatdepending on the location, type, and size of the installed DGs, smallamounts of DG may cause overvoltage problems. However, largeamounts of DG may not cause anyvoltage problems when Terms distributed generation (DG), low- voltage sec-ondary networks, maximum penetration of DG, voltage INTRODUCTIONDISTRIBUTED generation (DG) is becoming an increas-ingly viable option for the future of POWER systems. De-spite its higher price, the installation of DGs in distribution sys-tems offers advantages over the traditional unidirectionalflowof POWER from a distant generator.

4 For example, DG reduces theload that needs to be supplied from the substation. Although notgeneralized today, DG could be used to control voltage [1] [5]or dampen POWER oscillations [6]. There are, however, severalManuscript received October 03, 2011; revised April 09, 2012 and June 04,2012; accepted July 16, 2012. Date of publication September 10, 2012; dateof current version September 19, 2012. This work has been supported in partby the National Science Foundation Grant DMS-0906659 and in part by theConsolidated Edison Company of New York. Paper no. Chen, R. Salcedo, Q.

5 Zhu, F. de Leon, D. Czarkowski, Jiang, , and Z. Zabar are with the Electrical and Computer Engineering Depart-ment of Polytechnic Institute of New York University, Brooklyn, NY 11201 USA (e-mail: Uosef is with Consolidated Edison Inc., New York, NY 10003 USA(e-mail: versions of one or more of thefigures in this paper are available onlineat that DG pose to the safe and reliable operation of adistribution system [7] [15].A comprehensive literature review revealed that there are nosystematic studies reporting the effects of DG penetration inmeshed low- voltage (LV) secondary networks.))

6 There are, how-ever, a considerable number of research papers reporting theadvantages and disadvantages of DG for radial distribution sys-tems; see, for example, [16] [23]. The operation strategies of ra-dial and networked systems arequite different from each example, radial systems allow for bidirectional loadflow,but may require a different coordination of protection. How-ever, in secondary networks, reverse POWER from the LV net-work to the medium- voltage (MV) feeders is not possible. Forsafety reasons, all network transformers include network protec-tors that trip when reverse POWER is sensed.

7 The requirement forthe unidirectional active powerflow in the secondary networksimposes additional constraints that are not present in radial sys-tems and paper presents thefirst attempt to quantify the possiblenegative impacts on the voltage profile of different penetrationlevels of DG in secondary networked distribution systems. Thestudyisintendedtoelucidate what will happen if customers areallowed to freely install DGs on their premises and DGs becomewidespread. In our analysis, we focus on the situation when themaximum DG output coincides with light (minimum) load con-ditions.

8 This case is recognized inthe literature as the worst-casescenario [24], [25]. To simulate possible future scenarios, wehave probabilistically allocated DG in increments of 10% ofthe light load. The study is carried out using a very detailedrepresentation of the system components. Hundreds of time-do-main simulations with the Electromagnetic Transients Program(EMTP) are performed to determine if a given allocation of DGswould produce voltage profile have found (Section IV) that even with very small DGpenetration, there may be unacceptably low or high voltages atcertain loads when DG units are installed at the wrong , very large amounts of DG POWER (up to 100% of lightload) installed with the adequate strategy allow acceptable op-erating conditions.

9 Under the present operating strategy of sec-ondary networks, no POWER can be exported from the networkto the DG technologies, such as solar photovoltaic (PV)or wind conversion systems, could also affect secondary voltage0885-8977/$ 2012 IEEECHENet al.: ANALYSIS OF voltage PROFILE PROBLEMS DUE TO THE PENETRATION OF DG2021 Fig. 1. Schematic of an LV secondary network. Loads and network trans-formers are tied together in a highly meshed due toflicker. In addition, intermittent DG technologiesfrequently require optimal-management strategies to maximizepower delivery since the maximum POWER output mayfluctuate[26].

10 However, this topic is beyond the scope of afirst study onthe effects of DG penetration insecondary networks. The issuesrelated to intermittent DG are to be studied in future SECONDARYNETWORKUNDERSTUDYA. Description of LV Secondary NetworksAn LV secondary network is a distribution system configu-ration typical of the downtown cores of most cities in NorthAmerica. An area substation commonly supplies POWER to two(or more) independent underground networks through a numberof MV radial feeders. Each feeder delivers POWER through sev-eral tens of network transformers that reduce the voltage to theutilization level (say208/120 V).